Fusion Science and Technology / Volume 34 / Number 2 / September 1998 / Pages 128-136
Sonoluminescence (SL) may be explained by the Planck theory of SL, which treats the bubbles as miniature collapsing IRasers having a resonant frequency that always increases as the bubble collapses. Microwaves are created at frequencies proportional to the collapse velocity while optical waves in standing resonance with the characteristic dimension of the IRaser cavity are absorbed by the bubble wall molecules. The microwaves are absorbed at ambient temperature and accumulate to visible-ultraviolet photon levels through the rotation quantum state of the bubble wall molecules. In the Planck theory of SL, the collapse shape in multiple-bubble SL (MBSL) is treated as a pancake, whereas in single-bubble SL (SBSL) the collapse shape is treated as spherical. High bubble gas temperatures are unlikely in MBSL because the bubble gases in a pancake collapse are squeezed radially outward in almost constant volume at ambient temperature. However, SL spectra in MBSL are found to be far more intense than SBSL, yet the SBSL collapse shape is spherical. Because a bubble gas temperature increase is unlikely in MBSL, and because MBSL is more intense than SBSL, it is concluded that a temperature increase in an SBSL collapse is also unlikely even though the collapse is spherical. Hence, the prospects for hot fusion in a spherical SBSL collapse are not encouraging. However, a limited number of SL-induced fusion events in D2O may be possible in MBSL and SBSL as the bubble walls approach the spacing between D2O molecules in the liquid state. On average, reactions between the D's on colliding D2O bubble wall molecules do not occur as the Planck energy is limited to ~1.3 keV, but some fusion events with a Planck energy >10 keV are not impossible.