Allan Brewer wrote:
Indeed the whole problem arises because the fast-rising current is only conducted in the outer film of the metal anode. Another possible approach to this might be laminating the metal so there are effectively a very large number of separate parallel metal conductors all of which have an outer film and can carry current?

you have to consider *why* the fast-rising current is only conducted in the outer film: it’s because like-charges repel. they will seek to be as far from each other as possible.

if we had, say, a bunch of separate, concentric, conducting tubes, insulated layer-to-layer, then yes it might be possible to spill high current into each, if we adjust the timing slightly, since the rising edge will travel at different rates in different diameter tubes.

note, also, that this is affected by eddy currents. a moving charge in one tube induces a counter-current in another layer. this is potentially helpful: electrons travelling towards the tips of the cathodes will help induce desired anode counter-currents.

but eddy currents in adjacent layers would be detrimental, so it’s tough to say there would be overall improvement.

the sum of all these effects is a worthy modeling exercise, anyway.