High amplitude waves in the expanding solar wind plasma

Journal Article · Sat Jul 20 04:00:00 EDT 1996 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.51489· OSTI ID:21163493

Schmidt, J M; Velli, M; Grappin, R ^[1]

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1. Department of Astronomy and Space Studies, University of Florence, Largo Fermi 5. I-50125 Firenze (Italy)

We simulated the 1 D nonlinear time-evolution of high-amplitude Alfven, slow and fast magnetoacustic waves in the solar wind propagating outward at different angles to the mean magnetic (spiral) field, using the expanding box model. The simulation results for Alfven waves and fast magnetoacustic waves fit the observational constraints in the solar wind best, showing decreasing trends for energies and other rms-quantities due to expansion and the appearance of inward propagating waves as minor species in the wind. Inward propagating waves are generated by reflection of Alfven waves propagating at large angles to the magnetic field or they coincide with the occurrence of compressible fluctuations. It is the generation of sound due to ponderomotive forces of the Alfven wave which we can detect in the latter case. For slow magnetoacustic waves we find a kind of oscillation of the character of the wave between a sound wave and an Alfven wave. This is the more, the slow magnetoacustic wave is close to a sound wave in the beginning. On the other hand, fast magnetoacustic waves are much more dissipated than the other wave-types and their general behaviour is close to the Alfven. The normalized cross-helicity {sigma}{sub c} is close to one for Alfven-waves and this quantity is decreasing slightly when density-fluctuations are generated. {sigma}{sub c} decreases significantly when the waves are close to perpendicular propagation. Then, the waves are close to quasi-static structures.

• OSTI ID: 21163493
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 382; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
AMPLITUDES
ASTROPHYSICS
BOX MODELS
FLUCTUATIONS
HELICITY
MAGNETIC FIELDS
MAGNETOACOUSTIC WAVES
NONLINEAR PROBLEMS
OSCILLATIONS
PLASMA
PLASMA EXPANSION
PLASMA SIMULATION
PLASMA WAVES
PONDEROMOTIVE FORCE
REFLECTION
SOLAR WIND
SOUND WAVES
WAVE PROPAGATION