Re: [TCML] DRSSTC tuning at high power

[Michael Twieg <mdt24@xxxxxxxx>]

> Streamers grow in jumps, propagating pretty quickly (about 0.01-0.1c, as I
> recall).  Think of the streamer as a wire, with charge moving down it.. as
> wire gets fully charged, the e field at the end of the streamer/wire gets
> high enough to exceed the breakdown strength of air, and then it jumps
> forward, with the jump being fed by charge coming out of the charge stored
> along the streamer/wire.
>
> All that charge flowing also creates an IR drop, heating the air and
> keeping the channel alive.  But it's sort of a transmission line phenomena,
> and eventually, the streamer runs out of charge, and stops, waiting while
> it's filled with charge from the top load.
>
> The top load is pretty low inductance, so it can "fill" the streamer with
> charge fairly easily.  However, if the secondary is pushing charge into the
> topload faster than the streamer is accepting it (limited by the L of the
> topload and the L of the streamer, mostly), the voltage on the topload will
> start to rise, and you'll likely start another streamer.
>
This sounds like a very plausible explanation... perhaps my long breakout
point is presenting a relatively high inductance to the topload, leading the
streamers breaking out elsewhere.  I think we really need to try shortening
that thing. And as for the speed of energy delivery to the streamer, would I
have to decrease k in order to slow it down?  I was hoping to avoid lowering
k, since it seems to draw more energy per burst cycle.  This is probably
great for spark length, but for playing music it kind of sucks since the
power draw will become ridiculous at high tones.

>
>
> Take home message:  Topload size and shape will have a huge effect on spark
> growth.  There's a tradeoff between L and C that will provide the
> appropriate "impedance transformation" between the growing spark and the
> current from the secondary.
>
> For the mean time, empiricism is probably your best bet, until someone
> cranks out a good FEM code.

Yeah, an accurate streamer/arc model would definitely be nice, but I don't
see it ever happening... at least not in a way that would be usable for
design decisions for coils.

-Mike
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