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251.
D. J. Wu 《Space Science Reviews》2005,121(1-4):333-342
Nonthermal electrons play a major role during solar flares since not only they contain a large amount of the released energy
but also they provide important information of the flaring physics through their nonthermal radiation in radio and hard X-ray
bands. In a recent work Wu (Phys. Plasmas
10 (2003) 1364) proposed that dissipative solitary kinetic Alfvén wave (DSKAW) with a local shock-like structure could provide an efficient acceleration mechanism for energetic electrons in a
low-β plasma. In the present paper dynamical characteristics of the DSKAW acceleration mechanism in solar coronal plasmas
are studied and its application to the acceleration of flaring electrons is discussed. 相似文献
252.
Roger A. Kopp 《Space Science Reviews》1994,70(1-2):309-316
The working group on coronal streamers convened on the first day of the 2nd SOHO Workshop, which took place in Marciana Marina, Isola d'Elba, 27 September –1 October 1993. Recent progress in streamer observational techniques and theoretical modeling was reported. The contribution of streamers to the mass and energy supply for the solar wind was discussed. Moreover, the importance of thin electric current sheets for determining both the gross dynamical properties of streamers and the fine-scale filamentary structure within streamers, was strongly emphasized. Potential advances to our understanding of these areas of coronal physics that could be made by the contingent of instruments aboard SOHO were pointed out. 相似文献
253.
K. Shibasaki T. Takano S. Enome H. Nakajima M. Nishio Y. Hanaoka C. Torii H. Sekiguchi T. Bushimata S. Kawashima N. Shinohara H. Koshiishi Y. Shiomi 《Space Science Reviews》1994,68(1-4):217-224
The early phases of three flares, observed by the Nobeyama Radio Heliograph, are studied. Nonthermal and thermal radio sources are identified by comparison with soft X-ray images taken by the Soft X-ray Telescope onboard the Yohkoh satellite. Two of the flares are mainly of nonthermal origin and their location coincides with one of the footpoints of soft X-ray loops. Another flare has both thermal and nonthermal components which start to brighten simultaneously. This suggests that particle acceleration and plasma compression develop simultaneously. 相似文献
254.
Cecile Gry 《Space Science Reviews》1996,78(1-2):239-246
The distribution, kinematics and physical properties of the interstellar matter surrounding the Sun can be inferred from ground-based and UV spectroscopic observations. On a 200 pc scale the local interstellar matter appears inhomogeneous and asymmetric. Although it generally flows towards the lower density region, it is composed of numerous small components a few parsecs in size with slightly different velocities. On a smaller scale the extent and the nature of the Local Cloud which flows over the Sun are discussed based on HST-GHRS observations of nearby stars. 相似文献
255.
本文探讨了几种典型金属物体的低频散射问题。介绍了低频散射截面的计算方法;对计算结果进行了分析;并就雷达目标低频散射特性提出了作者的观点。 相似文献
256.
摘 要:为探究预混气组分对不同反应路径下NOx生成影响,针对高压射流反应器,基于CFD流场特征等,构建优化了单PSR、2PSR、3PSR以及PSR+PFR四种化学反应器网络模型。在贫预混燃烧条件下,研究了纯CH4及其混合气燃烧时不同反应路径下NOx的生成情况,得出了燃烧室内不同反应区域每条反应路径NOx的生成量。结果表明,纯CH4燃烧产生的NOx主要来自于热力型、快速型和N2O-中间体型三条反应路径。绝热火焰温度的提高主要促进了热力型和N2O-中间体型NOx的生成。随着CH4或CO中加入H2摩尔分数的增加,NOx排放总量降低,快速型NOx生成速率降低,特别是火焰刷区域的。另外,混合气中CO摩尔分数的增加会导致NOx生成量增多。 相似文献
257.
WM. A. Coles 《Space Science Reviews》1995,72(1-2):211-222
Until the ULYSSES spacecraft reached the polar regions of the solar wind, the only high-latitude measurements available were from indirect techniques. The most productive observations in regions of the solar wind between 5R
and 200R
have been the family of radio scattering techniques loosely referred to as Interplanetary Scintillation (IPS) (Coles, 1978). Useful observations can be obtained using a variety of radio sources, for example spacecraft beacons, planetary radar echoes and compact cosmic sources (quasars, active galactic nuclei, pulsars, galactic masers, etc.). However for measurement of the high-latitude solar wind cosmic sources provide the widest coverage and this review will be confined to such observations. IPS observations played a very important role in establishing that polar coronal holes (first observed in soft x-ray emission) were sources of fast solar wind streams which occasionally extend down to the equatorial region and are observed by spacecraft. Here I will review the IPS technique and show the variation of both the velocity and the turbulence level with latitude over the last solar cycle. I will also outline recent work and discuss comparisons that we hope to make between IPS and ULYSSES observations. 相似文献
258.
Y. -M. Wang 《Space Science Reviews》1995,72(1-2):193-196
I describe a simple procedure for extrapolating the observed solar magnetic field into the heliosphere, which averages the asymptotic fields computed using the standard source surface and current sheet models. The resultant field is characterized by strong latitudinal gradients (maintained by volume currents outside the source surface) and by abrupt reversals in direction at the current sheets. The model yields good agreement with the observed long-term variation of the radial IMF component in the ecliptic, and is used to predict the variation of |B
r
| along the latitudinal trajectory of Ulysses during 1990–1994. As found in earlier studies, the magnitude ofB
r
at any latitude is determined largely by the strength and relative orientation of the Sun's dipole moment. 相似文献
259.
260.