Jim Kovalchick -My attempt at smaller fusor

[Jim Kovalchick]

Richard,
The two extra beams I am seeing want to run down the center of the arms. Weird.
I am also concerned about the view port glass, but at this voltage and current the view port did not seem hot to the touch even though the chamber was too hot to touch.

I don't think that the electrons are penetrating micro holes, but I suppose it's possible. The titanium is not glowing red at all, even at the origin points of the beams.

I may try higher voltages or a different gas to see if things change.

Jim K

[Maciek Szymanski]

Personally I’d suspect that due to tight packing and quite complex space geometry the e-field is very anisotropic, so you get some focusing of the ions, and the secondary electrons get accelerated so much, that can’t be deflected toward the anode, fall into the cross arm working like a kind of a drift tube and hit the glass. You can easily check the charge sign with a deflecting magnet.

The secondary discharge looks for me like a typical glow discharge with cathode glow and positive column.

[Jim Kovalchick]

Thanks Maciek. The secondary beams remind me of stuff I've seen in higher pressure plasma. I am very curious what it will look like when I take it up the tail of the Paschen curve.

Jim K

[Jim Kovalchick]

I did my first d runs last night and this morning.

The plasma in my first run was very blue and was likely influenced by liberation of the party balloon helium from the grid and chamber walls. See blue picture.

The second run plasma was more lavender. I ran for an extended period of time between 26 and 29 -kV and around 4 to 6 mA. There is absolutely no sign of grid heating issues, but I did experience a fair amount of arcing that is gradually subsiding. The arcs played havoc with my instrumentation, and it looks like I may have fried a vacuum gauge controller .
At these voltages, xrays were not a big problem except out the view port as expected.

As others have also reported, the chamber pressure is high compared to the same electrical conditions in larger fusors. Much higher and I will be concerned about the turbo. Maybe a diff pump is a better fit.

My neutron indication is not reliable with all the arcing. I do not have a silver foil, but a silver foil did not measurably activate over background.

Jim K

[Jim Kovalchick]

Third d run tonight.

32 kg and 10 mA. Arcs mostly gone. Neutrons confirmed with moderator removal test. Estimate roughly 200 to 300 thousand per second.

Jim K

[Jim Kovalchick]

A couple other notes about the latest run...

Pressure at 32 kV and 10 mA was about 30 mtorr uncorrected.

Also, the fluorescence on my view port is back but no signs of heating. Blowing up a picture of the spot also shows rad speckles on my camera.

Jim K

[Richard Hull]

Great pix and great work. I am pacing myself, allowing all the pioneers get the arrows in their backs. I have already been on the first wagon train out to fusion land years ago. Pioneering the small chambers by trusted old boys teaches well. Plus, the unheated lab is no place to while-away the hours. Mechanical pump oil is like paving tar at 20 degrees. I actually burned out a motor's starting winding a few years back trying to force the issue of starting a freezing cold pump. If desperate, I will put a forced air heater on the pump body for an hour. From what I hear, I might just keep the already mounted and functional diff pump. We will see.

Jon and Jim, thanks for the intro to this work. I am sure I will see the twinkling sparks just as I did in 1997 as junk and micro projections burn off the grid, and in these close quarters, probably the sharp arm joints of the cross.

Richard Hull

[Jon Rosenstiel]

Nice going Jim, and congrats on first neutrons. The cube's pressure while running at 30 kV, 10 mA is around 27 mTorr... quite similar to your setup. And I noticed that the plasma beam coming from the left-hand end of your cathode looks a little thready, may be due to not having the cathode perfectly square (concentric) within your device's bore. (These things seem kind of touchy that way)

Jon Rosenstiel

[Jim Kovalchick]

Jon,
My beam is oriented vertically, but unless you open the image by clicking on it, the web page displays it 90 degrees off. Either way, I see the beam you are talking about. It looks like the intensity across the beam makes it look like a double beam. Perhaps you are right that my sloppy set up is affecting the beam. I'm going to leave it for now and see if my neutron numbers improve with more run time.
Thanks

Jim K

[Jon Rosenstiel]

Jim,

It'll be interesting to see what the neutron numbers do with increased runtime. With my cube the neutron numbers changed very little (if any) with increased runtime.

Jon