Journal article
Excitation of poloidal standing Alfvén waves through drift resonance wave-particle interaction
Geophysical research letters, Vol.40(16), pp.4127-4132
08/28/2013
DOI: 10.1002/grl.50800
Abstract
1] Drift-resonance wave-particle interaction is a fundamental collisionless plasma process studied extensively in theory. Using cross-spectral analysis of electric field, magnetic field, and ion flux data from the Van Allen Probe (Radiation Belt Storm Probes) spacecraft, we present direct evidence identifying the generation of a fundamental mode standing poloidal wave through drift-resonance interactions in the inner magnetosphere. Intense azimuthal electric field (Eφ) oscillations as large as 10mV/m are observed, associated with radial magnetic field (Br) oscillations in the dawn-noon sector near but south of the magnetic equator at L∼5. The observed wave period, Eφ/Br ratio and the 90° phase lag between Br and Eφ are all consistent with fundamental mode standing Poloidal waves. Phase shifts between particle fluxes and wave electric fields clearly demonstrate a drift resonance with ∼90 keV ring current ions. The estimated earthward gradient of ion phase space density provides a free energy source for wave generation through the drift-resonance instability. A similar drift-resonance process should occur ubiquitously in collisionless plasma systems. One specific example is the “fishbone” instability in fusion plasma devices. In addition, our observations have important implications for the long-standing mysterious origin of Giant Pulsations.
Details
- Title: Subtitle
- Excitation of poloidal standing Alfvén waves through drift resonance wave-particle interaction
- Creators
- Lei Dai - University of MinnesotaCraig Kletzing - University of IowaKazue Takahashi - Johns Hopkins University Applied Physics LaboratoryJohn R Wygant - University of MinnesotaLiu Chen - University of California, IrvineJohn Bonnell - University of California, BerkeleyCynthia A Cattell - University of MinnesotaScott Thaller - University of MinnesotaCharles W Smith - University of New HampshireRobert J MacDowall - Goddard Space Flight CenterDaniel N Baker - University of Colorado BoulderJ. Bernard Blake - The Aerospace CorporationJoseph Fennell - The Aerospace CorporationSeth Claudepierre - The Aerospace CorporationHerbert O Funsten - Los Alamos National LaboratoryGeoffrey D Reeves - Los Alamos National LaboratoryHarlan E Spence - University of New Hampshire
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.40(16), pp.4127-4132
- DOI
- 10.1002/grl.50800
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Publisher
- Blackwell Publishing Ltd
- Number of pages
- 6
- Language
- English
- Date published
- 08/28/2013
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199682102771
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