Quote:
Originally Posted by russell_w_b
Correct. As the frequency rises, the corona onset voltage falls. Not only that, but at RF, the corona onset voltage and flashover damage point are very close indeed, as opposed to power line networks where there is a distinct gap between corona and flashover. I take it you've no sharp edges?
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Thank you, Russell.
The pulse transformer should be a resilient component as it was designed to provide continuous 300mA to the magnetron, after a full-wave doubler. No sharp edges, except in the waveform driving it!! I have put silicon sleeving on the lead-outs but there is full-on plasma there at both sides. It's really odd, from just 18V (at 3.5A RMS on the Drain, goodness knows what it is pulsed) I need to get a move on with constructing my EHT probe (calibrated) too, to see the waveform here on the secondary.
I have ordered a power IGBT which has a much slower rise and fall time, and a long switch-off delay. I think the inconsistent behaviour of a bespoke pulse transformer, driven at its design frequency, must be the blistering fast dI/dT with the MOSFET I've been using. But do you think the open circuit nature of this phenomenon is relevant to David Knight transmission line theory?