Re: magnifier questions

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>

Tesla list wrote:
>
> Original poster: FIFTYGUY@xxxxxxx

>      This seems to historically have been a problem, although Dr. R
> recommends an auto-transformer configuration which sounds interesting.

Yes, and even higher effective coupling can be obtained by making the
lower part (primary) of the autotransformer a flat coil with the outer
end grounded.

>      That's what I ran into with the designs I made using Antonio's
> programs. If you make the driver inductance L2 small to get the ratio of
> L3/L2 around the "conventional wisdom" of 1:8 or so, C2 goes way up. At
> least this is simply a practical construction problem. And since the
> voltages at C2 are not as high as at C3, perhaps we could use some
> very-high-voltage rated caps, instead of isotropic capacitances like
> toroids and transmission lines? 600 pF at 200kV? That's a string of
> 100  .06uF 2000V caps. I suppose the safe place to ground them would be
> somewhere in the middle of the transmission line, though...

Terry tried to make one of these some time ago. The capacitor worked
well, but there were chronical insulation problems in the driver.

>      Isn't one reason for using the magnifier topology that the energy
> transfers out of the primary tank quicker? Or does the increase in gap
> current in low modes offset the losses over longer ringup times with lower
> current in higher modes?

The gap current doesn't increase. It actually -decreases- a bit in
the lower modes. Try the default example of the mrn6 program:
Mode 1:2:3 results in maximum primary current of 64.45 A
Mode 5:6:7 results in 75.05 A

>      FWIW, I'm not convinced the voltage gain has a proven effect on spark
> length, past the initial breakout before the streamer starts to grow. In
> fact, I'm wondering if too much voltage gain might be a BAD thing, in that
> it encourages extra breakouts (maybe even branching from the main streamer)
> that robs power. Pure conjecture on my part.

Too much voltage gain, caused by a small terminal that would break
out well before the maximum voltage is reached is probably a bad
idea, but if the terminal is designed to break out just before the
maximum voltage is reached, it will store a lot of energy to feed
streamers and sparks. As far as I know, there is no conclusive
answer about how much output voltage you need for good performance.

Antonio Carlos M. de Queiroz