From: "Malcolm Watts"
Date: Mon, 30 Sep 2002 09:21:50 +1200
Subject: Re: [TSSP] Top Voltage
Hi Terry, all, On 27 Sep 2002, at 18:54, Terrell W. Fritz wrote: > Hi Paul, > > At 06:33 PM 9/27/2002 +0100, you wrote: > >Terry wrote: > > > >> Good news. The fiber probe seemed to be working most of the > >> time so the previous data is fine. > > > >Well that's good. Those current signals looked too realistic > >to be an artifact. Hope the current probe is fit for battle. > > I have spare parts and all. I "think" it is ok but the problem seems a little > intermittent. No worries though. > > > > >Bert wrote: > > > >> Corona, and corona flashes (or streamers) are all "cold" > >> discharges, while leaders (what most coilers mistakenly call > >> streamers) are composed of hotter, highly conductive plasma > >> (actually more arc-like). > > > >So the leaders are plasma, but the streamers are un-ionised gas > >with the odd accelerated electron, insufficient in themselves > >to cause a bulk ionisation of the air, but enough when combined > >in their multitude to cause a leader to form? > > > >You see, in the back of my mind, I'm forming a hypothesis that > >Terry's topload is in fact breaking out rather earlier than > >the load current probe suggests. Could it be that streamers are > >forming at around the expected breakout voltage, but > > > >a) they are not bright enough to see, > >b) their large number plus their individual miniscule current adds > >up to a smooth average displacement current which is sufficiently > >smoothed by their large number to be indistinguishable from the > >displacement current that we can already see charging the rod and > >sphere. > > > >Perhaps the spikes we are taking to indicate breakout actually > >mark the formation of distinct, visible leaders, and that a much > >less visible (by eye or current probe) breakout is starting > >rather earlier. > > > >Malcolm has in the past reported a faint glow around his topload > >prior to obvious breakout. > > That all does sound very possible! The effect was very real. I had to pinch myself to make sure of what I was seeing. The most amazing thing was the volume of space the discharges occupied. The system was operated single shot and the gap covered (as well as the garage windows) to eliminate as much background light as possible. What I saw was not a solid glow but a ball of very faint streamers around 3' in diameter around all sides of a 9" sphere. If you took successive shots with a camera, you would see a solid glow rather than the streamers, with diminishing intensity at the outer extremity. I have it in mind to do exactly this when less pressing matters allow me to get back into active coiling. There are so many things I am aching to do. Regards, Malcolm > > > >If this hypothesis were correct, then if we measured base current > >and rod+sphere+load current simultaneously (average or RMS values > >here, not scope traces) and plotted their ratio as a function of > >variac setting, then we would see a departure from a constant > >ratio. At low power, definately no breakout, the value would be > >set by the fixed capacitance of the rod+sphere. As the voltage is > >turned up and invisible streamers begin to form, the load current > >would increase disproportionately above the base current. > > I think I see what you mean. > > > > >Conveniently, Terry's rod+sphere is of quite small C, therefore it > >should be fairly sensitive to a small additional streamer current. > > > >> http://www.physic.ut.ee/~tomas/phd_plank.pdf > > > >Thanks Bert. www.physic.ut.ee is not letting me download at > >the moment, I'll try again later. > > I have it at: > > http://hot-streamer.com/TeslaCoils/OtherPapers/phd_plank.pdf > > Looks like a great set of papers!!! At 168 pages, it will take a little time > ;-)) He talks of the exact subjects we are dealing with now! > > Cheers, > > Terry > > > >I'm away this weekend at > >the final round of the British rally championship, so if anyone > >posts anything, don't worry if it doesn't come through until Sunday. > > > >Cheers All, > >-- > >Paul Nicholson, > >-- > >
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.