---
abstract: 'Cyclotron resonance with high-frequency Alfv\''en waves has been proposed
  as an ion heating mechanism for producing high-speed winds and large ion temperatures
  in coronal holes. In the simplest version of the model (cyclotron sweep model),
  the waves propagate without interacting until they hit a resonance with the plasma
  ions at distance, where the ion cyclotron frequency becomes comparable to the wave
  frequency. We calculate the energetic test-particle mean free path lambda in solar
  corona heated by this mechanism. The primary result of our study is that energetic
  particles are efficiently coupled to the high- frequency MHD waves and may, thus,
  provide important feed back to wave-heating models. Detailed calculations are presented
  for a solar-wind stream of intermediate speed driven by the cyclotron sweep mechanism
  applying an extended quasi-linear theory for the mean free path. A local maximum
  of lambda is located near r=2 R\_\ensuremath\odot , but lambda is very small
  at distances close to the Sun ( r<1.3 R\_\ensuremath\odot ) helping the acceleration
  of particles to high energies on open coronal field lines there. Another minimum
  for the mean free path is obtained near r=10 R\_\ensuremath\odot enabling ion
  acceleration beyond 10 MeV/n in streams of intermediate speeds by CME shock waves
  in the test-particle approximation. However, the presence of high- frequency Alfv\''en
  waves in amounts required for the cyclotron sweep heating has to be limited below
  \raisebox-0.5ex\textasciitilde 10 R$_sun$ on field lines close to the ecliptic
  to avoid discrepancies with the inferred arrival times of solar energetic particles.
  Non-linear effects are discussed as a possible mechanism for removing the wave excess
  from the plasma.'
adsnote: Provided by the SAO/NASA Astrophysics Data System
adsurl: https://ui.adsabs.harvard.edu/abs/2001A&A...371..738V
authors:
- R. Vainio
- T. Laitinen
category: publications
date: '2001-05-01'
doi: 10.1051/0004-6361:20010411
draft: false
featured: false
journal: A&A
month: May
pages: 738-747
projects: []
publication: A&A
publication_types:
- '2'
tags:
- 'Sun: corona'
- 'Sun: particle emission'
- Solar wind
title: 'The relation between cyclotron heating and energetic particles on open coronal
  field lines'
type: ARTICLE
volume: '371'
year: '2001'
---