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New experiments on the study of the electric activity of He II at the excitation of second-sound waves

We present the results of new experiments on the observation of the electric response of superfluid helium (He II) at the excitation of second-sound waves in it. We used an acoustic resonator with dielectric case, in which the measurements of the electric and thermal signals were carried on simultaneously due to the disposition of a measuring electrode and a bolometer on the face wall. We measured the potential differences between the face electrodes, as well as between ring metallic electrodes disposed along the resonator case which were insulated from one another and from helium. It is shown that the distribution of the electric potential along the resonator coincides with that of the temperature in a standing second-sound wave. It is established that the ratio ΔT/ΔU in a second-sound wave is a constant equal to 2.3{\cdot}10^(4) K/V in the whole regions of temperatures, frequencies, and heat flow powers under study.