Nonlinear Ion Heating in Magnetized Plasma by Monochromatic Low-Frequency Waves

Heating of ions by monochromatic low-frequency waves, propagating perpendicularly to a dipole magnetic field, is analyzed theoretically and verified by simulations. The nonlinear acceleration mechanism involves a distortion of the ion trajectory by the external wave. An ion feels along its distorted trajectory field components at twice the wave frequency. When the wave frequency equals half of the local gyrofrequency, the resulting wave field at the gyrofrequency accelerates the ion. The perpendicular acceleration and the parallel motion determine the interaction time and the final ion energy.