I’ve seen that before. 🙁 I thought it was the disk part shattering but it is the cylinder. A plasma is forming behind the insulator. The rapid heating of the gas to plasma increases the pressure and shocks the insulator. I’ve cracked many insulators at the 0.25 MA level because of this. You need to increase the wall thickness of the alumina. It increases the inductance but you gain in lifetime by a great deal. It should take minor changes to the anode to make this work. The rest of the hardware can remain as is.
Also, the disk diameter seems to be overkill unless you’ve had arcs in the air before.
