From: Paul
Date: Sat, 11 May 2002 12:21:42 +0100
Subject: Re: [TSSP] Topload breakout potentials
For John's TT42 that we're looking at the voltage stresses on, tcap computes a maximum surface gradient of 0.051 V/cm/V occuring on the outer surface of large (upper) toroid at a point 24 degrees below the 'equator' of the tube's cross section. With an estimated 590kV peak topvolts for a 4J bang, that gives a peak surface field of 590 * 0.051 = 30kV/cm. For Bart's coil which we're also looking at on another thread, a 15.3 kV firing evolves 460 kV on the topload. The max surface gradient for Bart's topload is 0.026 V/cm/V at an elevation of +20 deg, which gives a field strength of 0.026 * 460 = 12kV/cm. These figures suggest that John's coil would break out much earlier than Bart's, and would perhaps produce more but shorter streamers. Assuming a smooth toroid and a 26kV/cm breakdown threshold, it looks as if Bart's topload shouldn't be breaking out at all without some assistance from a breakout point. I wonder if these characteristics are bourne out in practice? -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.