Title: Generation of lower and upper bands of electrostatic electron cyclotron harmonic waves in the Van Allen radiation belts

Abstract

Electrostatic electron cyclotron harmonic (ECH) waves generated by the electron loss cone distribution can produce efficient scattering loss of plasma sheet electrons, which has a significant effect on the dynamics in the outer magnetosphere. Here we report two ECH emission events around the same location L≈ 5.7–5.8, MLT ≈ 12 from Van Allen Probes on 11 February (event A) and 9 January 2014 (event B), respectively. The spectrum of ECH waves was centered at the lower half of the harmonic bands during event A, but the upper half during event B. The observed electron phase space density in both events is fitted by the subtracted bi-Maxwellian distribution, and the fitting functions are used to evaluate the local growth rates of ECH waves based on a linear theory for homogeneous plasmas. ECH waves are excited by the loss cone instability of 50 eV–1 keV electrons in the lower half of harmonic bands in the low-density plasmasphere in event A, and 1–10 keV electrons in the upper half of harmonic bands in a relatively high-density region in event B. Here, the current results successfully explain observations and provide a first direct evidence on how ECH waves are generated in the lower andmore » upper half of harmonic frequency bands.« less

Authors:

Zhou, Qinghua  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1117-4036"

Xiao, Fuliang  ^[1];

• Search DOE PAGES for author "Xiao, Fuliang"
• Search DOE PAGES for ORCID "0000-0003-1487-6620"

Yang, Chang  ^[1];

• Search DOE PAGES for author "Yang, Chang"
• Search DOE PAGES for ORCID "0000-0002-3060-3895"

Liu, Si  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-8465-9395"

He, Yihua  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-0541-0503"

Baker, D. N.  ^[2];

• Search DOE PAGES for author "Baker, D. N."
• Search DOE PAGES for ORCID "0000-0001-5909-0926"

Spence, H. E.  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-2526-2205"

Reeves, Geoffrey D.  ^[4];

• Search DOE PAGES for author "Reeves, Geoffrey D."
• Search DOE PAGES for ORCID "0000-0002-7985-8098"

Funsten, Herbert O.  ^[4]

• Search DOE PAGES for author "Funsten, Herbert O."
• Search DOE PAGES for ORCID "0000-0002-6817-1039"

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+ Show Author Affiliations

1. Changsha Univ. of Science and Technology, Changsha (China)
2. Univ. of Colorado, Boulder, CO (United States)
3. Univ. of New Hampshire, Durham, NH (United States)
4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Mon May 22 00:00:00 EDT 2017

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA); USDOE

OSTI Identifier:

1402656

Report Number(s):

LA-UR-17-28037
Journal ID: ISSN 0094-8276; TRN: US1702891

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Geophysical Research Letters

Additional Journal Information:

Journal Volume: 44; Journal Issue: 11; Journal ID: ISSN 0094-8276

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Heliospheric and Magnetospheric Physics; ECH waves; wave-particle interaction; RBSP results