自1957 年第一顆人造衛星進入太空後，五十年的太空探測已證實地球高層大氣自40 公里以上至整個太陽系邊際處處充滿電漿。這些高溫但密度稀疏的解離氣體，其特性與實驗室電漿有很大的不同，尤其是碰撞頻率極低，是許多非線性電漿現象產生之最佳環境。常見的非線性太空電漿現象包括無碰撞震波、磁層頂與磁尾中的電漿島、磁管與太陽風、磁鞘、磁層中之非線性波動、孤立波與磁洞等。由於太空電漿的獨特性是地面實驗室所無法複製的，理論與模擬研究，須與衛星觀測資料相互驗證始可對於這些現象之產生與演化的物理機制有所了解。而在理論與模擬的研究方面之最大困難為，並無單一模式可描述不同之太空電漿現象，且對於同一非線性電漿現象須由不同之物理模式互相驗證與比較，始可對於其產生與演化的物理機制有所了解。本研究計畫，為期三年，將應用電漿微觀動力論與磁流體力學理論探討下列幾個主要研究主題。(一) 我們將結合觀測資料與理論模式，應用磁流體與粒子模擬探討救火管與磁鏡不穩定性之非線性發展。(二) 我們將應用微觀動力理論與粒子模擬探討非高斯(non-Maxwellian) 之粒子速度分布對電漿不穩定性與非線性電漿波之效應。(三) 我們將應用二維磁流體模式探討磁重連過程、磁島、磁鏡波與震波之形成。(四) 我們將分析人造衛星資料，結合理論模式，研究地球磁層頂與磁尾之電漿島、磁管之分布與特性。(五) 其他的研究包括，探討地球磁層頂與磁尾電流片的結構與動力等非線性電漿問題。 Space exploration for the past fifty years by means of the instruments carried onboard spacecraft has revealed that the region above 40 km from the Earth to the edge of the solar system is filled with the ionized gas or plasma. In contrast with the laboratory plasma, the number density of space plasma is much lower. As a result, space plasma is highly collisionless and may develop a variety of nonlinear plasma phenomena that cannot be produced in the ground laboratory. Nonlinear plasma structures frequently observed in the Earth’s space environment include collisionless shocks, magnetic islands or plasmoid and flux ropes in the magnetopause and magnetotail, nonlinear waves/fluctuations and discontinuities, magnetic holes and solitary waves in the solar wind, magnetosheath and magnetosphere etc. Only through close comparison between the theoretical models and observational data, can we better understand the characteristics, formation and evolution of these nonlinear plasma phenomena. The difficulties with the theoretical and simulation studies of space plasmas arise from the fact that no single model is capable of describing plasma phenomena of all kinds and even for the same phenomena results from different models need be compared to identify the physics mechanisms behind. The proposed three-year research project will utilize plasma kinetic theory and hydromagnetic models to study the following problems. (1) Nonlinear evolutions of fire-hose and mirror instabilities will be examined based on fluid models and particle simulations. (2) Nonlinear waves and instabilities in non-Maxwellian plasmas will be studied based on the kinetic theory and particle simulations. (3) Two-dimensional MHD simulations will be conducted to study magnetic reconnection, formation of magnetic islands, shock waves/discontinuities and mirror waves etc. (4) Satellite data will be analyzed along with theoretical modeling to study the magnetic islands, flux ropes in the magnetopause and magnetotail. (5) Other problems include the equilibrium structures and dynamics of the magnetopause and magnetotail current layers etc. 研究期間：9908 ~ 10007
