| 摘要: | 磁重聯是一個很重要的物理過程，它可以很快速地將磁能轉換成電漿的流體動能與熱能。一般相信磁重聯與日冕加熱、太陽閃焰發生及地磁暴的發生有關。此外，最近的觀測也發現磁重聯過程發生於行星際空間，且位於磁重聯區的離子(exhaust)有被加速及加熱的現象。磁重聯過程可以產生各種不同的磁流體震波(快震波、慢震波及中速震波)，在太陽表面上磁拱廊結構(magnetic arcades)的形成與斷裂造成很大的擾動，產生了行星際震波以及磁雲。這些震波也造成日冕電漿的加熱與加速，即可以產生很高速的太陽風(400 – 800 km/s)。另一方面，太陽風與地球偶極磁場的交互作用形成了船頭震波(bow shock)、磁鞘、磁層頂及磁尾等結構。此外，各種不同型態的無線電輻射也發生於日冕、行星際震波及磁層裡，這些無線電輻射包括太陽I、II 及 III 型的射電暴(radio bursts)，以及極光區千米射電輻射(Auroral Kilometric Radiation, AKR)。在此計畫中，我們提出幾項發生在太陽系中的離子加熱、震波結構、磁重聯及無線電輻射的相關研究課題，包括：(A)在地球磁尾及日球層電流片中磁重聯所產生的慢震波、旋轉不連續結構及雙重不連續結構，(B)行星際震波與不連續結構中的熱流及溢動量通量的研究，(C)太陽風中旋轉不連續結構的產生機制及穩定性，(D)磁重聯過程中快震波的形成，(E)與日冕加熱相關的重離子-動力Alfvén 波交互作用，(F)由ring-beam 及loss-cone 電漿分布不穩定下無線電波及哨聲波的產生，(G)雲頂上方巨大噴流的發生機制。我們計畫利用理論模型、磁流體數值模擬及粒子數值模擬的方法來分析這些重要的電漿物理過程。我們所提出的研究計畫將可以讓我們對日冕、行星際空間及地球磁層中發生的物理現象及其過程有更深入的了解。 Magnetic reconnection is an important process which causes a rapid conversion of magnetic energy to the bulk flow and thermal energies of plasma. Magnetic reconnection is believed to be associated with corona heating, solar flares and geomagnetic substorms. In addition, recently magnetic reconnection is found to occur in the interplanetary space, which also heats the ions in the reconnection exhaust regions. Various MHD shocks (fast shocks, slow shocks, and intermediate shocks) are generated in the reconnection process. The generation and disruption of magnetic arcades over the solar surface leads to large disturbances, e.g., interplanetary shocks and magnetic clouds, in the solar wind. Particle heating takes place at various types of shocks. The hot coronal plasma leads to the presence of high speed (400 − 800km/s) solar wind. On the other hand, the interaction of so1ar wind with Earth’s dipole magnetic field leads to the formation of the magnetosphere, which includes the bow shock, magnetosheath, magnetopause and magnetotail. In addition, various types of radio emissions can occur in the solar corona, interplanetary shocks and magnetosphere, which include solar type I, II and III radio bursts and auroral kilometric radiation (AKR). In this proposal, we address several problem areas associate with ion heating, shock structure, magnetic reconnection and radio emissions in the solar system for study. These include: (A) Slow shock, rotational discontinuity and double discontinuity generated by magnetic reconnection in the magnetotail and heliospherical current sheet, (B) Study of heat flux and additional momentum flux at the interplanetary shocks and discontinuities, (C) Generation mechanisms and stability of rotational discontinuities observed in the solar wind, (D) Generation of fast shocks by magnetic reconnection, (E) Interaction between heavy ions and kinetic Alfvén waves associated with coronal heating, (F) Generation of radio waves and whistler waves in plasma with ring-beam and loss-cone distributions, and (G) Generation mechanism of gigantic jets. We plan to investigate the associated plasma processes by theoretical modeling, MHD simulations and particle simulations. The proposed study will provide a much deeper understanding of the relevant processes in the solar corona, interplanetary space, and Earth’s magnetosphere. 研究期間：9908 ~ 10007 |
