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Re: Sparklength inquiry





>Original Poster: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
>
>I think there is an inherent problem with trying to measure
>length/power:
>For example, I have got to a foot of airstreamers under repetitive
>conditions with Ep around 0.6J and BPS=100  (= 60W!). Now, with just
>1 BPS and 3.5J I can also get to one foot (=3.5W!).
<SNIP>

My first big coil generated an average of 72" running at rep rates of
approx. 100Hz, and single shot lengths of about 48". In each case the
primary cap (0u1) was charging to 10kV, which represents a stored energy of
5 joules.

This highlights Malcolm's comments, in that he suggested that a fixed amount
of stored energy is used per gap-firing, and the gap firing-rate is then
adjusted. This will then show the relationship between output arc length,
and power developed in the primary.

A nice way to do this might be to use a three-terminal gap. Then the trigger
electrode of the trigatron could be fired when the voltage across the pulse
cap has reached a threshold. In this way, although gap quenching might not
be optimum, at least we could guarantee that the energy per shot is fixed.
The charging rate and hence the firing rate could then be adjusted and a
relationship between rate and length could be determined.

Richard Craven, Malvern, England