[Blackbody radiation of cavitation luminescence from glycerin]

An improved conical bubble sonoluminescence U-tube was built. Using this setup, the spectra and light pulses of conical bubble luminescence in glycerin were detected. Results show that the spectra are continuum, which are well fitted by blackbody radiation. The cavitational temperature ranging from 2 600 to 3 050 K was calculated from the fitted spectra. The reasons for the existence of blackbody radiation in conical bubble luminescence were discussed both from special and temporal sides. The value of radius of cavitational bubble is about 1.7 cm theoretically, which is greater than that of the bubble acoustically excited. The width of light pulses of cavitational bubble reached 40-60 ms, and this provided enough time for the blackbody radiation. In addition, the light pulses at different wavelength were measured, and results show that the width of light pulses increased with the raise of wavelength of spectra, which proved the mechanism of blackbody radiation. Finally, based on the spectra and light pulses, the intensity of luminescence was calculated to be about 0.18 J.