Studies on the parametric decay of waves in fusion plasmas: Dissertation

Research output: ThesisDissertationCollection of Articles

Abstract

Parametric instabilities of large-amplitude electromagnetic waves are investigated in fusion applications. In laser fusion, the electromagnetic wave reflected from the overdense plasma can act as a secondary pump wave and excite parametric instabilities. In double stimulated Brillouin scattering (DSBS), both the incoming and the reflected pump wave scatter from a common ion sound wave. The stationary states and the dynamics of DSBS are investigated by using a simple envelope model. The ion sound wave that is excited in DSBS is shown to have soliton-like properties. The stimulated Raman scattering (SRS) of free-electron-laser radiation can be applied to current drive in tokamaks. SRS generates fast longitudinal electron plasma waves which accelerate electrons to relativistic energies. Since the energetic current-carrying electrons are almost collisionless, the current decays very slowly. The feasibility of the Raman current drive in tokamaks is investigated theoretically. The current drive efficiency and the optimum free-electron-laser parameters are determined. The energy transfer to the fast electrons from the electrostatic wave is studied with relativistic Vlasov-Maxwell simulations. The parametric decay of a wave to half-harmonics is investigated. It is shown that the growth rate of the decay vanishes in the limit of a long wavelength of the pump wave even for general elecromagnetic or electrostatic decay modes. The results are applied to the decay of a fast magnetosonic wave to two slow waves in tokamak plasmas.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Helsinki University of Technology
Supervisors/Advisors
  • Salomaa, Rainer, Supervisor, External person
Award date16 Oct 1992
Place of PublicationEspoo
Publisher
Print ISBNs951-38-4228-2
Publication statusPublished - 1992
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

fusion
decay
pumps
sound waves
free electron lasers
electromagnetic radiation
scattering
Raman spectra
laser fusion
electrostatic waves
electrons
plasma waves
electron plasma
ions
envelopes
solitary waves
energy transfer
laser beams
electrostatics
harmonics

Keywords

  • parametric instabilities
  • fusion
  • plasmas
  • scattering
  • Brillouin effect
  • SBS
  • DSBS
  • Raman effect
  • SRS
  • plasma waves
  • decay
  • fast magnetoacoustic waves

Cite this

Pättikangas, T. (1992). Studies on the parametric decay of waves in fusion plasmas: Dissertation. Espoo: VTT Technical Research Centre of Finland.
Pättikangas, Timo. / Studies on the parametric decay of waves in fusion plasmas : Dissertation. Espoo : VTT Technical Research Centre of Finland, 1992. 171 p.
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abstract = "Parametric instabilities of large-amplitude electromagnetic waves are investigated in fusion applications. In laser fusion, the electromagnetic wave reflected from the overdense plasma can act as a secondary pump wave and excite parametric instabilities. In double stimulated Brillouin scattering (DSBS), both the incoming and the reflected pump wave scatter from a common ion sound wave. The stationary states and the dynamics of DSBS are investigated by using a simple envelope model. The ion sound wave that is excited in DSBS is shown to have soliton-like properties. The stimulated Raman scattering (SRS) of free-electron-laser radiation can be applied to current drive in tokamaks. SRS generates fast longitudinal electron plasma waves which accelerate electrons to relativistic energies. Since the energetic current-carrying electrons are almost collisionless, the current decays very slowly. The feasibility of the Raman current drive in tokamaks is investigated theoretically. The current drive efficiency and the optimum free-electron-laser parameters are determined. The energy transfer to the fast electrons from the electrostatic wave is studied with relativistic Vlasov-Maxwell simulations. The parametric decay of a wave to half-harmonics is investigated. It is shown that the growth rate of the decay vanishes in the limit of a long wavelength of the pump wave even for general elecromagnetic or electrostatic decay modes. The results are applied to the decay of a fast magnetosonic wave to two slow waves in tokamak plasmas.",
keywords = "parametric instabilities, fusion, plasmas, scattering, Brillouin effect, SBS, DSBS, Raman effect, SRS, plasma waves, decay, fast magnetoacoustic waves",
author = "Timo P{\"a}ttikangas",
note = "Project code: YDI9006",
year = "1992",
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Pättikangas, T 1992, 'Studies on the parametric decay of waves in fusion plasmas: Dissertation', Doctor Degree, Helsinki University of Technology, Espoo.

Studies on the parametric decay of waves in fusion plasmas : Dissertation. / Pättikangas, Timo.

Espoo : VTT Technical Research Centre of Finland, 1992. 171 p.

Research output: ThesisDissertationCollection of Articles

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T1 - Studies on the parametric decay of waves in fusion plasmas

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N2 - Parametric instabilities of large-amplitude electromagnetic waves are investigated in fusion applications. In laser fusion, the electromagnetic wave reflected from the overdense plasma can act as a secondary pump wave and excite parametric instabilities. In double stimulated Brillouin scattering (DSBS), both the incoming and the reflected pump wave scatter from a common ion sound wave. The stationary states and the dynamics of DSBS are investigated by using a simple envelope model. The ion sound wave that is excited in DSBS is shown to have soliton-like properties. The stimulated Raman scattering (SRS) of free-electron-laser radiation can be applied to current drive in tokamaks. SRS generates fast longitudinal electron plasma waves which accelerate electrons to relativistic energies. Since the energetic current-carrying electrons are almost collisionless, the current decays very slowly. The feasibility of the Raman current drive in tokamaks is investigated theoretically. The current drive efficiency and the optimum free-electron-laser parameters are determined. The energy transfer to the fast electrons from the electrostatic wave is studied with relativistic Vlasov-Maxwell simulations. The parametric decay of a wave to half-harmonics is investigated. It is shown that the growth rate of the decay vanishes in the limit of a long wavelength of the pump wave even for general elecromagnetic or electrostatic decay modes. The results are applied to the decay of a fast magnetosonic wave to two slow waves in tokamak plasmas.

AB - Parametric instabilities of large-amplitude electromagnetic waves are investigated in fusion applications. In laser fusion, the electromagnetic wave reflected from the overdense plasma can act as a secondary pump wave and excite parametric instabilities. In double stimulated Brillouin scattering (DSBS), both the incoming and the reflected pump wave scatter from a common ion sound wave. The stationary states and the dynamics of DSBS are investigated by using a simple envelope model. The ion sound wave that is excited in DSBS is shown to have soliton-like properties. The stimulated Raman scattering (SRS) of free-electron-laser radiation can be applied to current drive in tokamaks. SRS generates fast longitudinal electron plasma waves which accelerate electrons to relativistic energies. Since the energetic current-carrying electrons are almost collisionless, the current decays very slowly. The feasibility of the Raman current drive in tokamaks is investigated theoretically. The current drive efficiency and the optimum free-electron-laser parameters are determined. The energy transfer to the fast electrons from the electrostatic wave is studied with relativistic Vlasov-Maxwell simulations. The parametric decay of a wave to half-harmonics is investigated. It is shown that the growth rate of the decay vanishes in the limit of a long wavelength of the pump wave even for general elecromagnetic or electrostatic decay modes. The results are applied to the decay of a fast magnetosonic wave to two slow waves in tokamak plasmas.

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KW - fast magnetoacoustic waves

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Pättikangas T. Studies on the parametric decay of waves in fusion plasmas: Dissertation. Espoo: VTT Technical Research Centre of Finland, 1992. 171 p.