Detection of Electric Response at Excitation of First Sound in He II
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The signal of electric response in superfluid helium was recently observed at the excitation of a second sound standing wave in an acoustic resonator (Rybalko in Low Temp Phys 30:994, 2004). It has been suspected that similar resonance signals may be observed also in a first sound wave; however, earlier experiments showed the absence of any electric response induced by the pressure wave. Here, we report the first experimental evidence of electrical activity that arises at the fundamental frequency of the first sound resonance. It is found that the signal of electric response agrees fairly well with the fundamental frequency of the first sound resonance. The absence of the signal of interest in the original experiment is discussed.
KeywordsSuperfluid \(^4\)He First sound Polarization effects Electric potential
The authors appreciate the technical assistance of F. Soukup and stimulating discussions with L. Melnikovsky, O. Ledenyov, L. Skrbek and V. Chagovets.