Magnetosonic analysis and the method for diagnostics of expansion of a plasma cloud in a magnetized background

The problem of sub-Alfvén expansion of a superconducting plasma sphere in a homogeneous magnetized background is considered. The specifics of a self-consistent model of a low-frequency linear MHD approximation that we used in the present paper is the simultaneous allowance for the energy necessary for maintaining the field and plasma equilibrium at a moving boundary and the additional perturbation of a decelerating field generated by the currents induced in a background plasma. This has allowed us to clarify significantly the dependence of the radiated magnetohydrodynamic energy on the Mach–Alfvén number. We found and calibrated universal dynamic characteristics on the basis of which we developed new techniques for determining the initial energy and the velocities of expansion of an explosive plasma cloud with the use of the peak values of magnetic signals in the near (quasistatic), transient, and wave zones. The possibility of effective application of these techniques in experiments on laser-plasma cloud generation in a vacuum homogeneous magnetic field is shown.