--- On Tue, 6/16/09, John Berry <[email protected]> wrote:
> Yes, though Gray has air and hence no inner tube between > the plasma and the metal terminal. What is he using as plasma? Corona? > > The outside of the envelope is metal > > foil. > That should work however everything indicates that the > results will be better if wire is used as it's > capacitance will not be greatly diminished but the contact > with the escaping charges will be reduced. Aluminum window screen then, if foil doesn't work. > This part is not a mystery, if the gas is not in a plasma > state, not a conductor then we have a single plate. > This raises significantly the voltage and energy of the > remaining plate. I understand that it will raise the voltage, more or less the same as if you charged a two plate capacitor and dragged the plates apart. As capacitance diminishes, the voltage on the plates rises. But in a situation where one plate more or less disappears, not sure. Have to think about this. If something unusual *does* happen, well, then things get very interesting. > Please note we want smooth, Stiffler used a medical HV > source as noisier options with ripples failed. Is it necessary to have a smooth DC exciter? Or just a smooth DC charging supply? Suppose we use a tube like a blacklight, a Wood's glass tube with a mercury vapor discharge inside. No phosphor usually there, AFAIK, so nothing to cause a problem. We wrap foil or screen around the glass envelope of the tube, this is plate A. Plate B is made when the gas inside is excited to a plasma. A DC potential is applied across this odd capacitor, plasma becoming the negatively charged "plate", foil/screen becoming the positively charged plate. But to excite the plasma into conduction, what if we used a separate 'exciter' supply? A brief HV pulse is used to ionize the gas in the tube, then a 'keep alive' current flows from one electrode (those built into the tube from the factory) to the other, keeping the gas ionized. The DC potential is placed then across the "capacitor", charging it to an energy of 1/2CV^2. At that point, the keep-alive supply is switched hard-off, maybe via a fast MOSFET. The plasma is gone, and the effect, if any, happens. We then repeat the whole cycle. Closer? Note that the keep-alive and exciter supply can be made battery operated, and isolated/floated at HV. Matter of fact, it doesn't even have to be a Wood's glass blacklight tube, I reckon a neon tube or bulb would work. > One thing though, Hiddink said that bulbs with a coating > would not work probably because the coating acts as a > capacitor plate? Not all phosphors are conductive. Some possibly are, but I'm not certain. To be safe, I'd start with a blacklight bulb. Behind glass, in case of excessive UV release. > Personally I favor the plasma having an absolute negative > potential while charged as I imagine electrons being easier > to have "fly away" than a positive charge, but for > completeness both should be tried. Can do it either way. I tend to make mirror images of most supplies I build, so if I have something making +10kV, I probably have a reverse supply somewhere. > The metal "plate" will function better if it is a > mesh or wire grid, we want capacitance but with as little > coverage as possible. (Stiffler confirmed mesh worked > better) > > Stiffler initially failed to get the effect when using a > regular HV source and only when he switched to a medical HV > supply for it's low ripple did he get any results. Low ripple is not hard to get, we just need plenty of smoothing caps. They can be pricey...but in a pinch, can be made at home. > Finally we want a very swift disconnection and Stiffler > seemed to agree with Hiddinks patent that disconnection at > both ends is desirible to de-excite the plasma fast. Too late tonight to go get a Wood's glass tube, but I can grab one on the way home from work tomorrow, do some tests. Matter of fact, I might try some things with my neon bulb now... --Kyle
