Fusor Forums

Below are some images of electrical activity when the pressure in the fusor is just barely too low for sustained glow discharge .

These are typical events in temporal order of a sustained plasma "strikes" and sustained continuous glow operation.

The last two photos are almost always look the same no matter what the initial visible electrical "tickles" are like. Those intitial "tickles" though are vastly different in location and appearance. See upcoming photo posts for those images.

Operating conditions were 40 KV at 2 ma. Pressure change between the top and bottom frames were miniscule as the first frame is right on the edge of sustained plasma formation at the operating voltage/current condition. Frames are 33.4 ms apart.



Frank Sanns

Hey there, Sir Lancelot!! You've got th' dragon clearly in your photographic sights.

Very nice pictures....Glow discharges in all their colors, have to be considered an high tech art form.

Do I presume correctly that these are from a hi-rez video of the plasma operating in the flickery, unstable mode.... when you're running up the left (low pressure) side of the Paschen curve?

Thanks for sharing these.

Dave Cooper

Yes, the photos are from movie stills on an HD camera taken at 30 (29.97) frames per second at taken on the left side of the Paschen Curve.

Here are some of the various failures to "light" photos whose duration was around for one frame only at 34 ms. Notice that the plasma does not go INTO the center grid on all of these but it is like a flint trying to ignite the inner grid to form a continuous glow discharge.

My chamber is NOT symetrical yet the attempts to start a plasma come from all directions.

I hope I do not over post the photos but I think much information is contained in these. More specific posts will follow.

Frank Sanns

The route to a stable glow plasma has an initiation phase, a development phase, and a stable phase.

Below is the same photo in the initiation phase but an incomplete development phase as the glow is not sustained after the 33 ms of this capture. It is at the low pressure, high voltage side of the Paschen cuve.

The first photo is just one of many that show this effect.

The second photo is a blow up of the left side of the fusor. It can be seen that an electron beam is being masked by the outer aluminum lattice grid and it is projecting its image, via fluorescence, onto the pyrex bowls.

The last photo is ray tracing from the patterns on the pyrex back through the holes in the outer lattice grid from whence they came and finding the intersections (origins) of the rays.

It can be seen that the electrons have a source either inside (possible) of the inner grid or the inner grid wires themselves (most likely).

Feel free to trace your own lines and make your own conclusions.

Frank Sanns