UPDATE #7 Hull-Raney Ion Gun Construction

[raneyt]

Guys,

I got side-tracked with other projects the last month: Marinov motor and Tesla thermo-magnetic motor. At other times, I've had to do house "chores" and the rainy weather hasn't helped.

The ion gun is now completely assembled with hard vacuum epoxy seals coated with Vacseal. Ultimate pressure so far has been 35 mTorr. However, I think the Pyrex has adsorbed a lot of water and it's not fully desorbed during the short pumping runs.

I my have to heat the whole assembly in the oven for a while; it can go up to about 100 degrees C or so. That may help a little.

At the 35 mTorr, I still cannot discern an ion beam. However, the ion gun almost "blacks out" then and its operation becomes erratic (similar to a "conventional" Fusor). I'll connect the voltage multiplier next...after I get rid of those pesky water molecules.

Below is an extract from my lab notebook, FYI. As I mentioned above, I've completed the work summaryized in the notebook.

Good luck in your experiments!

Reagards,

TIM RANEY

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Ion Source Fabrication Notes: Leak Detection. The prototype ion gun has been completely assembled for some time now. However, several iterations of "leak hunting" have failed to result in pressures below 50 mTorr. At these pressures an ion beam is not discernible. So, I've decided to disassemble the current configuration. I will replace the Viton o-rings, G-10 glass epoxy rods and RTV seals with "hard" vacuum epoxy seals. The original intent of using o-ring seals and tie-rods was to simplify system modification and allow for differences in the glass-metal joint coefficients of thermal expansion. However, this is a prototype system and I don't anticipate long run times where glass-metal joint heating will be a problem. If so, the epoxy seals should allow a little expansion. I won't run the ion gun any longer than the time it'll take to determine the ion beam current.