Relaxation of an electron beam during the onset of the electromagnetic filamentation instability

Results are presented from three-dimensional particle-in-cell simulations o f relaxation of an electron beam in a plasma. When penetrating into the pla sma, the electron beam generates the return current carried by the plasma e lectrons. In a collisionless plasma, the relaxation mechanism is related to the onset of an electromagnetic filamentation instability. The instability leads to the generation of a quasistatic magnetic field, which decays due to the magnetic field reconnection in the final stage of the system evoluti on. (C) 2001 MAIK "Nauka/Interperiodica".