Plasma Dynamics Associated with Auroral Potential Structures: A Three-Dimensional Multimoment, Multifluid Model

将建立第一个三维、多时刻、多流体模型来研究极光电离层中的等离子体输运现象及其与全球等离子体动力学的关系。极光电离层电势结构的形成、与低频波的联系以及与等离子体加热和加速的关系是电离层-磁层耦合的重要和突出问题。为了研究这些过程，我们将推广现有的一维（1D）多矩多流体输运模型。Granguli et al., 1988！通过调整现有的3D传输代码来实现三维？Guzdar et al., 1992！提议的3D代码将保留我们的一维模型的广泛磁场对齐动力学。三维流体方程允许同时处理一类低频流体不稳定性和相关的跨场输运。这些低频不稳定性对极光过程的影响，如潜在结构的形成，可能是重要的，但尚未被探索。跨场输运可以大大缓和一维或二维模型的结论。由于输运是由等离子体流体不稳定性自一致地产生的，因此需要一个包含不稳定性和输运过程的统一图像。我们将使用3D模型来研究(1)自洽产生的极光势结构和(2)相关的极光加速过程，包括由于动力学不稳定性引起的等离子体加热。相关动力学不稳定性（如静电离子回旋不稳定性）的宏观影响将通过异常碰撞项纳入我们的3D模型，正如我们在1D模型中所做的那样。理论建模工作将与西南研究所的J.L. Burch博士和NASA/MSFC的T.E. Moore博士的实验项目一起进行。

The first three-dimensional, multimoment, mulifluid model will be developed to study plasma transport phenomena in the auroral ionosphere and their relation to global plasma dynamics. The formation of potential structures in the auroral ionosphere, their connection to low-frequency waves and their association with plasma heating and acceleration are important and outstanding issues concerning Ionosphere-Magnetosphere coupling. To investigate these processes we will generalize our existing one-dimensional (1D) multimoment, multifluid transport model ?Granguli et al., 1988! to three-dimensions by adapting an existing 3D transport code ?Guzdar et al., 1992!. The proposed 3D code will preserve the extensive magnetic field-aligned dynamics of our 1D model. The 3D fluid equations permit a class of low-frequency fluid instabilities and the associated cross-field transport to be treated simultaneously. The consequences of these low-frequency instabilities on auroral processes, such as the formation of potential structures, could be significant but remain unexplored as yet. The cross-field transport can substantially moderate the conclusions of 1D or 2D models. Since the transport is self-consistently generated by plasma fluid instabilities, a unified picture that incorporates both the instability and transport processes requires a 3D formulation. We will use the 3D model to investigate (1) self- consistent generation of auroral potential structures and (2) the associated auroral acceleration processes including plasma heating due to kinetic instabilities. The macroscopic effects of relevant kinetic instabilities (such as the electrostatic ion cyclotron instability) will be incorporated into our 3D model via anomalous collision terms, as was done in our 1D model. The theoretical modeling effort will proceed in tandem with the experimental programs of Dr. J.L. Burch, Southwest Research Institute and Dr. T.E. Moore, NASA/MSFC.