Running The Fusor on a single charge of Deuterium?

[Tom Dressel]

I have spent the last few months trying to get a really tight vacuum system. The pump down consists of starting with the chamber valved off from the night before and at ~5 microns. Then I start Welch 1400, pumping the foreline down to 5 microns and I can hear no burping sounds, just the click of the reed valve. Then I start the diff pump and cold trap refrigerator. The diff pump starts working at ~150 deg. F. but I wait until the cold trap is ~-105 deg. F. Then I can open the chamber valve and the pressure will drop to 0.0 microns. I usually heat the chamber and the line from the diff pimp and chamber up with a heat gun, hot enough so I can barely keep my hand on them. After about 15 minutes, I can then close the chamber valve. The chamber will leak to about 5 microns in 24 hrs.

Last night, 48 hrs. after the last pump down, with the chamber at 12 microns and valved off, I turned on the high voltage supply, and the pressure dropped back to ~3 microns with a VERY stable star mode, no diddling with the valves. Tonight, with the chamber at 12 microns (69 houres after the pump down) I started the high voltage supply again, and again, I had a very stable star mode at 4 microns 9 KV and 10 ma. for 30 minutes again with no diddling with the valves.

I was wondering if it may be possible to pump the system down, back fill with deuterium at say ~100 microns, pump down to 15 microns and let the high voltage supply pump the chamber down to a stable star mode with everything valved off. This may be one way to get very stable fusor operation. Or do I need a constant supply of deuterium?

Tom Dressel

[Richard Hull]

Tom,

It sounds like you have a nice system there.

It is certainly possible that once pumped down to near diff pump levels, (10e-5 torr or better), and all leaks are sealed, that you might be able to just fill to 100u with D2 and then pump again to a few microns. If you back fill to that low micron level and the pressure doesn't rise much, then you should be able to run a closed fusor. This would indicate a really clean system indeed.

However, you WILL bury D2 and the pressure WILL drop as you raise your voltage to fusion levels. After a while you will reach a level of pressure where the thing won't stay lit. You will have to readmit, on the fly, D2 gas as needed to cover your loses due to ion pump action.

If the above is the case, expect a percipitous rise in gas pressure once the sealed off fusor is cooled off as the D2 outgasses from the walls and grids. Still, there may be a static equilibrium is a perfectly sealed system where just restarted at the higher pressure will bury to the point of good operation. Thus far none of us, even Joe Zambelli has had such a system. You may break the mold. Keep all of us closely informed on this.

With my somewhat leaky system continuously flowing D2 works well and I have become adept at operation with vacuum pumps in constant operation and leaking in D2.

Richard Hull