Damping of perpendicular magnetosonic pulses in a two-ion-species plasma

The damping of finite-amplitude magnetosonic pulses propagating perpendicular to a magnetic field in a collisionless plasma containing two ion species (majority light ions and minority heavy ions) is studied through theory and simulation. A magnetosonic pulse accelerates heavy ions in the direction parallel to the wave front; this cross-filed motion of heavy ions then generates a long-wavelength perturbation behind the original pulse. Because of these processes the original pulse is damped. The damping rate of a solitary pulse is theoretically obtained. It decreases with increasing amplitude. The damping is further investigated by means of a one-dimensional, fully electromagnetic code based on a three-fluid model. The theoretically obtained damping rate is in good agreement with the simulation result. Also, it is confirmed that small-amplitude periodic waves are not damped. (C) 1998 American Institute of Physics.