Evolution of Alfvén waves by three-wave interactions in super-Alfvénic shocks

Rami Vainio, F Spanier

Research output: Contribution to journalArticleScientificpeer-review

Abstract

"We calculate the evolution of Alfven waves in super-Alfvenic flows, such as the downstream region of a fast-mode shock, via three-wave interactions between two Aflven waves and a sound wave. We show that the process has a significant influence on the evolution of the Alfven wave spectra, driving the system toward a degenerate normalized cross-helicity, Hc -> +/- 1. Typical distances in which the system evolves are evaluated, and the effects of the calculated turbulence evolution on test-particle acceleration in super-Alfvenic quasi-parallel shocks are studied. We show that typically the spectrum of accelerated particles is determined by the first-order Fermi acceleration process as described earlier by Vainio & Schlickeiser (1998, A&A, 331, 793; 1999, A&A, 343, 303), and identify some regions of parameter space, where the earlier results are significantly modified either by changes in the predicted scattering-center compression ratio or by stochastic acceleration in the downstream plasma."
Original languageEnglish
JournalAstronomy & Astrophysics
Volume437
Issue number1
Pages (from-to)1-8
Number of pages8
ISSN0004-6361
DOIs
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 114 Physical sciences

Cite this

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title = "Evolution of Alfv{\'e}n waves by three-wave interactions in super-Alfv{\'e}nic shocks",
abstract = "{"}We calculate the evolution of Alfven waves in super-Alfvenic flows, such as the downstream region of a fast-mode shock, via three-wave interactions between two Aflven waves and a sound wave. We show that the process has a significant influence on the evolution of the Alfven wave spectra, driving the system toward a degenerate normalized cross-helicity, Hc -> +/- 1. Typical distances in which the system evolves are evaluated, and the effects of the calculated turbulence evolution on test-particle acceleration in super-Alfvenic quasi-parallel shocks are studied. We show that typically the spectrum of accelerated particles is determined by the first-order Fermi acceleration process as described earlier by Vainio & Schlickeiser (1998, A&A, 331, 793; 1999, A&A, 343, 303), and identify some regions of parameter space, where the earlier results are significantly modified either by changes in the predicted scattering-center compression ratio or by stochastic acceleration in the downstream plasma.{"}",
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pages = "1--8",
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}

Evolution of Alfvén waves by three-wave interactions in super-Alfvénic shocks. / Vainio, Rami; Spanier, F.

In: Astronomy & Astrophysics, Vol. 437, No. 1, 2005, p. 1-8.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Evolution of Alfvén waves by three-wave interactions in super-Alfvénic shocks

AU - Vainio, Rami

AU - Spanier, F

PY - 2005

Y1 - 2005

N2 - "We calculate the evolution of Alfven waves in super-Alfvenic flows, such as the downstream region of a fast-mode shock, via three-wave interactions between two Aflven waves and a sound wave. We show that the process has a significant influence on the evolution of the Alfven wave spectra, driving the system toward a degenerate normalized cross-helicity, Hc -> +/- 1. Typical distances in which the system evolves are evaluated, and the effects of the calculated turbulence evolution on test-particle acceleration in super-Alfvenic quasi-parallel shocks are studied. We show that typically the spectrum of accelerated particles is determined by the first-order Fermi acceleration process as described earlier by Vainio & Schlickeiser (1998, A&A, 331, 793; 1999, A&A, 343, 303), and identify some regions of parameter space, where the earlier results are significantly modified either by changes in the predicted scattering-center compression ratio or by stochastic acceleration in the downstream plasma."

AB - "We calculate the evolution of Alfven waves in super-Alfvenic flows, such as the downstream region of a fast-mode shock, via three-wave interactions between two Aflven waves and a sound wave. We show that the process has a significant influence on the evolution of the Alfven wave spectra, driving the system toward a degenerate normalized cross-helicity, Hc -> +/- 1. Typical distances in which the system evolves are evaluated, and the effects of the calculated turbulence evolution on test-particle acceleration in super-Alfvenic quasi-parallel shocks are studied. We show that typically the spectrum of accelerated particles is determined by the first-order Fermi acceleration process as described earlier by Vainio & Schlickeiser (1998, A&A, 331, 793; 1999, A&A, 343, 303), and identify some regions of parameter space, where the earlier results are significantly modified either by changes in the predicted scattering-center compression ratio or by stochastic acceleration in the downstream plasma."

KW - 114 Physical sciences

U2 - 10.1051/0004-6361:20042433

DO - 10.1051/0004-6361:20042433

M3 - Article

VL - 437

SP - 1

EP - 8

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

IS - 1

ER -