Emma - Fusor Number 1. First deuterium run

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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Richard - I did see mention of you using a fan to help blow away the corona, this is on this list to implement! It's perhaps worse in this setup being all inside a box. Also I could hear the corona, but even in the dark could not see it. I tried a "bat detector" to amplify any ultrasonic sound, which I think is similar to how commercial corona detectors work. It worked slightly better than the mark 1.0 ear but not a massive improvement.

I think Liam you are quite correct and its not indeed shorting through the ceramic but forming an arc all the way around the end due to contamination. The reason I thought it did was because when it flashed over the ceramic lit up brightly like a lightbulb, it's fine on the air side. Also both of the other used ebay feedthroughs leak it turns out. The feedthrough and stalk are absolutely filthy now.

I risked a very non-definitive test in air with the feedthrough on the bench and the arc indeed forms around the end of the ceramic not through it. Perhaps I was jumping to conclusions too soon. Maybe, after a deep clean and a stalk re-design it may actually be ok.

Matt - I was running it fairly warm for short periods of time - the cooling has become quite an issue.

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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Feed though has been cleaned by carefully using 1500 grit paper followed by an ultrasonic bath, with water based solvent to clean any sanding residue. Finally finishing with IPA and wipes to remove anything else. The feedthrough itself seems ok, yay!

As for the second part, posting as a failure for what not to do.

For the stalk re-design I should probably have actually done some simulating or indeed any calculations rather than throwing something together to experiment with. More thought less rush etc..... This sparks excessively in one place, even after a long cleaning run at low voltages. Issues seem to include:
-Glass is very thin & close to the stalk, meaning its insulating value is likely near zero.
-Stalk diameter is too large and the junction with the glass creates a horrible area of high field.


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Damage to the glass - post removal

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Liam David
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Re: Emma - Fusor Number 1. First deuterium run

Post by Liam David »

Yep, that would be a triple junction problem. The glass can also trap contaminants at the metal surface, shielding them from effective cleaning by the plasma. It'll do much better without the glass.

As you suggest, there's an ideal diameter for your 2.75 conflat port. Too small and the high theta curvature (r, theta, z coords) enhances the field. Too large, and proximity to the wall increases it again. This ideal region is actually pretty flat, so for the often dirty, crooked, or otherwise nonideal stalks in most fusors, its diameter never really becomes the limiting factor. For an ID of 3.65 cm, which is pretty typical for 2.75 conflats, the ideal diameter comes out to 1.35 cm. This diameter gets modified by the presence of a dielectric like feedthrough ceramic, but it remains analytically solvable.
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Richard Hull
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Re: Emma - Fusor Number 1. First deuterium run

Post by Richard Hull »

You want all the high field in the system at the central, grid, ring, sphere, etc. You have a lovely, smoothly radiused and polished ring!
The large diameter stalk would be just the thing, if, you had more clearance around it and the feed through insulator. I bet a sharp edged thin cylinder would cure many issues as long as you haven't "tracked". permanently. the insulator. It is forever all about low field control along the stalk merging to extremely high field conditions at your central toy, whatever that is.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Emma - Fusor Number 1. First deuterium run

Post by Liam David »

A high field at the cathode doesn't help, generally speaking. Quite the opposite, in fact. I'd argue it hurts the performance in most systems here. It also has little to nothing to do with where the plasma will form. My first suggestion would be to increase the cathode length several times and decrease its diameter somewhat, but the one you have now is nicely made and it would be worth collecting data on it.
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Re: Emma - Fusor Number 1. First deuterium run

Post by Matt_Gibson »

Is that a tungsten wedding ring?
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Friday update time

The cathode has been remade. I've downsized the stalk diameter by 2mm and pulled the glass right back, so its now just being used to keep everything central. I cut the glass using a simple tube cutter then melted the ends to smooth it out and get rid of any dust. Have only done the first couple of re-conditioning runs but so far no arcs. I'm picking up a new lathe soon so it should be a lot easier to make my own stuff going forward, be fun to get back into machining things.

I've also had to replace one of my PM1029B panel meters as the previous arc issue seems to have destroyed it. It now only displays nonsense segments. It's now in a metal box and the cables shielded.

Matt- yep from Amazon. I cut a hole in the side to thread the stalk on using a little diamond bit.

Before cleaning:
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Grid is now much better aligned to.
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

I wanted to experiment with using continuous albeit lower voltage in between runs to help keep the chamber clean, bit like an ion pump.

Not wishing to use my main supply for this I took a cheap ebay AC power supply, connected it to the fusor after it had sat overnight allowing for the pressure to rise. No pumps were turned on. Plasma struck at around 3.8kv and over a couple of minutes the pressure slowly dropped until the point at where 6kv plasma would flicker on and off as the pressure rises and falls. When the plasma is lit it's using no more than 0.5ma.

I tested it in this state for a couple of hours with no pumps running (see video) and the pressure stays put. I wonder if 5 minutes per hour in my setup would be enough to maintain a 6kv or higher plasma for long durations. More testing to follow.

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Dennis P Brown
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Re: Emma - Fusor Number 1. First deuterium run

Post by Dennis P Brown »

Unless you have a leak (real, not virtual) your system should hold vacuum and remain clean. Running continuous power (a plasma) really isn't necessary - my system holds a fairly good vacuum and after three months (all of 3 torr), fired up and ran flawlessly on its first attempt.
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Richard Hull
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Re: Emma - Fusor Number 1. First deuterium run

Post by Richard Hull »

Emma, What you observed is the norm for a tightly sealed system. If you vacuum to a very low level and are almost perfectly sealed and let in enough gas to strike a plasma, then keep that voltage on, over time, the plasma should go out as you are burying the gas. (especially hydrogen). with more voltage the plasma can restrike but ultimately, the system will go so "hard" in vacuum, no voltage will restart the plasma. (like you note, an ion pump like operation is occurring.)

With a leaky system the above scenario will not work out or ever go totally "hard" as gas will always leak in allowing the plasma to strike.

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
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

3 torr in 3 months is pretty cool. Richard I assumed that was the case, this is very much a learning experience, I'm still new to vacuum systems. After another hour or so of playing with it you indeed couldn't strike plasma at all. It's also possible that there is minor leak still but its on the order of microns per hour and not worth looking at while things are otherwise working nicely.

Rubbish photo but I had the tungsten grid glowing today. Interestingly as soon as the grid starts to glow the neutron numbers improve even when the current is dropped subsequently.

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Re: Emma - Fusor Number 1. First deuterium run

Post by Matt_Gibson »

What power levels are you seeing before the ring begins to glow?

-Matt
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

It starts to glow around 300W, 8-10ma at 35-40kv but only after about 20 minutes of bombardment. It's obviously more visible on the camera than by eye. There is no glow on the stalk at all.
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Re: Emma - Fusor Number 1. First deuterium run

Post by Jim Kovalchick »

Emma,
When I was using tungsten carbide wedding rings for my grid I found that they took a bit of doing to get them glowing, but it could be done. Attached is a picture of one of mine glowing to the point that it's incandescence dominates the color in the chamber versus the plasma.

I think this image was at over 400 W, but I would have to check my notes.

The other image is another TC ring grid after shutdown showing that it still glowed red for a while.

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Re: Emma - Fusor Number 1. First deuterium run

Post by Dennis P Brown »

Emma, a few microns an hour is almost certainly a "virtual" leak (i.e. simple out gassing.) As pressure climbs some, it will slow; ditto when you keep it under vacuum. Running a continuous high voltage voltage, as you found, doesn't remain lit. So your system is likely very sound.
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Jim, those photos are very cool. I was just reading through your original thread theorising on the reasons for the increase in neutrons once the grid glow starts. In terms of thermionic electrons generating plasma more efficiently.
You would think this would be the reverse and the electron emissions would start to ruin the fusion. However this is not what I seem to be seeing so far in this setup, it seems to increase non-linearly, which is confusing.
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Re: Emma - Fusor Number 1. First deuterium run

Post by Richard Hull »

All of this oddball behavior is due to what I have preached from the beginning over the 23 years here. This is a simple system! It is a simple system that is not directed in a specific single manner to do fusion. It does fusion over a wide range for an equally wide range of possible reasons in many zones. Just as it thwarts fusion for also many reasons and in many zones. You just can't simplify this simplistic fusion system. Suffice it to say, it does measurable fusion and that specific increased fuel pressure at elevated voltages and currents suited to a specific reactor will increase fusion.

It is generally found that to get the most fusion out of any design, the central cathode element will heat and glow or even nearly incandesce.

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
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Things have been busy but finally had some success and managed (I think) managed to activate some fine silver sheet to a credible level. This was at 40kv 6ma, with a 10 minute run, using cut up chopping boards as a moderator. The ludlum was showing between 5-7m/rem hour and has not been moved from its previous position.

Within the first 15 seconds I can get 2k cpm with a pancake probe, with the silver pressed between a sheet of lead, it then drops rapidly.

Image

Bad news however is that the leak seems to be both real and getting worse. Thanks to the very helpful "air duster" trick I believe I have managed to narrow it down to the valve stem on the valve I'm using to throttle the diffusion pump.
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Richard Hull
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Re: Emma - Fusor Number 1. First deuterium run

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Emma you have made the elite fusioneer club. I have added your name.

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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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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Amazing, thank you Richard. The amount of reading and effort involved with getting the system stable enough at for me the higher neutron numbers has been considerable, this place is a great resource.
Each time I stacked the moderator up, it felt like something would go wrong, from blown diodes to grid issues. Hopefully now I have appeased the problem gods enough to allow for some more experiments. Sticking with silver I would perhaps like to try some silver nitrate in solution next.

Secondly whist I'm sticking with "no upgrades", until all has been had out of the current system. It's hard not muse on of what to do next. More voltage would be nice so the power supply is the next likely target. Want to stick with the potential transformer PT so my initial thoughts/options are:

-Keep the PT at 50hz and use some monster caps to build a voltage doubler. Expensive and dangerous, but it would be bulletproof.
-As above but use increase the frequency of the PT via perhaps an audio amp, allowing for smaller caps.
-Use a second smaller transformer in between the PT and the bridge, that I wind myself. No idea about how well this would work or if it would be practical,

Edit - Thought I added this to the previous post, but here is the graph from one of my initial conditioning runs if anyone is interested. Voltage and current was maintained throughout at 35kv and 4ma by slowly increasing the D2 pressure.

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Richard Hull
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Re: Emma - Fusor Number 1. First deuterium run

Post by Richard Hull »

Excellent work and data reporting! You also have a good grasp of what to do to prevent problems while expanding your neutron numbers. Your electrical knowledge is advanced. While I think another HV transformer would be possible between the PT and the bridge, but as you note, would be a very special wind to stay on the 50hz. Likewise, I have considered big caps and a doubler on my X-ray transformer but the stored energy is a big nasty.
If, as you note, you wish to keep what you have and just add as needed to improve it before moving to a more advanced fusor, you will find you continue to learn. This is mostly in operational experience. Wring the system out to its max. I always say as a personal maxim, " never seek the better without first securing the good and all that it allows."

Finally, if it is not too personal, the name Emma is traditionally a woman's name. Is this the case? If so I would like to add this to the fact that you are the first woman to become an elite fusioneer in your note on becoming a fusioneer. It is kind of a big deal for me and I hope all who are here. As you will note you have not been treated with any preference or assumptions in our helping out here, nor will that change.

If a woman, I will have to stop using the "old boys" appellation to my future reference to those having done fusion and activation.

I really enjoy when we have a winner fusioneer and they acknowledge, as you did, the fact that these forums really assisted you in your winning effort. I do hope you will stick around and go as far as you feel you can in the amateur fusion effort. I hope for this with all the winners, especially the elites.

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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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Ha! yeah don't worry Richard at all, I've worked in the technical side of IT for many years and am very used to being the only girl. Things are changing slowly in the industry now though, but I amusingly remember being outnumbered 100 to 1 or 2 at various conferences. Before specialising in the security side, I spent a long time running various small IT & AV departments, the result being I know a little bit about a great number of things.

Something to think about upgrade wise, I would quite enjoy building a custom little transformer but need to figure out how that would look. The idea of having some huge amount of stored energy in a flashover situation is somewhat scary.
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Re: Emma - Fusor Number 1. First deuterium run

Post by Richard Hull »

I was never worried, just didn't want to do the elite writeup wrong. I have now updated the elite message. IT nerds, fusion nerds, and amateur science nerds are special people regardless of gender. All of us tend to go far beyond the norm into varying degrees of obsession once we latch onto an area that captivates us. Curiosity unchained and unbounded, coupled with the verve to do and driven by the "hands-on" imperative force us into projects few could accomplish.

Keep the great effort and reports.

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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Jim Kovalchick
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Re: Emma - Fusor Number 1. First deuterium run

Post by Jim Kovalchick »

Emma,
Congrats on making the Elite section of the Neutron Club. Your work shows that you're applying first rate skills and knowledge while you are also learning. Thanks for sharing while on your journey. We are all better for it.

Regards,

Jim K
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Emma Black
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Re: Emma - Fusor Number 1. First deuterium run

Post by Emma Black »

Thank you for the kind words, I think the childish excitement of getting something that only just possible (at home at least) to work, or puzzling on a strange result is very addictive.

That valve is leaking to an unusable amount now so I have treated myself to a brand new one. While the fusor is down for maintenance I'm taking the opportunity to add some cooling blocks to the end caps. In addition to moving things around for more moderator space. Beam pattern is interesting and not what I expected:

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