Photoionization

[Francisl]

Would it be practical to use photo-ionization of the insulating gas around the sparkplug to improve the timing of the spark discharge? A fast laser or photo-lamp tuned to the proper frequency of the insulating gas could provide a discharge channel for the capacitors at the exact time required.

[mchargue]

A good idea. See this thread,
https://focusfusion.org/index.php/forums/viewthread/471/

[Francisl]

This is the type of system that I am thinking of. Maybe it can be scaled up to the necessary size.

http://ieeexplore.ieee.org/search/freesrchabstract.jsp?tp=&arnumber=4948754&queryText;%3DSpark+Gap+Switching+Time%26openedRefinements%3D*%26searchField%3DSearch+All

[Brian H]

Certainly the speed is there; < 0.1 ns. But the voltage is quite low so far, 4.5kV.

[Henning]

Brian H wrote: Certainly the speed is there; < 0.1 ns. But the voltage is quite low so far, 4.5kV.

An increase of ten times the voltage could be possible, ie. with a gap of about 10mm, or with different fill gases. It doesn’t say anything about the maximum current, though. Currents would be constrained by the diameter of the electrodes, so this is maybe not a problem (anyone with more background please weight in).

They create a plasma that spans the complete gap, that’s what makes it so fast.

I haven’t read the paper as it’s behind a paywall. Anyone around who has read it?

[Author]

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