Gold is a great choice to minimize oxide. We didn’t want to deal with plating gold and it turned out we didn’t need to.

Our anode plate is SS304. Our anode is SS304. We use a small copper gasket (no silver plating) between the two surfaces. The anode contact diameter is 0.75″ and 30 mil thick. At 300 kA which is our normal upper limit of operation in rep rate mode, that translates to 0.63 MA/cm^2. We’ve fired a 450 kA shots at low rep rate without any problems or ~1 MA/cm^2. I’ve run over 20,000 shots on that contact without issue at 300 kA. We use a single 1/4″ screw to hold the anode. Our cathode contacts are far larger, more like 4″ with 30 mil thicknesses using SS304 on silver plated Al. We’ve also done Cu on SS304, W on SS304 and Moly on SS304 up to 400 kA/cm^2 when the harder metal has the contact.

I haven’t done the pressure calculations since the contacts are working well.