Very Oblique Whistler Mode Propagation in the Radiation Belts: Effects of Hot Plasma and Landau Damping

Q. Ma, A. V. Artemyev, D. Mourenas, W. Li, R. M. Thorne, C. A. Kletzing, W. S. Kurth, G. B. Hospodarsky, G. D. Reeves, H. E. Spence, J. Wygant

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)12,057-12,066
JournalGeophysical Research Letters
Volume44
Issue number24
DOIs
StatePublished - Dec 28 2017

Bibliographical note

Funding Information:
The work of Q. M. was supported by JHU/APL contracts 967399 and 921647 under NASA’s prime contract NAS5-01072 and by the EMFISIS subaward 1001057397:01 and ECT subaward 13-041. W. L. would like to acknowledge the NASA grants NNX17AD15G and NNX17AG07G, the NSF grant AGS-1723588, and the AFOSR grant FA9550-15-1-0158. The Van Allen Probes data from the EMFISIS instrument are available from http://emfisis.physics.uiowa.edu/ data/index/, data from the HOPE instrument are available from http://www.rbsp-ect.lanl.gov/data_pub/, and data from the EFW instrument are available from http://rbsp.space. umn.edu/data/rbsp/.

Funding Information:
The work of Q. M. was supported by JHU/APL contracts 967399 and 921647 under NASA's prime contract NAS5-01072 and by the EMFISIS subaward 1001057397:01 and ECT subaward 13-041. W. L. would like to acknowledge the NASA grants NNX17AD15G and NNX17AG07G, the NSF grant AGS-1723588, and the AFOSR grant FA9550-15-1-0158. The Van Allen Probes data from the EMFISIS instrument are available from http://emfisis.physics.uiowa.edu/data/index/, data from the HOPE instrument are available from http://www.rbsp-ect.lanl.gov/data_pub/, and data from the EFW instrument are available from http://rbsp.space.umn.edu/data/rbsp/.

Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.

Keywords

  • Landau damping
  • Van Allen Probes observation
  • maximum refractive index
  • oblique chorus waves
  • thermal electron effects

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