From: "Malcolm Watts"
Date: Mon, 6 Nov 2000 09:14:48 +1300
Subject: Re: [TSSP] NSVPI - Latter Results
Hi Paul,
On 5 Nov 00, at 18:33, Paul wrote:
> Malcolm Watts wrote:
>
> > My research on primaries suggests that the performance
> > differences between a bad secondary and a good one can be quite
> > significant (remember that I said that when we quantitatively find
> > out). Firing seems to bear this out also. There is no doubt a bad
> > primary can be a real drag on performance (also shown in practice)
> > but if it's a good one, the secondary should also be good.
> >
> > There is a way of trading one off against the other. If you
> > examine the beat envelope of the secondary e-field (no breakout so
> > no losses from that source) you will find that a good secondary will
> > show the linear ringdown of the primary dominating the envelope. If
> > you find that your envelope has a log ringdown, it means secondary
> > losses are dominating. It is obvious from this simple test where
> > improvements should be made to a given system.
>
> That's a neat point. I take it the linear ringdown is due to
> the resistance of the gap increasing as current decreases?
It is (taking an integral view/time of behaviour rather than a
nanosecond type examination of relaxation phenomena noted by Terry
which may be the detailed reason for it).
> What's the recipe for a high Q primary - a high voltage,
> small C, large L, or the opposite with a hot, high current arc?
The first. If you buy the notion suggested by a crude analysis of
that behaviour that gap loss is predominantly V.I rather than I^2.R
and that Vconducting is approaching constancy, you can see why.
My expts also suggest (and appear to be well supported by the
experiences of others) that as one moves to the high L/C - high V
regime, quenching type #2 (avoiding power ARCS) becomes more and more
of a bugbear. John Freau is one excellent experimenter whose
experiments with high L/C primaries have seen his efficiencies climb
markedly.
Regards,
Malcolm
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.