dorsal/arxiv
View SchemaFormation of Power-law Energy Spectra in Space Plasmas by Stochastic Acceleration due to Whistler-Mode Waves
| Authors | Chun-yu Ma, Danny Summers |
|---|---|
| Categories | |
| ArXiv ID | physics/9810049 |
| URL | https://arxiv.org/abs/physics/9810049 |
| DOI | 10.1029/1998GL900108 |
| Journal | Geophysical Research Letters 25, No.21, 4099, 1998 |
Abstract
A non-relativistic Fokker-Planck equation for the electron distribution function is formulated incorporating the effects of stochastic acceleration by whistler-mode waves and Coulomb collisions. The stationary solution $f$ to the equation, subject to a zero-flux boundary condition, is found to be a generalized Lorentzian (or kappa) distribution, which satisfies $f\propto v^{-2(\kappa+1)}$ for large velocity $v$, where $\kappa$ is the spectral index. The parameter $\kappa$ depends strongly on the relative wave intensity $R$. Taking into account the critical energy required for resonance of electrons with whistlers, we calculate a range of values of $R$ for each of a number of different space plasmas for which kappa distributions can be expected to be formed. This study is one of the first in the literature to provide a theoretical justification for the formation of generalized Lorentzian (or kappa) particle distribution functions in space plasmas.
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"abstract": "A non-relativistic Fokker-Planck equation for the electron distribution\nfunction is formulated incorporating the effects of stochastic acceleration by\nwhistler-mode waves and Coulomb collisions. The stationary solution $f$ to the\nequation, subject to a zero-flux boundary condition, is found to be a\ngeneralized Lorentzian (or kappa) distribution, which satisfies $f\\propto\nv^{-2(\\kappa+1)}$ for large velocity $v$, where $\\kappa$ is the spectral index.\nThe parameter $\\kappa$ depends strongly on the relative wave intensity $R$.\nTaking into account the critical energy required for resonance of electrons\nwith whistlers, we calculate a range of values of $R$ for each of a number of\ndifferent space plasmas for which kappa distributions can be expected to be\nformed. This study is one of the first in the literature to provide a\ntheoretical justification for the formation of generalized Lorentzian (or\nkappa) particle distribution functions in space plasmas.",
"arxiv_id": "physics/9810049",
"authors": [
"Chun-yu Ma",
"Danny Summers"
],
"categories": [
"physics.plasm-ph",
"astro-ph",
"physics.space-ph"
],
"doi": "10.1029/1998GL900108",
"journal_ref": "Geophysical Research Letters 25, No.21, 4099, 1998",
"title": "Formation of Power-law Energy Spectra in Space Plasmas by Stochastic Acceleration due to Whistler-Mode Waves",
"url": "https://arxiv.org/abs/physics/9810049"
},
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