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Very Oblique Whistler Mode Propagation in the Radiation Belts: Effects of Hot Plasma and Landau Damping
Author(s) -
Ma Q.,
Artemyev A. V.,
Mourenas D.,
Li W.,
Thorne R. M.,
Kletzing C. A.,
Kurth W. S.,
Hospodarsky G. B.,
Reeves G. D.,
Spence H. E.,
Wygant J.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl075892
Subject(s) - physics , landau damping , whistler , electron , van allen radiation belt , computational physics , pitch angle , dispersion (optics) , scattering , wave propagation , plasma , optics , geophysics , magnetosphere , nuclear physics
Satellite observations of a significant population of very oblique chorus waves in the outer radiation belt have fueled considerable interest in the effects of these waves on energetic electron scattering and acceleration. However, corresponding diffusion rates are extremely sensitive to the refractive index N , controlled by hot plasma effects including Landau damping and wave dispersion modifications by suprathermal (15–100 eV) electrons. A combined investigation of wave and electron distribution characteristics obtained from the Van Allen Probes shows that peculiarities of the measured electron distribution significantly reduce Landau damping, allowing wave propagation with high N ∼ 100–200. Further comparing measured refractive indexes with theoretical estimates incorporating hot plasma corrections to the wave dispersion, we provide the first experimental demonstration that suprathermal electrons indeed control the upper limit of the refractive index of highly oblique whistler mode waves. Such results further support the importance of incorporating very oblique waves into radiation belt models.