壓力均向電漿中慢速震波形成之混合式粒子碼模擬;Hybrid simulations of slow shock formation in isotropic plasmas

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Title:	壓力均向電漿中慢速震波形成之混合式粒子碼模擬;Hybrid simulations of slow shock formation in isotropic plasmas
Authors:	張巍耀;Chang,Wei-Yao
Contributors:	太空科學研究所
Keywords:	電漿模擬;慢速震波;混合式粒子碼;plasma simulation;slow shock;hybrid particle code
Date:	2015-07-23
Issue Date:	2015-09-23 10:50:00 (UTC+8)
Publisher:	國立中央大學
Abstract:	震波廣泛出現於太空電漿環境之中。根據Petschek的磁重聯模式，慢速震波為將磁能轉換成電漿粒子動能的重要機制。在本研究中，我們以黎曼問題之方法作為初始條件，採用混合式粒子碼數值模式模擬震波之形成。探討之自由參數包含電漿初始熱壓與磁壓比β_0，以及初始切線不連續結構兩側磁場方向和波傳播方向夾角θ_0。從模擬結果中我們發現: (1)β_0和θ_0值之改變皆會直接影響慢速震波的移動速度；(2)在高β_0(β_0≥3)的案例中，會出現異常之慢速震波，且產生慢速震波位於旋轉不連續面上游之混合結構(SS-RD)；(3)在低θ_0(θ_0≤55°)環境下，慢速震波難以於模擬系統中產生。;Shock waves may exist extensively in space plasma environments. According to the Petschek’s reconnection model, slow shocks are responsible for transferring the magnetic energy into kinetic energy of plasma. In this study, we use hybrid particle code to simulate shock formation via the initial-value Riemann problem. Free parameters in the numerical model are the initial plasma beta(β_0) and initial angle between wave vector and magnetic field (θ_0). We found that : (1) Both β_0 and θ_0 may affect the moving speed of slow shocks directly; (2) High β_0 case (β_0≥3) may generate anomalous slow shocks and compound structures of slow shock-rotational discontinuity (SS-RD) type; and (3) In low θ_0 case (θ_0≤55°) , slow shocks cannot be easily generated.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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