Extreme High Voltage: Electric Grid Connection as Cathode

The Copper-screen Grid is now electrically connected.

I broke the system down and installed another feedthrough in the plastic base. For the feeds I am drilling and tapping a hole in the top plate, thru the reinforcing lower plate, and tapping for 1/4-20 thread. Then I apply Permatex sealant to the threads of a threaded brass rod and secure it in the hole with nuts and washers on both sides. This seems to seal fairly well and provides plenty of mechanical support, as well as some heat-sinking. The electrodes do get hot!

So I tried several hookups and found this one the most interesting of the ones I tried. I’ve hooked the center sphere and the outer ring together as anodes and the grid as cathode. You can see what happens in the video.

I’ve also included a couple of interesting stills at the end. At one point I tried a “corona motor” in the chamber. It only worked as a motor when the pressure was at ambient or a little below, but at the max vacuum it got interesting, if stationary. The blue cathode glow fills the entire chamber apparently uniformly, and the anode wire has these stationary white tufts clinging to it. I think this is as close to St. Elmo’s Fire that I have come. The ordinary blue cathodic corona doesn’t really fit the legendary descriptions of SEF, but the way these anodic tufts appear, embedded within the general cathode glow, is uncanny. Even ghosty.

Also, in larger anodic discharges at somewhat higher pressures, I often see these concentric shells in the emission. Even from the tips of the corona motor, these shells or “striations” can be seen. Since I can move all around my transparent chamber, I can tell that these dark and light bands are the boundaries of nested shells in 3-d. They must be following equipotentials in the 3-d electric field, but I have no clue as to what accounts for their spacing, regularity, and persistence. I have ruled out interaction between the vacuum pump pulsations and the approx. 38.5 kHz flyback output ripple…. the “striations” or shells occur even when the vac pump is off, as in the image at the end of this video.

I am going to try filtering the flyback output with some HV capacitors, to see if the shells persist even with smooth DC supply. But that gets kind of scary — capacitors at high voltage I mean — so I need to think about it for a while first.

DANGER WARNING: You can easily kill your sorry self doing this crap, in two or three distinctly different and painfully spectacular ways. I am not responsible for dealing with your crispy remains or your burned-out shell of a home. I will however gladly adopt any furry fourfooted pets that manage to outlive you. So go have fun.

YOLO. Seriously.


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