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61.
P. Pappa Kalaivani O. Prakash Li Feng A. Shanmugaraju Liu-Guan Ding Lei Lu Weiqun Gan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3390-3403
We have established a data set of 58 major hybrid SEP events associated with meter-to-decahectometer wavelength (m-to-DH) type II bursts, solar flares, and radio-load CMEs during the period of 1997–2014. The main focus of our study is to address the following two questions: Does the interaction of CMEs play a role in the enhancement of SEP intensity? Is there any difference in the seed population, and parent eruptions in the SEP events with and without CME interactions? Hence, the sample of 58 events is classified into two sets: (i) 35 non-interacting-CME-associated SEP events; (ii) 23 interacting-CME-associated SEP events. All the characteristics of SEPs, their associated CMEs/flares and the relationships between them are statistically analyzed and compared. Some of the basic attributes and relative elemental abundances (Fe/O ratios) of the both the sets are also compared. The results indicate that the seed particles in non-interacting-CME-associated SEP events are mostly from solar wind/coronal materials. But in the case of interacting-CME-associated SEP events, it may be associated with both flare material from preceding flares and coronal materials from solar wind/preceding CMEs. The correlation studies reveal that there are clear correlations between logarithmic peak intensity of SEP events and properties of CMEs (space speed: cc?=?0.56) and solar flares (peak intensity: cc?=?0.40; integrated flux: cc?=?0.52) for non-interacting-CME-associated SEP events. But these correlations are absent for the interacting-CME-associated events. In addition, the results suggest that interaction of primary CMEs with their preceding CMEs plays an important role in the enhancement of peak intensity of SEPs at least for a set of m-to-DH type II bursts associated SEP events. 相似文献
62.
I.B. Ievenko S.G. ParnikovV.N. Alexeyev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(8):1252-1260
Investigation results of a diffuse aurora (DA) and stable auroral red (SAR) arc dynamics based on spectrophotometric observations at the Yakutsk meridian (199°E geomagnetic longitude) are presented. The relationship of an equatorward extension of DA in the 557.7 nm emission to a substorm growth phase during the magnetospheric convection intensification after the turn of IMF BZ to the south is shown. The formation of SAR arc during the substorm expansion phase is investigated. The association of SAR arc dynamics with the development of asymmetric ring current (substorm injection) during the main phase of a storm is analyzed. It is shown how the pulsating precipitations of energetic ring current particles develop in the outer plasmasphere based on photometric observations. 相似文献
63.
A.V. Grigoryev S.A. Starodubtsev V.G. Grigoryev I.G. Usoskin K. Mursula 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(6):955-961
Fluctuations of cosmic rays and interplanetary magnetic field upstream of interplanetary shocks are studied using data of ground-based polar neutron monitors as well as measurements of energetic particles and solar wind plasma parameters aboard the ACE spacecraft. It is shown that coherent cosmic ray fluctuations in the energy range from 10 keV to 1 GeV are often observed at the Earth’s orbit before the arrival of interplanetary shocks. This corresponds to an increase of solar wind turbulence level by more than the order of magnitude upstream of the shock. We suggest a scenario where the cosmic ray fluctuation spectrum is modulated by fast magnetosonic waves generated by flux of low-energy cosmic rays which are reflected and/or accelerated by an interplanetary shock. 相似文献
64.
R. Rodríguez-Gasén A. Aran B. Sanahuja C. Jacobs S. Poedts 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The shape of flux profiles of gradual solar energetic particle (SEP) events depends on several not well-understood factors, such as the strength of the associated shock, the relative position of the observer in space with respect to the traveling shock, the existence of a background seed particle population, the interplanetary conditions for particle transport, as well as the particle energy. Here, we focus on two of these factors: the influence of the shock strength and the relative position of the observer. We performed a 3D simulation of the propagation of a coronal/interplanetary CME-driven shock in the framework of ideal MHD modeling. We analyze the passage of this shock by nine spacecraft located at ∼0.4 AU (Mercury’s orbit) and at different longitudes and latitudes. We study the evolution of the plasma conditions in the shock front region magnetically connected to each spacecraft, that is the region of the shock front scanned by the “cobpoint” (Heras et al., 1995), as the shock propagates away from the Sun. Particularly, we discuss the influence of the latitude of the observer on the injection rate of shock-accelerated particles and, hence, on the resulting proton flux profiles to be detected by each spacecraft. 相似文献
65.
R. A. Mewaldt 《Space Science Reviews》2006,124(1-4):303-316
Recent progress in measuring the composition and energy spectra of solar energetic particles (SEPs) accelerated by CME-driven
shocks is reviewed, including a comparison of the observed charge-to-mass dependence of breaks in SEP spectra with model predictions.
Also discussed is a comparison of SEP and CME kinetic energies in seventeen large SEP events, and estimates of the SEP radiation
dose that astronauts would be subject to once they venture outside the protective cover of Earth’s magnetosphere. 相似文献
66.
67.
A. Naam M.T. Meftah S. Douis S. Alexiou 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
In the present work we compute the real part of the impact collision operator for the electron broadening of ion lines in plasmas, taking into account relativistic effects in the dynamics of the perturbing electron. Specifically two relativistic effects are included: The modification of the trajectory due to non-Newtonian mechanics and the modification of the velocity distribution (Maxwell–Juttner). The results are compared to the non-relativistic case. 相似文献
68.
69.
针对微放电过程中的电子累积效应,探索二次电子累积对微波部件传输特性的影响,提出二次电子累积“等效介质”的理论模型,通过将电子累积等效为“特殊介质”,从介质的角度探索电子累积对传输特性的影响,推导得到不同电子累积密度所形成不同“等效介质”的相对介电常数。仿真和计算结果表明,微放电过程中,电子累积密度从0增长至1016/m3数量级时,传输特性基本不发生变化; 但是当电子累积密度达到1017/m3数量级时,阻抗变换器的通带内回波损耗恶化了15dB;随着电子累积密度继续增大,“等效介质”对电磁波的反射迅速增强,微波部件的传输特性急剧恶化;在电子累积密度达到4×1017/m3时,电磁波在阻抗变换器中的传输处于完全截止状态。为了进一步探讨导致传输特性恶化的深层原因,发现在电子累积密度达到4×1017/m3时,在2.5~5GHz的频率范围内,电子累积形成“等效介质”的相对介电常数呈现为负值,电磁波传输截止,“等效介质”表现出单负介电常数超材料的特性,即导致阻抗变换器传输特性恶化的原因是单负介质材料的形成。研究有益于更深入地认识微放电形成过程中的深层物理机理及其对宏观电性能的影响,为寻求更加有效的抑制方法提供理论依据。 相似文献
70.
N. Duric 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
The problem of cosmic ray production in the spiral galaxy NGC 3310 is addressed by analysing and comparing optical and radio continuum data. Tentative results indicate that on global scales relativistic electrons may be produced in the shock front associated with teh density wave while on local scales extreme population I objects may be producing them. It is inferred that the same conclusions apply to all cosmic rays produced in the disk. 相似文献