Title: Electrostatic and whistler instabilities excited by an electron beam

Abstract

The electron beam-plasma system is ubiquitous in the space plasma environment. Here in this paper, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency (ω_pe) is larger than the electron cyclotron frequency (Ω_e). The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slower-growing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity and (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between the beam electrons and electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on the ratio ofmore » ω_pe/Ω_e. In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region, whereas beam-generated whistler waves transport energy away from the beam.« less

Authors:

An, Xin  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2507-8632"

Bortnik, Jacob ^[1]; Van Compernolle, Bart  ^[2];

• Search DOE PAGES for author "Van Compernolle, Bart"
• Search DOE PAGES for ORCID "0000-0002-5853-6233"

Decyk, Viktor ^[2]; Thorne, Richard ^[1]

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+ Show Author Affiliations

1. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
2. Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy

Publication Date:

Mon Jul 17 00:00:00 EDT 2017

Research Org.:

Univ. of California, Los Angeles, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1474311

Alternate Identifier(s):

OSTI ID: 1371492

Grant/Contract Number:  

SC0010578

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 24; Journal Issue: 7; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY