Kinetic Alfven Waves Excited by Cometary Newborn Ions with Large Perpendicular Energies

摘要

Stability of the kinetic Alfven wave in a plasma of hydrogen, oxygen and electronsis studied. Each species is modeled by drifting ring distributions in the direction parallel to themagnetic field, while in the perpendicular direction the distribution is simulated with a loss conetype distribution obtained through the subtraction of two Maxwellian distributions with differenttemperatures. It is found that for frequencies ω* < ωch with ω* and ωch the Doppler shifted andhydrogen ion gyro-frequencies, respectively, the growth rate of the kinetic Alfven wave increaseswith the increase in propagation angles and density of oxygen ions. On the other hand, forfrequencies ω* < ωcO with ωcO the oxygen ion gyro-frequency the growth rate is independent ofthe oxygen ion density.