Francisl wrote:

A plasma is forming behind the insulator. The rapid heating of the gas to plasma increases the pressure and shocks the insulator.

Can the gas behind the insulator be displaced by more insulation as either a solid or packed in powder? Can some type of pressure relief be formed in the insulator or the anode to accomodate the shock wave?

I have not tried either solution. In my case, the problem is the thermal expansion of the anode. You need to leave a little room for the anode to expand. LPP likely has tight tolerances for other reasons. My concern with powders is that gas can get into the powder. The plasma forms and explodes the powder. After some number of shots the powder is all over the vacuum chamber. Good, bad, other…I don’t know. The another insulator would still have to be plasma facing so it would likely need to be alumina or some other ceramic material. I don’t know of a flexible ceramic.

To be fair, the insulator problem is a very hard problem and with limited resource it hasn’t been fully explored. Packed powder or another solution might work. In the case of limited funds, I typically suggest the tried and the true…add more of what you need. It comes at a cost, but I think that cost can be handled more easily than venturing into the world of materials development. I might not have pointed it out, but many machines at the >1 MA level have insulator lifetimes of hundreds of shots at most with tens of shots being more common. There are ideas on how to increase the insulator lifetime but there are tradeoffs. It depends largely on your pulse power requirements and goals. I know for my work, a thicker insulator was an acceptable solution. It cost me 5-10 kA at peak current but I can easily compensate with a slightly larger charge voltage. I’m sure these discussions are going on at LPP.