Nonlinear response of a relativistic plasma to intense fields: Generation of strong quasistatic magnetic fields

The generation of quasistatic magnetic fields by nonlinear interactions of two high-frequency waves are studied on the basis of a correct relativistic kinetic theory for a thermal plasma. The plasma response in the presence of nonlinear excitations is a nonlinear current, which is calculated here within the framework of the relativistic theory. Quasistationary magnetic fields are generated due to the magnetization current. The latter is derived solving the kinetic integrals in the long wavelength limit and it holds for arbitrary plasma temperatures. It also allows for deducing the magnetization currents at nonrelativistic or ultrarelativistic temperatures. The magnitude of quasistationary magnetic fields is estimated for fully relativistic plasma temperatures, where the relativistic contribution dominates. For typical laboratory or numerical experiments the magnetic field strength can reach values higher than 10 MG