Parallel and lower hybrid turbulence in low {beta} plasmas driven by strong parallel currents and the resulting parallel electron and perpendicular ion energization
Abstract
In plasmas with strong field aligned currents, the most unstable mode is not always at parallel propagation, but may be at intermediate and very oblique angles. 2D particle simulations are performed in order to examine the interaction between the plasma waves at various angles and the electron and ion distributions in low {beta} collisionless plasmas with strong electron drifts. The parallel Buneman instability is known to arise in this situation, but the simulations demonstrate that the very oblique lower hybrid (LH) waves, until recently considered unimportant, may actually play a role just as significant as the waves at parallel propagation. The LH waves are energized by a currentdriven linear instability, which may be seen as the oblique limit of the Buneman or ionacoustic instability. The simulations resolve strong LH turbulence, substantial perpendicular ion tail heating and parallel electron heating. The combined action of parallel and oblique modes results in more complete electron relaxation than may be produced by the parallel Buneman instability alone.
 Authors:
 School of Physics, Sydney University, NSW 2006, Sydney (Australia)
 Publication Date:
 OSTI Identifier:
 20960081
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 1; Other Information: DOI: 10.1063/1.2409764; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COLLISIONLESS PLASMA; CURRENTS; ELECTROMAGNETIC RADIATION; ELECTRON DRIFT; ELECTRONS; ION ACOUSTIC WAVES; IONS; LOWER HYBRID CURRENT DRIVE; LOWER HYBRID HEATING; PLASMA BEAM INJECTION; PLASMA INSTABILITY; PLASMA SIMULATION; TURBULENCE
Citation Formats
McMillan, Ben F., and Cairns, Iver H.. Parallel and lower hybrid turbulence in low {beta} plasmas driven by strong parallel currents and the resulting parallel electron and perpendicular ion energization. United States: N. p., 2007.
Web. doi:10.1063/1.2409764.
McMillan, Ben F., & Cairns, Iver H.. Parallel and lower hybrid turbulence in low {beta} plasmas driven by strong parallel currents and the resulting parallel electron and perpendicular ion energization. United States. doi:10.1063/1.2409764.
McMillan, Ben F., and Cairns, Iver H.. Mon .
"Parallel and lower hybrid turbulence in low {beta} plasmas driven by strong parallel currents and the resulting parallel electron and perpendicular ion energization". United States.
doi:10.1063/1.2409764.
@article{osti_20960081,
title = {Parallel and lower hybrid turbulence in low {beta} plasmas driven by strong parallel currents and the resulting parallel electron and perpendicular ion energization},
author = {McMillan, Ben F. and Cairns, Iver H.},
abstractNote = {In plasmas with strong field aligned currents, the most unstable mode is not always at parallel propagation, but may be at intermediate and very oblique angles. 2D particle simulations are performed in order to examine the interaction between the plasma waves at various angles and the electron and ion distributions in low {beta} collisionless plasmas with strong electron drifts. The parallel Buneman instability is known to arise in this situation, but the simulations demonstrate that the very oblique lower hybrid (LH) waves, until recently considered unimportant, may actually play a role just as significant as the waves at parallel propagation. The LH waves are energized by a currentdriven linear instability, which may be seen as the oblique limit of the Buneman or ionacoustic instability. The simulations resolve strong LH turbulence, substantial perpendicular ion tail heating and parallel electron heating. The combined action of parallel and oblique modes results in more complete electron relaxation than may be produced by the parallel Buneman instability alone.},
doi = {10.1063/1.2409764},
journal = {Physics of Plasmas},
number = 1,
volume = 14,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}

Parallel currents are usually in the form of fieldaligned electron drifts in collisionless plasmas. The fieldaligned drifts often drive instabilities. For instance, Drake et al. [Science, 299, 873 (2003)] found growth of parallel propagating turbulence initially and strong levels of oblique lower hybrid (LH) waves at later times; substantial parallel electron acceleration was also found. We use collisionless linear theory and quasilinear simulations to study wave growth and parallel electron dynamics in similar systems. In low{beta} plasmas with intense parallel currents and both with or without parallel E fields, LH waves are shown to grow even for electron distributions stablemore »

Laboratory observations of electron energization and associated lowerhybrid and TrivelpieceGould wave turbulence during magnetic reconnection
This work presents an experimental study of currentdriven turbulence in a plasma undergoing magnetic reconnection in a lowbeta, strongguidefield regime. Electrostatic fluctuations are observed by small, highbandwidth, and impedancematched Langmuir probes. The observed modes, identified by their characteristic frequency and wavelength, include lowerhybrid fluctuations and highfrequency TrivelpieceGould modes. The observed waves are believed to arise from electrons energized by the reconnection process via direct bumpontail instability (TrivelpieceGould) or gradients in the fast electron population (lowerhybrid). 
Lowerhybrid collapse, caviton turbulence, and charged particle energization in the topside auroral ionosphere and magnetosphere
In 1981, Chang and Coppi [Geophys. Res. Lett. [bold 8], 1253 (1981)] suggested that lowerhybrid turbulence could be the prime candidate for the acceleration of ions and generation of ion conics'' in the highlatitude ionosphere and magnetosphere. Subsequently, Retterer, Chang, and Jasperse [J. Geophys. Res. [bold 91], 1609 (1986)] demonstrated that nonlinear wave interactions near the lowerhybrid frequency through modulational instability, such as the collapse of waves into soliton (caviton) turbulence could play a key role in the energization of both the ambient ions and electrons. Recent sounding rocket observations in the source region of the topside auroral ionosphere seemmore » 
Dependence of synergy current driven by lower hybrid wave and electron cyclotron wave on the frequency and parallel refractive index of electron cyclotron wave for Tokamaks
The physical mechanism of the synergy current driven by lower hybrid wave (LHW) and electron cyclotron wave (ECW) in tokamaks is investigated using theoretical analysis and simulation methods in the present paper. Research shows that the synergy relationship between the two waves in velocity space strongly depends on the frequency ω and parallel refractive index N{sub //} of ECW. For a given spectrum of LHW, the parameter range of ECW, in which the synergy current exists, can be predicted by theoretical analysis, and these results are consistent with the simulation results. It is shown that the synergy effect is mainlymore » 
Parallel and perpendicular velocity sheared flows driven tripolar vortices in an inhomogeneous electronion quantum magnetoplasma
Nonlinear equations governing the dynamics of finite amplitude driftion acousticwaves are derived by taking into account sheared ion flows parallel and perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a tripolar vortex for specific profiles of the equilibrium sheared flows. The tripolar vortices are, however, observed to form on very short scales in dense quantum plasmas. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.