The role of electromagnetic ion-cyclotron waves in solar 3He-rich events

The preferential heating of 3He by the electromagnetic ion-cyclotron waves, which propagate in the direction parallel to the magnetic fields in the solar corona, is investigated. The results obtained from this study indicate that the parallel propagating electromagnetic ion-cyclotron waves, if driven, can be efficient at heating 3He through the first harmonic resonance. This preferential heating of 3He can lead to a high temperature ratio THe3/THe4∼10–20 and thus largely increases the number of 3He to be further accelerated to high energies. Comparing to the electrostatic ion-cyclotron waves, we find that the electromagnetic ion-cyclotron waves can be even more efficient at heating 3He than the electrostatic ion-cyclotron waves if both types of waves are excited with comparable wave energy densities. Therefore, the electromagnetic ion-cyclotron waves, if generated in solar flares, should also play an important role in solar 3He-rich events along with the electrostatic ion-cyclotron waves.

► Studied the role of electromagnetic ion-cyclotron waves in solar 3He-rich events.
► Studied the dispersion relation of electromagnetic ion-cyclotron waves in plasma with the solar corona composition.
► Computed the heating of 3He by the electromagnetic ion-cyclotron waves.
► Compared the efficiency at heating 3He between electromagnetic and electrostatic ion-cyclotron waves.