I wrote: But when it appears, you would get a z-pinch effect, as happens in a > lightening rod, and the walls of the containing wire would violently > collapse in on the cavity. What happens to a lightening rod is fairly > dramatic: > > > http://www.physics.usyd.edu.au/images/content/about/Fig_3_crushed_rod_final.jpg >
I take back that thought about violent collapse of the walls. Maybe the collapse would be violent; or maybe it would be gradual, occurring as the walls soften and current passes through as a result of superconductivity (I was thinking DC, but it might be AC). If the collapse was gradual, you would get a steady increase in pressure. You might also get some interesting things happening with the frequency of the resonant light. Eric
