Generation of Electron Suprathermal Tails in the Upper Solar Atmosphere: Implications for Coronal Heating
Abstract
We present a mechanism for the generation of non-Maxwellian electron distribution function in the upper regions of the solar atmosphere in the presence of collisional damping. It is suggested that finite-amplitude, low-frequency, obliquely propagating electromagnetic waves can carry a substantial electric field component parallel to the mean magnetic field that can be significantly larger than the Dreicer electric field. This long-wavelength electric fluctuation is capable of generating high-frequency electron plasma oscillations and low-frequency ion acoustic-like waves. The analysis has been performed using 1-1/2D Vlasov and PIC numerical simulations in which both electrons and ions are treated kinetically and self consistently. The simulation results indicate that high-frequency electron plasma oscillations and low-frequency ion acoustic-like waves are generated. The high-frequency electron plasma oscillation drives electron plasma turbulence, which subsequently is damped out by the background electrons. The turbulence damping results in electron acceleration and the generation of non-Maxwellian suprathermal tails on timescales short compared to collisional damping. Bulk heating also occurs if the fluctuating parallel electric field is strong enough. This study suggests that finite-amplitude, low-frequency, obliquely propagating electromagnetic waves can play a significant role in the acceleration and heating of the solar corona electrons and in the coupling of medium and small-scale phenomena.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2000
- DOI:
- 10.1086/308151
- Bibcode:
- 2000ApJ...528..509V
- Keywords:
-
- ACCELERATION OF PARTICLES;
- PLASMAS;
- SUN: CHROMOSPHERE;
- SUN: CORONA;
- WAVES;
- Acceleration of Particles;
- Plasmas;
- Sun: Chromosphere;
- Sun: Corona;
- Waves