Lower hybrid waves at the shock front: a reassessment

Lower hybrid waves at the shock front: a reassessment

The primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary...

Full description

Bibliographic Details
Main Authors: S. N. Walker, M. A. Balikhin, H. St. C. K. Alleyne, Y. Hobara, M. André, M. W. Dunlop
Format: Article
Language:English
Published: Copernicus Publications 2008-03-01
Series:Annales Geophysicae
Online Access:https://www.ann-geophys.net/26/699/2008/angeo-26-699-2008.pdf
id doaj-21950c2981f94950813b1941a8323510
record_format Article
spelling doaj-21950c2981f94950813b1941a83235102020-11-24T23:51:56ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762008-03-012669970710.5194/angeo-26-699-2008Lower hybrid waves at the shock front: a reassessmentS. N. Walker0M. A. Balikhin1H. St. C. K. Alleyne2Y. Hobara3M. André4M. W. Dunlop5Department of Automatic Control and systems Engineering, University of Sheffield, Sheffield, UKDepartment of Automatic Control and systems Engineering, University of Sheffield, Sheffield, UKDepartment of Automatic Control and systems Engineering, University of Sheffield, Sheffield, UKDepartment of Automatic Control and systems Engineering, University of Sheffield, Sheffield, UKSwedish Institute for Radio Physics-Uppsala Division, University of Uppsala, SwedenSpace Physics Division, SSTD, CCLRC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UKThe primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary shocks, comets, and their effects are observed in astrophysical phenomena such as supernova remnants and jets in the form of X-ray bremsstrahlung radiation. One of the physical models for electron acceleration at supercritical shocks is based on low-hybrid turbulence due to the presence of reflected ions in the foot region. Since lower hybrid waves propagate almost perpendicular to the magnetic field they can be simultaneously in resonance with both the unmagnetised ions (&omega;=<I>V<sub>i</sub>k</I><sub>&#x22A5;</sub>) and magnetised electrons (&omega;=<I>V<sub>e</sub>k</I><sub>||</sub>). In this paper, Cluster observations of the electric field are used to study the occurrence of lower hybrid waves in the front of the terrestrial bow shock. It is shown that the lower hybrid waves exist as isolated wave packets. However, the very low level of the observed lower hybrid turbulence is too small to impart significant energisation to the electron population.https://www.ann-geophys.net/26/699/2008/angeo-26-699-2008.pdf
collection DOAJ
language English
format Article
sources DOAJ
author S. N. Walker
M. A. Balikhin
H. St. C. K. Alleyne
Y. Hobara
M. André
M. W. Dunlop
spellingShingle S. N. Walker
M. A. Balikhin
H. St. C. K. Alleyne
Y. Hobara
M. André
M. W. Dunlop
Lower hybrid waves at the shock front: a reassessment
Annales Geophysicae
author_facet S. N. Walker
M. A. Balikhin
H. St. C. K. Alleyne
Y. Hobara
M. André
M. W. Dunlop
author_sort S. N. Walker
title Lower hybrid waves at the shock front: a reassessment
title_short Lower hybrid waves at the shock front: a reassessment
title_full Lower hybrid waves at the shock front: a reassessment
title_fullStr Lower hybrid waves at the shock front: a reassessment
title_full_unstemmed Lower hybrid waves at the shock front: a reassessment
title_sort lower hybrid waves at the shock front: a reassessment
publisher Copernicus Publications
series Annales Geophysicae
issn 0992-7689
1432-0576
publishDate 2008-03-01
description The primary process occurring at a collisionless shock is the redistribution of the bulk upstream energy into other degrees of freedom. One part of this process results in the acceleration of electrons at the shock front. Accelerated electrons are observed at the terrestrial and other planetary shocks, comets, and their effects are observed in astrophysical phenomena such as supernova remnants and jets in the form of X-ray bremsstrahlung radiation. One of the physical models for electron acceleration at supercritical shocks is based on low-hybrid turbulence due to the presence of reflected ions in the foot region. Since lower hybrid waves propagate almost perpendicular to the magnetic field they can be simultaneously in resonance with both the unmagnetised ions (&omega;=<I>V<sub>i</sub>k</I><sub>&#x22A5;</sub>) and magnetised electrons (&omega;=<I>V<sub>e</sub>k</I><sub>||</sub>). In this paper, Cluster observations of the electric field are used to study the occurrence of lower hybrid waves in the front of the terrestrial bow shock. It is shown that the lower hybrid waves exist as isolated wave packets. However, the very low level of the observed lower hybrid turbulence is too small to impart significant energisation to the electron population.
url https://www.ann-geophys.net/26/699/2008/angeo-26-699-2008.pdf
work_keys_str_mv AT snwalker lowerhybridwavesattheshockfrontareassessment
AT mabalikhin lowerhybridwavesattheshockfrontareassessment
AT hstckalleyne lowerhybridwavesattheshockfrontareassessment
AT yhobara lowerhybridwavesattheshockfrontareassessment
AT mandre lowerhybridwavesattheshockfrontareassessment
AT mwdunlop lowerhybridwavesattheshockfrontareassessment
_version_ 1725475419278278656

Similar Items