Vidura
posted this
05 April 2019
For all who are working practically on switched devices here a short addition regarding the switches: Although I believe that the superfast switching is not the only way to achieve AU, I'm quite sure that many of the discussed devices are depending on it.
The most critical parameter is the FALLTIME of the switch(maybe under certain circumstances the rising puls give a similar effect),
the switch can be a quenched sparkgap or a high speed semiconductor. Experiments have shown that the critical falltime is around 20ns. When I was revising datasheets I found that the only transistor I have in stock wich maches this criterium is the IR730 with 15ns falltime. Then beside the device used by Sergei Deyna many of the SIC mosfet from CREE meets the criteria , some as fast as 4 ns.
(Graham Gunderson used this recommending strongly the original from CREE)
The other critical parameter is the voltage rating, as due to the high BEMF a low voltage device will avalanche and the radiant effect will not be present.
Hopefully this will be useful for some,
Regards VIDURA.