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Re: Spark Gap Gasses Experiment



>Jim, this must be some older technology. I have been working with
>radar from a few kwatts to 5 megawatts for the past 10 years and have never
>heard
>of a trigatron.

Trigatrons are still in demand and are made in quantity by EEV and EG&G.
They are low-jitter with simple trig arrangements and low pre-fire. As you
say, they don't turn up in radar apps because radars are generally low power
cf. what you use trigatrons for, and also trigatrons are not generally run
in the same high rep-rate conditions. They are often used in low rep
applications (laser firing, FXR, EBW stuff).

There are lots of derivations on the original three terminal gaps now, but
in terms of bulk coulomb switching there is nothing to beat them. Thyratrons
are an O-M below trigatrons in terms of peak power switching. Although
three-terminal gaps could be used in TC apps ( I have played with using them
in a dc charged cct ), they are good at switching on accurately but not good
at switching off. You have to use all of the multi-surface, gas-flow
technques as being discussed at the moment. Seeing as that is the case, you
end up using two terminal gaps and using the self-break characteristics of
it to get the best effect.

However, someone recently came up with the excellent idea of using a length
of RG213  (URM67) or RG6 inner as the third or trigger electrode on a Cu
pipe series gap. That way, you could promote synch. triggering to occur by
changing the phase angle of the trigger pulse relative to the mains charging
cycle, or you could use a dc supply to change the peak P available.


Richard Craven, Malvern, England