what does a sparkgap do

evostars

what does a sparkgap do
«  »
a spark, is a discharge.
if it is short and intense, it sends a longitudinal pulse down the line.

the same like a short circuit.

I believe a mosfet can do the same.
it can create a dielectric 'channel' where energy can move through.

A mosfet is limited in the amount of energy it can pass in an impulse, and, has ON resistance. Is the ON resistance slowing down the impulse? Whats is it that resists and produces heat?

Matt Watts

Re: what does a sparkgap do
« Reply #1,  »
A MOSFET typically can achieve very high turn-on speeds, but suffers from the slow turn-off, just like a spark gap does unless magnetically quenched.  But there are improvements, specifically with Silicon Carbide MOSFETs.  The catch with SiC MOSFETs is you need powerful gate drivers to overcome the gate capacitances.  These gate drivers actually pull the gate negative, not just to zero.  When done properly, switching is pretty darn fast.  You will note however, fall-time is still slower than rise time which may be important to achieve the longitudinal pulse you are after.

 Cree-C2M0280120D-SIC-Mosfet.pdf - 781.74 kB, downloaded 5 times.


evostars

Re: what does a sparkgap do
« Reply #2,  »
thanks Matt
cant download it on my phone. remember this being a problem a year ago. damn computers. should make life easier.

mosfet might not do the trick after all
more and more thinking about disruptive discharging the capacitor by over charging it with negative voltage. see how it holds up.