I doubt it would be beneficial, James, since the design is entirely about moving magnetic fields. ‘Sides, you know what more moving parts do to MTBF and profitability projections….

Otherwise, the similarities to the spark plug are one of FF’s strongest safety points- one spark, one cycle.

jamesr wrote: I have been thinking about the similarities between a plasma focus device and an internal combustion engine.

Both are a pulsed process in which a plasma is created in a metal container. The spark plugs in cars need to be able to cope with millions of repetitions without wearing down. The combustion chamber needs to be cooled externally to a level so that the internal surface temperature of the metal doesn’t get too high. etc.

Would it be sensible to add a piston onto the plasma focus vacuum chamber? The piston could withdraw after a pulse, expanding the plasma/gas cooling it. Then go back in just before the next pulse was set off to get the pressure & temperature quickly back to optimal conditions before discharging the capacitor bank through the overgrown sparkplug. The piston could also draw off some of the waste heat and make it into useful energy, albeit and insignificant amount, but maybe enough to power a coolant pump. Thus providing a secondary passive cooling circuit that would follow demand.

The alloys used for spark plug contacts have been refined over the years, such as Iridium Spark Plugs. These, however, contain heavy metals and would not be very conducive to the xray flux. However there must be a compromise between the physical robustness of the alloy and resistance to wear and the extra absorption & heating due to the X-rays.

Most of the diagrams show the cathodes as simple rods surrounding the anodes. Would there be an advantage in putting a couple of narrow spikes on the end of each cathode, made of something like the Iridium alloys used in spark plugs. These would then act as the point where the filament forms when the sheath reaches the end of the cathode. So whereas the rest of the cathodes may be copper or even beryllium. the area where the highest wear rate is tailored to be able to cope with the load.