Alexey's fusor progress

[Richard Hull]

Another warning about oil seals against a direct vacuum.... "oil finds a way"....

Richard Hull

[Alexey Khrushchev]

Dennis, I would not want the epoxy in direct contact with the plasma in the chamber. This could cause it to break down and off-gas. Fluorosilicone is much more plasma resistant, even better than Viton.

Dennis and Richard, the oil will not get into the chamber because the fluorosilicone seal is additionally filled with one layer of JB-Weld and a layer of epoxy. I am sure that the oil container is absolutely hermetically sealed.

Joe, the triple junction is only at the point where the KF25 flange meets the fluorosilicone gasket. There will be an increased electric field strength at that location, but since that location is inside the hole in the glass I would hope that the discharge would not be able to travel to the chamber wall, since to do so the electrons would have to travel at a 90 degree angle, first down the glass surface and then sideways towards the chamber wall. I think this is very unlikely. In my previous cathodes, the electrode came straight out of the hole in the glass and at that point the current burned a Lichtenberg figure on the glass. Therefore, I decided to increase the length of the electrons traveling along the glass surface and to give the trajectory a curvilinear shape.
It is not very clear to me about the current flow on the polymer surface. I tried to avoid this possibility in the design. Could you please draw this on my schematic?

[Dennis P Brown]

JD weld is epoxy and what I use. It does wear down some but both gets a hard outer resistant coating and offers little significant surface area if done correctly. However, your choice. I think the risk is high with that design vs. the down side of a trace bit of epoxy but it is solely your call. Hope it works well.

[Rich Gorski]

This discussion about the problems using oil remind me of a bad experience during my university days in the physics department. Myself along with a couple of other physics students designed and built a 125kV positive ion accelerator. The 125kV supply essentially was a 30kHz high voltage flyback transformer as input to a 20 stage multiplier. Being mostly unsupervised students, on a very limited budget and with very little practical experience decided to use a standard fish type aquarium as a tank to immerse the multiplier in transformer oil. All worked well for more than a year then one day upon returning to the lab we found oil all over the floor. Yep, the seals in the aquarium eventually failed. I guess the oil degraded the silicone sealing material enough to start leaking. What a mess it was to clean up 30 gallons of oil ☹ ☹. I think we went through a few cases of paper towels. However the concrete floor was nice and shiny after that.

Rich G.

[Alexey Khrushchev]

I can put vacuum oil in. I have cheap diff pump oil. It is more viscous and has low vapor pressure in case of that magic leak. I think the insulation properties will be similar.