Resonator design for stimulated third sound amplification in He-4 films

We propose a new resonator to detect the amplification of third sound waves due to stimulated condensation of normal vapor atoms into the superfluid f ilm. We describe the phenomenon and present the conditions required for its achievement. Third sound amplification by stimulated condensation (TASC) i s thus an extension of film growth at a fixed DC velocity to a situation in volving a continuous AC energy transfer. (C) 2000 Elsevier Science B.V. All rights reserved.