Pulsed Nonlinear Sound in Superfluid 4He and 4He-3He Mixtures

Sound modes in4He and4He-3He mixtures which arise out of the two-fluid equations are made up up a vector convective flow and scalar temperature changes. A method for modeling nonlinear pulses of sound with geometric approximations to the vector and scalar components has recently been applied towards understanding nonlinear second sound near the lambda point.6The same method may be used, in general, for modeling linear and nonlinear sounds in Helium II. We demonstrate with a model for nonlinear second sound pulses in3He-4He mixtures and compare the results to experimental observations.