Pumping in He II by Low-Frequency Sound
Since 1965, when Richards and Anderson1 first demonstrated successfully the analog of the Josephson effect in helium, there have been several successful improvements of this experiment.2 In all of the successful experiments an essentially identical arrangement of the crystal sound generator and orifice has been used. In all of these experiments a pumping effect has been observed where the helium is pumped toward the crystal generator. The pumping action seems essential for the observation of the Josephson effect. In the course of a similar experiment a pumping effect has been observed that seems to have rather different characteristics than those in Refs. 1 and 2. The experimental apparatus is shown in Fig. 1.
KeywordsVortex Ring Generator Voltage Helmholtz Resonator Josephson Effect Helium Level
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