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Spectral characteristics of the plasma dispersionless injection during the storm recovery phase on 11 March 1998
He, Z. H.; Chen, T.; Liu, Z. X.; Pu, Z. Y.; Roth, I.; Duan, S. P.; Dunlop, M. W.; He, ZH (reprint author), Chinese Acad Sci, Ctr Space Sci & Appl Res, State Key Lab Space Weather, Beijing 100080, Peoples R China.
Department空间科学部
Source PublicationJOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
2012
Volume117Pages:A11210
ISSN0148-0227
Language英语
AbstractA substorm dispersionless injection event observed during the storm recovery phase on 11 March 1998 at geosynchronous orbit is carefully studied. The event shows the notable characteristics that for energetic ions the flux enhancement ratio before and after injection increases and remains elevated with increasing energy, while for energetic electrons it tends to decrease with increasing energy. In order to explain the unique injection feature, the authors propose a possible mechanism that velocity space diffusion in common to electric acceleration adjusts the particle injection state. Spectral characteristics of four different phases (pregrowth phase, the growth phase, the substorm expansion phase, and the recovery phase) have been investigated. The differential fluxes of electrons from 50 keV to 1.5 Mev and ions from 50 keV to 1.2 MeV measured by Synchronous Orbit Plasma Analyzer (SOPA) instrument onboard LANL satellite 1991-080 are found to be best fitted with the three-parameter kappa distribution function (f similar to A(0) . E[1 + E / (kappa E-0)](-kappa-1)) by Levenberg-Marquardt and Universal Global Optimization methods. The evolutions of the three parameters in the above kappa distribution in different substorm phases have been depicted for both electrons and ions. In each phase, E-0 and kappa show an approximately linear relationship kappa(E-0) = kappa(0) + eta E-0. This linear relationship can be obtained by solving the velocity space diffusion equation with an initial superthermal kappa distribution. Ion and electron are found to have opposite trend of parameters kappa(0) and eta in each phase, which indicates that the different species of particles exert different velocity space diffusion processes so that their flux enhancement ratios before and after injection are rather different. This implies that not only electric field acceleration, but also velocity space diffusion plays a very important role in the particle injection.; A substorm dispersionless injection event observed during the storm recovery phase on 11 March 1998 at geosynchronous orbit is carefully studied. The event shows the notable characteristics that for energetic ions the flux enhancement ratio before and after injection increases and remains elevated with increasing energy, while for energetic electrons it tends to decrease with increasing energy. In order to explain the unique injection feature, the authors propose a possible mechanism that velocity space diffusion in common to electric acceleration adjusts the particle injection state. Spectral characteristics of four different phases (pregrowth phase, the growth phase, the substorm expansion phase, and the recovery phase) have been investigated. The differential fluxes of electrons from 50 keV to 1.5 Mev and ions from 50 keV to 1.2 MeV measured by Synchronous Orbit Plasma Analyzer (SOPA) instrument onboard LANL satellite 1991-080 are found to be best fitted with the three-parameter kappa distribution function (f similar to A(0) . E[1 + E / (kappa E-0)](-kappa-1)) by Levenberg-Marquardt and Universal Global Optimization methods. The evolutions of the three parameters in the above kappa distribution in different substorm phases have been depicted for both electrons and ions. In each phase, E-0 and kappa show an approximately linear relationship kappa(E-0) = kappa(0) + eta E-0. This linear relationship can be obtained by solving the velocity space diffusion equation with an initial superthermal kappa distribution. Ion and electron are found to have opposite trend of parameters kappa(0) and eta in each phase, which indicates that the different species of particles exert different velocity space diffusion processes so that their flux enhancement ratios before and after injection are rather different. This implies that not only electric field acceleration, but also velocity space diffusion plays a very important role in the particle injection.
Indexed BySCI
Funding Project中国科学院空间科学与应用研究中心
Document Type期刊论文
Identifierhttp://ir.nssc.ac.cn/handle/122/3263
Collection空间科学部
Corresponding AuthorHe, ZH (reprint author), Chinese Acad Sci, Ctr Space Sci & Appl Res, State Key Lab Space Weather, Beijing 100080, Peoples R China.
Recommended Citation
GB/T 7714
He, Z. H.,Chen, T.,Liu, Z. X.,et al. Spectral characteristics of the plasma dispersionless injection during the storm recovery phase on 11 March 1998[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2012,117:A11210.
APA He, Z. H..,Chen, T..,Liu, Z. X..,Pu, Z. Y..,Roth, I..,...&He, ZH .(2012).Spectral characteristics of the plasma dispersionless injection during the storm recovery phase on 11 March 1998.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,117,A11210.
MLA He, Z. H.,et al."Spectral characteristics of the plasma dispersionless injection during the storm recovery phase on 11 March 1998".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 117(2012):A11210.
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