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Title: Undamped electrostatic plasma waves

Abstract

Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule ofmore » thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.« less

Authors:
; ;  [1]; ;  [2];  [3];  [4]
  1. Dipartimento di Fisica and CNISM, Universita della Calabria, 87036 Rende (CS) (Italy)
  2. Dipartimento di Fisica and CNISM, Universita di Pisa, 56127 Pisa (Italy)
  3. Institute for Fusion Studies and Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States)
  4. Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)
Publication Date:
OSTI Identifier:
22086108
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 19; Journal Issue: 9; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOLTZMANN-VLASOV EQUATION; DISTRIBUTION FUNCTIONS; ELECTRON PLASMA WAVES; ELECTRONS; EXCITATION; IONS; LANDAU DAMPING; NONLINEAR PROBLEMS; OSCILLATIONS; PHASE VELOCITY; PLASMA; PLASMA SIMULATION; POISSON EQUATION

Citation Formats

Valentini, F, Perrone, D, Veltri, P, Califano, F, Pegoraro, F, Morrison, P J, and O'Neil, T M. Undamped electrostatic plasma waves. United States: N. p., 2012. Web. doi:10.1063/1.4751440.
Valentini, F, Perrone, D, Veltri, P, Califano, F, Pegoraro, F, Morrison, P J, & O'Neil, T M. Undamped electrostatic plasma waves. United States. https://doi.org/10.1063/1.4751440
Valentini, F, Perrone, D, Veltri, P, Califano, F, Pegoraro, F, Morrison, P J, and O'Neil, T M. Sat . "Undamped electrostatic plasma waves". United States. https://doi.org/10.1063/1.4751440.
@article{osti_22086108,
title = {Undamped electrostatic plasma waves},
author = {Valentini, F and Perrone, D and Veltri, P and Califano, F and Pegoraro, F and Morrison, P J and O'Neil, T M},
abstractNote = {Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.},
doi = {10.1063/1.4751440},
url = {https://www.osti.gov/biblio/22086108}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 9,
volume = 19,
place = {United States},
year = {2012},
month = {9}
}