Effect of two ion species on the propagation of shear Alfvén waves of small transverse scale
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- S. T. Vincena
- University of California Department of Physics and Astronomy, , Los Angeles, Los Angeles, California 90095, USA
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- G. J. Morales
- University of California Department of Physics and Astronomy, , Los Angeles, Los Angeles, California 90095, USA
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- J. E. Maggs
- University of California Department of Physics and Astronomy, , Los Angeles, Los Angeles, California 90095, USA
書誌事項
- 公開日
- 2010-05-01
- DOI
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- 10.1063/1.3422549
- 公開者
- AIP Publishing
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説明
<jats:p>The results of a theoretical modeling study and experimental investigation of the propagation properties of shear Alfvén waves of small transverse scale in a plasma with two ion species are reported. In the two ion plasma, depending on the mass of the heavier species, ion kinetic effects can become prominent, and significant parallel electric fields result in electron acceleration. The theory predicts the appearance of frequency propagation gaps at the ion-ion hybrid frequency and between harmonics of the lower cyclotron frequency. Within these frequency bands spatial structures arise that mix the cone-propagation characteristics of Alfvén waves with radially expanding ion Bernstein modes. The experiments, performed at the Basic Plasma Science Facility (BaPSF) at UCLA, consist of the spatial mapping of shear waves launched by a loop antenna. Although a variety of two ion-species combinations were explored, only results from a helium-neon mix are reported. A clear signature of a shear wave propagation gap, as well as propagation between multiple harmonics, is found for this gas combination. The evanescence of shear waves beyond the reflection point at the ion-ion hybrid frequency in the presence of an axial magnetic field gradient is also documented.</jats:p>
収録刊行物
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- Physics of Plasmas
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Physics of Plasmas 17 (5), 052106-, 2010-05-01
AIP Publishing