Coupling of Micro- and Meso-Scale Processes During Early Stage Plasmaspheric Refilling

本文研究了离子束驱动波及其对电离层等离子体在外等离子层积累的影响。这解决了磁层物理学中的一个主要问题，即地磁风暴后等离子层的重新填充。该项目的主要目标是牢固地建立以下基本范式和建模方法的方法，假设一旦等离子体流动参数越过波的边缘稳定条件，就会触发不稳定并将流动限制在边缘稳定条件附近。因此，从波和不稳定性的观点来看，等离子体的准稳态是先验的。当宏观过程将等离子体从这种状态推向不稳定状态时，我们知道需要通过不稳定过程热化的多余动量和定向动能。这有助于在不知道不稳定过程细节的情况下，计算出基于等离子体输运方程的中尺度模型中包含的异常等离子体输运系数。这种方法被称为反常等离子体效应或APE模型。研究策略包括：1)系统地确定充注过程中等离子体边缘稳定条件的易使用的半经验关系；2)通过不稳定性来表征等离子体加热的小尺度粒子池模拟，并对APE模型进行测试；3)使用包括异常输运系数在内的双流流体力学代码进行中尺度模拟。

This study addresses the problem of ion-beam driven waves and their effects on the accumulation of ionospheric plasma in the outer plasmasphere. This addresses a major problem in magnetospheric physics, that is, the refilling of the plasmasphere following geomagnetic storms. The primary goal of the project is to firmly establish the methodology of the following basic paradigm and modeling approach assumes that as soon as the plasma flow parameters cross marginal stability conditions for the waves, the instabilities are triggered and clamp the flow near the conditions for marginal stability. Thus, from the waves and instability standpoint, the quasisteady state of the plasma is known a priori. When the macroscopic processes drive the plasma away form this state toward instability, we know the excess momentum and the directed kinetic energy which need to be thermalized by the instability process. This facilitates an easy calculation of the anomalous plasma transport coefficients to be included in a mesoscale model based on plasma transport equations without knowing the details of the instabilityprocess. This approach is termed the Anomalous Plasma Effects or APE model. The research strategy consists of 1) systematic determination of easy-to-use semiempirical relations for the marginal stability conditions for the plasma during the refilling situation, 2) small-scale particle- in-cell simulations to characterize plasma heating by the instabilities and to test the APE model, and 3) mesoscale modeling using two-stream hydrodynamic code including the anomalous transport coefficients.