Jim Kovalchick Plasma Club entry

[Jim Kovalchick]

Tonight I lit my first plasma in the new fusor. I used air at -5 kV. My current indication failed, but it didn't look too high based on the color of the grid. There was a few brief moments of minor sparking when it first lit, but otherwise the plasma seemed very stable. On this chamber arrangement, pressure indication was 9 microns. I suspect actual pressure at point of ignition is a little higher than that because I admit gas at the base of the power feedthrough and my baratron connects near the exhaust. As I was shutting it down, the plasma stayed visible and stable even down to just below a -1 kV.

Next steps: I need to fix my current indication and condition the chamber to higher voltages.

[Richard Hull]

Good startup Jim! There is a huge on-off voltage hysteresis with gas diodes. (fusor) This is normal. Higher strike voltage than maintain voltage. Simple little NE-2 lamps are a prime example and use this feature to make ultra simple astable multivibrator circuits. GM tubes in the early days relied totally on ultra high ohm resistors to buckle the fixed supply voltage/current in order to quench the ionic discharge prior to modern fill gas auto quenchers. Fun stuff, gas tubes at reduced pressures.

Richard Hull

P.S. thanks for the diodes.

[Jim Kovalchick]

http://youtu.be/Ru9L6PASJGc

[Jim Kovalchick]

Here's another progress picture. I've switched over to deuterium now for chamber conditioning. This is at -18.5 kV and 9.5 mA. I can tell I am still driving out chamber water because the current drifts a little and flash pressure is increasingly higher for a given voltage . Still a ways to go before my PNC-1 will be called out to play.

This picture was taken in a mirror behind the fusor because I intentionally pointed it at the wall instead of me. This also gives a good look at the way I fitted the sacrificial pyrex inside if the view port using aluminum foil stuffing.

[Richard Hull]

Jim, Thanks for the continuous photo updates. the fact that you are at 18kv and 9ma and haven't melted your grid shows that you are on your way. Glow cleaning usually runs the entire grid red hot like in your picture, but at only 5-6kv and 20ma! You have a decent vacuum there.

That nice big viewport will turn purple brown real quick once real fusion is being done and in rather short order go more of less opaque to most visible light, but oddly not to IR. Making most simple video cameras able to see through in effective B&W only...Even if they are color cameras.

To clean viewports - The best way, is by abrasion. I tend to use "mothers" chrome polish, (auto stores), as it is an aluminum oxide paste. A little elbow grease over about 20 minutes should have it cleaned up.

Smart move with the mirror. That will be a nasty x-ray port if you get to the mega mark or even near it. I am sure you have it directed "down range" like out into a direction of a large open back yard. Fortunately such opeartions are limited in run time and the house/garage wall and the inverse square law tame the blast to a trivial level rapidly. As you know, I have my 1" diameter view port pointed down into a concrete ground floor.


Richard Hull

[Jim Kovalchick]

I ran the device again this morning. Managed some operation at -24 kV. I made a quick measurement with our PNC-1 and saw 30 cpm. I am not petitioning for the club yet. I will do that when I can photograph a moderator test.

I did notice that an aluminum cap I made for an a small Wilson fitting on the front of my fusor streams a tight little beam of x-rays. I need to fab up a little lead or steel cap for it.

[Richard Hull]

Jim you are now in the Plasma Club listing and it sounds like you won't have your name there long. Your past experience with your son's effort and success at admission into the Neutron Club gives you a leg up in fusor operation.

X rays scatter to a degree and a low Z material like aluminum, rubber, plastic, etc., anywhere in the device can be a leak for x-rays. I note this in my first fusor video produced back in 2000 and show an example of such leakage from fusor III.
As you note sheet lead is a handy and simple solution.

You have detected the leak with proper gear and will solve the issue quickly. We can't overstate the need for proper detection gear by anyone serious about building a full fusor.

Richard Hull