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Re: Triggered Spark Gap



Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

I think UV radiation alone will get the job done. The
notion of a UV triggered gap has been visited before
on this list, but I never heard of anyone building a
working example.

Small, short wavelength "hard" UV lamps are available
as replacement bulbs for EPROM erasers. I've seen them
surplus for a few bucks. Likewise, and ordinary spark
gap in air creates UV. Perhaps a small "trigger" spark
gap and a main spark gap located physically near each
other could do the job. UV from the "UV source" gap
could illuminate the main gap, triggering the main
discharge. This might allow a fairly small,
low-powered spark gap to control a much larger,
high-current main gap a short distance away.

Another interesting idea is a rotating opaque disk
with one or more holes in it. The disk would mask a CW
UV source, allowing it to illuminate the main gap only
when a hole lines up--sort of a rotary UV gap.

Actually, the recently popular 3-terminal triggered
spark gap is so simple and effective, I'm not sure
what the benefit of a UV triggered gap would be.

Regards,

Greg
http://hot-streamer-dot-com/greg

--- Tesla list <tesla-at-pupman-dot-com> 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
> 
> 
> 


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