RE: Primary current feedback on the DRSSTC-3

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Steve Conner" <steve.conner@xxxxxxxxxxx>

>im getting about 30" sparks

Wow, that is hardcore stuff considering the small size of your DRSSTC-3. I'm
really not surprised that it detunes by 22% :-o


>i noticed the primary
>current had a much nicer linear ring up, instead of the choppy looking
>current ring up when tuned in the middle

The transient simulation I have predicts this. It also says that the lower
tuning you're using produces less output voltage for a given primary
current. That explains why you have to turn the DC bus voltage higher to
achieve breakout, and also explains the "snap" effect. When the streamers
form, they pull the secondary down to match the primary which has the effect
of increasing the output voltage, hence reinforcing the streamer growth. So
your streamers explode out all of a sudden.

They don't keep growing infinitely because pulling the secondary down lowers
the primary current too (and also the real part of the streamer load damps
the resonance)

You need to be careful going down this road. You'll probably find that the
tuning for best eventual streamer output produces insanely high primary
currents prior to breakout. I expect the pre-breakout primary current will
be what limits how far you can go with the detuning thing. Eventually you'll
reach a point where the IGBTs explode before any sparks appear at all.

Steve C.