Cavitation in Liquid Helium

Ultrasonic cavitation has been induced in liquid helium over the temperature range 1.2 to 2.3°K, using a pair of identical transducers. The transducers were calibrated using a reciprocity technique and the cavitation threshold was determined at 90 kc/sec. It was found that this threshold has a sharp peak at the $\lambda$ point, but is at all temperatures quite low, with an approximate range of 0.001-0.01 atm. The significance of these results is discussed.