Re: vacuum spark gaps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>



>Original poster: "Jason Johnson by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<hvjjohnson13-at-hotmail-dot-com>
>
>Will vacuum spark gaps work in a tesla coil?

Hi Jason!

That is something I have wanted to try for ages.  They should be very efficient
indeed.

The American inventor, Mr. D. McFarlan Moore, patented around 100 years ago a
new lighting system based on low pressure gas discharge tubes, the power supply
for  which was basically a 'kicking coil' plus Wagner/Neef-hammer-type contact
breaker (as per induction coil) which had the contacts mounted in a vacuum.
 The
great benefit of his system (which amongst other places was installed in the
Savoy Hotel, London) was that sparking at the contacts was eliminated, without
the need for a Foucault-type condenser across the points, and contact point
wear
with it.  This of course was because the back emf from the coil has nothing
ionic to conduct it across the widening gap between the contacts.

In a vacuum gap the flashover happens by field-induced free electron emission.
The gap ought to quench very promptly (electron emission will stop pretty
sharpish once the field sinks below a particular level) and shouldn't have too
much by way of overheating problems, especially if there is external
heatsinking
by way of fins or whatever.  Should be excellent for a small coil.

I'd be very interested to know how you get on.  I've wanted to try this for
ages
but have no vacuum pump!

Dunckx