See: http://www.bbc.com/news/science-environment-15876145
This is a 2011 article that discusses a proposal by Seth Putterman, a professor well-known for investigating sonoluminescence. The proposal is that in sonoluminescence, a plasma is created that is hundreds of times more dense than plasmas found in nuclear fusion experiments. This proposal has been mentioned in connection with a demonstration made by Andrea Sella consisting of a glass tube filled with phosphoric acid and traces of xenon. When the glass tube is gently shaken, a clinking sound occurs like that of a ball bearing hitting the glass wall, along with visible blue sparks. The temperature transients that are believed to occur in the glass tube are up to 10,000 degrees, but they are nowhere near sufficient to strip the electrons witnessed in the sonoluminescence. So there must be something else going on as well in addition to temperature spikes. Putterman does not suggest fusion, but he does offer the dense plasma. I think this suggestion is interesting in two ways. First, a very dense plasma might be good for accelerating alpha and beta decay in already unstable radionuclides. Second, several xenon isotopes have double-beta decay modes. It would be interesting indeed to ultimately discover that sonoluminescence is just accelerated beta decay, and that those blue sparks are Cherenkov radiation. Eric
