Fusor V - yet another whack at it.

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Mark Rowley
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Re: Fusor V - yet another whack at it.

Post by Mark Rowley » Fri Jun 04, 2021 8:46 pm

Always inspirational to see neuts being made at the provenance of the amateur fusion community.

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Richard Hull
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Re: Fusor V - yet another whack at it.

Post by Richard Hull » Sat Jun 05, 2021 5:00 am

It gets better and better.... Tonight I took the system up again and it worked like a charm with double the output. The video image still showing razor like rays with an intense little dot dead center.

Best Run was 41.6kv @ 9ma with 14 microns of deuterium pressure. with two results. 61,016 cpm on the neutron counter, (see image below) which works out to 244,000 n/s TIER. I also fully activated, at this level, the Rhodium from dead to 540cpm.

I assume most here now that my background count on the 3He neutron counter is forever 7-9 cpm. (Except during a severe solar CME) Tonight it was 8CPM averaged over a 10 minute background count. (81 counts)

About the run: I turned on the mechanical pump and started my stop watch. Once I hit 15 microns on the foreline through the turbo and into the fusor, I turned on the turbo. I pumped to submicron level and put in about 12 microns of D and worked the system up to the above stated pressure, voltage and current. The Rhodium fully activates in about 200 seconds. I then turned off the voltage, killed the gas and opened up the throttle valve to pump the chamber back submicron. Turned on my rhodium GM system to determine the activation level. Finally, I stopped the stop watch at 21min 18 seconds. Fabulous I think! The fusor V is comin' back a lot faster than ever before.

Aidan asked about grid geometry. No, that has not changed, but the fusor did get a brand new tungsten grid just like the old one in a new metal machined stalk/holder. The old grid shattered like glass when I injudiciously set in on the work bench while still in the insulator feedthrough. (image of the broken rings attached). The old grid had been in service, according to my lab notes, since 2009. All grids will work harden over time and suffer horrible hydrogen embrittlement, making them like glass at the grain structural level. Since all tungsten is sintered this makes it even worse.

The old grid had a large bore in the stalk and the ring wires went in easy. I filled the grid stalk hole with silver solder to retain them. This was probably a terrible move as everything in silver solder (braze), is far more volatile than the tungsten and would slowly deposit on everything. I used this grid since 2009, as I said. It obviously did OK once I had cleaned my viewport glass over 4 times since then #@%$&*^!

Determined to not have any volatiles near white heat in the new structure I machined and threaded the new post and on the flat end, using 1/64-inch stepped drills close to 6 wire diameters, I bored deliberately too tight for the 6 straight grid wires to fit, I then worked, drill by drill, boring until the 6 wires were an incredibly tight fit. Now the horror began. Hand winding the super springy W wire over the sub sized mandrel was a bear. If that wasn't hard enough, trying to force the 6 much battered, highly springy ends of the 3 loops into the hole took over 30 minutes and resulted in three puncture wounds in my fingers. Once in the hole, the wires were so tight I had to get a suitable flat-end punch, mount the stalk into a vice and hammer at the base of the grid system which yielded to brute force, seating them and the grid fine within the stalk. Nothing but the tension of the wires holds the loops in the stalk. I was gravely worried about release due to expansion and contraction over time. So far, so good.

A great run and I am happy once more as I will get it up to the mega level soon, I know.

Richard Hull
Attachments
June 4 21.JPG
The final count on the Ortec during my final 1 minute run of fusor V.
June 4 21 rings.JPG
rings are so work hardened they have lost any of the devilish springiness so frustrating while trying to assemble a grid. They are frozen to perfect rings.
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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Fusor V - yet another whack at it.

Post by Richard Hull » Fri Jun 11, 2021 3:08 am

I have, for the first time since 5 June, turned on the fusor and again timed my run.

Starting from no vacuum anywhere in the system. I turned on the mechanical pump and started the stop watch. I ran the fusor up to 425,000 n/s TIER ending at 43kv 10ma at 11 microns of D2. I activated the Rhodium to 9.3 times the background count. Killed the supply, turned off the turbo and stopped the watch at 16 minutes 53 seconds. A true hit and run after laying fallow for 5 days.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Fusor V - yet another whack at it.

Post by Richard Hull » Thu Jul 29, 2021 7:58 pm

The current fusor is doing OK, but with the cube numbers blowing the socks off the classic fusor, I want one! Unfortunately, if you go back to the first post in this thread, I had made a good purchase of a 6-inch 6 way cross. I haven't moved on it because the conflats would be about $800 more to make it go.

Jim Kovalchick and I have been doing a lot of personal e-mails lately, mostly about neutron numbers and calibrations related to our PNC-1 and PNR4-remball systems that are either not working or suspect due to one reason or another. (another issue to be sure)... I have been mulling over the idea, with Jim, of purchasing the LDS 4.5-inch SS cube for just shy of $1200, making my expenditure of $550 for the 6-inch cross a bust. Even with the cube I would need another $600 worth of conflats. Also, an uncooled cube is a non-starter. Being hydro-phobic or hydro ambivalent about fusors, yet still keeping this old body well hydrated, I wonder what to do?...What to do?

I came up with an idea to make a cube fusor out of my 6" cross with a number of ideal add-ons and suitable kludges that offer a number of advantages, avoid the hydro issue and let me save my original investment. I feel like I am on a mission to "save Private Ryan", but in this case it is my 6-inch cross while perhaps improving on the cube design philosophy of a form of B.O.T. fusion.

In effect the B.O.T. cube is a sphere in that the long, high field sharp arms of a full cross tend to take current from beaming into the long arm tunnels to the target. The cylindrical grid is the B.O.T. beamer to the cube's closely situated targets.

Study my diagram below.

Using compression fittings to allow for sliding targets, the high field areas are avoided, and the targets might be moved in or out for optimal operation over a wide range of voltages should higher voltage supplies be obtained down the road. The heavy solid copper rods will immediately transmit heat from the targets outside the system to cooling fins of copper that can have high speed air forced over them via a plenum or what ever is satisfactory. A bigger better cubic, B.O.T. system of adjustable geometry is the result without water. note: The 1-inch copper rods are a mere suggestion 1.5-inch and 2" compression fittings are readily available, should more massive heat transfer be desired. Add to all the above, the targets can be changed out with some ease.

I think with this in mind LDS will get to keep their 4.5-inch cube and I will keep most of the $1800 needed to buy it and its conflats.

Opinions?
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6 way to cube.jpg
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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Mark Rowley
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Re: Fusor V - yet another whack at it.

Post by Mark Rowley » Thu Jul 29, 2021 10:14 pm

Richard, you can probably guess that I really like the idea of going in this direction.

I think your best results will be utilizing a cube instead of the larger chamber. However, the concept of electrical confining the electrodes within a larger chamber to “in effect” replicate a smaller fusor has always piqued my interest. I’m unaware of anyone trying it yet.

From what I can tell, you and I have a similar assortment of machining tools. Making a cube is really a simplistic operation and shouldn’t take you much time. My only complaint about the process is polishing the interior surface. It’s not really time consuming but it’s messy. Once complete, the area around the drill press is a dusty nightmare. Regardless, it’s well worth the result.

If you use a cube you could easily employ water cooled endcaps for the target material.

viewtopic.php?t=14096

The idea of swapping different materials is nothing short of intriguing. However, after my latest experience of beams hitting different materials it became ultra clear water cooling is the only way to go. I’m doubtful copper rods and air cooling will suffice. Chilled water will need to be cycled directly under the target at probably no more than 0.25”.

Mark Rowley

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Richard Hull
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Re: Fusor V - yet another whack at it.

Post by Richard Hull » Thu Jul 29, 2021 11:46 pm

Chilled water is possible even with channels board through the copper rod to the base of the target. Lots of options with pure copper's rocket fast heat conduction and water channels.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Aidan_Roy
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Re: Fusor V - yet another whack at it.

Post by Aidan_Roy » Fri Jul 30, 2021 1:46 am

I like that idea Richard, having cooled water plumbed through the copper cooling rods. That may be the best way to go for this idea to be highly successful. If you choose air cooling alone, a ridiculously high volume would have to be forced over the fins every second to maybe have a chance. But with that, the ambient room temperature, and intensity variations from run to run would add to the difficulty of keeping it cool and could limit you more than would be liked.

Aidan

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Finn Hammer
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Re: Fusor V - yet another whack at it.

Post by Finn Hammer » Fri Jul 30, 2021 6:49 am

It is hard to say, without isolating the end caps from the chamber, but it is my impression that the cube itself heats up as much as the endcaps. So only cooling the endcaps will not do.
Otherwise, great idea to have axially adjustable targets.
In case you go for a cube:
Polishing the internals: I used a special tool, made from 4mm steel rod, and bent like a hairpin, only so that one leg is longer than the other, and the longer leg goes into the chuck of power drill.
I then introduce blanket material into the slot and wrap enough turns to form a cylinder of carpet that is a tight fit into the hole to be polished. Polishing agent is liquid Brazzo or Silvex, or whatever the local brand of silverware or copperware polish. Apply generously, but no need to spill it allover. It soon saturates the surface and forms a black layer of ....., well I guess it is swarf, really.
Place disposable material under and around the immediate area.
Start the drill and pull the polishing rod back and forth inside the hole, just like when you hone a cylinder on a combustion engine. You may have to add more blanket as the mop compresses, just unwind a turn, and stick the new strip of blanket under, then rewind and resume polishing.
This method gave me a polished chamber in less than an hour.
Hope this helps.

Cheers, Finn Hammer

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Re: Fusor V - yet another whack at it.

Post by Jon Rosenstiel » Sat Jul 31, 2021 5:34 pm

When I initially built my cube the only polishing I did was with a fine 3M pad. After a few months of running/testing I disassembled it and gave her a proper, shiny, gleaming, polish. I saw no change in neutron output one way or the other. Maybe some others here have had a different experience with polishing, if so, please share your thoughts.

Jon Rosenstiel

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Jim Kovalchick
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Re: Fusor V - yet another whack at it.

Post by Jim Kovalchick » Sat Jul 31, 2021 8:51 pm

I have never bothered to do anything other than clean a chamber with acetone.

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