ION-NEUTRAL COLLISION EFFECT ON AN ALFVEN-WAVE

This paper reports that ion-neutral collisions in a magnetized plasma cause a drastic change in the dispersion relation of the shear Alfven wave with poloidal mode number m = 0, connecting to the branch of the m = + 1 compressional Alfven wave at frequencies below the ion-cyclotron frequency. An anomaly of the dispersion then appears on the refractive index curve and a wave packet in this frequency range undergoes strong amplitude damping and profile deformation. It is confirmed that the Kramers-Kronig relation holds for the dielectric function, estimated from both the measured refractive index and damping rate.