Publications of the Astronomical Society of Japan | |
Theory of the jitter radiation in a magnetized plasma accompanying a temperature gradient | |
Hattori, Makoto1  Fujiki, Kazushiro1  | |
[1] Astronomical Institute, Graduate school of science, Tohoku University, 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan | |
关键词: instabilities; plasmas; "relativistic processes"; | |
DOI : 10.1093/pasj/psw014 | |
学科分类:天文学(综合) | |
来源: Oxford University Press | |
【 摘 要 】
Thelinearstabilityofamagnetizedplasmaaccompanyingatemperaturegradientisreexaminedbyusingplasmakinetictheory.Weproposethattheanisotropicvelocitydistributionfunctionshouldbedecomposedintotwocomponents.Oneisproportionaltothetemperaturegradientparalleltothebackgroundmagneticfield.Theotherisproportionaltothetemperaturegradientperpendiculartothebackgroundmagneticfield.Sincetheamplitudeoftheanisotropicvelocitydistributionfunctionisproportionaltotheheatconductivity,andtheheatconductivityperpendiculartothemagneticfieldisstronglyreduced,thefirstcomponentoftheanisotropicvelocitydistributionfunctionispredominant.Theanisotropicvelocitydistributionfunctioninducedbythetemperaturegradientalongthebackgroundmagneticfielddrivesplasmakineticinstabilityandcircularpolarizedmagneticplasmawavesareexcited.WeshowthattheinstabilityisalmostidenticaltotheWeibelinstabilityintheweaklymagnetizedplasma.However,inthecaseoftheinstabilitycausedbythetemperaturegradient,whetherwavevectorsofmodesareparalleltoorantiparalleltothebackgroundmagneticfield,thegrowthrateofonemodeissuppressedandthegrowthrateoftheothermodeisenhancedduetothebackgroundmagneticfield.Inthestronglymagnetizedplasma,onemodeisstabilizedandonlyoneofthemodesremainsunstable.Theformulaeforthejitterradiationspectrumemittedbyrelativisticelectronswhentheytravelthroughthemagnetizedplasmawiththeplasmawavesdrivenbytheinstabilityarededucedatthefirsttime.Weshowthatthesynchrotronemissionandthejitterradiationaresimultaneouslyemittedfromthesamerelativisticelectron.Thejitterradiationisexpectedtobecircularlypolarizedbutwithaverysmallpolarizationdegreesincealmostthesameamountsofleft-handedandright-handedcircularpolarizedmagneticwavesareexcitedbytheinstability.
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