Joe Ballantyne Fusor v1.

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JoeBallantyne
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Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So after ~15 years since I first starting lurking on the site, ~10 years of being a registered user that posted very infrequently, 3+ years of attending HEAS gatherings, and 1+ years of being retired, I am FINALLY actually building my first fusor.

I am going to document the progress in this thread.

My plan is to start as small and simple as I can. Complexity and increased size will no doubt follow. Just like every other fusion project on the planet. :-)

Feedback and suggestions are always welcome.

It is fun to finally be building something.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So here are some pictures of the chamber and cathode. Since the goal is to keep it as simple as possible, and get it running as quickly as possible, everything is off the shelf standard stuff, or repurposed items that can be easily acquired from Ebay, Amazon or Home Depot. The less custom construction required the better.

The chamber is built from 2 KF50 tees, 1 KF50 KF16 tee, 1 KF16 4 way cross, 1 KF50 butterfly valve, 1 KF50 viewport, 1 KF50 blank, 1 KF50 KF40 conical adapter, and 1 KF40 30kV feedthrough acquired from Joe Gayo, with of course the appropriate KF centering rings and clamps to plug it all together.

IMG_20220226_193546360.jpg
IMG_20220226_194332848.jpg

The cathode is just a 1.2 inch diameter stainless steel wire shaker ball bought from Amazon. (1 of a set of 6 (3 large, and 3 small) that cost ~$7) The cathode is connected to the feedthrough using a piece of 2mm stainless rod "drive shaft" and 3mm "drive shaft couplers" also purchased on Amazon. VERY high tech! NOT! :-) I don't expect it will work particularly well, but the goal for this iteration is not Q>1, it is first plasma, and then neutrons. If the Q ends up being 1e-10, so be it. Custom cathodes and Q improvements will come later.

IMG_20220226_180552680.jpg
IMG_20220226_193912256.jpg
Next I plan to get the vacuum pump system running and connected, followed by the high voltage supply setup. The last thing will be to get the deuterium gas supply system built and connected.

Joe.
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Dennis P Brown
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Re: Joe Ballantyne Fusor v1.

Post by Dennis P Brown »

Glad you are making a run. So far, a very nice start - through not a traditional chamber; certainly the vacuum system will require a bit of work - from a pump, then the high vac system/valves, and gauges. But the last items should be your neutron detection system. Of course, safety features added all during construction phases as needed are important.
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Re: Joe Ballantyne Fusor v1.

Post by Paul_Schatzkin »

Well, this is certainly exciting news, Joe.

And the photos are beautiful. It's gonna be quite a rig.

I'm glad we're getting things settled here so that (knock wood) those picture will be assured their posterity .

And congrats on the retirement. I find myself in a similar condition at the moment. I won't be building a fusor, but Iv'e got some stories to tell...

--PS
Paul Schatzkin, aka "The Perfesser" – Founder and Host of Fusor.net
Author of The Boy Who Invented Television - http://farnovision.com/book.html
"Fusion is not 20 years in the future; it is 50 years in the past and we missed it."
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Joe, I am glad you have leaped into the construction phase of your journey here. You are the beneficiary of years of fits and starts by many who have come before. You will surely enjoy the journey at all stages. You are wise to keep it simple with real vacuum components as this usually leads to less pain for the wallet and a much more likely successful effort.

I look forward to future reports and images of your progress.

Again I wish you well and all the best in your efforts.

Richard Hull
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Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Thanks Dennis, Paul and Richard for your kind words.

I'm currently working on getting a roughing pump up and running and connected to a vacuum gauge. I have 3 pumps I am working with right now, and unfortunately none of them are in a state where I can connect them to a vacuum gauge or any of my other vacuum hardware.

I have a Welch 1405 that is running, but I have no idea what kind of vacuum it pulls. I'm waiting on a KF40 to 20mm hose barb so I can connect the pump to the rest of the vacuum equipment I have. It has a hose barb on it, but I have no KFxx hose barbs at all at the moment. I have some I ordered already on ebay, but they may take a while to show up. I flushed the oil out of this Welch, and it at least runs OK.

I have an Edwards E2M8 I am also working on, but it is a 220V pump, and looks like it has a British motor in it, that wants to be run from 3 wires, one ground (yellow and green wire), one neutral (blue), and one hot (brown) that should be 220V RMS relative to ground and neutral. Of course I can't find any definitive documentation from Edwards that says whether it is OK to connect blue and brown to the pair of hot 240V lines I have access to in my house. (Hot water heater, dryer and stove all have 2 wire 240V connections.) Problem is that each of those wires is only 120V RMS relative to neutral and ground. When I did just that and plugged the pump into the dryer connection, I got NADA. No pop, no boom, no flash, no sparks, and no movement. Not even a sound. Not even a hum.

So, I then unplugged it, took off the side panel and tried manually moving the pump in the direction shown on the top. I could move it, but it would periodically get hard stuck. The oil inside was very dirty. So I manually rotated the pump for a few minutes, poured new vacuum pump oil in the intake as I did so, and then after a while, I drained the old oil which took a while because it was very dirty and thick. Put in new oil, and continued manually turning the pump over, about an 8th of a turn at a time or less. Eventually I got it to the point that it was no longer getting hard stuck as I turned it. (When It got stuck, I would back it up and then go forward again, and doing that would get it unstuck.)

So, now that it appears the pump is no longer getting stuck, I have to figure out what the proper way to wire a British 220V motor into 2 wire US 240V circuit is. I suspect I may be stuck having to using a transformer, so that I can make the hot line 220V relative to neutral and ground. It would be really nice if there was any documentation from Edwards that just told you what the right thing to do was, but I haven't been able to find it.

The last pump I am working with is an Ulvac 200V pump from a Joel electron microscope. It only has two wires as input, and given that it says 200V, not even 220V, I am reluctant to do anything with it until I can get it connected to a variac and run it at its nominal voltage. 240V vs 200V is just a little too much off, for comfort. Plus I don't really fancy connecting 2 hot 240V wires to a motor and nothing else.

So later today (its already very early Saturday morning for me) I will go try to dig up a transformer or two, and see if I can get any of these foreign single phase high voltage pumps to actually turn over. Why the whole world can't share the same electrical standards, I don't understand. (Well I actually do - its all about money and control and not invented here mentality, but those are all STUPID reasons IMO, for not just biting the bullet and standardizing across the board.) But once you have lots of incompatible expensive infrastructure built up, its not going to change. Oh well.

Hopefully later today I can get the Edwards spinning over, because that has a KF25 vacuum connector on it, so I could then get it connected to other hardware and see what vacuum it pulls, pull down my chamber, etc.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Dennis P Brown »

I would suggest you wait to test your normal voltage Welch pump since they are good vacuum pumps. Also, such a pump should be the easiest to deal with since a repair kit should be available if it does have issues.

I do not think American 220 v (three phase) can be used for a 230 v (single phase) device (as you discovered - it will not turnover.) As you mentioned, a step up transformer is required - one that can handle the current load. Before running a pump that is 'sticking' I would suggest you dissemble it and make sure surfaces are fairly clean - this assumes you have ruled out the Welch pump. That is the safest method to clean a pump for service. Of course, it is possible to destroy gaskets so that does carry risks but if one is careful it isn't too difficult.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

I can't imagine a ground wire path on the Edwards making any contact with any part of the motor windings. If it does that is not good. I have a 220 volt Edwards here in my lab and it works on a normal U.S. 220 volt outlet just fine. (I have several 220 outlets in my lab.) I have had it in plain view for sale at the last 3 HEAS conferences. It pulls to about 10 microns. However, no takers due to the 220 volt requirement.

Have you ohm checked the ground wire to the other motor leads? It should read open if it is a normal 220 volt motor. You should only read short from it to the motor's metal body.

You might check for continuity between the other two wires. You should read some low ohm reading. If not then you may have a stuck open or dirty centrifugal switch on the internal rotor or an open start winding.

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Re: Joe Ballantyne Fusor v1.

Post by John Futter »

Your pump will be fine on 240 volts two phase as used in the states
We use these pumps @ work and our power is a bit over volts due to the substation being 15 yards away from our lab so we get 240 instead of 230 anyway.
your pump being stuck is a sign of the sliding vanes NOT sliding ie gummed up hope fully you have not bent them they are made out of a phenolic type stuff.
rebuild kits are available for these pumps includes all gaskets and new vanes if you get the right kit
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

You need to get the motor running regardless of vanes. The 240 stock 2 lead and ground is the right connection and is what you need. Not turning? .... Motor problem.

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Re: Joe Ballantyne Fusor v1.

Post by Dennis P Brown »

The motor, as long as the case floats relative to the ground side of the motor coil's "grounding side" wire, then I guess two of the hot phases of the 220 would drive it. Is that how your pump works off the 220? Might be good to give some guidance on the wiring configuration for the 220 plug and clarify the grounding issues, maybe. I have not done this so am mostly in the dark on this issue.

If the Welch pump works, why not wait to test that and if it is good, that would be an excellent pump.
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Re: Joe Ballantyne Fusor v1.

Post by Rex Allers »

On the vacuum pumps. The old Welch pumps are great and take a lot of abuse before they become much below their specs.

I have a 1402 and it gets, at the input, around 3 micron. Your 1405 is smaller but may still be good in a fusor application.

I just made a post about converting the hose input on my 1402 to a KF-25. I suspect the input on your 1405 is the same part. Doing this mod requires access to a metal lathe and some courage.

FWIW, here's the link to my post.
Convert Welch Duo-Seal Hose Nipple to KF-25
viewtopic.php?p=94728#p94728
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So, in some ways I made lots of progress today, but still failed at what I really wanted to get done, which was to get my chamber pumped down to a few microns.

I figured out why I got NADA on the Edwards E2M8 pump, it was because the 240V 2 wire circuit breaker in my panel going to the dryer was bad. I switched to a gas dryer about 20 years ago, and never used the dryer circuit, so didn't know the breaker was bad. I had another 30A 240 breaker in the panel for a water heater, which had also been switched to gas even before I bought the house, so I swapped the unused water heater breaker for the bad dryer breaker, and bingo, the E2M8 spun right up. Unfortunately the motor was squealing, so ran some oil down one of the 300mm long 2mm diameter stainless "drive shafts" I bought for connecting cathodes to feedthroughs to the actual motor drive shaft next to the bearing on front and back, let it sit for a little bit, turned it back on and the motor squealing cleared up.

So then I swapped the blank off on the inlet port for a Varian 531 Thermocouple connected to a Varian 801 display, turned the pump back on, and was immediately disappointed. Pump pulled down to about 200 microns, and then just sat there. Now granted I haven't run it for several hours and then rechanged the oil, but given the amount of exhaust coming out the exhaust port, even when the gas ballast is fully off, I suspect it may have a leaky seal around the drive shaft. I suppose I could let it run for a few hours, come up to temperature, and see if it performs better. But 200 microns right off the bat seems pretty bad.

Turns out I found another Edwards E2M18 that actually had a US motor on it, setup for 115, so I tried that one, it also appears not to pump below 200 microns, and although the motor runs fine for a few minutes it eventually gets a chatter in it, and oiling the shaft does not appear to resolve the issue. (If it isn't already obvious, 15+ years of collecting vacuum and other fusor related equipment, means I actually have quite a lot of stuff.) None of which appears to work very well. :-)

I also tracked down a large Superior Electric 240V-280V 40A variac that appears to be configured for 120V in, and 0-140V out, as well as a 120/240 500KVA transformer, but the 120/240 transformer didn't have enough oomph to get the Joel pump to turn over. I got a hum, but no motor turning. I suppose I could just directly wire the Joel to my 240, but I really don't want to ruin it, by running it over voltage. It is spec'ed for 200V. I probably need at least a 1200KVA 120/240 transformer, but I don't have one.

As far as the Welch 1405 goes, I have ordered a KF40 hose barb that should let me get connected to it, as well as a rather pricey KF25 adapter made specifically for Welch pumps with a 3/4" 20 thread, which this pump supposedly has - and is what the 7/8 hose connector on the pump is screwed into. (Per the old 1970's Welch pump manual which you can find online as a pdf.) So, when one or the other of those items arrives, I can then figure out whether that pump's vacuum sucks too. (ie: sucks, as in doesn't actually suck... just like the 2 Edwards pumps.) I'm hopeful that it will be better, but so far my experience has been that surplus pumps, were surplussed for a reason...

It is conceivable that my 531 TC, or the 801 display are off as well. I have a second set of both, so will see if they agree with each other on the Edwards pumps that I can measure vacuum on.

I really don't want to spend a lot of time doing a pump or motor teardown/rebuild. So until I have exhausted my full inventory of pumps, I will keep just trying to find a pump I already own that works reasonably well. I would be happy if I can find one that gets me down to 2-5 microns.

We'll see.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Rex, thanks for the pointer to the mod for the 1405 hose barb input. Unfortunately I do not own a lathe, nor do I currently have access to one, so that is not an option for me. You can buy a KF25 adapter that should just screw right into the 3/4" 20 tapped hole for about ~$80 on ebay, so that is what I did. It hasn't arrived yet. When it does, I will report on how well it works or not.

Joe.
Last edited by JoeBallantyne on Sun Mar 06, 2022 5:49 am, edited 2 times in total.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

John Futter, do you think that just connecting the Joel pump directly to the 2 wire 240V I have in my house would be OK, or is 200V too far off to be worth the risk. The Edwards did work fine, but it was a 220V motor running at 240. The Joel pump looks like it is in pretty decent condition, so I really don't want to ruin it. Since if I can get it working at its nominal voltage, and it pulls a good vacuum (<3 microns) I will just use it.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Dennis, the plug in my laundry room for the dryer is an old style US 230-240V 30A plug. On each side of the top of the plug it has two slots for slanted wide, thick prongs, and on the bottom in the center a hole for a prong that looks like the left and bottom side of a square. The prong itself is bent 90 degrees.

The bottom prong is neutral, the top two prongs are each 120V RMS, but 180 degrees out of phase, so that the voltage difference between the two wires is 240V RMS. Evidently the 240V wires typically come off a center tapped pole pig transformer, where the center tap is neutral and is grounded.

The old style plug I have has no 4th prong for the earth ground wire, just the single neutral connection. New 240V plugs all have 4 connectors in them so you can have an earth ground in addition to neutral and the hot line1 line2 wires.

Turns out the Edwards E2M8 runs just fine connecting blue wire to one of the 2 hot 240 wires, and the brown wire to the other of the hot 240 wires.

Per Richards suggestion I tried measuring the impedance from the blue and brown wires to the case, and it was an open circuit. No connection between the wires driving the motor and the case.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Info for newbies monkeying with home electrical systems.

Ground is neutral at the breaker box that feeds the home. The other two wires coming in from the power company are 120 volt lines referenced to ground/neutral at the box. A second demanded driven ground at the house also goes to the breaker box. Just remember that neutral wires in all homes is are at ground potential back at the breaker box where it's case is also ground. All of this is modern by comparison to the old two wire systems where neutral was often looked at as ground. Ground was run separately not long after WWII for safety going to all metal bodied tools and appliances.

In general all 240 volt appliances, motors, etc., never reference internally to ground or neutral. The grounded metal case of 240 volt items protect against either of the 120 volt hot lines from energizing the case.

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Re: Joe Ballantyne Fusor v1.

Post by John Futter »

Joe
I weould try the 200 volt pump on 240
if it gets hotter than you can touch after some time running ie half an hour thewn you will have to get a 240 volt to 40 transformer and connect it in buck in series with the input in your case 2 x 20 volt windings would balance the load to your local transformer but that is not necessary unless you have a 20 0 20volt 5 amp transformer lying around
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

An update on the current state, plus a few pictures.

I decided that I would run the Edwards E2M8 pump for several hours today. As prep, to make absolutely sure it would be OK, I oiled the motor bearings again, as well as the bearing in the center plate of the pump, and where the drive shaft enters the pump body. I used clean vacuum pump oil, as it is high quality non detergent oil, and by definition has a very low vapor pressure. I then powered it up, and pretty much let it run all day long. It is still running as I write this. The motor eventually got quite warm, but not to hot to touch, and the pump was quite a bit cooler than the motor, but also warm. The motor bearings were much cooler than the outer cylindrical shell of the motor housing.

Since I had another Varian 531 thermocouple, as well as another Varian 801 gauge, I put a KF16 cross on the pump, and connected both of the 531 TCs and 801 gauges to the pump. To my surprise I got VERY different readings from the second TC. Instead of reading ~200 microns, it showed the pressure at closer to 40 microns. I then switched which TC was connected to which gauge, and the readings on each gauge stayed pretty much the same. The gauge that had read 200 now read about 205 microns, and the gauge that had read 40 now read 35 microns. That was great news, as it means that the TCs themselves are in pretty close agreement. One reads about 5 microns higher than the other. Neither of the 801 gauges has been calibrated, or zeroed, since that requires that I get the pressure on the TC down to less than a micron, which I currently can't do. Clearly one of the gauges is off quite a lot. Which one I can't determine yet.

However, I'm feeling better about the pump, as I am hopeful that the lower reading is closer to the actual true pressure, than the higher one. I do have a capacitance manometer, that I may attempt to get up and running, if I can find or acquire the appropriate cable. I can use that to determine which of the TC readings is closer to the proper pressure (most likely they are both off at least slightly), but I am hopeful that the higher reading gauge will prove to be off by a lot.

Next I added a connection from my vacuum chamber to the Edwards pump and pumped down my chamber for the first time. It went down to about 50 microns per the lower reading gauge, pretty quickly. After an hour or so of pumping, it went down to the 35 micron to 40 micron range.

I valved off the pump to see if I had a leak, and the pressure in the chamber with the pump valved off was pretty stable. It rose about 10 microns or so in a minute. So not perfect, but I haven't done any glow cleaning yet, and the parts were not cleaned with solvent before I assembled them, so I am sure there is outgassing going on in the chamber. I did not make any effort to not leave fingerprints on or inside the chamber, hence my fingerprints are pretty much all over it, And I'm sure there is oil from my hands on some of the flanges and centering rings as well. In addition I live in the Seattle area, and so there is a lot of moisture in the air, and I am sure there is a lot of adsorbed water vapor all over every inch of the inside of that chamber.

I was happy with the fact that there were no major leaks. KF fittings really do work very well. They are easy to use and assemble, and they do the job. Plus you can reuse the centering rings as much as you please. Unlike copper conflat seals.

Here are some pictures of the chamber, TC gauges and vacuum pump setup. Note that the only useable 240V outlet I have in my house is in the laundry room, and I need to plug the pump into that. So you can probably surmise what is underneath the tablecloth. :-)

Here is the Edwards E2M8

IMG_20220306_205735553.jpg

Here is the whole current setup

IMG_20220306_205649634.jpg

Here are closeups of the TC gauges showing the disparate readings. The first shot was just before closing off the vacuum pump from the chamber, the second shot is two minutes later after the pressure has risen, and the last shot is a few seconds after reopening the valve when the chamber has pumped down again.

IMG_20220306_205944676.jpg
IMG_20220306_210201375.jpg
IMG_20220306_210225117.jpg

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Give the TC gauges an even break! Wash out each tube with a solvent like MEK/Acetone. Rinse two or three times sloshing the filled tube around.
This should warrant there is little filth and old oil on the thermo couplet junction.

Next, you know that zeroing is a must. You are off to a good start is you measure the current draw to the heater it has a fixed value to start with and this is in the manufacturers spec sheet. These are 531 tubes. In the vacuum post in the FAQs, I give a table for design currents for many TC gauge tubes. A good tube, when zero'd will be very close to this current value.

viewtopic.php?t=14378

I note that the 531 is a filthy current hog compared to most other TC gauge tubes needing 163-165ma of heater current. If you can, put an ammeter in series with the heater. Take the gauge tube as low in vacuum as you can and use the zero pot (current control) to set the meter to this rated current and you should be close to the real reading, assuming the tubes are good and clean. Cleaning the tubes may solve all issues by itself.

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Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Richard -

I'm pretty sure that the meter on the right in the pictures is just bad. It won't go much under 200 microns period. I had a couple supposedly brand new old stock 531 tubes I bought on ebay, and they each came in a little Varian box, and swapping one of those tubes in doesn't make almost any change to the readings on either gauge/meter. I'm not real keen on rinsing the tubes out with Acetone, especially not the "brand new" ones. If the tubes I was using looked trashed/dirty I would try rinsing them out in a heartbeat. These don't look like they need a rinse. Granted, one can't really tell, and they could have oil or other contaminants up in the TC, but I want to try a few other things to figure out the pressure (like using a capacitance manometer) before I do any rinsing.

One of the reasons I think that meter on the right in the pictures is bad, is because after leaving the chamber valved off from the pump, but still under vacuum last night (Sunday 3/6/2022), this morning the gauge on the left was reading about 500 microns pressure, and the gauge on the right was above the ATM mark. But I then opened up the chamber, and it was definitely still under vacuum, as there was the normal hiss of air going in, and the left hand gauge rose up to dead center of the ATM mark on the gauge. The gauge on the right almost didn't move at all.

So while I still have no idea if the pressure reported by the LH gauge is actually correct - since I don't know if I have a good enough vacuum to zero it, I'm pretty confident it is working much better than the gauge on the right.

I will at some point get a vacuum setup that pulls submicron, and at that point I will zero the TC gauges.

Joe.
Last edited by JoeBallantyne on Tue Mar 08, 2022 6:48 am, edited 1 time in total.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So, today, Monday 3/7/2022 was a productive day fusor wise, and I got first light of plasma! That was a very satisfying sight.

Pictures of that will come in a later post, but lets start at the beginning...

I received some of the things I ordered on ebay recently. One was a couple of sets of rubber stopper sets of sizes 00 up to 8. One set with holes and one without any holes. I got them because I read, I think in the Welch pump documentation, that one way to quickly measure the pressure on a pump was to use a rubber stopper with a hole in it, and screw the TC gauge into the top of the hole. Then stop the intake of the pump with the stopper, and run the pump and measure the pressure.

So, I tried that with the Welch pump, and the technique seemed to work just fine. That pump doesn't pull down nearly as fast as the Edwards E2M8, but then it is a lower capacity pump. After a few minutes of pumping it got down to about 40 microns, and some time after that it got down down to 30 microns as measured on the TC gauge that was on the LHS of the fusor system pictures. (The TC gauge I have that appears to not be busted.)

So, the Welch 1405 pump works, but it doesn't pull a significantly better vacuum than the Edwards E2M8. I have seen the Edwards pull the chamber down to about 20 microns after the chamber sat all night long under vacuum, and on first pump down after it sat, it got down to 20, and then the pressure in the fusor slowly rose again to about 40 microns.

A picture of the welch and its initial vacuum measurement:

IMG_20220307_150813508.jpg

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

One of the other ebay purchases that showed up today, was the special KF16 Welch 1405 intake that I ordered. I was going to swap it on first thing, but the hose barb on the Welch is on REALLY REALLY tight, and I thought, well, I will measure the pressure first with the rubber stopper method, and then if it looks good, I will swap the intake, and remeasure the pressure using the new KF16 part.

However, since the pressure was not much better than my other pump, and since I know I have a brand new Welch pump (no motor, just the pump head) of some unknown model, I thought I would wait to use this fancy little KF intake, in case it will fit on the other pump head. I don't recall at the moment what kind if intake if any is on the new pump, and I don't know the model, but it looks like about 10"x"12"x12", so it might be a 1402 like Rex has. Not sure.

In any case, for now the Welch 1405 is going to stay as is, with its hose barb, and I will probably end up using it as a backing pump with either a diffusion pump or a turbo in front of it.

I was very pleased with the KF16 intake part. It looks very nice, and came with 2 extra gaskets.

Here is a picture, that includes info on the seller, who appears to also be on Amazon, as the package arrived with an Amazon receipt and in an Amazon package, even though I ordered it on Ebay!

IMG_20220307_184416696.jpg

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Now for the good stuff...

I spend a good part of the day (Monday 3/7/2022) setting up a simple, pretty inexpensive, medium voltage power supply on the fusor. I had previously verified that the key parts of it were capable of outputing the claimed voltage.

The first piece of the supply is a Universal Voltronics BPE 22-5.5 DC power block capable of putting out 22kv at 5.5ma. Not that high a voltage, and definitely not too much current. But at 121 Watts it should be able to at least light up a plasma at lower than its rated voltage, and I am hopeful that with my Neutron detection hardware, I will be able to even measure neutrons. We shall see. This power block was purchased on Ebay for about $150.

The block is connected to a clearly vintage 7.5KVA variac that was likely purchased from UW Surplus as part of a large lot of variacs and other assorted stuff. The variac will put out 0 - 140V on the secondary when driven with stock 120V on the primary.

I verified that I could get out the rated voltage from the BPE using a couple Pomona HV DC probes. One that goes up to 15KV, and another that goes to 35KV. The Pomona probes only measure positive voltage so I can't use them in the fusor configuration because the HV lead that needs measuring is at a negative potential. The nice thing about the Voltronics supply is that it has 2 HV leads coming out of it one positive and one negative so you can configure it to be either a positive or negative supply by just grounding the opposite polarity lead. These power blocks are used as a component in stand alone power supplies built by Universal Voltronics that have meters, and a variac, output polarity switching, etc.

The Voltronics has 8 solderable pins in a circle on the side opposite the HV leads, and I could not find documentation on the pinout. I am sure that you can change how the supply operates by varying what you connect to those pins. Fortunately the supply I bought was prewired, and appears it was wired so that it puts out its full rated specs on 120V in. The wiring it came with also had a fuse block in the 120V supply line.

After getting everything setup on the fusor, I set the variac to about 20 on its dial - which corresponds to about 20V RMS AC input on the BPE, which should make it put out about 3.5kv. I switched it on, and BINGO, plasma immediately lit up in the fusor. I was surprised, but very happy.

Interestingly the plasma would pulsate on and off, and after little while it extinguished, and I had to raise the voltage up to 25 on the variac to get it to light off again. Eventually I had to raise the variac up to 40 to get the plasma to light off, 40 should correspond to about 7.3kv (1/3 of the output as 40V RMS is 1/3 of 120V.) At that voltage I could switch the variac output on and off, and the plasma would just go on and off with it. It was very cool.

Now for the requisite eye candy...

The Univeral Voltronics BPE 22-5.5 attached to the fusor.

IMG_20220307_172039804.jpg

The very vintage variac, with (I know) a cracked outer sheath on the input power line. Note that I measured with a multimeter to be absolutely sure which of the plug prongs on the output plug was neutral and which was hot, and they are labeled N and H with a sharpie on the variac body itself. In addition, I marked N and Hot on the plug of the white cord so there would be no mistake about how it should be plugged in. Granted, it would be better to use a 3 prong power cord plugged into the variac. Which will happen in a future iteration.

IMG_20220307_172103764.jpg

The whole system with plasma lit up inside the fusor.

IMG_20220307_171929577.jpg

Finally a close up of the plasma. The picture doesn't do it justice, as when you look at it with your eye, the bright plasma center is much smaller than what shows up in the picture. What you see with your eye is a little dot about 1/8th of an inch in diameter in the exact center of the wire circle. It does NOT fill up the entire center like the picture shows. What the eye sees is much cooler.

IMG_20220307_171214260.jpg

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Dennis P Brown »

A few words - first, nice start. You're advancing. Second, be aware that micron gauges (as I've had experience with) can be a bit off. As such, your pumps could be doing better then you think. In any case, both will work with a turbo or diffusion pump even if those values are precise. I could ask about pump oil and condition but seriously, not critical if you are below 50 microns (though those pumps should get to under 5 microns no problem.)

You should aim to measure your fusor's voltage, current, and vacuum and submit for the plasma club. That is a good first step here and your basically there with only a minor bit more effort.

Do be aware that as vacuum improves the required voltage for a plasma to remain "lit" goes up so those results you are seeing follow.

In the pic of your plasma, you have two TC gauges (located on the same stem) and they are showing wildly different values - one in the 30's and the other in the 250's?

Finally, and as always, be careful with that supply because the voltage in those ranges are dangerous. Even for a 'mock' setup, a star ground system is essential.
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Re: Joe Ballantyne Fusor v1.

Post by Matt_Gibson »

You probably also want to add an oil mist filter to your pump before you get everything coated in oil :-).
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Have you adjusted the zero control on the supposedly defective meter? Someone could have monkeyed with that and the meter may be perfect! See if it will adjust downrange towards your other "good meter" reading under vacuum. The zero control is not electronic it is electrical and controls the tube current. If you see no movement or if it has no effect then your meter itself is bad.

You can easily take off the back of the meter and view the abysmally simple non- electronic circuit. See if one of the resistors is burned or discolored.
Most of the 531 meters of this type have a tiny little transformer, a couple of resistors and a pot and this is the entire circuit. The little transformer is the weak link in the meter.

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Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Well today Tuesday 3/8/2022, I had hoped to get my deuterium gas system setup, connected to the fusor, and to make a few neutrons.

It was a nice dream. But it didn't happen. :-)

I have a 100L bottle of D2 that I bought from Cambridge Isotope Labs back when a they sold it for ~$250 including the bottle. (I think it was about 2015.) When I checked with them before I retired in 2020, the price had gone up to almost $700, and part of that was they charged you explicitly and separately for the bottle. I had been hoping to buy 2-3 more bottles so I had a lifetime supply, but at that price, I just passed and didn't buy any.

Anyway, I did hook up a nice SS Matheson regulator that shows vacuum pressures (> 0 PSI) on the regulated side to my bottle, but I was stymied in my goal by the fact that this regulator had a Swagelok connector on the small on off valve on the low side of the regulator, but no nut for the swagelok. And of course no double ferrule. Which of course I don't have yet, because I knew nothing about Swagelok (other than that I had heard of it and had some notion of what the connectors looked like, and that they were typically SS) until today. I had what I thought was a brilliant idea to work around my lack of a correct connector for my fancy regulator, which was to just get some reinforced PVC tubing down at HD that would fit over the male threads of the Swagelok, and then clamp it down good and tight with an SS hose clamp.

What a fail.

I did implement my idea, but it completely destroyed my vacuum. Once I swapped in a KF16 that also had another Swagelok 1/4 male connector attached to the tubing the same way I attached the regulator, I couldn't pull the chamber lower than about 1000 microns, where it had been getting down easily to 20 microns or so. Turns out that getting a good vacuum may be easy with KF fittings that are designed to make it easy to get good vacuum, but it is really hard to do with hose clamps. ( I suppose I could try again, and this time wrap all the threads with a large amount of teflon tape, and see if that will resolve the problem. I may do that later today.) I am now again in waiting mode, for Swagelok 1/4 inch nuts and double ferrules to show up, so I can properly attach some D2 gas supply tubing to my system.

So I was very disappointed because I wanted D2 in my system so I could see if I detected any neutrons.

That will have to wait.

One good thing that came out of the failure, is that I was blocked from doing anything really fun (ie: make neutrons), so per Richards advice, I opened up the RHS TC gauge that has been reading high since day one, and found that there was a 1cm spot of rust on the back of the very simple circuit board. It is actually pretty astonishing how simple that gauge is. I like simple. I think the most elegant solutions to problems are the simplest ones. In any case, I cleaned off the rust using a slightly damp paper towel, and then some gentle scratching with a sharp knife tip, put the gauge back together, plugged it in, turned it on, and although it came down a little lower it got stuck.

So, just for good measure, and since I was a little exasperated, I gave the gauge a few good firm taps on the top edge with my finger. The needle jumped around, and then tracked down lower and matched pretty closely with the other gauge! I think there may have been some dust or something else inside the gauge itself that was preventing the needle from travelling down range. Anyway the taps and the rust cleanoff seem to have fixed the second TC gauge, so that is good. Although I can't trust it exactly because I messed with both the mechanical zero, and the electrical zero, earlier, when I was trying to get it to function without taking it apart. So, it will definitely need to be properly rezeroed.

But it gives a reading that is pretty close to the other TC gauge. (It actually reads a little bit lower.)

Anyway, thanks Richard for the push to investigate a little further. It is nice to now have 2 pressure gauges in reasonable agreement.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

If anyone knows a supplier that might have Swagelok compatible nuts and double ferrules in stock in the Seattle area, I would very much appreciate a heads up. Since then I could just make a local drive, get the parts I need and get my D2 system up later today.

Thanks.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Paul_Schatzkin »

Joe, the narrative you're running here is going to be a very useful long-term resource. Richard, Frank, and others have offered similar step-by-steps of their projects, but having a current account like this puts another brick on top of those foundations, i.e. "this is what we've learned, this is how I'm applying that knowledge." That sort of recycle/refresh will be useful for newcomers.
JoeBallantyne wrote: Wed Mar 09, 2022 5:10 am I like simple. I think the most elegant solutions to problems are the simplest ones.
Hard to argue with that. It reminds me of something the Farnsworth family told me in one of our first meetings ca. 1975.

I was surprised to learn that NASA had used an updated version of the Image Dissector in the camera that was deployed on Apollo 11. I think it was Philo III who explained to me that that configuration was used because it "had everything it needed and nothing that it didn't need."

That seems like a good definition of 'simple and elegant' to me.

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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Joe, I have experience with that very metering system and it is why I pleaded with you to investigate. Simple is good and bad. (There is that @#^%*! double edged sword again). Most folks do not realize that 100% of all TC gauge systems have near zero components in them. I am going to add to the tube chart FAQ the simplified facts about manufactured TC gauge systems. I now supply that full expanded explanation at the URL below to go with the chart of TC gauge tubes.

viewtopic.php?p=94827#p94827

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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So I had a post I wrote last night - an update on yesterday's efforts - and it took me a couple of hours to write. I did a cut and paste to a backup notepad .txt file halfway through, so I wouldn't lose it. But forgot do do another backup of the post before I clicked submit. And because of either my TP-Link router, or Comcast, the post was lost, because for some reason I keep getting disconnected from sites repeatedly. So when I clicked submit, fusor.net kicked me to the "you must be logged in to post page" and AFAIK dumped my post completlely on the floor. Sometimes I can't get connected to mainline sites either because of DNS issues. Comast + TPLink in the Redmond WA area is certainly not a good combination.

I was so angry about losing an hour+ of work, that I punted. Still haven't summoned the will to rewrite the damn thing.

Coalman, does the server keep http POST requests that it rejects around anywhere. If so, and you can dig up a post submission from about 1am PST last night, I would certainly love to get my work back.

It is really pathetic that neither chrome nor edge nor any other web browser I know of, doesn't make a browsable backup of every web form you click submit on. Or are even just working on. It would save users so much frustration and anger, and wasted hours of life. The browser had all the data, but there is no easy way to get it back. Unfortunately I closed the tab, so there is now really no way of getting it back. I mean browsers have been around for basically 30 years now, and they STILL don't save work you are doing on forms on websites so that you can recover your entries if something goes wrong. LAME!

I guess now I have to be hard core about always writing every post in Word, so I don't risk losing it due to typing it directly in the site. Pretty sad how technology still SUCKS in so many ways.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Joe you are not alone. I tend to compose in word and save frequently. Over my 23 years here I have lost many posts by composing in this editor at fusor.net. If I choose to not go to word, some here might have noted that I hit submit before I am done and leave a little note..."still working on this".
I just keep submitting until I am done. There is no real fix other than composing in Word and saving as you go and then transfer the finished text.

If I write a "teaching paper", of some length, I do it in word and save it as a PDF. I then do a 3 line intro in a post in the forums to tell what the attached PDF is all about.

I hope you finish your build on your post and share your thoughts with us.

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Re: Joe Ballantyne Fusor v1.

Post by Paul_Schatzkin »

Cue Billy Crystal: "I hate it when that happens!"

I couldn't quite follow you off the cliff their Joe. It sounds like you had the right idea when you started copying to a .txt file. What I don't quite follow is: once the post got past a few sentences and you were pasting into a different window (the .txt file) why didn't you just stay in that window until you finished the post. Does Winders Text Editor auto save or is it still you-have-to-remember-to-save? (all the numerous text-editing applications I run on a Mac auto save by default).

Anyway, my usual MO is, once I get into the second or third paragraph I jump to a text editor, finish there, then paste back into the post window. And if it's a short one like this, I'll select/copy to the buffer before I hit 'submit.'

Sorry for the lost effort. Damn, Billy Crystal again.

--P
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So I'm going to resurrect this thread and continue posting about my efforts. (Yeah, I REALLY hate losing work to stupid computer glitches. 5+ months is a long time to cool off.) I have a half written post about where I was, which I will complete and then I will make a few posts about different areas of effort, as the day by day, blow by blow account is no longer possible as too much time has gone by, and although I can remember the highlights and the take aways from the work, I cannot recall the exact timelines.

I have a couple of large (1x24 inch) He3 tubes I bought from Richard Hull at HEAS a few years back, and have been looking into building a moderator for them. I found what I think is really quite a good deal on HDPE on Amazon. It is $129 plus whatever sales tax is in your jurisdiction for 3 25x450x600mm slabs of HDPE sold as cutting boards. That works out to approximately 1x17.7x23.6 inch slabs, or rounded off, 1x18x24 which of course is what they are marketed as being. The metric dimensions are actual however, so you don't get the full 18x24 inches. This was MUCH cheaper than the equivalent from TAPPlastics which wanted $284 plus $78 shipping for 3 1x18x24 inch HDPE cutting boards.

Of course I'm assuming if you use Amazon you have Prime, and so the shipping is free. (It was free for me here in Redmond, WA. YMMV. The item is NOT a Prime item, but shipping was free anyway.) There are currently 19 of these left in stock.

I figure I can make 2 5x5x24 inch moderators for my He3 tubes with that plastic. It is about 50lbs of HDPE. The HDPE is natural - not dyed - and they are REALLY nice cutting boards... but pretty soon for me they will be in pieces.

Here is a link: https://www.amazon.com/Hakka-3-Board-Wh ... ast_sto_dp

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

I lost a lot of of file material I put up in the last terrible undesired backup purge this year. I found my original super moderator for the 1X24 tube pdf file missing in one of my FAQs for those interested here is my precise build.

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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Richard, thanks for the .pdf describing your moderator setup.

My plan is similar, but will have 4 1x5x24 inch pieces, and 2 1x2x24 inch pieces. That should use up one of the 18x24 slabs completely, and use a little more than 7 inches of the 18 inch width of the second slab.

So looking at the 5x5 inch end straight on, the He3 tube will go in the center where there is no X.

XXXXX (1x5)
XXXXX (1x5)
XX XX (1x2) (1x1 hole) (1x2)
XXXXX (1x5)
XXXXX (1x5)

That means there is a minimum distance of 2 inches of moderator which is 5.08cm A little less than the optimal 5.5cm for 2.5MeV neutrons, but should be OK. We shall see. I am going to build it and try it out. I will actually probably make each piece slightly bigger than 5 inches so that I get 3 equal sized large pieces ~5.1 inches and 1 smaller piece of ~2.05 inches from each of the first 2 18x24 slabs. The exact widths will depend on the kerf of the saw blade I use to cut the material. But the goal is to make 3 24 inch long cuts and end up with 4 pieces that are all exactly the right width.

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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

I am sure your design will perform flawlessly. Anywhere from 2.4 to 3-inches of total containment all around with HDPE will do a fine job.

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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So here follows the first half of the post that I lost back on the early morning (probably about 3AM or so) of March 10th. This is the part that was backed up in a notepad doc.

Today, Wednesday 3/9/2022, I got my deuterium system connected to the fusor, in a vacuum tight configuration. I of course immediately tried to see if I could get any neutrons out, but it was not to be, yet.

To make the deuterium delivery system vacuum tight, and get it done today, I ordered a couple of unions from Grainger online, drove over to Seattle, forked over the $50+ for 14 tiny pieces of 316 stainless steel (7 pieces per union). Swagelok uses a nut, and a double ferrule to clamp down on the circumference of the tubing as the nut is tighted on the male thread/seat, and make a high pressure seal which is normally stainless steel on stainless steel, and can support pressures into the thousands of PSI. Lots of manufacturers now make Swagelok compatible parts. The unions I got were A-LOK made by Parker, but they worked just fine with the Swagelok male connectors I had on my equipment.

I needed to be able easily move and form the tubing, and I only need this to be vacuum tight, so the highest pressure it will see is 14PSI or so. (1 atm) I therefore chose to use 1/4 copper tubing, acquired from HD (Home Depot) in a coil of 20 ft. The copper tubing was very malleable, so it was easy to unbend it from the coil, and make some big loops to get from the deuterium cylinder to the top of the KF16 cross that currently has the 2 TC tubes attached. I moved the TC tubes to the side, so that I could run the tubing to the top, since that minimized the amount of bending required, and also puts the least stress on the connection, as the weight of the tubing is coming straight down instead of hanging off to one side.

I had to cut the end off the tube as it came from HD, because it was dented, and I couldn't get the nut, or the ferrules over the end. The dent made it out of round, and there was no way the nut or ferrules would go on. So I cut an inch off the end using a copper pipe cutter (a must, because the tubing must stay perfectly circular). This is one of those things where you have a circular cutting wheel that you clamp down gently on the location you want to cut, then spin it once around the tube, tighten it a little, spin around the tube again, rinse and repeat until the tube or copper pipe is cut. You can't hope to cut the tubing with wire cutters or a hack saw, and think you will get the swagelock parts over the end. You won't.

After cutting the tubing, you put the nut, then the back ferrule, then the front ferrule on the tubing, insert the tube all the way into the male seat, slide the nut and ferrules up to the connector, and first hand tighten the nut, and then tighten it with a crescent wrench. Because I was using copper tubing with stainless (not ideal, it is better to use brass, but I just got stainless because that is typically these parts come in), and because I only needed this to be vacuum tight, I was VERY gentle when tightening with the wrench. Especially because I want to be able to reuse the connection if possible, and if I crunch it all the way on the first use, I won't be able to do that. I probably tightened the nut to 2-4 ft lbs. Maybe less. Again I just need vacuum tight not 5000 PSI. Plus I'm tightening into copper which is SOFT.

Once I got the Swagelok connectors attached, I gently worked the KF25 connector that was on the other end of the copper tube so it was sitting nice and square on the top of the KF16 cross + KF25 adapter, without exerting any sideways forces on the KF25 connector. This was easy to do because the copper tubing is soft. I then clamped the KF25 in place, and opened the butterfly valve on the pump, and the chamber and tubing pumped right down to ~35 microns. Just to check if things were tight, I closed the valve to the pump, and watched the TC gauges to see how fast the chamber would rise in pressure. Normally it rises about a micron or two a minute. It was a little faster than that, so I put a little bit more torque on each of the Swagelok connections. Repumped the chamber down, closed off the pump, and this time the vacuum stayed put at 35 microns like it normally does.

With the copper tubing supply line under vacuum, I also opened up the valve on the low side of the regulator, to pump out everything all the way up to the regulator. This regulator has a gauge that shows the vacuum level on that side of the gauge, and it was off course pegged at -30 inHG. The gauge is interesting in that it is graduated in PSI for pressures above 0, and in inches of mercury for vacuum. The regulator appears to also regulate into vacuum which is very nice.

I had previously fully closed (turned it CC until it was clearly not regulating and the handle would turn easily) the regulator so that it should not allow any gas through. Then I very carefully cracked open the valve on the cylinder just a bit - it actually took more turns than I thought it would to start to open up - and there was a little hiss, and the gauge on the high pressure side ramped up to 500psi, and held steady. I immediately shut the valve on the cylinder off again fully, since I have read on fusor.net from multiple folks, that just that charge on the regulator is enough to run things for a while. I realize now, that BEFORE doing that I should have also partially closed the regulator while the low side was under vacuum to also evacuate the other side of the regulator all the way to the valve of the tank. Then reclose the regulator, and crack open the main valve on the tank.
Unfortunately I did not do that, which means my charge of deuterium is on the high pressure side of the regulator is actually mixed with air. But its not that bad, because 1 atm is 14 psi, and I added 500 psi, so (500/500+14) = 97.27% of the gas on the high side is D2. Not too bad. But it would have been better if I had evacuated that side too.

At this point the chamber was being pumped, and was at ~30 microns as was the gas feed tube. I closed the low side regulator valve, tightened the regulator down until it just started to admit deuterium into the low side of the regulator, it got up to about -15 inHG, and stopped, I figured that was likely good enough. I then cracked open the low side regulator valve and watched the TC gauges on the chamber. They rose steadily all the way up to ATM - they don't have any resolution up there, it was probably more like what the regulator pressure was showing which was -15inHG or about 1/2 ATM. At this point I had basically filled the evacuated chamber with D2. I shut off the regulator ou

And there you have it - yes the backed up text in the notepad .txt file did cut off mid word for some reason.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Everything that follows is now what I can recall 5+ months later of what I did. I will do my best to recall things accurately, but it is not the same as when documented the night following the work. Some things I do have notes on, but much I do not, of necessity there will be significantly less detail.

What I did that evening was to fill the fusor with D2 gas up to the max pressure allowed by the regulator. Then closed off the D2 regulator output valve and opened up the vacuum butterfly valve to pump out the fusor. I repeated this probably 3 times or so. The intent being to flush the fusor chamber with D2 repeatedly, so that on the last fill, the D2 concentration would be maximized. After closing of the D2 valve, I brought the voltage up as high as I could to light off a plasma, and try to make neutrons. As I recall, I wasn't able to get the voltage up to the max of the power supply because the pressure in the chamber was too high - the lowest I could get it on my TC vacuum gauges at the time was what looked like about 35 microns or so on the gauge. If I raised the voltage too high, the current would spike, and the fuse on the input to the high voltage supply would blow.

So the next task was to improve my vacuum system so that I could get a lower pressure in the chamber so I could raise the voltage higher than 15kV or so.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Dennis P Brown »

The first step for any fusor is to get the chamber below 10^-3 and at least mid 10^-4 torr; of course, lower is better. Flushing a fusor at low pressure (10 of microns or higher) is not a very effective methodology. This does a very poor job of removing water vapor (a serious contaminate) and other contaminates.

Far better to get down to a few microns and add a little D2 and strike a plasma to attempt to clean the chamber; however, if their is small leakage, unlikely you will get a system clean enough for measurable fusion.

First, can your pump (no load) get to a few microns? If so, next the chamber must have little leakage (like a micron a minute - not out gassing; that will improve with cleaning.) After getting the chamber/system well sealed, then use a plasma of D2 to clean it. After that an attempt to obtain measurible fusion can be attempted.

Best if you can get in the low 10^-4 torr range.

I will warn you - lack of instrumentation (being blind to vacuum parameters) makes doing fusion extremely difficult. Not knowing your actual pressure readings is a serious problem that (if you haven't already) must be corrected. Of courser, reaching only 15 kV or so means your pressure is far too high for fusion; and flushing with hD2 won't fix that issue. Unable to get into the 10^-4 torr is not making your life any easier, either.
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

So one of the most awesome things about this site is how people share and help each other.

Last March when I was posting about my first efforts building a fusor, and the problems I was having accurately measuring vacuum, Bruce Meagher messaged me out of the blue, and offered to loan me an MKS901p with a KF16 connector to which he had attached a board he had assembled that was the design Finn Hammer had made for a digital display of the MKS901p pressure.

Of course, I immediately took him up on his offer, and a few days later I got a package in the mail with a beautiful MKS901p with the display board and power supply for running it.

Amazing! Everything I have done since with my fusor was possible because of the help Bruce offered me, and because Finn Hammer designed a great little board, and sent some of the bare boards to Bruce - who added all the components and got them working. Thank you Bruce, and Finn.

Comparing the MKS901p with the digital display to the Varian 531 TC and Varian 801 gauge, is like comparing a Ferrari with a Yugo. OK, they both may be able to move you from one spot to another, but MAN, the driving experience is NOT the same.

The other thing that was great about the MKS901 Bruce loaned me, was that he zeroed it for me before he sent it out, as he had a vacuum setup that allowed him to do so. So from mid March on, I finally had an accurate way to measure my vacuum pressure levels, and to better calibrate the 531 TC gauges I had. This allowed me to get my pumping system properly setup and to find and fix leaks in the fusor setup. I’m a little embarrassed to admit that I am still using his loaned digital display board with my own MKS901p as I have not yet finished building my own digital display setup although I have gotten most of the parts.

One of the great things about the 901p is that a digital readout of pressure that can go well under 1 micron is so much easier to read and use, than trying to squint at a Varian 801 gauge and decide which tiny narrow line, the tiny narrow needle is sitting on. When the single digit micron pressure lines on the gauge display are about half a millimeter apart, and shifting your head even a little from side to side gives you different readings from parallax. (Yes I know that is why good meters have a reflective bar behind the needle on them, so you can eliminate parallax by lining the needle up directly in front of its reflection. That is still a PITA compared to immediately reading a number off a very bright little screen.)

The MKS901p with a digital display is great. Thanks Bruce!

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Paul_Schatzkin »

JoeBallantyne wrote: Sun Jan 22, 2023 12:49 pm So one of the most awesome things about this site is how people share and help each other.
That is really cool to read, Joe. Heartwarming in a very real way. Like by setting all this up I've done something worthwhile after all (something my ex-wife would take issue with...).

While the world is focused on a (not really) net-gain reaction that lasted a billionth of a second, the people here are learning how to build and run sustainable fusion systems.

Yeah yeah, I know. Countless orders of magnitude from Q...

but,

still...

... this is a thing of unimaginable – and promising, goddammit – beauty.
.
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(Fusor 'star mode' photo by Brian McDermott)

I look forward to seeing yours when it happens, Joe. Send pictures!

--P
Paul Schatzkin, aka "The Perfesser" – Founder and Host of Fusor.net
Author of The Boy Who Invented Television - http://farnovision.com/book.html
"Fusion is not 20 years in the future; it is 50 years in the past and we missed it."
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Here are some pictures of the deuterium gas setup I was previously discussing. This is the state as it was back on March 9th 2022.

The nice Matheson SS regulator that regulates into vacuum. Note the high pressure side is charged with D2 at 500psi as discussed previously. It is really comforting to be able to keep the actual cylinder always valved off so the max possible lost D2 at any time is just the amount sitting in the tubing on the high pressure side of the regulator.

IMG_20220309_204932909.jpg

The D2 cylinder itself.

IMG_20220309_215511153.jpg

The D2 supply plumbed with Swagelok connectors and a 1/4 inch copper line to the fusor.

IMG_20220309_215846198.jpg

One thing to keep in mind when dealing with the CGA350 connectors that come on most D2 cylinders is that they use a LEFT HAND THREAD!
Critical to remember especially when you are first trying to unscrew the nice pretty cap that covers the 350 connector on the high pressure valve that ships with the cylinder. You must turn it CLOCKWISE to take it off. That bit me when I first tried unscrewing it. Fortunately after I first tried to get it off (by unscrewing normally - in the wrong direction) without using very much torque, I thought, this is brand new, it is just a cap, and it should be pretty easy to get off, maybe it is LHT, and indeed it was. Turning in the direction that would tighten normal connections (clockwise), it loosened immediately and came off. It is a very strange experience the first time you "tighten" something hoping it will indeed loosen instead.

I labeled the nut on the regulator to remind myself in the future if I ever need to swap in a new cylinder.

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

I had a 59 De Soto and took it to a June car show some years ago. I had one of my lady friends along for the ride. It blew a tire on I-64. Now, like any guy, I know to merely loosen all the lug nuts before jacking the car. I struggled in the hot sun to loosen one lug nut after another. Not one of them would cooperate. The girl I was with said, "let me try". What!? Silly girl thing! Ha! I was bushed and fetched a cool drink from our ice chest and let her have at it. With my back turned, slogging down the cold soda, I suddenly heard the unmistakable screech of a lug nut breaking loose. I turned around and she was now working on a second nut!

I did not know that in the 50's, MOPAR (Chrysler cars), had normal CCW loosening nuts on one side of their cars but CW loosening nuts on the other side.
She didn't know either, but when it wouldn't loosen one way she tried the other way, (tightening to we normal He-Men) and it broke loose.

We replaced the tire and with a bit of egg on my face, went on to win "best unrestored car" in the show. A photo of that day with me at the wheel driving to the awards table.

Nuts can be nuts and make you nuts. They can, on rare occasions, be very backward things.

Richard Hull
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Fusor Vacuum Pump Saga

This post will detail my efforts at getting a vacuum pump setup that is sufficient for fusor work. One of my goals was to do this without using a 2 pump setup. (Yes, I DO know that the vast majority of folks building fusors, use a 2 pump solution for their vacuum system.) I wanted to see whether I could dispense with using either a diffusion pump or a turbo pump. Primarily because having a second pump doubles the probability of failure of the pump station – 2 things that can fail instead of one. Furthermore turbos require a somewhat complicated electronic controller – which means if you are using a turbo, you now have 3 things that can fail – mechanical backing pump, turbo pump itself, and the turbo controller. Furthermore, using two pumps requires more vacuum plumbing than one, as you must plumb the pumps together in addition to plumbing them to the fusor.

It turns out that you CAN get a pump setup that only uses one pump, which will get you down to fusor level vacuums ie: ~1 micron, but you either have to get lucky, or be willing to spend a pretty penny.

Fortunately, I got lucky.

My very first vacuum pump setup on the fusor was using an Edwards E2M8 dual stage direct drive pump, but with that I could not get down to less than about 5 microns, and typically it liked to run after getting hot, at more like 12-14 microns. This was good enough to let me make a plasma, but not good enough to properly evacuate the fusor for D2 runs.

I also had an old Welch 1405, but that would only pump down to about 35 microns. Much worse and not even close to what is needed for a fusor.

However, I also had bought from a University of Washington (UW) surplus auction at some point about 10 years ago what looked to be a brand new old stock, still in the box Welch 1402 pump head, that appeared to be at least 40 years old, but never used. It still had the factory tags on it. It turns out that both the Welch 1405 and Welch 1402 use a 1/2HP electric motor, and the diameter of the drive pulley on both pumps is 10 inches. So, I decided to replace the 1405 pump head that only pulled down to 35 microns with the 1402. This entailed properly locating and drilling 4 new holes in the pump base plate for the 1402 (the hole layout IS different between the 1405 and 1402), and then bolting the 1402 head down, and then reattaching and adjusting the tension of the drive belt. One thing I discovered about these old Welch pumps is that they have plates that go across the bottom of the pump base, underneath the drive motor that the motor mount bolts screw into, which function just like conflat plate nuts, so you can just loosen the motor mount bolts and retighten them to remove and adjust the drive belt tension without ever having to access any nuts underneath the pump base. Very nice touch, IMO. Especially since the complete pump assembly is NOT light. The 1402 with motor and base weighs in at 120+ pounds. Unfortunately, the pump bolts do not screw into similar plates, so you are stuck tilting the base up and getting 2 wrenches on bolt head and nut to attach the pump head to the base. But even if there had been plates on the 1405, they wouldn’t have worked for the 1402 anyway because the bolt spacing is different.

The new old stock 1402 pump head came filled with oil that looked brand new – I drained it to take a look, and it was a clear pale yellow clean oil. I had purchased some Inland 19 Ultra vacuum pump oil, which I decided to use instead. So I saved the original drained oil and loaded in a batch of brand new completely clear 19 Ultra. Then since the pump had been sitting for decades, I manually turned the 10” pully drive forward, and backed it up a bit if it got stuck, and then moved it forward again. There is an arrow on the pulley indicating the normal direction of rotation. It has been several months since I first brought this pump up, so I don’t remember how much time I spent manually turning the pump. But it is very important that you are sure that the pump can turn manually in its normal direction without getting hard stuck, before you switch on the motor to run it. If the vanes are sticking, they will loosen up the more the pump is turned. Everytime it sticks in the forward direction, just move it back and forth a bit until it unsticks and you can turn it more in the forward direction. The pump will loosen up the more you turn it manually until it stops getting stuck. You may need to spend and hour or more working the pump manually to make sure it won’t get stuck.

Once the pump would turn in the forward direction normally without getting stuck, I plugged in the pump motor, and it ran just fine. For a while. Then I heard the start of what sounded like a clanking noise. Unfortunately the clanking noise got worse as the pump heated up. I wasn’t sure exactly how a new old stock Welch mechanical pump was supposed to sound, but I was pretty sure that a loud metallic clank was not good, so I powered it off. After letting it sit a while, I fired it up again, and at first again the pump sounded fine, but eventually it again started to clank. I thought perhaps that oil wasn’t circulating properly in the pump, so I pulled the 00 rubber stopper plugging the pump hose barb intake, and added a bit more Ultra 19 oil down the pump throat as it was running. Didn’t seem to make much difference to the clanks. Of course doing this caused the pump to gurgle loudly and spew oil mist “smoke” out its exhaust while the stopper was out of the intake.

Basically, whenever the pump started to heat up, the clanking would start.

I thought maybe it was the new oil I was using. The new oil looked a bit less viscous than the old oil, perhaps the pump required a heavier weight oil. So, I swapped in the original oil.

No difference. Still clanked when it got hot. Plus I noticed that the ultimate vacuum that I could get with the old oil (5+ microns) was significantly worse than the vacuum I could pull with the Island Ultra 19 (~2 microns). So, I swapped back in the Inland Ultra 19. It wasn’t the oil viscosity or type that was causing the clanks.

After getting frustrated with the repeated clanking, I mused that maybe the clank wasn’t really that bad after all, and perhaps the pump just clanked normally. So, I decided to just let it run and clank. (Really BAD decision… DO NOT do that if you have a Welch vacuum pump that clanks. They are NOT supposed to clank.) Pump ran for a while, clanking, and the clanking got louder and more frequent as the pump got hotter, and the pump kept getting hotter, and hotter, and started to slow down… and the motor was getting really hot. And the pump kept slowing down and slowing down until it stopped. At which point I realized I was being a total moron, and that I might have frozen up my brand new old stock pump head, and that I was probably going to burn out the motor as well! So, I immediately switched off the pump, and let it cool down for a several hours. (I’m telling you about my stupidity, so that you don’t make the same mistake.)

After the pump cooled off, I then tried carefully moving the 10” diameter pump pulley back and forth by hand to make sure it wasn’t actually frozen, and fortunately it was not. Once it would again rotate fully in the normal drive direction by hand, I drained the oil, and put in a brand new batch of Inland 19 Ultra. (1402 pumps actually hold quite a lot of oil – a little more than ½ a gallon.) The drained oil was full of tiny particulates, and was no longer clear, but instead slightly grey – likely due to the presence of both metallic and vane particulates in it. It looked much like the very first oil change made on brand new lawn mower engines – assuming that first oil change is made after 10 hours or so of use and the oil is still clear enough to see through.

After this epic fail, I decided to try a new tack, which was to run the pump until it just first started to clank and then immediately switch it off and wait for it to cool down. Then then turn it on again until it clanked, switch it off, cool, rinse and repeat. My theory was that most likely the pump vanes which are typically phenolic (the original label states they were fiber vanes) had absorbed moisture during the several decades the pump had been sitting at atmosphere in the Pacific northwest humidity. So, when the pump heated up, the vanes would get too constricted to slide freely up and down in their slots in the rotors, and would cause the clanking. I reasoned that if I ran the pump enough up to the point where the vanes started to be constricted, but not let it actually damage itself by clanking, I could slowly wear the sides of the vanes down (and dry them out by keeping them at vacuum pressures for significant time), and eventually the pump might run continuously with no clanking.

This is exactly what happened. At the beginning the clanking would happen when the pump got to about 95 to 100 degrees Fahrenheit. As the runs continued, the temperature at which the clanking would start slowly rose. Eventually, after many cycles of running until clanks started, and then stopping to cool off, the pump could get fully up to its running temperature of 120-125 degrees Fahrenheit, with no clanking! (An inexpensive Chinese made handheld electronic thermometer with a laser pointer was very useful in keeping track of the temperature of both the pump head and the motor during this process.)

Once the pump finally appeared to be able to run continously with no clanking, I decided to just let it run for 24 hours straight, which it did without any clanking. After that, I measured the vacuum the pump was pulling at the end of the hose it was connected to, and measured 1.5 microns.

Success!

Morals of the story:

1) Welch makes really nice mechanical pumps. The 1402 pumps are especially nice.

2) If you have a brand new (or brand new old stock) Welch mechanical pump, it can pull down enough by itself to run a fusor – down to 1 micron or less.

3) Never let a Welch pump clank. That is not how they are supposed to sound. When running they make a quiet gurgle, with perhaps some random aperiodic clicking that is not very loud. While they are pumping down from atmosphere, the gurgling sound is much louder. The manual specifically warns against letting the pumps pump against too high a pressure continuously. Pumping at 1 torr or higher for extended periods of time can damage the pump. (It also spews oil mist out its exhaust vent, or into the exhaust filter.)

4) If your pump has been stored a long time and clanks when it starts to warm up, bring it into service by repeatedly running it until it first starts to clank. Then shut it off, let it cool, and run it again. Do this repeatedly, until it can run continuously without clanking. Once it runs continuously, you should probably consider replacing the oil used during the bring up process with new clean oil. You will also probably have more success eliminating the clanking, if you replace any decades old oil right away before starting the bring up process, since the old oil is probably full of moisture as well, and will therefore slow down the process of getting the pump vanes to slide properly when the pump gets hot. (Since oil already loaded with moisture will take a lot longer to pull moisture out of the vanes, than oil with no moisture.)

5) The oil you use in your mechanical pump really does matter. Especially if you are trying to do a single mechanical pump solution for a fusor. Modern mechanical pump oil that has been doubly refined – like Inland 19 Ultra – is going to perform better than oil that has been absorbing moisture while sitting at atmospheric pressure for decades, and likely was never as refined as the new oil is anyway.


The original tags that came attached to the Welch 1402 pump head. Pretty clearly 60's or early 70's era tags.

IMG_20220313_155130638.jpg

The pump after swapping on the 1402.

IMG_20220322_183450526.jpg

The initial pressure measured at the end of the vacuum hose using the MKS901p and display loaned to me by Bruce Meagher.

IMG_20220322_191832234.jpg

An early pressure pulled on the fusor by the 1402. Later the pressure would drop significantly as the chamber outgassed its adsorbed moisture.

IMG_20220322_202651427.jpg

Joe.
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

I have two 1402's sitting around that pump deep like yours. In addition, I have two 1396 Pumps by Welch. I have tried to sell all of them at HEAS for years, but their simple mass of hundreds of pounds, each, keeps them anchored fast to my lab floors. I would use them, but the Precision 5 CFM I have used since 2000 matches them. Thus, I let a sleeping dog lie.

I used a 5 CFM yellow jacket direct drive from 1997-2000 and did my first fusion in 1999 using only the yellow jacket( 5 micron low end) before switching to the belt drive precision in 2000 and continued to do fusion without any secondary pump until 2003!

I wasted a bit of deuterium gas purging what little air remained via the normal differential pumping of the single pump, but I did fusion! It can be done! All you need is a good deep pumping ( below 10 micron) mechanical pump. (note: I did have the famous and unobtainable micro sieve sold by Lesker that helped a lot.) I think it left the market as it fouled the oil in the mechanical pump as you used the electric heater in the thing to clean it up. This forced you to gas ballast for an hour or two to clean the oil as you heated the micro-sieve. A tedious process to be sure and chased me to a diff pump in 2004.

My system got a diff pump in 2004 and a Turbo in 2018. Both made fusion a lot easier, saved a lot of Deuterium gas and made startup to fusion a lot faster.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Additional Pump “Improvements”

Once my 1402 pump was running, and connected to the fusor with a vacuum hose. One of the first things I decided I wanted to do, was get rid of the ugly 2” diameter red rubber vacuum hose, and replace the hose barb connector on the pump with a KF25 connector. That way I could plumb from the pump directly to the fusor using standard KF fittings and stainless steel bellows. The Welch 1402 has a 1-20 threaded connection for the intake connection. One inch diameter – 20 threads per inch. It is NOT an NPT (national pipe thread), or a BPT (british pipe thread) connection. Straight 20 tpi all the way through – which means you HAVE to buy an adapter made specifically for that threaded hole. I purchased a KF25 Welch pump adaptor for 1-20 for a good price on Amazon from Brownian Motion Technology, and then unfortunately had to immediately return it once I got (with quite great difficulty – more on this later) the hose barb connection off.

Why you ask did I have to return my brand new adapter? Because it turns out that Welch has “old style” and “new style” pump heads, and the adapter I bought initially from Amazon was for “new style” Welch pumps. I had no idea there were two types of pumps and corresponding KF25 adapters, until the one I bought didn’t work. My pump head is probably about 50 years old, and requires an “old style” adapter. The new style adapters have an o-ring that comes in them and which gets clamped around the circumference of the threaded input hole, and you simply screw them in, and the o-ring seals directly to the outside of the pump body. Old style pumps however, have a recessed seat machined into them about a quarter of an inch deep, and then a smaller threaded 1 inch hole inside of that. The machined recess is too small for the outside of the o-ring holder of a “new style” KF25 adapter to fit through, and too large to allow the o-ring to seal properly. So, you HAVE to get an “old style” KF pump adapter that fits properly in the recessed seat, and which uses a metal gasket like the hose barb which comes standard on “old style” Welch pumps.

You can find these “old style” KF25 1-20 adapters from a couple different suppliers, but they are about 50% more expensive than the new style ones which are available from a bigger pool of suppliers. Straightforward capitalistic competition (or lack thereof) at work.

Getting the original hose barb off my Welch 1402 pump was surprisingly difficult. They are installed VERY tight. I had to use an oversized ~20 inch long crescent wrench to get mine off, and I had to put a LOT of torque on it. The thread is a standard thread (not left hand), but I would estimate those hose barbs are put on with at least 125 ft-lbs of torque and probably closer to 175-200 ft-lbs. I had to tip the pump up on one end of its platform so that the hose barb was horizontal with the floor, and the motor was directly above the pump, and then put the crescent wrench on the hose barb so that the wrench was at right angles to the hose barb, but also parallel to the floor, and then essentially put all of my 200+ pounds on the end of that 20 inch wrench with an impulse to get the hose barb to start to loosen. You can’t use a standard socket because the hose barb is too long, so it is important to get the crescent wrench very tight on the barb so there is no way it will slip and bugger up the machined in hex nut at the base of the barb. Bugger it up, and you will NEVER get it off. (Unless of course you are then OK with using a 3 ft or longer pipe wrench on your buggered up hose barb.) Fortunately I got mine broken loose without messing up the machined hex nut.

Once you break it loose, it comes right out, but the 1-20 threads are very fine, and getting my newly purchased KF25 “old style” Welch pump adapter to start cleanly in the threads was also tricky. Be careful to fully clean out the machined seat recess in the pump (without having anything fall into the pump). Make absolutely sure you start threading the adapter in by hand, and be sure it is not cross threaded, before you tighten it with a wrench. The trick I used was to put the adapter on the threaded input, then “unscrew” it until I felt the spot where the initial thread starts (you can usually feel it click down a little, but it is really tough with 20 tpi), and then gently screw it in by hand. It took a few tries for me to get it, and unfortunately even when I had it right, the adapter screws in pretty tight. I could not screw the adapter in by hand all the way down to the metal washer, not even close, but I could get it to go enough turns by hand to be sure it was not cross threaded.

Another thing I would suggest – and which I regret not doing myself, is to place the metal washer in the recessed seat and get it perfectly centered in the seat and around the 1-20 threaded hole BEFORE you start screwing in the adapter. That way the washer will hopefully stay centered until the adapter clamps it to the pump body when tightened fully. The metal washer that came with my KF25 adapter was sized in a way that makes it difficult to get it correctly positioned – especially if you don’t do it beforehand with the adapter out of the seat so you can see how it is aligned. Ideally the washer would have an outer diameter that is almost as large as the diameter of the machined recess it fits into, and an inner diameter just a bit larger than the threads of the adapter. Neither was the case, the washer was significantly smaller in OD than the recess into which it seated, and the ID was significantly larger than the threads of the adapter, which means it had a significant amount of play in it, and I suspect that in my case it ended up completely off center when finally clamped down, because in the end, after the new KF25 was fully installed, and the pump ran for a while, the new adapter seal leaked.

Of course it didn’t leak immediately. That would have made the cause of the leak obvious. At first the pump worked great. Pumped down to about 1.5 microns on the input immediately. So I then connected it to the fusor, and it pumped that down to the mid single digit microns also. But after about an hour, all of a sudden the pressure in the fusor started to rise until it hit 18-20 microns. When nothing had changed. It didn’t make any sense. I checked all the KF clamps, tightened ones a bit that needed it, but no change. Pressure in the fusor stayed at about 20 microns.

I started to get worried that I would have to try to track down a leak somewhere in the fusor, and was feeling a little bit sick about it – as it would probably take a long time, when I sat back and thought, wait a minute. I just changed the hose barb on the pump to KF, that is what has changed most recently, and is most likely the cause of the problem. What if there was some residual oil (because when I cleaned the machined recess where the KF adapter screws in, I used clean Inland 19 Ultra oil) that had been preventing a leak, but it got sucked through the leak, and now the pump is pulling on atmosphere though a tiny orifice. (Likely where the metal seal was misaligned to the adapter seat itself.)

I thought if that were the case, then I could drip some new pump oil in the recessed seat around the base of the KF25 adapter, and fill it with pump oil all the way around, and see if that resolved the higher pressure the fusor was at.

BINGO. A few seconds after I dripped some pump oil off the end of a screwdriver into the crack between the base of KF25 adapter and the recessed seat, and filled it up with new pump oil, the pressure in the fusor dropped right back down to single digit microns, like a switch had been thrown. It was almost instantaneous.

So, now I had a nice KF25 adapter on my great Welch pump head that worked fine as long kept the space between the side of the adapter and the machined recess in which it was seated filled with high quality pump oil. But as soon as all of that oil got sucked through the leak, which typically takes a couple of hours or so, my KF25 adapter leaks, when the hose barb it replaced never did.

Sigh.

One step forward, two steps back.

Does the “old style” KF25 adapter come with multiple metal gaskets? Of course not. Is the metal gasket easy to acquire on its own. Of course not. Is the metal gasket made out of the same stuff as say a typical washer – of course not. I didn’t examine it that closely but from the quick glance I gave it before installing the adapter, it looked like it was probably made out of aluminum. It was definitely a softer metal so that it would make a nice metal to metal seal between the stainless steel of the KF25 adapter, and the cast iron of the pump body. The only problem with it IMO was that it was sized so that if you didn’t line it up perfectly beforehand, it is not big enough to ensure that the offset seal will actually make a vacuum tight seal all the way around the base of the KF25 adapter. It certainly did not in my case.

Now, I did buy more than one of those KF25 “old style” adapters, because I have more than one old style Welch 1402, but I wasn’t keen on effectively wasting one of them just for its metal washer.

So, for now, since I don’t typically run the pump for more than a couple of hours at a time anyway, I simply make sure to drip some clean oil around the base of the KF25 adapter in the recessed seat, so that it will pull a good vacuum for a couple of hours. And I have to remember if the pressure suddenly starts to rise – seemingly inexplicably – that I need to drip a bit more oil into the recess in the pump head around the adapter.

Kind of a pain, but I do still prefer to have everything plumbed in with KF fittings and metal bellows than using a big ugly long old red rubber hose – that of course never leaked at all. The price of vanity I suppose… Someday, I will bite the bullet and attempt to reinstall the KF25 adapter with a metal seal that is very carefully and perfectly centered in advance. But not yet.

When I installed the adapter I did torque it a lot, but not quite as much as the original hose barb was torqued. I did not want it to be quite so difficult to take off, if I ever actually needed to take it off. Based on how it felt when I was torquing it at the end, I am quite sure that the washer did get clamped tight, and that it was off center and one side might have possibly been extruded so the inner edge of the washer was on the outer edge of the adapter. I won’t know for sure until I take it apart and examine it carefully before installing it again with a new metal washer/seal.


Takeaways:

1) Make sure you get the metal seal lined up and centered perfectly before installing any of the “old style” KF25 Welch 1402 pump intake adapters. Do NOT just slip in on the threaded end of the adapter, and screw in the adapter, and hope for the best. That’s what I did. It was a fail. Should the metal seal be sized so that slipping it on, would just always work. Of course it SHOULD be. But it is NOT.
2) Although KF is wonderful, and looks really nice, if you have a working hose barb, and hose, and you know it doesn’t leak, think long and hard about whether you really need to swap out the ugly hose, for pretty stainless KF. It really might not be worth it.
3) If you have a mechanical pump, and it doesn’t pull a great vacuum when you put a vacuum gauge on the inlet, BEFORE you decide to tear the pump apart, try dripping some clean new high quality mechanical pump oil around the base of the pump inlet where it screws into the pump body (be it hose barb, KF, or otherwise) and see if all of a sudden your pump pulls down better. If so, you have a leak right at the base of the inlet where it seals to the pump body. It will only take a few seconds to check, and may save days of unnecessary work. On my current Welch 1402, it means the difference between a pump that pulls down to 1 micron or less, and a pump that pulls down to 5-18 microns or so. (The longer I let the pump leak, the worse the leak gets, as more and more of the oil that was blocking the leak gets sucked through the leak, and the effective leak aperture gets larger.)
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Richard Hull
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Let all sleeping dogs lie! The KF25 idea is great, but.......... With straight threads, Welch, I am sure, used some sealant that would seize like the hand of god when they installed the barb years ago. I would solve your problem with a thick vacuum grease around the base.

I would have used only a short length, of the thick red India rubber hose to the factory, welch installed, barb. (sleeping dog left to lie) Then stuff into the hose a "barb to KF 25" adapter. (cheap, Duniway Stockroom)

I my case I use a 6" length of red rubber hose to the barb to KF 25 adapter to my 4 way KF25 SS cross and then to all SS plumbing thereafter.

The thick rubber hose is totally vacuum tight and seals to any barb over 100% of all imperfections with a good SS clamp at both ends. There would have been nothing wrong with a one inch length of hose Welch barb and clamp to a barb to KF25 with a clamp where the metal to metal distance was near zero. I found the old fashion huge diameter red rubber hose to be fantastic! I purchased my 1 foot length new from Duniway back in 1999. I still have the 6" cutoff from that original length. The rubber is far more supple and gives great vibrational separation from the pump to the hard plumbing.

You went to a lot of trouble to be a purist, which is laudable, but you woke up the sleeping dog and got bit!
Attachments
6&quot; Red Rubber hose pump down test after about 10 seconds to 8 microns. to verify hose to head clamping. this was in the earliest build stages of the 2004 fusor IV vacuum station assembly.  Precision pump barb clamped to hose to barb to KF25 adapter clamped to hose and then to my TC gauge tube with a KF25 clamp assembly. <br /> Indicated perfect operation really quick!<br /><br />Note: copper exhaust line to hole through building wall to vent oil vapor to the outside world.
6" Red Rubber hose pump down test after about 10 seconds to 8 microns. to verify hose to head clamping. this was in the earliest build stages of the 2004 fusor IV vacuum station assembly. Precision pump barb clamped to hose to barb to KF25 adapter clamped to hose and then to my TC gauge tube with a KF25 clamp assembly.
Indicated perfect operation really quick!

Note: copper exhaust line to hole through building wall to vent oil vapor to the outside world.
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
JoeBallantyne
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Joined: Tue Jul 20, 2010 4:08 pm
Real name: Joe Ballantyne
Location: Redmond, WA

Re: Joe Ballantyne Fusor v1.

Post by JoeBallantyne »

Neutron Moderator Construction

This post will detail the construction efforts for the neutron moderator design that I mentioned in an earlier post.

Last summer, the best price I could find on 1 inch thick HDPE was a set of 3 18”x24”x1” HAKKA cutting boards from Amazon. I bought a couple of sets. In August 2022 they ran $129 for the set of 3, now in January 2023 the same set is $150. I’m sure as the Federal Reserve (FED) continues their eternal crusade to debase the dollar the price will continue to rise. Somehow the FED thinks its rai·son d'ê·tre is to steal 2% a year from everyone on the planet who holds any amount of dollars. I guess if you steal just a little bit at a time from EVERYONE, on a permanent ongoing basis, it is somehow OK. But I digress…

I used one set of these 3 1x18x24 inch cutting boards, to build 2 5x5x24 inch moderators, the design of which I outlined in an earlier post. There was also enough left over to build the core of a small neutron oven for activation purposes.

It turns out that cutting HDPE is non trivial. I read online that the best way to do so is to use a triple chip grind (TCG) blade. So, I bought a Diablo D1084L TCG blade from Amazon https://www.amazon.com/gp/product/B001TH8HK8?th=1 that was highly rated (a LOT of people really like Diablo saw blades, and they make a 10 inch TCG carbide tipped blade). Swapped it onto my table saw, and then made a partial sacrificial 1” cut in a board so I could measure the kerf (width of the cut made by the blade). Turns out this blade had about a 0.1” kerf so 3 cuts would burn 0.3” of the 17.7” wide boards. I calculated that I should be able to make 3 pieces 5.1” wide with 2.05” left over. (Just FYI, cutting wood with that blade was like cutting through butter with a hot knife. It was a lot easier to cut through wood, than to cut through the HDPE.)

I very carefully adjusted the rip fence on my table saw, and made another sacrificial cut (or two) into a piece of wood to be sure that I would have exactly 5.1” of material cut off, and then I went for it. You can’t cut HDPE too slowly, because the plastic will heat up too much and start to melt, but you can’t go too quickly either. The feed rate I used on the 1” boards was about ½ to 1 inch per second. I made 3 cuts down the 24 inch length of each of two of the boards, and ended up with six 5.1x24 inch pieces, plus two 2.05x24” pieces. I then made two more 5.1” wide cuts in the 3rd cutting board, to get a total of eight 5.1x24” pieces, and then I had to adjust the rip fence to cut two more 2.05x24 inch pieces off. After that I had a piece left over that was a little over 2.9 inches wide, and I had 2 complete 5x5x24 inch moderators for my 24” long He3 tubes.

I decided to use that extra strip to make a neutron oven in conjunction with another ½ x 12 x 18 inch HDPE cutting board. I cut that 2.9x23.7 inch long strip into 4 equal lengths, and then cut the ½ inch thick cutting board into 9 ~4x6 inch pieces. It turns out that it was MUCH harder to cut the ½ inch HDPE than the 1” HDPE as it tended to start melting quickly. The feed rate on the ½ inch thick HDPE had to be significantly faster than the 1”. Even with a faster feed rate, I could not prevent the ½ inch HDPE from starting to melt by the end of the cut. I think the HDPE material itself for the ½ inch cutting board was different from the 1”. It seemed to be less dense, and it certainly appeared to have a lower melting point as well. The other issue, is that since the board was thinner, it was less able to sink heat away from the cut. I managed to get the ½ inch board cuts completed, but had to do significant cleanup of the cuts after they were done because of the melting. The 4x6 inch squares cleaned up reasonably well by scraping the edges with the edge of the blade of a flat tipped screwdriver, but I was happy that the 1” thick boards cut beautifully and needed no cleanup at all. (I didn’t realize how nicely they had cut until I started trying to cut the ½ inch thick cutting board.)

Since the 1” thick HDPE cutting boards were actually 25mm thick, not 25.4, they were just a tad under 1” thick. This meant that I could not slide my 1” diameter neutron tubes easily in and out of the central slot in the moderator. Side to side was not an issue, as I could just adjust how far apart the two 2.05” wide central strips of HDPE were, but top to bottom was just a tad too small. To fix that, I used another Amazon HDPE 18x24 inch cutting board I had purchased that was just 1/16th of an inch thick. I used a box cutter razor to cut off two 2.15” wide strips (intentionally a little wider than the central 1x2.05x24 pieces of HDPE, and I put them directly underneath those 2 central strips. This gave me enough headroom to be able to easily slip the He3 tube in and out of the moderator. Here is a link to those boards: https://www.amazon.com/gp/product/B07B89ZLTC/ it turns out that the price differential from end of August to now on this set of four cutting mats is even more dramatic. End of August 2022 one set of these cost $10. Now one set is $31. Ya gotta love the FED!

One of the original 25x450x600mm cutting boards.

IMG_20220824_130724321.jpg

Three of them in the ~50lb box they shipped in.

IMG_20220824_130803743.jpg

Actual dimensions of the cutting boards.

IMG_20220824_130852921.jpg

First completed moderator with central pieces sitting on top.

IMG_20220907_192808985.jpg

Both moderators and neutron oven.

IMG_20220907_192853467.jpg

Moderators, neutron oven, and large pile of shredded HDPE created by the cutting.

IMG_20220907_192923865.jpg

The very excellent blade that did all the work. (This was removed from my table saw as soon as this project was complete, as this blade is only for cutting HDPE.)

IMG_20220907_195312509.jpg

Joe.
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Richard Hull
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Re: Joe Ballantyne Fusor v1.

Post by Richard Hull »

Great post on the moderator build. Others will benefit from this post, I am sure. While certainly the above post was part of Joe's fusor construction post, it related directly to neutron detection. I think Joe should also post a copy of this in the radiation forum so that it might be accessed in relation to that aspect of radiation detection. I just like to see a great post like the one immediately above posted where it won't be lost in the deep clutter of construction posts. Don't move it, just reproduce or copy it to the radiation forum. It is too good to get lost here in construction.

I am so glad I bought my moderator pre-cut back in 2020 from the local Piedmont Plastics facility here and picked it up in person. Joe's is a virtual same cut as we have the same 3He tubes. I put out a post on my work back then with a PDF. The total cost for it all 100% pre-cut HDPE with tax was $97.00

viewtopic.php?t=13553

If you are in possession of such a wonderful long tube, regardless of price for the HDPE, the finished project results in one of the most sensitive neutron detectors around, once all the electronics are hummed in to perfection. It creates a roar of counts from a whisper of neutrons.

I felt the pain of the recent price increases when I went back to buy pre-cut strips, 6 feet long to create a Lego/Lincoln Log-like set of small blocks of HDPE to assemble any number or forms of small HDPE moderators for activation work around the intimate contact rhodium/Russian STS-5 GM tube.

I got group of long strips of 1-inch thick X 1-inch and 1-inch X 1.5-inch HDPE all 6 feet long. This required my 10-inch chop saw to get a similar blade to what Joe purchased. I was fortunate to have to be able to cut only 1-inch and 2-inch cuts in a series of rapid, near instantaneous chops.

I find that for activation, a "fusor hugging" activation moderator, a "small block" assemblage is just the ticket, especially for fast decay isotopes where a GM tube can be placed for instantaneous counting at shutdown of the fusor. I still have a couple of those long, HDPE strips left, yet to be cut up and a box full of those "toy-like" HDPE blocks. This group of precut strips cost me about $125.00 one year later in 2021. (this was a plank of HDPE 1-inch thick, 6-inches wide and 6-feet long with several flawless, length-wise cuts by Piedmont.)

For the block moderator post, I turned into a FAQ found at......

viewtopic.php?t=14107

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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