Thread: Vacuum Spark Gap

I am interested in purchasing a vacuum spark gap to replace the air filled spark gap that I am currently using in my 250 KV Tesla Coil. I have been unsuccessful in finding a dealer or manufacturer of vacuum spark gaps. I did not find a vacuum spark gap on ebay. I would appreciate any advice or knowledge of where to buy a vacuum spark gap.

David

I admit I am curious drumfunk. I didn't think you would get a spark in a vacuum. I thought you needed a gas that would ionize and that these charged particles then allowed a path for current to flow. In doing so, the gas path heats up, glows visibly and is seen as a spark.

I could understand the electrodes offering electrons to a vacuum in a strong electric field. Is this the mechanism a "vacuum spark gap" would use?

If so, and at 250 kV/Tesla Coil you might be able to string some vacuum capacitors in series. These are used at RF and very high voltages and might "act" in such a fashion if their breakdown voltage is exceeded. However will the conduction be internal or just an external arc around the outside casing (glass, perhaps ceramic)?

Also I'm curious, what do you want 250 kV for? Are you making a "Mad Man Markus" time machine?

For an explanation of a vacuum spark gap check out http://en.wikipedia.org/wiki/Vacuum_arc

I want a vacuum spark gap instead of a normal air filled spark gap for my Tesla Coil because a vacuum spark gap does not form ozone when a discharge occurs unlike the air filled spark gap. Ozone is a poison; therefore, I prefer the vacuum type.

Thanks for your reply,
David

Yes drumfunk, I thought that was the discharge mechanism. If you were a home hobbyist with limited cash flow I might suggest digging up a number of old thrown out TV sets and wiring their TV tubes in series over a glass insulating support. These have a "hard vacuum" and operate on about 15 kV when their filament is heated (no need to do this). Also, the HV diodes could be used - these have to withstand 30 kV when the input AC reverses polarity and the 'tube retains its charge. I'm unsure if the breakdown VI is "sharp" but the approach might give some regulation without costing anything (assuming old Black&White TV's aren't antique collector items by now!)

Still 250 kV sounds more like a commercial venture

I think he already possesses the 250kv transformer.

Where did you find it? The highest I've found on Ebay was around 120Kv.

You can actually buy a material that converts O-zone to another harmless chemical.

You can probably find the specifications for the spark gap distances in a specific vacuum. I would recommend building it yourself from a very large burnt out bulb. Some of the commercial bulbs should be easy enough to find if you ask a maintenance person at your workplace, schoolplace, etc. You can create the vacuum with some heat and then epoxy the cap/electrode assembly on. Try to make it so the gap is adjustable after the bulb is sealed.

Are you just trying to make it more compact? Why do you care about a vacuum spark gap?

Originally Posted by drumfunk

For an explanation of a vacuum spark gap check out http://en.wikipedia.org/wiki/Vacuum_arc

I want a vacuum spark gap instead of a normal air filled spark gap for my Tesla Coil because a vacuum spark gap does not form ozone when a discharge occurs unlike the air filled spark gap. Ozone is a poison; therefore, I prefer the vacuum type.

Thanks for your reply,
David

Could you argon or helium fill the tube?

I have never tried an ARC in a sealed tube of argon and helium. But I have made thousands of arcs in argon and helium being feed a constant supply, of argon and helium to keep the area being heated, from being exposed to the atmosphere.
And to carry away any contaminants in the molten metal I create, as the contaminants evaporate. This is done at a pressure just slightly over atmospheric pressures. Probably fractions of an inch of static pressure, very low pressures, just above atmospheric pressure.

You should probably keep the container very small, for safety.


Sincerely,


William McCormick