The contribution of the temperature dependence of the thermal expansion coefficient on the wave equations of the first and second sound in superfluid helium

Present article is devoted to contribution of the temperature dependence of the thermal expansion coefficient on the wave equations of the first and second sound in superfluid helium. The system of wave equations for the vibration of the pressure and temperature in superfluid helium with takes into account the dependence the a_T(T)-coefficient of thermal expansion of the temperature has been obtained. This will create a theory of acoustic waves of the first and second sound laser beam in superfluid helium through the thermal mechanism near a special point of superfluid helium when a_T(T₀)=0. (author)