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Title: Roles of hot electrons in generating upper-hybrid waves in the earth's radiation belt

Electrostatic fluctuations near upper-hybrid frequency, which are sometimes accompanied by multiple-harmonic electron cyclotron frequency bands above and below the upper-hybrid frequency, are common occurrences in the Earth's radiation belt, as revealed through the twin Van Allen Probe spacecrafts. It is customary to use the upper-hybrid emissions for estimating the background electron density, which in turn can be used to determine the plasmapause locations, but the role of hot electrons in generating such fluctuations has not been discussed in detail. The present paper carries out detailed analyses of data from the Waves instrument, which is part of the Electric and Magnetic Field Instrument Suite and Integrated Science suite onboard the Van Allen Probes. Combined with the theoretical calculation, it is shown that the peak intensity associated with the upper-hybrid fluctuations might be predominantly determined by tenuous but hot electrons and that denser cold background electrons do not seem to contribute much to the peak intensity. This finding shows that upper-hybrid fluctuations detected during quiet time are not only useful for the determination of the background cold electron density but also contain information on the ambient hot electrons population as well.
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [5] ;  [5] ;  [2]
  1. Korea Univ. of Science and Technology, Daejeon (Korea, Republc of); Korea Astronomy and Space Science Inst., Deajeon (Korea, Republic of)
  2. Chungbuk National Univ., Cheongju (Korea, Republic of)
  3. Univ. of Maryland, College Park, MD (United States); Kyung Hee Univ., Yongin (Korea, Republic of)
  4. Univ. of Iowa, Iowa City, IA (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-24832
Journal ID: ISSN 1070-664X; TRN: US1703117
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
National Aeronautic and Space Administration (NASA); USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Heliospheric and Magnetospheric Physics
OSTI Identifier:
1402640