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Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Sat Jan 04, 2020 3:35 pm
by Jim Kovalchick
Some interesting and bothersome results. At 38 kV and 10 mA I recorded roughly 750,000 neutrons/sec. I noticed that it appears that my neutron probe saw significantly more neutrons at the lower end of my chamber corresponding to one end of the beam. There were some on the opposite end but not as much.

I also noticed my chamber outgases a lot as it heats up. I think maybe it's my titanium grid.

I did a second run at 38 to 40 kV later today and neutron numbers were way down. Even pictures I took were noticeably less speckled. I moved my gas to throttle ratio to flow more d with no improvement. Hmmm.

I have an idea for a new grid design that does not involve titanium and has only one opening...a cup grid. This will have to wait because it's back to the grindstone for me.

Jim K

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Sun Jan 05, 2020 2:13 am
by Jim Kovalchick
With poor results from my last grid I decided on another approach. This time I used a coil of tungsten braided wire. This grid does not make a tight beam, but I'm happy with the proof of concept. Some minor design modifications should fix it.

Jim K

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Sun Jan 05, 2020 8:32 am
by Richard Hull
Did you get that twin braided W wire from the "orphan pile" at Midwest Tungsten? I picked up 20 strands a few years back of that double twist wire and it has been the grid in fusor IV for about 5 years. Works great!
I enjoy your reports on your project and the issues with the system. It will help me a lot.

Richard Hull

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Sun Jan 05, 2020 8:43 am
by Jim Kovalchick
Richard,
Yes, from the orphan pile. Sadly, it appears that the orphan pile web page is gone. I gave some of my pieces away and still have a few. They are perfect for our work.

Jim K

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Tue Jan 14, 2020 1:39 am
by Jon Rosenstiel
Jim,

As to outgassing, was your titanium cathode pure Ti or an alloy? (The one I made was an alloy, 6Al-4V)

Jon R

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Tue Jan 14, 2020 2:11 am
by Richard Hull
Good Question Jon! I have some 3n6 1/2" rod stock. The alloy sold by many suppliers is to allow for a more machinable product without hampering strength.

Richard Hull

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Tue Jan 14, 2020 5:42 am
by Jim Kovalchick
Jon, I wouldn't be surprised if it was, but I don't know if the titanium I used was an alloy or not. I bought a small sheet of it at a past HEAS. I think from T.R. Leary.

I'm away from my lab for a while now to check, but I think the sheet had some numbers and/or letters etched on it.



Jim K

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Fri Jan 31, 2020 8:57 pm
by Jim Kovalchick
Trying yet another grid. This one is a simple piece of stainless tube. Not a lot of neutrons yet.

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Fri Jan 31, 2020 11:23 pm
by Richard Hull
Absolutely lovely!! Too bad about the lagging neutron production. I am glad good old fusor IV is standing by just in case fusor V disappoints me. I have just finished mounting my Turbo, (positioning it and bolting it into place). I hope to test it at its head soon. My fingers are a bit numb in the 35 degree lab. If the turbo disappoints, well, I have the diff pump all cleaned and standing by as well. It is all wait and see while giving the system every opportunity to shine.

Jim, I hope your system climbs over time. Hopefully, some wall effect D2 absorption can work its way into climbing numbers in your system.

Richard Hull

Re: Jim Kovalchick -My attempt at smaller fusor

Posted: Sat Feb 01, 2020 1:12 am
by Jim Kovalchick
Thanks for the words of encouragement Richard. I'm sure the numbers will come up. Best of luck with your next fusor. Spring and warmer temps are coming soon!

Jim K