From: "Malcolm Watts"
Date: Tue, 3 Jul 2001 08:42:31 +1200
Subject: Re: [TSSP] Toroid breakdown voltage indirect meas.
Hi Paul, On 2 Jul 01, at 11:59, Paul wrote: > 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. I've decided to set up a coil this coming Sunday to see this again. I will make the pertinent observations and answer the other questions below. > 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? I've seen daylight affecting the striking voltage of neon lamps. I wouldn't know how such an effect affects TC operation. Regards, malcolm
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.