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Instabilities and growing waves: power absorbed or generated by the various excited modes in a plasma; Instabilites et ondes croissantes: puissance absorbee - ou engendree - par les differents modes excites dans un plasma

Abstract

The character, stable or unstable, of a medium can be deduced from the behavior of an ideal model of a semi-infinite medium which is subjected to an excitation only at the boundary. A new analytic method is used to solve this problem. The results obtained show a connection between the character of the medium and certain properties of the dispersion equation, and agree with those derived from other methods. Then, the energy exchange between a medium and a source of excitation is investigated. In order to include the case of growing waves associated with convective instabilities, this problem is treated in the context of the wave packet theory. We find that - even in the absence of collisions - there still is a power exchange. Thus a connexion can be established with the kinematic theories of growing waves and the modes generating power can be found. Moreover, the power absorbed by spatial dispersion is found to be identical with that due to Landau's effect for long waves. This confirms the kinematic character of the latter and bridges a gap between macroscopic and microscopic theories. (author) [French] Le caractere, stable ou instable, d'un milieu peut etre deduit du comportement d'un milieu  More>>
Authors:
Rolland, P [1] 
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
Publication Date:
May 01, 1969
Product Type:
Thesis/Dissertation
Report Number:
CEA-R-3862
Resource Relation:
Other Information: TH: These docteur es sciences; 18 refs; PBD: May 1969
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BEAM-PLASMA SYSTEMS; BRIGGS CRITERION; COLD PLASMA; CONVECTIVE INSTABILITIES; DISPERSION RELATIONS; ENERGY TRANSFER; FOURIER TRANSFORMATION; LANDAU DAMPING; PLASMA WAVES; SINGULARITY; WAVE PACKETS; WAVE PROPAGATION
OSTI ID:
20552695
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France); Faculte des Sciences d'Orsay, Universite de Paris, 91 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR04R3862007952
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
[118] pages
Announcement Date:
Feb 20, 2005

Citation Formats

Rolland, P. Instabilities and growing waves: power absorbed or generated by the various excited modes in a plasma; Instabilites et ondes croissantes: puissance absorbee - ou engendree - par les differents modes excites dans un plasma. France: N. p., 1969. Web.
Rolland, P. Instabilities and growing waves: power absorbed or generated by the various excited modes in a plasma; Instabilites et ondes croissantes: puissance absorbee - ou engendree - par les differents modes excites dans un plasma. France.
Rolland, P. 1969. "Instabilities and growing waves: power absorbed or generated by the various excited modes in a plasma; Instabilites et ondes croissantes: puissance absorbee - ou engendree - par les differents modes excites dans un plasma." France.
@misc{etde_20552695,
title = {Instabilities and growing waves: power absorbed or generated by the various excited modes in a plasma; Instabilites et ondes croissantes: puissance absorbee - ou engendree - par les differents modes excites dans un plasma}
author = {Rolland, P}
abstractNote = {The character, stable or unstable, of a medium can be deduced from the behavior of an ideal model of a semi-infinite medium which is subjected to an excitation only at the boundary. A new analytic method is used to solve this problem. The results obtained show a connection between the character of the medium and certain properties of the dispersion equation, and agree with those derived from other methods. Then, the energy exchange between a medium and a source of excitation is investigated. In order to include the case of growing waves associated with convective instabilities, this problem is treated in the context of the wave packet theory. We find that - even in the absence of collisions - there still is a power exchange. Thus a connexion can be established with the kinematic theories of growing waves and the modes generating power can be found. Moreover, the power absorbed by spatial dispersion is found to be identical with that due to Landau's effect for long waves. This confirms the kinematic character of the latter and bridges a gap between macroscopic and microscopic theories. (author) [French] Le caractere, stable ou instable, d'un milieu peut etre deduit du comportement d'un milieu semi-indefini soumis a une excitation a la frontiere. Une nouvelle methode analytique est developpee pour resoudre ce probleme. Les resultats obtenus montrent une connexion entre le comportement du milieu et certaines proprietes de l'equation de dispersion, et generalisent les resultats obtenus par d'autres methodes. On etudie ensuite les echanges d'energie entre un milieu et une source d'excitation. Pour inclure le cas des ondes croissantes associees aux instabilites convectives, on traite ce probleme dans le cadre de la theorie du paquet d'ondes. On trouve que meme en l'absence de collisions, la puissance echangee n'est pas nulle. Ceci permet d'etablir une connexion avec les theories cinematiques des ondes croissantes, tout en precisant quels sont les modes generateurs d'energie. Par ailleurs, la puissance absorbee par dispersion spatiale se revele identique a la puissance absorbee par effet Landau pour les grandes ondes, ce qui confirme le caractere cinematique de ce dernier et fait la jonction entre les theories microscopique et macroscopique. (auteur)}
place = {France}
year = {1969}
month = {May}
}