Title: Generation of Highly Oblique Lower Band Chorus Via Nonlinear Three-Wave Resonance

Abstract

Chorus in the inner magnetosphere has been observed frequently at geomagnetically active times, typically exhibiting a two-band structure with a quasi-parallel lower band and an upper band with a broad range of wave normal angles. But recent observations by Van Allen Probes confirm another type of lower band chorus, which has a large wave normal angle close to the resonance cone angle. It has been proposed that these waves could be generated by a low-energy beam-like electron component or by temperature anisotropy of keV electrons in the presence of a low-energy plateau-like electron component. This paper, however, presents an alternative mechanism for generation of this highly oblique lower band chorus. Through a nonlinear three-wave resonance, a quasi-parallel lower band chorus wave can interact with a mildly oblique upper band chorus wave, producing a highly oblique quasi-electrostatic lower band chorus wave. This theoretical analysis is confirmed by 2-D electromagnetic particle-in-cell simulations. Furthermore, as the newly generated waves propagate away from the equator, their wave normal angle can further increase and they are able to scatter low-energy electrons to form a plateau-like structure in the parallel velocity distribution. As a result, the three-wave resonance mechanism may also explain the generation of quasi-parallelmore » upper band chorus which has also been observed in the magnetosphere.« less

Authors:

Fu, Xiangrong  ^[1];

• Search DOE PAGES for author "Fu, Xiangrong"
• Search DOE PAGES for ORCID "0000-0002-4305-6624"

Gary, Stephen Peter  ^[2];

• Search DOE PAGES for author "Gary, Stephen Peter"
• Search DOE PAGES for ORCID "0000-0002-4655-2316"

Reeves, Geoffrey D.  ^[3];

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

Winske, Dan  ^[4];

• Search DOE PAGES for author "Winske, Dan"
• Search DOE PAGES for ORCID "0000-0003-1600-4084"

Woodroffe, Jesse Richard  ^[4]

• Search DOE PAGES for author "Woodroffe, Jesse Richard"
• Search DOE PAGES for ORCID "0000-0002-2149-7883"

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+ Show Author Affiliations

1. New Mexico Consortium, Los Alamos, NM (United States)
2. Space Science Institute, Boulder, CO (United States)
3. New Mexico Consortium, Los Alamos, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Tue Sep 05 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:

1415428

Report Number(s):

LA-UR-17-30358
Journal ID: ISSN 0094-8276; TRN: US1800821

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Geophysical Research Letters

Additional Journal Information:

Journal Volume: 44; Journal Issue: 19; Journal ID: ISSN 0094-8276

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Heliospheric and Magnetospheric Physics; oblique whistler; three-wave resonance; PIC simulation; ray tracing