Re: Triggered Spark Gap

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

Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ludev-at-videotron.ca>

Hi Kelly & Phillipa,

I need to remember not to start my post by "Hi guy" any more we
have a women on the list now ;-) welcome.

Some commercial trigger gap are trigged by light, most of the
time they used only an open arc near the main gap.

Cheers,

Luc Benard

Tesla list wrote:
> 
> Original poster: "Kelly & Phillipa Williams by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <kellyw-at-ihug.co.nz>
> 
> Dear All,
> 
> While reading my physics textbook this week I came up with a really neat, if
> fairly esoteric, idea for a triggered spark gap.
> 
> All metals have a certain energy barrier preventing electrons from leaving
> the surface of the metal. (Analougous to a rounded curb at the edge of a
> flat road, it keeps a slow-moving soccer ball on the road unless it is
> kicked hard enough.) This energy can be provided by heating the metal very
> hot (thermionic emission),
> 
> Or by bombarding the metal with photons (light) of a high enough frequency
> so that when an electron on the surface absorbs a photon, it jumps off the
> metal.
> 
> Now suppose an enclosed spark gap in a box, surrounded by an xenon
> flash-tube or similar source of light.
> The electrodes a slightly too far for the voltage to jump alone, but when
> the tube flashes and the electrons jump off the metal they ionise gas and
> fly across to the other electrode, thus initiating the spark. I know this
> effect occurs in a slight vacuum, but I would have to investigate it's
> effect in air.
> 
> The only problem is that the cut-off frequency for this emission for many
> metals, and tungsten too I would imagine, is in the ultraviolet range and
> slightly above.
> 
> Could those with a working knowledge of x-ray tubes tell me whether an x-ray
> tube can be PULSED at 100 (50 Hz)
> or 120 (60Hz) to trigger a gap like this? Forced air quenching may also be
> necessary, although this technique could be applied to a single static gap
> all the way through a multi-gap-static-gap, provided the metal of the gap
> itself was exposed.
> 
> I would very much appreciate knowing whether vacuum tubes can be pulsed -
> maybe a pulsed supply to the x-ray tranny, would that work?
> 
> Best Regards,
> 
> Alan Williams