From: Paul
Date: Mon, 02 Jul 2001 11:59:28 +0100
Subject: Re: [TSSP] Toroid breakdown voltage indirect meas.
So we have observations of a blue/violet 'cloud', diffuse, very faint, Malcolm wrote: > ...on closer examination looks like faint streamers emitted in all > directions but of the same order of radius as the eventual streamer length, occuring at a voltage distinctly lower than that at which obvious streamers appear. If we can observe this effect and at the same time apply a direct top- volts measurement, we can try to relate it to the toroid surface field strength. We do have a problem already with this surface field issue, in that Thor does not break out at the point we think it should - at a Vpri of 14.7kV. We can surely trust the Vtop estimates based on this, since Thor remains below breakout and there is no significant corona. We may have to look at the field calculations again and try to cross check them, but this is a clear and large discrepancy even without a direct Vtop measurement. Malcolm wrote: > It is very close to what one would consider to be the breakout > threshold. Are we talking just a few percent below the the breakout volts, or as much as 10 or so percent? Of course, it would be very nice if Marco reports observation of this faint aurora at say 16 kV. Does anyone know anything about photo-ionisation? UV photons emitted by relaxing ions in the streamer passing some distance through the air to ionise an atom some way away, thus seeding a new electron avalanche from that point? Does this phenomena play a role in TC discharges? Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.