Direct Measurement of Low‐Energy Electron Foreshock Beams

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F19%3A00510734" target="_blank" >RIV/68378289:_____/19:00510734 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11320/19:10407573

Výsledek na webu

<a href="https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JA026470" target="_blank" >https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JA026470</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2019JA026470" target="_blank" >10.1029/2019JA026470</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Direct Measurement of Low‐Energy Electron Foreshock Beams

Popis výsledku v původním jazyce

Electrostatic plasma waves above and below the local electron plasma frequency represent a characteristic feature of the foreshock region. These waves are known to be generated by electron beams originating from the bow shock and their spectrum varies from narrowband intense waves close to foreshock edge to weaker broadband emissions further downstream. We present a statistical analysis of electron beams observed in the terrestrial foreshock by the Cluster spacecraft. We compared the energy of foreshock electron beams with the spectrum of electrostatic waves and established a clear correspondence between beam energy and spectrum of the waves. The broadband emissions are correlated with low-energy beams, while high-energy electron beams are associated with narrowband Langmuir waves. Next we solved the linear dispersion relation for a subset of observed electron plasma distributions. We discovered that while the observed electron distributions often exhibit a 'bump on tail' feature necessary for an instability, the observed combination of beam energy, density, and temperature typically corresponds to a stable situation. This indicates that strongly unstable electron beams are quickly dissipated by the quasi-linear processes and only stable or marginally stable beams persist long enough to be observed by the instrument.

Název v anglickém jazyce

Direct Measurement of Low‐Energy Electron Foreshock Beams

Popis výsledku anglicky

Electrostatic plasma waves above and below the local electron plasma frequency represent a characteristic feature of the foreshock region. These waves are known to be generated by electron beams originating from the bow shock and their spectrum varies from narrowband intense waves close to foreshock edge to weaker broadband emissions further downstream. We present a statistical analysis of electron beams observed in the terrestrial foreshock by the Cluster spacecraft. We compared the energy of foreshock electron beams with the spectrum of electrostatic waves and established a clear correspondence between beam energy and spectrum of the waves. The broadband emissions are correlated with low-energy beams, while high-energy electron beams are associated with narrowband Langmuir waves. Next we solved the linear dispersion relation for a subset of observed electron plasma distributions. We discovered that while the observed electron distributions often exhibit a 'bump on tail' feature necessary for an instability, the observed combination of beam energy, density, and temperature typically corresponds to a stable situation. This indicates that strongly unstable electron beams are quickly dissipated by the quasi-linear processes and only stable or marginally stable beams persist long enough to be observed by the instrument.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Geophysical Research: Space Physics

ISSN

2169-9380

e-ISSN

—

Svazek periodika

124

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

13

Strana od-do

2380-2392

Kód UT WoS článku

000477707800002

EID výsledku v databázi Scopus

2-s2.0-85064175144