Kit- I'm a broadcast engineer and electronics hobbyist. I've been making high voltage and arc discharge devices for around 30 years also.
I think we're probably talking at cross purposes here. The idea I had is to create an AC arc that lasts for around half an engine revolution, from the start of the combustion cycle until the exhaust valves open.
I don't see how a small capacitor can sustain an arc through a sparkplug for tens of milliseconds, given that the impedance of the arc is very, very low.
Do you still have the trace of the current sensor? I'd be interested in seeing it, if you do.
A low frequency (tens of kHz) AC signal at 10-40kV delivered by a flyback type transformer is an easy way to get an arc of arbitrary duration. I've used a similar circuit to keep a lean-burn forge burner lit, although this was at a very low power and voltage.
It's probably not even relevant, as there have been so many attempts to 'improve' the classic pulse transformer ignition system.
I've been enjoying discussing it with fellow enthusiasts, though.
