From: Paul
Date: Wed, 27 Jun 2001 23:28:03 +0100
Subject: Re: [TSSP] Toroid breakdown voltage indirect meas.
Malcolm Watts wrote: > This is generally observed on all coils. I watched Greg Leyh doing > some single shot tests on Electrum. 34kV - no streamers at all. 35kV - > 7 foot single-rooted air streamers with the usual multiple branching > at the tips. There is a well defined voltage required to cause > breakout for any given configuration. It is most pronounced with a > large emitting surface (virtual, as in the case of Electrum's topload > with its welded bars, or real "filled in" surface). That's marvelous to hear. Fits in perfectly with the understanding I've gained from reading Bert's posts about the breakout threshold and streamer formation. Once that 26kV/cm is reached at the surface, the streamer(s) can immediately form to considerable length. That seems to imply that any given toroid has associated with it a minimum streamer length. Depending on your coil and voltage, you'll either get no streamers, or streamers of at least this length. I expect Bert would say that this minimum streamer length is a function of the stored topload charge and minimum radius of curvature. What happens when the voltage is raised above the breakout threshold, do you get longer streamers, or just more of them, or both? Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.