Magnetic fields from high-intensity laser pulses in plasmas

In a plasma interacting with ultra-short, high-intensity laser pulses, the magnetic part of the Lorentz force on the electrons can become as important as the electric part. In this case, we can expect the magnetic field to change the pattern of the nonlinear laser-pulse - plasma interaction drastically. The relativistic nonlinearities introduced by the magnetic interaction are of general interest in relation to the field of ultra-strong electromagnetic waves propagating in media, high-energy space plasmas and laser - plasma interaction under laboratory conditions. We present a summary of analytical and numerical results concerning the generation of quasi-static magnetic fields by high-intensity laser pulses in underdense plasmas and in thin plasma foils, and discuss the dynamical effects of these fields on the plasma motion and on the pulse propagation. This analysis indicates that phenomena such as current pinching, reconnection of magnetic-field lines and vortex propagation etc, that have been previously discussed in the case of space and laboratory plasmas, are also important for laser - plasma interactions.