Kinetic Alfven waves: Linear theory and a particle-in-cell simulation

An Alfven-cyclotron fluctuation of sufficiently short wavelength has a strong proton cyclotron resonance at propagation parallel to the background magnetic field B-o in a homogeneous, collisionless electron-proton plasma. As k(parallel to), the wavevector component parallel to B-o, decreases, the proton cyclotron wave-particle interaction becomes nonresonant, and the electron Landau resonance becomes effective at propagation oblique to B-o. Here linear Vlasov theory is used to determine the dispersion and damping properties of Alfven-cyclotron fluctuations associated with the transition from the proton cyclotron resonance regime to the electron Landau resonance regime. Also, a particle-in-cell plasma simulation is used to examine the electron response to the initial imposition of an Alfven-cyclotron wave in the electron Landau resonance regime. The computation shows heating of the electrons in the direction parallel to B-o and the formation of a beam in the direction of the parallel component of k.