skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Stimulated ion Compton scattering instability of whistlers in plasmas

Abstract

The nonlinear interactions between magnetic field-aligned broadband whistler wave packets (hereafter referred to as whistlerons) and ion quasimodes in magnetized plasmas are considered. By treating the whistlerons as quasiparticles, their nonlinear propagation in a slowly varying medium supported by ion quasimode density perturbations is studied. A nonlinear dispersion relation within the framework of the wave-kinetic (for the whistlerons) and Vlasov (for the ion quasimodes) descriptions is derived. The dispersion relation admits a kinetic modulational instability. The growth rate of the latter is presented. The present result can improve our understanding of the nonlinear propagation of incoherent whistlers, which have been frequently observed in the Earth's magnetosphere as well as in laboratory plasmas.

Authors:
; ;  [1]
  1. Institut fuer Theoretische Physik IV and Centre for Plasma Science and Astrophysics, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)
Publication Date:
OSTI Identifier:
20860471
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 12; Other Information: DOI: 10.1063/1.2423251; (c) 2006 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; COMPTON EFFECT; DISPERSION RELATIONS; DISTURBANCES; EARTH MAGNETOSPHERE; IONS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; PLASMA; PLASMA INSTABILITY; QUASI PARTICLES; WAVE PACKETS; WHISTLERS

Citation Formats

Shukla, P. K., Shukla, Nitin, and Stenflo, L.. Stimulated ion Compton scattering instability of whistlers in plasmas. United States: N. p., 2006. Web. doi:10.1063/1.2423251.
Shukla, P. K., Shukla, Nitin, & Stenflo, L.. Stimulated ion Compton scattering instability of whistlers in plasmas. United States. doi:10.1063/1.2423251.
Shukla, P. K., Shukla, Nitin, and Stenflo, L.. Fri . "Stimulated ion Compton scattering instability of whistlers in plasmas". United States. doi:10.1063/1.2423251.
@article{osti_20860471,
title = {Stimulated ion Compton scattering instability of whistlers in plasmas},
author = {Shukla, P. K. and Shukla, Nitin and Stenflo, L.},
abstractNote = {The nonlinear interactions between magnetic field-aligned broadband whistler wave packets (hereafter referred to as whistlerons) and ion quasimodes in magnetized plasmas are considered. By treating the whistlerons as quasiparticles, their nonlinear propagation in a slowly varying medium supported by ion quasimode density perturbations is studied. A nonlinear dispersion relation within the framework of the wave-kinetic (for the whistlerons) and Vlasov (for the ion quasimodes) descriptions is derived. The dispersion relation admits a kinetic modulational instability. The growth rate of the latter is presented. The present result can improve our understanding of the nonlinear propagation of incoherent whistlers, which have been frequently observed in the Earth's magnetosphere as well as in laboratory plasmas.},
doi = {10.1063/1.2423251},
journal = {Physics of Plasmas},
number = 12,
volume = 13,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}
  • The electron-density fluctuation spectra induced by stimulated Compton scattering (SCS) are directly observed for the first time. A CO{sub 2} laser is focused into plasmas with densities {ital n}{sub {ital e}} spanning (0.4--6){times}10{sup 16} cm{sup {minus}3}. The fluctuations corresponding to backscatter are probed using Thomson scattering. At low {ital n}{sub {ital e}}, the scattered spectrum peaks at a frequency shift {Delta}{omega}={ital kv}{sub {ital e}} and appears to be in a linear convectively saturated regime. At the highest {ital n}{sub {ital e}}, a nonlinear saturation of the SCS instability is observed possibly due to a self-induced perturbation of the electron distributionmore » function.« less
  • This Erratum addresses errors that occurred in some of the analysis in our recent publication (Ref. 1). The main elements of Ref. 1 are (1) the presentation of kinetic simulations of simulated Brillouin backscattering (SBS) and the accompanying secondary instability of the primary SBS ion acoustic wave (IAW) with and without the inclusion of the second harmonic of the primary IAW; (2) analyses of the four-wave (primary IAW, low-frequency IAW, and two sidebands of the primary IAW) and seven-wave (includes the second harmonic of the primary IAW and its two sidebands, as well as the four waves defined in themore » foregoing) dispersion relations for the secondary IAW instability; (3) comparisons of the results of solving the dispersion relations to the two particle simulations; (4) mode coupling calculations for SBS and the four-wave system of IAWs that model the particle simulations; and (5) a discussion and summary. However, the simplified 7-wave dispersion relation used in Ref. 1 propagated a typographical error in Eq.(44) in Ref. 2, the Pesme, Riconda, and Tikhonchuk (PRT) paper. This Erratum corrects Eq.(44) of Ref. 2 (discussed in more detail in an Erratum3 for Ref. 2) and revises Sec. IV of Ref. 1 by correcting the analysis and comparisons of the 4-wave and 7-wave dispersion relations, and the comparison of the 7-wave dispersion relation to the particle simulations. We find that the results of the corrected 7-wave dispersion relation are not profoundly different from the corresponding results in Ref. 1 and the 7-wave growth rates of the most unstable modes are more similar to the results of the 4-wave dispersion relation. The main results of Ref. 1 are unchanged: (1) the particle simulations exhibit a secondary IAW instability that is a modulational instability involving parallel and obliquely propagating IAWs; (2) the two types of particle simulation exhibit similar spectra, and the second harmonic IAW is a transient feature in the first particle simulation that is not well differentiated from the noise in the streak spectra shown in Ref. 1; (3) the 4-wave dispersion relation fits the simulation data relatively well, and only the 4-wave dispersion relation is applicable to the simulation with the second harmonic IAW suppressed; (4) the results of the 7-wave dispersion relation do not differ profoundly from the 4-wave results for the modulational instability when frequency mismatch effects are included; and (5) it is problematic justifying the application of the 7-wave dispersion relation even to the first particle simulation because the second harmonic signal is either transient or weak. The 7-wave dispersion relation is not a primary focus of Ref. 1.« less
  • Stimulated Brillouin instability of a beat-wave of two lasers in plasmas with multiple-ion-species (negative-ions) was studied. The inclusion of negative-ions affects the growth of ion-acoustic wave in Brillouin scattering. Thus, the growth rate of instability is suppressed significantly by the density of negative-ions. To obey the phase-matching condition, the growth rate of the instability attains a maxima for an appropriate scattering angle (angle between the pump and scattered sideband waves). This study would be technologically important to have diagnostics in low-temperature plasmas.
  • A Comment on the Letter by R. P. Drake, E. A. Williams, P. E. Young, K. Estabrook, W. L. Kruer, H. A. Baldis, and T. W. Johnston, Phys. Rev. Lett. 60, 1018 (1988).
  • The effects of beam smoothing on the stimulated Brillouin and Raman backscattering instabilities (SBBS and SRBS) in a long scale length exploding foil plasma are experimentally investigated using the Nova laser. We observe strongly time-dependent and blueshifted SBS emission and broadband SRS emission in time-resolved spectral measurements of the backscattered light. The results of this paper focus on the SBS scattering, where we find that random phase plate spatial beam smoothing leads to a decrease in the total SBS reflectivity. Adding temporal smoothing to this spatial smoothing leads to an even greater decrease in the total reflectivity, as well asmore » changes in the spectral nature of the backscattered light. Beam smoothing induced changes to the instabilities are limited to plasmas with a peak density below about 0.2{ital n}{sub cr}; beam smoothing causes little change in the backscattered emission for higher densities. We describe the measurements and discuss models that may explain certain aspects of the results. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less