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Title: Full-wave modeling of EMIC waves near the He+ gyrofrequency

Electromagnetic ion cyclotron (EMIC) waves are known to be excited by the cyclotron instability associated with hot and anisotropic ion distributions in the equatorial region of the magnetosphere and are thought to play a key role in radiation belt losses. Although detection of these waves at the ground can provide a global view of the EMIC wave environment, it is not clear what signatures, if any, would be expected. One of the significant scientific issues concerning EMIC waves is to understand how these waves are detected at the ground. In order to solve this puzzle, it is necessary to understand the propagation characteristics of the field-aligned EMIC waves, which include polarization reversal, cutoff, resonance, and mode coupling between different wave modes, in a dipolar magnetic field. However, the inability of ray tracing to adequately describe wave propagation near the crossover cutoff-resonance frequencies in multi-ion plasmas is one of reasons why these scientific questions remain unsolved. Using a recently developed 2-D full-wave code that solves the full-wave equations in global magnetospheric geometry, we demonstrate how EMIC waves propagate from the equatorial region to higher magnetic latitude in an electron-proton-He+ plasma. We find that polarization reversal occurs at the crossover frequency frommore » left-hand polarization (LHP) to right-hand (RHP) polarization and such RHP EMIC waves can either propagate to the inner magnetosphere or reflect to the outer magnetosphere at the Buchsbaum resonance location. Lastly, we also find that mode coupling from guided LHP EMIC waves to unguided RHP or LHP waves (i.e., fast mode) occurs.« less
Authors:
 [1] ;  [1]
  1. Princeton Univ., Princeton, NJ (United States)
Publication Date:
OSTI Identifier:
1254688
Report Number(s):
PPPL--5210
Journal ID: ISSN 0094-8276
Grant/Contract Number:
NNH09AM53I; NNH09AK63I; NNH11AR07I; NNX14AM27G; NNH14AY20I; ATM0902730; AGS-1203299; AC02-09CH11466
Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 43; Journal Issue: 1; Related Information: Movie S1 MPEG video, 5331K grl53851-sup-0001-supinfo.mpgMovie S2 QuickTime video, 8366K grl53851-sup-002-supinfo.mov; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Research Org:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
This work was facilitated by the Max Planck / Princeton Center for Plasma Physics
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY EMIC waves; mode conversion; polarization reversal; wave modeling; numerical simulation