From: "Malcolm Watts"
Date: Mon, 14 Oct 2002 13:24:42 +1300
Subject: Re: [TSSP] Top Voltage
Hi Paul, On 13 Oct 2002, at 23:33, Paul wrote: > Boris wrote: > > 1" sphere will have much higher surface field > > (multifold) for given voltage than 1" thick wire > > (which is long ,"perpendicular" to ground plane (at > > average height say 10 m). > > In support of Boris's answer, the familiar bathtub > shape applies to the long horizonal wire over ground plane, > (both distributed C and charge distribution) so the > surface field over most of the conductor may be quite > a bit less than you'd expect just by its radius. > > Malcolm wrote: > > The absolute losses in the secondary ground path are increasing as > > base current goes up. Too early in the morning for me to look from > > the point of view of percentage losses. Does this make sense? > > Not entirely, although the absolute losses are going up, the > Q should remain constant, or increase slightly. The slight > increase comes from the assumption of a constant saturation > voltage of the IGBTs, so that the VI loss in the devices > becomes a smaller fraction of total loss as the current > goes up. Which of course I realize and have espoused in the past. My mistake - I thought the post was referring to the Q of the secondary alone. Told you it was too early in the morning. Regards, malcolm > As Vfire is raised from 25V to 300V we would expect the > Q to first rise as primary device loss becomes less significant, > then would start to fall as streamer loading takes over. > Seems that we may be seeing that fall start as early as 100V? > Wonder if if rises before that. > > Terry, have you looked in the dark for signs of early > breakout? > > Oh well, too late at night for me at this end. I'll have > to recompute things using a revised secondary Q, but it's > not going to make more than a few % difference, I think. > -- > Paul Nicholson, > -- >
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.