Quasistatic magnetic field generated by a short laser pulse in an underdense plasma

The quasistatic magnetic field generated by short laser pulse in a uniform rarefied plasma is found analytically and compared to that of two-dimensional particle simulations. It is shown that an axisymmetric laser pulse generates an azimuthal magnetic field the structure of which is rather complicated inside the laser pulse body. Behind the pulse in the wake region the magnetic field contains a component that is homogeneous in the longitudinal direction and a component that is oscillating at the wave number 2k(p), where k(p) is the wave number of the plasma wake. Particle simulations confirm the analytical results and are also used to treat the case of high intense laser pulses. (C) 1997 American Institute of Physics.