Hysteresis curves for some periodic and aperiodic perturbations in magnetosonic flow

Abstract

A thermodynamic relation between perturbations of pressure and mass density in the magnetohydrodynamic flow is theoretically studied. Planar magnetohydrodynamic perturbations with the wave vector, which forms a constant angle with the equilibrium magnetic field, are under study. The theory considers thermal conduction of a plasma and the deviation from adiabaticity of a flow due to some kind of heating–cooling function. It also considers nonlinear distortion of a waveform and nonlinear excitation of the entropy mode in the field of intense magnetosonic perturbations. In some conditions, the total density of a plasma enlarges over a cycle of magnetosonic perturbations. These conditions depend on the type of magnetosonic waveform, heating–cooling function, thermal conduction, and equilibrium parameters of a plasma. They depend also on the angle between the wave vector and the magnetic field. The diagrams in the plane of total variation of pressure vs total variation of density indicate the nonlinear phenomena and irreversible processes in a flow. Harmonic perturbation and a bipolar impulse of pressure are considered as magnetosonic exciters of the entropy mode. Exemplary diagrams are plotted and discussed for these particular cases of exciters.