DAMPING OF PERPENDICULAR MAGNETOSONIC PULSES IN A 2-ION-SPECIES PLASMA

The damping of finite-amplitude magnetosonic pulses propagating perpen dicular to a magnetic field in a collisionless plasma containing two i on species (majority light ions and minority heavy ions) is studied th rough theory and simulation. A magnetosonic pulse accelerates heavy io ns in the direction parallel to the wave front; this cross-filed motio n of heavy ions then generates a long-wavelength perturbation behind t he original pulse. Because of these processes the original pulse is da mped. The damping rate of a solitary pulse is theoretically obtained. It decreases with increasing amplitude. The damping is further investi gated 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 Insti tute of Physics.