Theoretical Computation of Anomalous Resistivity for Substorm and Reconnection Onset

亚暴和重联爆发异常电阻率的理论计算

• 批准号: 0535824
• 负责人: Peter Yoon
• 金额: --
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-12-15 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0535824&HistoricalAwards=false
• 关键词: Theoretical; Computation; Anomalous; Resistivity; Substorm

The proposed research project comprises a theoretical study of the non-linear theory of anomalous resistivity in thin current sheets. Anomalous resistivity is thought to play an important role in the triggering of magnetic substorms in Earth's magnetosphere. The concept of anomalous resistivity is widely invoked in the literature, but no systematic theoretical discussion has been carried out which can be readily applied to the problem of magnetic reconnection. This project will develop a self-consistent theory of anomalous dissipation which arises from the excitation of a high-frequency electromagnetic instability called the modified-two-stream instability and the lower-hybrid drift instability. These instabilities are likely to be active in thin current sheets just prior to the onset of reconnection. In contemporary research on reconnection (both theory and simulation), the simple Harris model is usually used as the starting point. However, the current sheet structure just prior to the substorm onset cannot be described adequately by the Harris model. The proposed research will therefore model the current sheet structure by generalizing the customary Harris model. The methodology will be a non-local, kinetic, linear Vlasov theory coupled with quasilinear treatment of the anomalous transport coefficient. The theoretical equations will then be solved by numerical means. The notion of excitation of electromagnetic fluctuations being correlated with the onset of substorm or reconnection derives from well-established (but poorly understood) experimental evidence such as the MRX laboratory experiment and AMPTE spacecraft measurements.

拟议的研究项目包括对薄电流片中异常电阻率的非线性理论进行理论研究。 异常电阻率被认为在触发地球磁层中的磁亚暴中起着重要作用。 异常电阻率的概念在文献中被广泛引用，但没有进行系统的理论讨论，可以很容易地应用到磁重联问题。本项目将发展一种反常耗散的自洽理论，这种反常耗散是由一种称为修正双流不稳定性和低杂波漂移不稳定性的高频电磁不稳定性的激发引起的。这些不稳定性很可能是活跃的薄电流片之前发生的重联。在当代重联的研究（理论和模拟），简单的哈里斯模型通常被用作出发点。然而，电流片结构之前的亚暴发病不能充分描述的哈里斯模型。因此，拟议的研究将通过推广习惯的哈里斯模型来模拟当前的片结构。该方法将是一个非本地的，动力学的，线性的弗拉索夫理论加上准线性处理的异常传输系数。然后用数值方法求解理论方程。激发电磁波动与亚暴或重连的发生相关的概念来自于公认的（但知之甚少的）实验证据，如MRX实验室实验和AMPTE航天器测量。