From: Paul
Date: Tue, 15 Oct 2002 07:28:58 +0100
Subject: Re: [TSSP] Top Voltage
Terry wrote: > I see that dual slope waveform a lot but I never > realized what it meant, till now :-) Yes, there's a distinct knee to the ringdown in many of your scope traces. This is why tcma is reporting a large error on Q factors in your ringdown, eg at 300 Vfire, raised medium sphere, > PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL > 1 36.693 (0.01%,4Hz) 38.48 (13.28%, 5.1) -0.1dB > 2 115.250 (0.01%,13Hz) 26.23 (37.56%, 9.9) -21.6dB > 3 176.060 (0.01%,20Hz) 32.00 (22.33%, 7.1) -24.3dB > 4 109.558 (0.01%,13Hz) 76.51 (63.17%,48.3) -26.4dB > 5 225.888 (0.01%,26Hz) 39.60 (13.28%, 5.3) -26.6dB > 6 178.144 (0.01%,20Hz) 26.29 (22.33%, 5.9) -23.6dB > Accounted for 95.16% of input signal It thinks the error is some 10s of percent, because it's failing to match a single Q ringdown with the given waveform. The Q that it reports is a good average Q over the whole event (or part of the CSV that I cut out and tcma separately). Thus the reported Q is good for putting into the efficiency formula. A slight digression: When looking at Ibase waveforms during breakout into air, I've not seen sign of any of those transients reaching the bottom of the coil. Whatever's going on between topload and leaders, it seems 'smooth' enough not to put any noticeable transients into the coil. Discharges to a grounded terminal I suppose will be another matter. I guess the large toroid is having a desirable smoothing effect as far as the leader currents are concerned. The toroid C can supply the high current pulses into leaders without being limited by the secondary impedance. Might be a bit different with breakout from the toroid. (At 480kV based on 30kV/cm, which is a Vfire of around 640 volts). -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.