The effects of external magnetic field on laser beam self focusing through plasma


In this work, the nonlinear dielectric constant due to the relativistic electron motion by the high intense laser beam has been derived. From this, one can evaluate the effect of longitudinal external magnetic field in comparison with transverse external magnetic field on relativistic self focusing of laser beam inside collisionless plasma. Theoretical and numerical calculations show that the increase in the values of external magnetic field, in both cases, lead to the laser beam self focusing is faster and stronger. Furthermore, for fixed values of magnetic field, the self focusing of laser beam in existence of transverse external magnetic field is greater comparing with longitudinal external magnetic field case.