Field-Aligned Lorentz Forces with Application to Thermal-Ion Upflows into the Magnetosphere

这是一项为期三年的研究计划，旨在调查新发现的电离层离子能量和传输源的性质。离子充能是磁层物理学中最重要的课题之一，因为离子携带了大部分粒子能量，因此在形成磁层环境中起着核心作用。该计划直接解决了离子充能最令人困惑的问题之一——即，重离子（O+）是如何在电离层的低空加速并大量向上输送到磁层的？这个问题是至关重要的，因为(1)在整个磁层中发现的O+离子的丰度需要一些手段，通过这些手段，大量的热离子从电离层向上输送，(2)在电离层低至400公里的高度观察到热离子向上流动（TIU）和横向加速离子（TAI）。其他观察已经证明至少存在一类TIU事件，其特征是没有离子摩擦加热和电子温度升高，这些特征无法用已知机制轻易解释。这些发现表明，大通量陆地离子向磁层输送的过程尚未确定。我们最近描述了一种新的离子能量源，Tsunoda和Kagan（1995）似乎是缺失的机制。新的源由伦兹型力组成，这种力是由于扰动磁场的存在而产生的，例如，与大规模场向电流系统有关。这种扰动磁场与纬度压力梯度或电流（相互正交，横向于B）一起作用，在与B平行或反平行的方向上产生洛伦兹型力。正如Tsunoda和Kagan 1995年所描述的那样，在这个提议中，这种机制能够解释没有离子加热发生的TIU事件。然而，更令人兴奋的是，这些场向的洛伦兹力可能可以解释一些相关但仍然令人困惑的观察结果，包括(1)离子加热产生的tiu，(2)分子离子向磁层的传输，(3)离子回旋加速器和离子声不稳定性的触发，(4)静电离子回旋波对离子的横向加速，(5)离子声湍流和异常电阻率的发展，(6)向上场向电流区电子温度升高。考虑到场向洛伦兹力在解释各种离子加速相关现象方面的潜力，将对一个更大的非相干散射雷达数据数据库进行调查，以确定观察结果是否支持这一新理论的预测。

This is a three-year research program to investigate the nature of a newly discovered ionospheric source for ion energization and transport. The topic of ion energization is one of paramount importance in magnetospheric physics because ions carry the bulk of the particle energy and thereby play a central role in the molding of that environment. The proposed program directly addresses one of the most puzzling problems of ion energization - that is, how are heavy (O+) ions accelerated at low altitudes in the ionosphere and transported upward in large numbers to the magnetosphere? This question is crucial because (1) the abundance of O+ ions found throughout the magnetosphere requires some means by which large fluxes of thermal ions are transported upward from the ionosphere, and (2) thermal-ions upflows (TIU) and transversely accelerated ions (TAI) have been observed at altitudes as low as 400 km in the ionosphere. Other observations have demonstrated the existence of at least one class of TIU events that is characterized by the absence of ion frictional heating and the presence of elevated electron temperature, features that cannot be easily explained by known mechansisms. These findings indicate that the process responsible for the transport of large fluxes of terrestrial ions to the magnetosphere has not yet been identified. We have recently described a new, ion energization souce Tsunoda and Kagan, 1995 that appears to be the missing mechanism. The new source consists of Lrentz-type forces that arise because of the presence of a perturbation magnetic field, for example, that associated with a large-scale field-aligned current system. This perturbation magnetic field acts together with a latituinal pressure gradient or current (directed orthogonal to one another and transverse to B) to produce a Lorentz-type force in a direction parallel or antiparallel to B. As described by Tsunoda and Kagan 1995 , and in this proposal, this mechanism is capable of accounting for the class of TIU events that occur without ion heating. More exciting however, is the likelihood that these field-aligned Lorentz forces can account for a number of related but still puzzling observations including (1) TIUs produced by ion heating, (2) the transport of molecular ions into the magnetosphere, (3) the triggering of the ion-cyclotron and ion- acoustic instabilities, (4) the transverse acceleration of ions by electrostatic ion-cyclotron waves, (5) the development of ion- acoustic turbulence and anomalous resistivity, and (6) elevated electron temperatures in upward field-aligned current regions. Given the potential of field-aligned Lorentz forces for explaining a variety of ion-acceleration-related phenomena, an investigation of a larger database of incoherent scatter radar data will be undertaken of determine if the observations support the predictions of this novel theory.