Nonlinear evolution of electromagnetic ion cyclotron waves

Journal Article · Fri Apr 15 04:00:00 EDT 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3571598· OSTI ID:21537631

Silin, I; Sydora, R D; Mann, I R; Sauer, K ^[1]; Mace, R L ^[2]

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1. Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada)
2. School of Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)

Hybrid Vlasov-Fourier modeling is used to investigate the nonlinear evolution of electromagnetic ion cyclotron (EMIC) waves driven by proton temperature anisotropy in plasmas with a population of He{sup +} ions and a cold proton background. In the pure proton-electron plasma, most of the free energy is converted into high-amplitude waves and currents. In the nonlinear stage, within a few hundred proton gyroperiods after the saturation, the wave spectrum shifts toward lower wave numbers and frequencies, from {omega}{approx}0.6{Omega}{sub p} to below {omega}{approx}0.25{Omega}{sub p}. In the presence of even a small population of He{sup +} ions almost all of the free energy is used in He{sup +} heating. The wave activity in the saturated state moves from the linearly unstable upper branch to the linearly stable lower one. In the presence of a background of cold protons, the waves can propagate in the frequency stop-band. Our results demonstrate that linear stability theory cannot be used to estimate the characteristics of the expected saturated wave spectra in the terrestrial magnetosphere. Significantly, our nonlinear simulations produce wave spectra which are in close agreement with the EMIC waves observed in situ by satellites as well as by ground-based magnetometers positioned at the ends of the magnetic field lines.

• OSTI ID: 21537631
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 18; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANISOTROPY
CHARGED PARTICLES
ELECTROMAGNETIC RADIATION
EVOLUTION
HELIUM IONS
ION PLASMA WAVES
ION WAVES
IONS
NONLINEAR PROBLEMS
PLASMA SIMULATION
PLASMA WAVES
PROTON TEMPERATURE
RADIATIONS
SIMULATION
WAVE PROPAGATION