Resonant Interactions Between Protons and Oblique Alfven/Ion-Cyclotron Waves

Journal Article · Thu Mar 25 04:00:00 EDT 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3395966· OSTI ID:21371733

Pongkitiwanichakul, Peera; Chandran, Benjamin D. G.; Isenberg, Philip A; Vasquez, Bernard J ^[1]

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1. Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham NH, 03824 (United States)

Resonant interactions between ions and Alfven/ion-cyclotron (A/IC) waves may play an important role in the heating and acceleration of the fast solar wind. Although such interactions have been studied extensively for 'parallel' waves, whose wave vectors k are aligned with the background magnetic field B{sub 0}, much less is known about interactions between ions and oblique A/IC waves, for which the angle theta between k and B{sub 0} is nonzero. In this paper, we present new numerical results on resonant cyclotron interactions between protons and oblique A/IC waves in collisionless low-beta plasmas such as the solar corona. We find that if some mechanism generates oblique high-frequency A/IC waves, then these waves initially modify the proton distribution function in such a way that it becomes unstable to parallel waves. Parallel waves are then amplified to the point that they dominate the wave energy at the large parallel wave numbers at which the waves resonate with the particles. Pitch-angle scattering by these waves then causes the plasma to evolve towards a state in which the proton distribution is constant along a particular set of nested 'scattering surfaces' in velocity space, whose shapes have been calculated previously. As the distribution function approaches this state, the imaginary part of the frequency of parallel A/IC waves drops continuously towards zero, but oblique waves continue to undergo cyclotron damping while simultaneously causing protons to diffuse across these kinetic shells to higher energies. We conclude that oblique A/IC waves can be more effective at heating protons than parallel A/IC waves, because for oblique waves the plasma does not relax towards a state in which proton damping of oblique A/IC waves ceases.

• OSTI ID: 21371733
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1216; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALFVEN WAVES
ASTROPHYSICS
ATMOSPHERES
BARYONS
CHARGED PARTICLES
CYCLOTRON RESONANCE
DAMPING
DISTRIBUTION FUNCTIONS
ELEMENTARY PARTICLES
FERMIONS
FLUID MECHANICS
FUNCTIONS
HADRONS
HEATING
HYDRODYNAMICS
HYDROMAGNETIC WAVES
ION PLASMA WAVES
ION WAVES
IONS
LOW-BETA PLASMA
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
NUCLEONS
PHYSICS
PLASMA
PLASMA HEATING
PLASMA WAVES
PROTONS
RADIATIONS
RESONANCE
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SOLAR WIND
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
STELLAR RADIATION
STELLAR WINDS
VELOCITY