vansig wrote:

Using Ohm’s law (apologies if I am being naive) for 1MA through a 20nm skin of the copper electrode does indeed give an answer, in the expected range, of around 2MW of heat from the anode and about the same from the cathodes. Beryllium has twice the resistivity so would double the heat “problem” (and increase the power required to initiate each shot?).

can you give the area and the length also, for us to check?

I used 20nm skin x circumference of 5cm diameter anode to give area, and 15cm of length. In practice the length varies during the pinch cycle, and I guess the length of feed cable from the capacitor bank will also heat, but approximate calculation only.