PARAMETRIC CYCLOTRON-RESONANCE IN-SPACE PLASMAS

The parametric interaction of waves with particle cyclotron motion has been studied. A wave with a compressional magnetic field component mo difies the cyclotron motion of the particles, which enables them to re sonate with other waves which have perpendicular electric fields. Reso nance occurs when the frequency difference of the two wave modes (comp ressional and perpendicular) matches the cyclotron frequency. This so- called parametric cyclotron resonance mechanism can provide a means to exchange energy between particles and low-frequency waves. We discuss the specific example of energy exchange between an Alfven wave and io n Larmor motion.