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Re: Primary Qs
Hello everyone,
Well it seems it is time for me to admit past errors
in my earlier measurements and in particular the quality of the
components I used. For the first time I checked the Q of a circuit
using one of my CP capacitors.
First the figures : L = 350uH (helix wound with heavy Litz)
C = 25nF
Voltage : 3kV 6kV 9kV 12kV
Q : 10.9 19.1 27.4 30 (and still climbing)
The first point I noted was that the waveform decrement was perfectly
linear showing the virtual absence of resistive losses other than the
gap. The reason this is so :
Igap = x/Rgap where x is some constant equating to gap voltage
(zener characteristic in full glory)
Wgap (power dissipation) = Igap^2 * Rgap
So power loss scales linearly with gap current. If the gap is replaced
by a normal resistor the loss would scale according to a square law
since R would then be constant. The circuit rang for over 1mS at 12kV.
Fr = 53.8kHz (I must have botched the frequency calc I did yesterday)
Surge impedance = 118.3 Ohms
For a Q of 30, Rgap = X/Q = 3.9 Ohms
Igap approx V/X = 12kV/118.4 Ohms = 101.4 Amps
=> Vgap = 395 Volts
Check : For Q= 19.1 -at- 6kV : Rgap = 6.2 Ohms
Igap = 50.7 Amps => Vgap = 314 Volts
Not a perfect knee but then even zener diodes vary with current.
You can work out peak power in the gap.
Guys, I'm sorry I've put you wrong all this time. I would have
felt worse not admitting it however (bad enough as it is). I would
like to say that apart from this I stand by the other measurements I
have made in the past. I think it is truly time I was put out to
pasture.
Malcolm