Jim Kovalchick -My attempt at smaller fusor

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Frank Sanns
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Frank Sanns » Fri Apr 10, 2020 4:13 am

Part of the issue that I have with this thread has nothing to do with your work Jim. It is the fact that Richard and I have not moderated it so that the technical discussions occur elsewhere on the forum rather than in your showcase thread. This is YOUR images thread and as such the rest of us should take the technical into another thread. Only complements or minor commentary should be going on in this section by others. Going round and round on the details of fusion in general are not critiques of your work but rather discussions outside of your work but trigger by your work. That did not come out right but you get the idea.

I looked back through it and I do not see a good way to relocated the discussions without destroying your thread, which we will not do. The problem is that discussions on the matter seem to be directed at you are they are not. They are good technical questions, suppositions, and answers for a stand alone post. Appearing in your showcase though feels personal to you as I saw earlier today. I think a new generic technical discussion on such matter is warranted.

The other problem is that historically, the Images section gets thinned and deleted except for the very best. You of course have nothing to worry about there but in the future, Richard and I need to catch this sooner. Again, my bad.

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Richard Hull
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Richard Hull » Fri Apr 10, 2020 4:26 am

Like I noted, I leave this field and its associated problems as an activity for the advancing student. I am a neutron guy, not a fusion guy. I have to work with fusion to get my neutrons.

The cross has 6 arms welded at sharp right angles at less than one inch from the grid. You can't radius these weldments to a level suitable in a common 1.5 inch cross without risking cutting into the weld so deep as to damage the cross. I see no sparkling at the weldments which had no little beads, etc. (smooth).

In my perpetually vigilant video image sprayed over a 9"X 9" Monitor screen there is no warning, no creeping currents, just instant unpredictable white arcs. These tight little cross systems are RF and EMI nighthmares! Subtle tritchel pulses aplenty to add to the RF mayhem. I would be highly suspect of any electronic neutron counting around them. This is from several hundred of times I spent hitting the reset button on the counter.

My actual grid diameter in the direction of the discharge streams is .40 inch and was originally a .501 sphere. Enjoy the hunt gentlemen. I need neutrons and neutrons alone. Cylinders and spheres, cylinders and spheres.

Like Frank, this is nothing to do with Jim's effort. I learned much of what I know of value prior to my beginning this cross work in this thread solely from Jim and a few others. Jon R. is always a special case for successes. This is why I leave all this work to the other gentlemen here who will persist in this effort. I had fun and burned off over 40 hours mostly from 11PM at night until stumbling into bed about 8 AM in the morning. Awaking at 4 PM in time for my 1 mile walk, supper, some time with the wife and back at it again. All the time, looking for a sweet spot that never came due to arcs. I went through 8 conflat copper gaskets removing and replacing the grid system and HV insulator that took 44kv on fusor IV I have a robust system. All of my efforts came to naught. (polishing, rounding, careful alignment, etc.) The big x-ray power supply and turbo controller really took some nasty belts on the chin and got up off the canvas to start over again. As the owner of this less than a champ, I now throw in the towel. This system will sit as a trophy until I decide to move on the newer fusor V as this was a non-fusing system in my view, but a winner for any DIY newbie.

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: Jim Kovalchick -My attempt at smaller fusor

Post by Dennis P Brown » Fri Apr 10, 2020 9:38 am

Hello and glad you posted your results on your fusor. Your work has been excellent.
I apologize if you think I am "casting stones". I did not intend this. I too built such a small volume device (though, didn't have the success you achieved.)
Again, your experimental work is very good and do stay at it and continue to post - small volume fusors are and remain an interesting project for people building fusors (as I pointed out, they offer superior performance for smaller power supplies.)

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Jim Kovalchick
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Jim Kovalchick » Fri Apr 10, 2020 1:41 pm

To investigate my diminishing neutron numbers I opened my chamber last night. I found no discernable issues with the inner surfaces. I do not have an endoscope camera, and not wanting to open my beam end conflats, I did not exam those surfaces. The stainless steel grid looked better than I thought. No signs of melting. The outside of the grid tube was tarnished with a shiny pale blue. I wish I could get a good picture of this, but the inner surface of the grid tube was a dull light gray. I can't make any specific conclusions from these observations.

I elected to put the fusor back together with a new grid. I dont have a tungsten tube to try yet, so I decided to return to using titanium. My first grid was a poorly formed demo tube of Ti. This time I formed and polished a short tube of Ti sheet. I recycled my titanium clip from the latest grid. I decided to make the grid a little shorter than my last one to give more margin to arc shorting. The tube is also wider to more closely match the bigger diameter of other small fusors on this forum. I forgot to take exact measurements of the grid before sealing the chamber, but the opening is about .75 inches. I put a slight bend in my stem to compensate for sag to center the grid in the chamber. The attached photo is my new grid before placing it in the chamber.
In the coming days, I expect to test the new grid. I will continue to post results here.
Jim K
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Jim Kovalchick » Fri Apr 10, 2020 4:31 pm

I walked the new grid up to - 38 kV and 5 mA with almost no difficulty. Some sparkles now and then, but that subsided quickly. I kept my current at 5 mA or below.

Obviously my grid is heating unevenly, and my guess is that is related to my grid clamp. The beam also looks a little feathery, but I'm not sure if that is significant.

Initial neutron numbers at 38 kV were more than twice what I recorded yesterday for the same conditions. 559 counts in one minute on a beam end of the cross using an Eberline PNC tube that read 400 cpm when held against the shell of Richard's fusor IV. From here, I would like to see if these numbers change with successive runs.
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Jim Kovalchick » Wed Apr 22, 2020 3:52 pm

You guys are probably tired of hearing about iterations of my grid, but here is the latest. I have added some bulk to it to try to time extend the heat driven window to H desorption. My stainless grid would get yellow hot quickly with any real current. My titanium grid was thin and heated unevenly. My goal is maximizing neutrons for my top end voltage of 40 kV by driving current. I hope to try this new one in the next couple days.

Tungsten carbide. 12 mm tall, 17 mm inner diameter, 22 mm outer diameter. Definitely my heaviest grid in this fusor and hightest melting point.
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Jim Kovalchick » Thu Apr 23, 2020 12:56 am

Tungsten carbide grid
I walked up voltage on the new grid to -37 kV with no difficulty. There was a little cleaning sparks but not much to speak of.

I did manage to make the grid glow red, but it took a long time to do it at 6 mA. No really bad colors like yellow. Also heating looks even.

Neutron numbers were about as good as I've seen on this fusor, and I did not go to 40 kV.

The real test will be going to top voltage quickly after the chamber is conditioned and see what the numbers look like then.
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Richard Hull » Thu Apr 23, 2020 3:25 am

Great work Jim, I have secretly, and without comment, also changed my grid to a custom made machined titanium cylinder and done very limited fusion with it. (just under 100k n/sec) before the *%$@#! thing arced shutting down the Turbo. I remain very frustrated with the entire cross system, and shall still rip this thing apart, ultimately. I just feel that the tolerances are just too close due to the grid/stalk positions relative to the 6 sharp right angle weldments of the arms. If a 4" six way cross was not so expensive, that might be the way to go, but the smooth warranted spherical system is a proven performer.

I will continue what effort I can with this system until it so frustrates me that without a care, at that point, I will gleefully tear it to pieces. The work is so pathetic that I just haven't the heart to report on it. It is a beautiful system in looks and operation if you like sudden arc breakdowns about the time you think you are getting there through careful operation and a couple of hours of tedious nursing. Yes, it is an easy win for newbies who just want a win and then leave, but for a seasoned veteran attempting to equal and better his previous work it is a study in frustration.

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: Jim Kovalchick -My attempt at smaller fusor

Post by Jim Kovalchick » Thu Apr 23, 2020 10:56 am

Richard,
I too am frustrated, but I remain inspired by Jon Rosenstiel. I am starting to believe though that the man is some kind of wizard.
Regarding the sparks, I have found that the dimensions of the grid are very important that way, but more importantly, I can't rely on glow cleaning to get rid of my sins. I suspect your construction techniques are better than mine, and you have less sparking. I find that as voltage goes up, the glow cleaning sparks are what initiate the nasty arcs. Yesterday, I had to slow down at 37 kV because my grid clamp started sparking too much for my liking, and I suspected I was close to striking a continuous arc. I am going to try baking longer at lower voltages, and I'm confident I will be able to get to stable 40 kV ops.
My new grid was intended to get somewhat close to Jon's dimensions at least in diameter. I also wanted some mass to give it some heat capacity, a high melting point, and a ultra smooth finish. I'm not sure of the overall impact of it, but to me, I think a higher desorption temperature would be advantageous. Picking tungsten carbide gets me closer to my goal. I certainly can't sinter my own WC grid, but why bother, when they sell wedding rings in various sizes for a little over 15 bucks polished? This grid is a size 7 lol.
My neutrons seem to plateau as things heat up. My next goal is to figure out if the culprit is grid heating or chamber heating. I am working on some ideas for figuring it out that involve operations and construction.
More to come.
Jim K
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Re: Jim Kovalchick -My attempt at smaller fusor

Post by Dennis P Brown » Thu Apr 23, 2020 11:01 am

First, very good work on your fusor, Jim. Sorry to hear, Richard but the issues with 'real' small fusors, apparently, can be difficult but that has made Jim's work both rather original and interesting.

This work by Jim makes me think I should re-explore creating a small fusor via my first and rather successful method - using a large fusor but with a small "anode cage".

But that fusor project will have to wait till I build a new building to house my next generation equipment (I also have a lot of research equipment for making my new armor that is based on my revolutionary composite that is a flexible glass.) That equipment, along with the fusor, has my garage filled so I have no room for my car - lol.

I gave up on working on fusors in my Den due to safety issues since that is just too small/restrictive an area. A few months ago I laid out, dug and built the foundation of the new facility but thanks to the virus, have been forced to put that build on hold - also, I've rebuilt many parts of my existing dwelling - apparently, my endurance isn't what it use to be - ;).

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