The gyroresonant interaction between electromagnetic ion cyclotron （EMIC） waves and energetic particles was studied in a multi-ion （H^＋, He^＋, and O^＋） plasma. The minimum resonant energy Emin, resonant wave fr...The gyroresonant interaction between electromagnetic ion cyclotron （EMIC） waves and energetic particles was studied in a multi-ion （H^＋, He^＋, and O^＋） plasma. The minimum resonant energy Emin, resonant wave frequency w, and pitch angle diffusion coefficient Daa were calculated at the center location of the symmetrical ring current： r ≈3.5RE with RE the Earth＇s radius. Emin is found to decrease rapidly from 10 MeV to a few keV with the increase in ca in three bands： H^＋-band, He^＋-band and O^＋-band. Moreover, EMIC waves have substantial potential to scatter energetic （～100 keV） ions （mainly H^＋ and He^＋） into the loss cone and yield precipitation loss, suggesting that wave-particle interactions contribute to ring current decay.展开更多
We study the characteristics of cyclotron way,particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ω, and pitch angle diffusion coeffi...We study the characteristics of cyclotron way,particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ω, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ω for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with ω for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic （10 keV-100 keV） electrons and protons and cause precipitation loss at L = 4, indicating that perhaps waveparticle interaction is a serious candidate for the ring current decay.展开更多
We present a study on the second-order resonant interaction between the ring current protons with Whistler-mode waves propagating near the quasi electrostatic limit following the previous second-order resonant theory....We present a study on the second-order resonant interaction between the ring current protons with Whistler-mode waves propagating near the quasi electrostatic limit following the previous second-order resonant theory. The diffusion coefficients are proportional to the electric field amplitude E, much greater than those for the regular first-order resonance, which are proportional to the electric field amplitudes square E^2. Numerical calculations for the pitch angle scattering are performed for typical energies of protons Ek = 50 keV and 100 keV at locations L = 2 and L = 3.5. The timescale for the loss process of protons by the Whistler waves is found to approach one hour, comparable to that by the EMIC waves, suggesting that Whistler waves may also contribute significantly to the ring current decay under appropriate conditions.展开更多
A concise and elegant expression of cyclotron harmonic resonant quasi-pure pitch-angle diffusion is constructed for the parallel whistler mode waves, and the quasi-linear diffusion coefficient is prescribed in terms o...A concise and elegant expression of cyclotron harmonic resonant quasi-pure pitch-angle diffusion is constructed for the parallel whistler mode waves, and the quasi-linear diffusion coefficient is prescribed in terms of the whistler mode wave spectral intensity. Numerical computations are performed for the specific case of energetic electrons interacting with a band of frequency of whistler mode turbulence at L ≈ 3. It is found that the quasi-pure pitch-angle diffusion driven by the whistler mode scatters energetic electrons from the larger pitch-angles into the loss cone, and causes pitch-angle distribution to evolve from the pancake-shaped before the terrestrial storms to the flat-top during the main phase. This probably accounts for the quasi-isotropic pitch-angle distribution observed by the combined release and radiation effects satellite spacecraft at L ≈ 3.展开更多
The quasi-pure pitch-angle scattering of energetic electrons driven by field-aligned propagating whistler mode waves during the 9～15 October 1990 magnetic storm at L≈ 3 ～ 4 is studied, and numerical calculations fo...The quasi-pure pitch-angle scattering of energetic electrons driven by field-aligned propagating whistler mode waves during the 9～15 October 1990 magnetic storm at L≈ 3 ～ 4 is studied, and numerical calculations for energetic electrons in gyroresonance with a band of frequency of whistler mode waves distributed over a standard Gaussian spectrum is performed. It is found that the whistler mode waves can efficiently drive energetic electrons from the larger pitchangles into the loss cone, and lead to a flat-top distribution during the main phase of geomagnetic storms. This result perhaps presents a feasible interpretation for observation of time evolution of the quasi-isotropic pitch-angle distribution by Combined Release and Radiation Effects Satellite （CRRES） spacecraft at L ≈ 3 ～ 4.展开更多
Observation has clearly shown that natural space plasmas generally possess a pronounced non-Maxwellian high-energy tail distribution that can be well modeled by a kappa distribution. In this study we investigate the p...Observation has clearly shown that natural space plasmas generally possess a pronounced non-Maxwellian high-energy tail distribution that can be well modeled by a kappa distribution. In this study we investigate the proton cyclotron wave instability driven by the temperature anisotropy （T⊥/TH 〉1） of suprathermal protons modeled with a typical kappa distribution in the magnetosheath. It is found that as in the case for a regular bi-Maxwellian, the supratherreal proton temperature anisotropy is subject to the threshold condition of this proton cyclotron instability and the instability threshold condition satisfies a general form T⊥/T｜｜ - 1 = S/β｜｜^α, with a very narrow range of the fitting parameters： 0.40 ≤ α ≤ 0.45, and a relatively sensitive variation 0.27 ≤ S ≤ 0.65, over 0.01 ≤β｜｜ 〈 10. Furthermore, the difference in threshold conditions between the kappa distribution and the bi-Maxwellian distribution is found to be small for a relatively strong growth but becomes relatively obvious for a weak wave growth. The results may provide a deeper insight into the physics of this instability threshold for the proton cyclotron waves.展开更多
The enhanced growth rate of whistler mode waves has been evaluated during an injection event associated with an isolated terrestrial substorm that occurred at 23：00 UT, on January 21, 1991. The electron phase space d...The enhanced growth rate of whistler mode waves has been evaluated during an injection event associated with an isolated terrestrial substorm that occurred at 23：00 UT, on January 21, 1991. The electron phase space density observed by an LEPA instrument on the board of the CRRES spacecraft is modelled by using a bi-loss-cone distribution function （composed of a high anisotropic component and a quasi-isotropic component）. During the injection event, the path integrated gain may increase by a factor of 5 over a frequency range near a few tenths of the electron gyrofrequency, which is consistent with the enhancement observed in the CRRES plasma wave experiment （PWE） emissions. Scattering of electrons by the enhanced whistler mode waves causes the pitch angle distribution of resonant electrons to a quasi isotropic （fiat-top） distribution during the terrestrial substorm injection event.展开更多
We adopt a recently developed relativistic kappa-loss-cone （KLC） distribution to model energetic electrons energy spectra observed at the geostatlonary orbit in the storm of 3-4 November 1993. The KLU distribution i...We adopt a recently developed relativistic kappa-loss-cone （KLC） distribution to model energetic electrons energy spectra observed at the geostatlonary orbit in the storm of 3-4 November 1993. The KLU distribution is found to fit well with the observed data from four satellites during different universal times. This suggests that the electron flux obeys the power-law not only at the lower energies but also at the relativistic energies, and the KLU distribution may provide a better understanding of environments in those space plasmas where relativistic electrons are present.展开更多
基金National Natural Science Foundation of China (Nos.40874076,40774078,40774079 and 40536029)the Special Fund for Public Welfare Industry (meteorology)GYHY200806072the Visiting Scholar Foundation of State Key Laboratory for Space Weather,Chinese Academy of Sciences
文摘The gyroresonant interaction between electromagnetic ion cyclotron （EMIC） waves and energetic particles was studied in a multi-ion （H^＋, He^＋, and O^＋） plasma. The minimum resonant energy Emin, resonant wave frequency w, and pitch angle diffusion coefficient Daa were calculated at the center location of the symmetrical ring current： r ≈3.5RE with RE the Earth＇s radius. Emin is found to decrease rapidly from 10 MeV to a few keV with the increase in ca in three bands： H^＋-band, He^＋-band and O^＋-band. Moreover, EMIC waves have substantial potential to scatter energetic （～100 keV） ions （mainly H^＋ and He^＋） into the loss cone and yield precipitation loss, suggesting that wave-particle interactions contribute to ring current decay.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40774078, 40774079, 40536029 and 40621003, the Natural Science Foundation of Hunan Province under Grant No 07JJ3123, and the Visiting Scholar Foundation of State Key Laboratory for Space Weather, Chinese Academy of Sciences.
文摘We study the characteristics of cyclotron way,particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ω, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ω for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with ω for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic （10 keV-100 keV） electrons and protons and cause precipitation loss at L = 4, indicating that perhaps waveparticle interaction is a serious candidate for the ring current decay.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40774078, 40404012, 40474064 and 40674076, and the Visiting Scholar Foundation of State Key Laboratory for Space Weather, Chinese Academy Sciences.
文摘We present a study on the second-order resonant interaction between the ring current protons with Whistler-mode waves propagating near the quasi electrostatic limit following the previous second-order resonant theory. The diffusion coefficients are proportional to the electric field amplitude E, much greater than those for the regular first-order resonance, which are proportional to the electric field amplitudes square E^2. Numerical calculations for the pitch angle scattering are performed for typical energies of protons Ek = 50 keV and 100 keV at locations L = 2 and L = 3.5. The timescale for the loss process of protons by the Whistler waves is found to approach one hour, comparable to that by the EMIC waves, suggesting that Whistler waves may also contribute significantly to the ring current decay under appropriate conditions.
基金Supported by the Natiopal Natural Science Foundation of China under Grant Nos 40474064 and 40404012, the Scientific Research Foundation for R0CS of the Ministry of Education of China, and the Youth Foundation of Education Bureau of Hunan Province under Grant No 04B003.
文摘A concise and elegant expression of cyclotron harmonic resonant quasi-pure pitch-angle diffusion is constructed for the parallel whistler mode waves, and the quasi-linear diffusion coefficient is prescribed in terms of the whistler mode wave spectral intensity. Numerical computations are performed for the specific case of energetic electrons interacting with a band of frequency of whistler mode turbulence at L ≈ 3. It is found that the quasi-pure pitch-angle diffusion driven by the whistler mode scatters energetic electrons from the larger pitch-angles into the loss cone, and causes pitch-angle distribution to evolve from the pancake-shaped before the terrestrial storms to the flat-top during the main phase. This probably accounts for the quasi-isotropic pitch-angle distribution observed by the combined release and radiation effects satellite spacecraft at L ≈ 3.
基金National Natural Science Foundation of China(Nos.40774078,40404012,40674076,40474064)the Visiting Scholar Foundation of State Key Laboratory of Space Weather,Chinese Academy of Sciences
文摘The quasi-pure pitch-angle scattering of energetic electrons driven by field-aligned propagating whistler mode waves during the 9～15 October 1990 magnetic storm at L≈ 3 ～ 4 is studied, and numerical calculations for energetic electrons in gyroresonance with a band of frequency of whistler mode waves distributed over a standard Gaussian spectrum is performed. It is found that the whistler mode waves can efficiently drive energetic electrons from the larger pitchangles into the loss cone, and lead to a flat-top distribution during the main phase of geomagnetic storms. This result perhaps presents a feasible interpretation for observation of time evolution of the quasi-isotropic pitch-angle distribution by Combined Release and Radiation Effects Satellite （CRRES） spacecraft at L ≈ 3 ～ 4.
基金supported by the National Natural Science Foundation of China （Nos. 40474064, 40404012） the Scientific Research Foundation for R0CS, SEM+1 种基金 the Scientific Research Fund of Hunan Provincial Science and Technology Department grant 05FJ3045 the Visiting Scholar Foundation of State Key Laboratory of Space Weather, Chinese Academy of Sciences
文摘Observation has clearly shown that natural space plasmas generally possess a pronounced non-Maxwellian high-energy tail distribution that can be well modeled by a kappa distribution. In this study we investigate the proton cyclotron wave instability driven by the temperature anisotropy （T⊥/TH 〉1） of suprathermal protons modeled with a typical kappa distribution in the magnetosheath. It is found that as in the case for a regular bi-Maxwellian, the supratherreal proton temperature anisotropy is subject to the threshold condition of this proton cyclotron instability and the instability threshold condition satisfies a general form T⊥/T｜｜ - 1 = S/β｜｜^α, with a very narrow range of the fitting parameters： 0.40 ≤ α ≤ 0.45, and a relatively sensitive variation 0.27 ≤ S ≤ 0.65, over 0.01 ≤β｜｜ 〈 10. Furthermore, the difference in threshold conditions between the kappa distribution and the bi-Maxwellian distribution is found to be small for a relatively strong growth but becomes relatively obvious for a weak wave growth. The results may provide a deeper insight into the physics of this instability threshold for the proton cyclotron waves.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40474064 and 40404012, and the 0utstanding Youth Foundation of Education Bureau of Hunan Province under Grant No 04B003.
文摘The enhanced growth rate of whistler mode waves has been evaluated during an injection event associated with an isolated terrestrial substorm that occurred at 23：00 UT, on January 21, 1991. The electron phase space density observed by an LEPA instrument on the board of the CRRES spacecraft is modelled by using a bi-loss-cone distribution function （composed of a high anisotropic component and a quasi-isotropic component）. During the injection event, the path integrated gain may increase by a factor of 5 over a frequency range near a few tenths of the electron gyrofrequency, which is consistent with the enhancement observed in the CRRES plasma wave experiment （PWE） emissions. Scattering of electrons by the enhanced whistler mode waves causes the pitch angle distribution of resonant electrons to a quasi isotropic （fiat-top） distribution during the terrestrial substorm injection event.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40674076, 40404012, 40436016, and 40474064, and the Natural Science Foundation of Hunan Province under Grant No 06JJ4002.
文摘We adopt a recently developed relativistic kappa-loss-cone （KLC） distribution to model energetic electrons energy spectra observed at the geostatlonary orbit in the storm of 3-4 November 1993. The KLU distribution is found to fit well with the observed data from four satellites during different universal times. This suggests that the electron flux obeys the power-law not only at the lower energies but also at the relativistic energies, and the KLU distribution may provide a better understanding of environments in those space plasmas where relativistic electrons are present.
