Preferential energization of alpha particles in polar coronal holes at one solar radius above the photosphere

TL;DR

This study investigates how radio wave interactions at lower hybrid frequencies preferentially heat alpha particles over protons in polar coronal holes, providing insights into solar wind acceleration.

Contribution

It introduces a novel sensitivity analysis using a three-fluid Maxwell model to explore plasma heating mechanisms in polar coronal holes.

Findings

Indicates preferential alpha particle heating via lower hybrid instabilities

Shows effects of alpha-proton differential mass and velocity on heating

Provides a dispersion relation for plasma waves at two solar radii

Abstract

Heating of polar coronal holes during solar minimum and acceleration of the fast solar wind issuing therefrom lack comprehensive theoretical understanding. Wave particle interactions are considered to have crucial effects on the extreme properties of heavy ions in the collision-less region of the polar coronal holes. In this article, we have presented a novel sensitivity analysis to investigate plasma heating by radio waves at lower hybrid frequencies. We have employed a three fluid Maxwell model comprising electrons, protons, and alpha particles at around two solar radius heliocentric distance in the polar coronal holes and derived a dispersion relation as a thirteenth order polynomial for the frequency. Our model provides indications of preferential heating of alpha particles in comparison with protons by means of lower hybrid instabilities. We have employed the electron velocity and spatial charge distribution as our basic study tools so as to show the effects of alpha proton differential mass and differential perpendicular velocity on the preferential heating of alpha particles.