Heating of ions by low-frequency Alfv\'{e}n waves in partially ionized plasmas

TL;DR

This paper shows that low-frequency Alfvén waves can significantly heat ions in partially ionized plasmas, providing insights into solar atmospheric heating mechanisms beyond traditional resonant or collisional damping models.

Contribution

It introduces a non-resonant Alfvén wave heating mechanism in partially ionized plasmas, highlighting the dependence on ion-neutral collision frequency and offering a new perspective on solar atmospheric heating.

Findings

Non-resonant Alfvén wave heating is less efficient with ion-neutral collisions.

Heating efficiency depends on the ratio of collision frequency to gyrofrequency.

Ions can be substantially heated by low-frequency Alfvén waves in partially ionized plasmas.

Abstract

In the solar atmosphere, the chromospheric and coronal plasmas are much hotter than the visible photosphere. The heating of the solar atmosphere, including the partially ionized chromosphere and corona, remains largely unknown. In this paper we demonstrate that the ions can be substantially heated by Alfv\'{e}n waves with very low frequencies in partially ionized low beta plasmas. This differs from other Alfv\'{e}n wave related heating mechanisms such as ion-neutral collisional damping of Alfv\'{e}n waves and heating described by previous work on resonant Alfv\'{e}n wave heating. In this paper, we find that the non-resonant Alfv\'{e}n wave heating is less efficient in partially ionized plasmas than when there are no ion-neutral collisions, and the heating efficiency depends on the ratio of the ion-neutral collision frequency to the ion gyrofrequency.