Hi Greg,
Thanks for the explanation of R=0.6 ohm for the rotary gap
of your coil (it makes sense).
But what do you mean by saying there is no IGBT switching loss?
Switching losses of IGBTs at typical tesla coil frequencies
are not so insignificant (althought generaly much lower than
in a spark of SGTC of same power).
The price paid for reduced conducting state voltage drop of IGBT,
compared with say that of MOSFET are increased switching times.
As it should be known IGBT turn-off transition exhibits
phenomenon known as current tailing during which increased power
loss occur.Typical turn-off times of IGBTs are in the range
0.3...3 microsec.Assume ,for example,a typical coil frequency of
100 khz and coupling between primary & secondary k=0.2.
Assume that this is a high power coil and one decides to use a
typical commercialy available HV IGBT module rated 4500 V.
It has Toff~1.25 microsec.
Turning-off last for about 25% time of 1 semicycle of the coil's
operating frequency.
For the coil posted in the link before,that's not DRSSTC.
That's normal coil only with IGBT instead of a spark gap.
Characteristic surge impedance of the primary can be calculated
from 2 parameters given in the coil's specification:
Cp = 30 uF
F = 66 kHz (w = 414 000 s^-1)
And so:
Zch=1/(Cp*w)=0.081 ohm