[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*To*: tesla-at-pupman-dot-com*Subject*: RE: Vortex gap loss measurements*From*: "Lau, Gary" <Gary.Lau-at-compaq-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)*Date*: Sat, 02 Sep 2000 20:02:23 -0600*Delivered-To*: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Dan: Comments interspersed: >Original poster: "Daniel Boughton" <daniel_boughton-at-yahoo-dot-com> > >Gary: > >This is a very interesting experiment. First, when you >measured the slope during the ring down, did you see >the same size decrement of each succesive oscillation? >Is this what you mean by linear as oppossed to >logarithmic? Yes, the envelope of the ringdown is precisely triangular. You can line up a straight edge on the ramp and it follows the envelope exactly, right down to zero. >Traditional wisdom purports that the >decay is according to V(t)=V(i)e^-rt where V(i) is the >forced initial potential on the capacitor. Your >results are very interesting however in that it flies >in the face of convention. The derived equation must >be something like V(t)= V(i)*-krt. I think the thing wrong with the traditional equation is that it assumes a constant arc resistance. I'm guessing that the arc resistance is a function of arc current, and not a constant. >I wonder if without >the secondary it is linear due to resistive losses >only. Without the secondary the additional absorption >of energy via the secondary mutual inductance is >missing which accounts for the linear decay? I think all of the losses have to be resistive, it's just a question of whether it's a constant resistance. >Also what >I found interseting was that with the gap distance the >slope remained constant. I would have expected greater >gap resistance at further distances but it seems that >the plasma provides a constant resistance no matter >how wide the spark gap is set (within reason of >course-I 'm sure at a foot the resistance would be >substantial as compared to 300 mil). Yes indeed! I also expected the losses to be proportional to arc length. But with a wider gap, the breakdown voltage is higher with proportionately higher tank currents, and if my belief that arc resistance diminishes with higher currents, it may all be a wash. Here's a thought experiment. I don't know the answer, perhaps someone else does. If one has a 3 foot long neon sign tube and a 6 foot neon sign tube, the longer one will obviously require a higher voltage to start ionization. But once started, won't they both draw the same current from the same NST? If so, this suggests that gap arc resistance is strictly a function of gap current, not distance. If not, then I give up! >Also, does your scope generate a data file? If so, can >you share it? It does, but it's in a format native to the Tektronix scope. I haven't figured out how to convert it to a GIF or BMP (the scope is borrowed from work and doesn't have a manual). I didn't save any of the traces since the slope measurements were easy to make with the cursors, but I can repeat a subset of the measurements and just take a picture of the screen with my digital camera. [Crude, crude, crude!] It may take a week or so to find the time, but I'll post it to my web site with a heads-up to the List when I do. >Regards, >Dan Regards, Gary Lau Waltham, MA USA --- Tesla list <tesla-at-pupman-dot-com> wrote: > Original poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com> > > Today I found some time and performed a comparison > between the gap losses of > my single vacuum gap, and my new single vortex gap. > To do so, I scoped the > primary ringdown with no secondary in place. I used > a Terry Fritz fiber > optic voltage probe across the primary coil and a > digital storage scope to > record the results. I have not yet accurately > calibrated the voltage > readout, so for now, the results are just relative > to each other. > > With no secondary in place, the ringdown is a > linearly decrementing > waveform, not logarithmic. As such, the slope of > the ringdown indicates the > losses in the circuit and is independent of the gap > firing voltage. I > performed ringdown slope measurements at a variety > of gap widths to vary the > initial voltage, but the ringdown slope is a > constant, independent of Vgap. > > The power to the blower motor is varied through a > lamp dimmer and I tried > varying the motor speed to see what effect that had. > At very low speed, the > linearly decrementing waveform became slightly > logarithmic-looking, but > still predominantly linear. The gap breakdown > voltage appeared to change > slightly at low speed, but this was hard to measure > as it was slight and the > bang-to-bang gap breakdown voltage is not as > consistent as one might hope. > > The slope decrement figures are assuming that my > probe is accurately > calibrated for voltage, though I suspect it may not > be, so the figures are > useful only for relative comparison purposes. > The pressurized vortex gap decremented at 200V/usec. > The vacuum gap decremented at 235V/usec (17.5% > faster). > The vortex gap breakdown voltage is about 20% higher > than the vacuum gap at > the same gap distance. > > Vortex gap web page: > > http://people.ne.mediaone-dot-net/lau/tesla/vortexgap.htm > > <http://people.ne.mediaone-dot-net/lau/tesla/vortexgap.htm> > > Vacuum gap web page: > > http://people.ne.mediaone-dot-net/lau/tesla/onegap.htm > > <http://people.ne.mediaone-dot-net/lau/tesla/onegap.htm> > > > Regards, Gary Lau > Waltham, MA USA

- Prev by Date:
**Re: More tube coil stuff (Carl Willis)...** - Next by Date:
**RE: Vortex gap loss measurements** - Prev by thread:
**RE: Vortex gap loss measurements** - Next by thread:
**RE: Vortex gap loss measurements** - Index(es):