Numerical simulations of relativistic double layers

Summary form only given, as follows. Particle-in-cell numerical simulations of one-dimensional, time-dependent, fully relativistic double layers have been carried out. The scaling law for the layer width has been extended to relativistic potential drops and plasma temperatures. The layer creation and disruption cycles, as well as the beam-plasma instabilities driven by the layer, have been studied. Relativistic double layers may be a mechanism for producing intense radiation as observed in active galactic nuclei and pulsars, primarily by collective bremsstralung involving the charge-bunched electron beam and background plasma electrons.<>