Micro-processes Driven by Shear Alfvén Waves Generating Parallel Potential Drop in the Auroral Plasma

由剪切阿尔文波驱动的微过程在极光等离子体中产生平行电势下降

• 批准号: 0647157
• 负责人: Nagendra Singh
• 金额: $ 36万
• 依托单位: University of Alabama in Huntsville
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-15 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0647157&HistoricalAwards=false
• 关键词: Micro; processes; Driven; Shear; Alfv

Alfven waves are thought to play a significant role in the auroral particle acceleration process, but the plasma processes, which convert the Alfven wave energy into the electrostatic energy in a parallel potential drop (PPD), are still not fully understood. This project will continue a line of research in this topic that has used a two-fluid magnetohydrodynamic (MHD) model. In this two-fluid model the electric field parallel to the magnetic field lines is calculated from the electron momentum equation. The electron momentum equation includes linear and nonlinear inertial terms as well as an anomalous collision term. The anomalous collision term is an heuristic model of the electrostatic ion cyclotron (EIC) instability. The two-fluid model has been successful on a number of fronts, but these types of models are know to miss kinetic and microphysical processes such as (i) multi-streaming of charged particles and resulting micro-instabilities, (ii) plasma heating resulting in plasma evacuation and cavity formation, (iii) formation of micro-scale PPD like a double layer (DL) and (iv) effects of mirror force.The main thrust of this project will be to study the meso-scale propagation of shear Alfven waves (SAWs) using kinetic simulations that include the appropriate microphysics in a self-consistent way. The simulations will be done with a 2.5-dimensional particle-in-cell code. The primary focuses of attention for the project will be (i) the wave modes responsible for the anomalous resistivity, (ii) anomalous plasma heating resulting in cavity creation, (iii) cavity creation by nonlinear ponderomotive force, and (iv) double layer formation localizing E-parallel in cavities as seen in data from the FAST and Polar satellites. The research will determine the relative importance of double layers, anomalous resistivity, and mirror force in establishing the PPD in a propagating SAW, and will augment MHD and two-fluid MHD modeling efforts by providing rigorously determined expressions for the anomalous resistivity. The project will include research experience and support for a graduate student and undergraduate students. The parallelized kinetic code is used as a teaching tool for teaching parallel computing courses.

Alfven波被认为在极光粒子加速过程中起着重要的作用，但等离子体过程，将Alfven波能量转换为静电能量的平行电位降（PPD），仍然没有完全理解。 本计画将继续使用二流体磁流体模型进行研究。 在这个双流体模型中，平行于磁力线的电场由电子动量方程计算。 电子动量方程包括线性和非线性惯性项以及反常碰撞项。 反常碰撞项是静电离子回旋不稳定性的一个启发式模型。 双流体模型已经在许多方面取得了成功，但是已知这些类型的模型错过了动力学和微物理过程，例如（i）带电粒子的多流和由此产生的微不稳定性，（ii）等离子体加热导致等离子体抽空和空腔形成，（iii）微尺度PPD的形成，如双层（DL）;（iv）镜力的影响。本项目的主要目的是研究剪切阿尔芬波的中尺度传播（SAW）使用动力学模拟，包括适当的微观物理在一个自洽的方式。 模拟将使用2.5维粒子细胞代码进行。 该项目的主要关注点将是（i）负责异常电阻率的波模式，（ii）导致空腔产生的异常等离子体加热，（iii）由非线性有质动力产生的空腔，以及（iv）在FAST和Polar卫星的数据中看到的空腔中定位E平行的双层形成。 这项研究将确定的相对重要性，双层，异常电阻率，并建立在传播SAW的PPD镜力，并将增加MHD和双流体MHD建模工作，提供严格确定的表达式异常电阻率。 该项目将包括研究经验和支持研究生和本科生。 将并行化的动力学代码作为并行计算课程的教学工具。