From: Paul
Date: Tue, 10 Oct 2000 07:12:30 +0100
Subject: Re: [TSSP] The Corum's model?
Terry referred me to > http://63.225.104.49/TeslaCoils/OtherPapers/Corum1/ I'll keep this short and skip passed all the stuff pages 1-7 and go straight to the controversial pages 8 and 9, http://63.225.104.49/TeslaCoils/OtherPapers/Corum1/2-08.jpg http://63.225.104.49/TeslaCoils/OtherPapers/Corum1/2-09.jpg in which we are shown figure 4 depicting a large voltage rise which begins at the opening of the primary gap. The peak voltage which is achieved at the end of 'coherence time' is obliged to be commensurate with the energy budget. The secondary resonance, released from its coupling with the primary, evolves into that of the familiar steady state quarter wave resonance. Therefore the normal energy budget applies to the system and no extraordinary voltages can be expected. I'll just make clear what I mean by 'normal energy budget'. Twice each cycle when the current is momentarily zero all along the coil the entire net energy is stored in the distributed capacitance and topload. The top voltage achieved for a given stored energy thus depends on both the capacitance distribution and the instantaneous voltage distribution. * This energy cannot exceed the initial primary tank energy, yet the distributed capacitance and topload have to be charged. There lies the fundamental limit to output voltage. * You may argue over how the energy is put in, or how precisely the voltage distribution evolves over the time during which the energy is being fed in, but the eventual resonant voltage distribution is a function only of the geometry of the system, the net energy, and the choice of resonant mode. I might put it this way: during the 'coherence time' the resonator forgets where it got its energy from. So what do we make of the results hinted at in figure 5? Since, on the firm basis of energy considerations alone, there is no prospect for an 'extraordinary' increase in output voltage, we must assume that the final voltage achieved was merely typical. The only reasonable question then is why was the secondary voltage abnormaly low before the primary gap opened? This is hard to say since the authors have omitted to tell us what initial primary tank energy was involved, so we are unable to do the obvious elementary energy budget calculations. Nor are we allowed to scrutinize the experimental setup so we can but speculate on the meaning of figure 5. There are some other peculiarities: why is the Q factor so low for the coil described? Why do they open the gap at exactly the wrong place in the beat? Considering the authors are reporting 'astonishing' and controversial results, and in view of the experience and qualifications claimed by the authors, one would expect the presentation of experimental results to be both thorough and impeccable. I won't bother to comment on the rest of this document! Both these Corum documents are pretty poor. Elementary conceptual errors combined with a tendency to introduce extraneous concepts which can only be intended to impress rather than inform lead to thoroughly confusing and misleading documents which would not survive a professional review body, nor even it seems, an amateur one! The onus remains firmly with the authors to get their act together, meanwhile I'm not inclined to waste any further time on this, unless any present list members need points clarifying. Regards All, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.