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*To*: tesla@xxxxxxxxxx*Subject*: Re: Racing Spark Prediction*From*: "Tesla list" <tesla@xxxxxxxxxx>*Date*: Tue, 16 May 2006 11:01:28 -0600*Delivered-to*: testla@xxxxxxxxxx*Delivered-to*: tesla@xxxxxxxxxx*Old-return-path*: <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>*Resent-date*: Tue, 16 May 2006 10:49:12 -0600 (MDT)*Resent-from*: tesla@xxxxxxxxxx*Resent-message-id*: <0oSBFPq-XtF.A.B-F.IKgaEB@chip1>*Resent-sender*: tesla-request@xxxxxxxxxx

Original poster: Paul Nicholson <paul@xxxxxxxxxxxxxxxxxxx> Dimitry wrote: > secondary, say 72cm long .... let H:D ratio would be 4:1 > 1565 turns ... 0.46mm enamelled copper wire > A ten turn primary at 20kV ... not flat but solenoidal primary > 15cm hight, OD is 28cm only, so you would have only 5cm of > clearance I confirmed Dimitry's calculations by modelling the above with the tssp simulator. I added a topload and groundplane and aligned the bottom of the two coils, so the thing looks like http://www.abelian.demon.co.uk/tmp/fd1.plan.gif The dual resonator mode frequencies came out to be 74.7kHz and 102.8kHz, so giving an effective k of 0.309. (Dimitry got 0.307, calculated from the 'dc' mutual inductance and self inductances, whereas tssp first computes the normal modes of the structure, then calculates k from their ratio. Nice that we get the same answer.) The terminal V/I waveforms (spanning 2.5 beats) are http://www.abelian.demon.co.uk/tmp/fd1.wave.gif and a secondary V/I animation (spanning 1 beat) is in http://www.abelian.demon.co.uk/tmp/fd1.anim.gif Dimitry calculated the vertical voltage gradient due to transformer action alone by considering the distribution of mutual inductance. When we look at the instantaneous voltage gradients we find the max vertical gradient briefly reaches 26kV/cm as seen in the voltage gradient animation http://www.abelian.demon.co.uk/tmp/fd1.grad.gif and is generally peaking at around 20kV/cm. This is a little higher than Dimitry's estimation because we have some higher overtone content which is flicking the gradients up higher than you would get with just the fundamental modes. When we add the radial voltage gradient, the combined stress is totally excessive, as might be expected with the solenoid primary being so close and reaching so far up the coil. But it's clear that even with this outrageous primary, the secondary volts/turn due to induction by the primary is barely enough - by itself - to produce vertical breakdown. -- Paul Nicholson Manchester, UK. --

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