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Titolo:
Electron hole structure and its stability depending on plasma magnetization
Autore:
Singh, N; Loo, SM; Wells, E;
Indirizzi:
Univ Alabama, Coll Engn, Dept Elect & Comp Engn, Huntsville, AL 35899 USA Univ Alabama Huntsville AL USA 35899 Comp Engn, Huntsville, AL 35899 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A10, volume: 106, anno: 2001,
pagine: 21183 - 21198
SICI:
0148-0227(20011001)106:A10<21183:EHSAIS>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHASE-SPACE HOLES; SOLITARY WAVES; BEAM; INSTABILITIES; MAGNETOTAIL; SIMULATIONS; GEOTAIL; REGION; FIELDS; DRIVEN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Singh, N Univ Alabama, Coll Engn, Dept Elect & Comp Engn, Huntsville, AL 35899 USA Univ Alabama Huntsville AL USA 35899 n, Huntsville, AL 35899 USA
Citazione:
N. Singh et al., "Electron hole structure and its stability depending on plasma magnetization", J GEO R-S P, 106(A10), 2001, pp. 21183-21198

Abstract

Observations from Polar have revealed that electron hole (e-hole) structure depends on the plasma magnetization determined by the ratio <(<Omega>)over bar> = Omega (e) /omega (pe), where Omega (e) and omega (pe) are the electron cyclotron and plasma frequencies, respectively. Using three-dimensional parallel particle-in-cell) simulations, we have studied the formation andstructure of e-holes by varying <(<Omega>)over bar> showing that (1) for <(<Omega>)over bar> <1 e-holes are highly transitory while for <(<Omega>)over bar> > 1 long-lasting e-holes form, especially when <(<Omega>)over bar> greater than or equal to 2, (2) in the transitory e-holes for <(<Omega>)overbar> < 1, the e-holes are essentially planar with parallel electric fieldsE-parallel to > > E-perpendicular to, the perpendicular field, (3) when <(<Omega>)over bar> greater than or equal to 2 a variety of structures are possible ranging from spheroidal structures with E-x similar to E-y similar to E-parallel to to a planar one with E-x similar to E-y E-parallel to, where E-x and E-y are the x and y components of the perpendicular field E-perpendicular to. It is also possible that E-x < < E-y similar to E-parallel to. We find that e-holes with long transverse structures undergo a perpendicular modulation, which eventually breaks the long structures into fragments of e-holes. The fragments are seen to further decay by emitting lower hybrid(LH) waves. A linear model of these instabilities is developed showing an e-hole is an effective radiator of plasma waves. An e-hole with long transverse structure is effective in radiating high-frequency whistler waves which have long perpendicular wavelengths. When such waves are radiated out, the remnant structure is transversely modulated and has relatively short scale length. On the other hand, the fragments with the short perpendicular scale lengths are effective in radiating the LH waves. These findings from thesimulations are compared with findings from the data from Polar [Franz et al., 2000].

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Documento generato il 30/03/20 alle ore 13:32:35