Acoustic bubble traps

A small, oscillating bubble in a liquid can be trapped in the antinode of an acoustic standing wave field. Bubble stability is required for the study of single-bubble sonoluminescence (SBSL). The properties of the acoustic resonator are essential for the stable trapping of sonoluminescing bubbles. Its acoustic modes were measured by means of holographic interferometry and hydrophones. Flasks of different geometries (spherical, cylindrical, rectangular, ovoid) were investigated as well as different acoustic modes. Higher harmonic modes were used to trap several single, stable sonoluminescencent bubbles within one acoustic resonator (few bubble sonoluminescence, FBSL). This opens up the possibility to study bubble–bubble interactions (secondary Bjerknes forces).