Numerical study of the partitioning of magnetic field energy and plasma energy during the penetration of the magnetic field into the plasma

Abstract

The partitioning of magnetic field energy and plasma energy during the penetration of the magnetic field into the plasma, in a time scale much larger than the electron cyclotron period, is studied. We solve numerically a two-dimensional model problem assuming that the plasma is unmagnetized initially. Plasma-directed kinetic and heat energies are calculated. Numerical results show that the partitioning of the magnetic field energy and the plasma energy is sensitive to the time dependence of the magnetic field at the plasma boundary. When the magnetic field at the boundary of the plasma remains constant with the onset of time, the magnetic field energy is equal to the plasma energy. On the other hand, the numerical result is consistent with the experimental result for the time dependence of the magnetic field B=B0 tanh(t/τ).