Ionic currents modulated by film flow in superfluid helium

The oscillations of two helium baths coupled by the saturated film have been studied with a new method employing positive ions. The sensitivity of such a method for the variation of liquid-level height is found to be of the order of 10−6 cm. The film current was observed to be modulated with a frequency double that of the level oscillations. This interesting new feature is discussed in the framework of the present theory of liquid helium.