Sigh... I forgot to respond to the specific question you raise... One of the items in their research report is specific calculation by way of computer simulation of the temperature achieved in these very small collapsing bubbles. Those calculations utilize well known and validated Physical Chemistry equations and do indeed show temperatures easily in the millions of degrees would be reached, and defuse a major easy route of criticism.
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Those calculations utilize well known and validated Physical Chemistry equations and do indeed show temperatures easily in the millions of degrees would be reached, and defuse a major easy route of criticism.This could be an answer, then, to the problem of producing hign pressure and temperature. The Russians have been dinking around with their "tokamak" and Livermore, I believe, have had that laser monstrosity without any practical results so far. I'll bet the experiment could be used with some low-order hydrocarbon line liquified methane as well.