From: Paul
Date: Fri, 10 Nov 2000 23:47:49 +0000
Subject: [TSSP] Primary gap questions
Carried forward from another thread, Re: [TSSP] NSVPI - Latter Results If I've understood things so far, Malcolm has suggested that the V across the gap when conducting (Vcond) is to a first approximation constant, implying Rgap is a function R(I). Evidence for this is the approximately linear or steeper decay envelope occuring when gap loss is significant compared with the other (linear) primary circuit losses. Malcolm Watts wrote: [concerning 'resistive phase'] > It is probably more appropriate to consider it when looking at the > physics on sub-uS timescales. Since it doesn't really show up in the > longer term smoothed waveforms and doesn't seem terribly relevant to > the view one obtains at Fr where the circuit is highly selective I > personally haven't bothered with it too much. Others may think > otherwise. It would be nice if we could just take the gap resistance as a function R(I) and not have to include the time since the gap closed! Sorry, further demonstrating my ignorance about spark gaps, more questions... Do we have any idea whether the gap resistance is a function of frequency as well as current? We've seen evidence of DC levels appearing in the LC circuits when an arc gap or corona loading is present. It take it this is due to Vcond having a different level for opposite polarities of current? I guess a symmetric gap would not show this, and a very asymmetric gap, eg point to sphere, would demonstrate it the most. Looking at some of Terry's scope traces in http://hot-streamer.com/TeslaCoils/MyPapers/spark1/sparkgap.html we seem to be seeing the gap extinguish and re-ignite on every zero crossing of the primary current - is that correct? And finally! What sort of typical magnitudes do we get for Vcond? Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.