From: Paul
Date: Fri, 18 Oct 2002 07:44:31 +0100
Subject: Re: [TSSP] Top Voltage
Hi All, There's something wrong with the modeling software. I sat down last night to run some thorough tests against the formula for max gradient between sphere and plane, North rpt, section 7, figure 7-2 and the equation at the top of page 57. Thinking that previous tests have shown good agreement I expected this to be a formality, but what I'm finding is that tssp diverges from north for spheres that are small compared with the sphere-plane distance. In fact, tssp is ending up almost a factor of two high on the field (which leads to breakout almost a factor of two low). That factor of two sound familiar? This problem bypasses any issues over what the breakout field actually is. The model should match the gradient given by the equ on p57 very closely indeed. It doesn't. (It does diverge at small sphere-plane separation too, but this is to be expected when the gap gets down to the dimensions of an electrode surface element. However, it should definately not diverge at large distance. This is baffling because I'm pretty sure I checked this (quite some time ago, when we first started calculating surface fields). The surface field comes out wrong, but the C is accurate...equals a program screw up, somewhere. Something's wrong and I'm an idiot. I'll figure it all out and report back later today, but for now, hold off on worrying further about model/measure discrepancies on breakout. Was too tired to figure it out last night, so either the mistake is in the model, or the stuff I set up last night to run the tests. -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.