GEM: Experimental Identification of Plasma Wave Modes in Vicinity of KH Vortices and in Plasma 'Mixing' Regions in Low Latitude Boundary Layer

太空并不是空的，而是充满了从太阳吹来的高能电子和离子，它们携带着太阳磁力线。这种介质中包含的危险能量和动量水平不断轰炸着地球。尽管地球磁场起到了屏蔽的作用，使地球周围的大部分介质偏转，但仍有一小部分穿过地球的磁屏蔽(称为磁层顶)，即使是这么小的一小部分，也可以为地球周围空间高海拔的太空风暴提供动力。如何做到这一点是一个重要的问题，因为严重的空间风暴可能会对我们相互关联的社会所依赖的各种技术产生负面影响。最近，极端空间天气事件有可能扰乱全球范围内的电网，导致各种重要社会基础设施的连锁中断，这是国家和国际关注的主题。人们普遍认为，将太阳风能输送到磁层的主要机制是通过磁合并过程将地球的磁力线与太阳的磁力线连接起来。然而，另一条路线最近浮出水面，尽管具体细节和相对重要性尚不清楚。通常在磁层顶内部的冷热离子混合群和开尔文-亥姆霍兹波附近观测到大幅度的低频等离子体波。开尔文-亥姆霍兹波是太阳风吹过时在磁层顶表面产生的波。目前的理论表明，这些表面波在与磁层顶相关的等离子体和场梯度上，沿着磁场线耦合到内波(称为动力学阿尔芬波)。这些波能够加热磁层内的离子。实际上，这一过程将来自太阳风的能量传输到磁层内的离子群中。然而，目前还没有实验证实该地区观测到的低频波确实是动力阿尔芬波。该方案引入了一种新的数据分析技术，能够识别观测到的等离子体波的模式。如果成功，这将是向前迈出的重要一步。这里讨论的科学主题与太阳日冕加热问题有相似之处；因此，太阳和天体物理学界也会对进展感兴趣。一名研究生将在从事这一项目的同时接受培训和指导，REU本科生将在夏季几个月参与该项目。最后，PI自己也是一名职业生涯早期的女物理学教授，由于这一项目，她将能够继续她在恩布里-里德尔航空大学的研究计划。该项目使用一种新演示的新技术来实验确定色散关系，从而识别经常出现在低纬边界层中的大幅度等离子体波的波模。这项技术需要两个具有适当间隔的星系团航天器来观测混合等离子体群区域中的等离子体波或磁层顶附近的K-H波。两个航天器对电场和磁场的观测被用于建立色散关系，从而能够识别特定的等离子体波模式。该技术已在一例中获得成功。确定满足上述条件的大量此类事件会给项目的成功带来相当大的风险，但如果成功，回报会很高。

Space is not empty but is filled with energetic electrons and ions that blow outward from the Sun carrying with them solar magnetic field lines. The dangerous levels of energy and momentum, contained in this medium, constantly bombard the Earth. Though the Earth's magnetic field acts as a shield deflecting most of this medium around the Earth, some small fraction makes its way through the Earth's magnetic shield (called the magnetopause) and, even this small amount can power space storms at high altitudes in the space surrounding the Earth. How this happens is an important problem because severe space storms can negatively impact a variety of technologies upon which our interconnected society relies. Most recently, the potential of extreme space weather events to disrupt power grids over global scales with cascading disruption of a large variety of critical social infrastructures has been the subject of national and international attention. It is commonly accepted that primary mechanism to deliver solar wind energy into the magnetosphere is the joining of the Earth's magnetic field lines with the Sun's through the process of magnetic merging. However, another route has recently come to light though the exact details and relative importance are not yet known. Large amplitude low frequency plasma waves are commonly observed just inside the magnetopause in the vicinity of mixed populations of heated and cold ions and Kelvin-Helmholtz waves. Kelvin-Helmholtz waves are waves generated on the magnetopause surface by the solar wind blowing past. Current theories suggest that these surface waves couple to internal waves along magnetic field lines (called kinetic Alfven waves) at the plasma and field gradients associated with the magnetopause. These waves are able to heat ions within the magnetosphere. This process, in effect, transmits energy from the solar wind into the ion populations within the magnetosphere. However, there has been no experimental confirmation yet that the observed low frequency waves in this region are indeed kinetic Alfven waves. This proposal introduces a novel data analysis technique that is able to identify the modes of the observed plasma waves. If successful this represents a major step forward. The science topic addressed here has parallels with the problem of solar coronal heating; therefore advances will also be of interest to the solar and astrophysics communities. A graduate student will receive training and mentoring while working on this project and undergraduate REU students will participate in the project over the summer months. Finally the PI is herself an early career female physics professor who will be able to continue her research program at Embry-Riddle Aeronautical University as a result of this project.This project uses a newly demonstrated novel technique to experimentally determine the dispersion relation and thus identify the wave modes of large-amplitude plasma waves frequently present in the low latitude boundary layer. This technique requires two Cluster spacecraft with the appropriate separation to observe a plasma wave in a region of mixed plasma populations or K-H waves in the vicinity of the magnetopause. Observations of electric and magnetic fields by the two spacecraft are used in the construction of the dispersion relation, which allows identification of the particular plasma wave mode. The technique has been successfully for one case. Identifying a significant number of such events where the above conditions are met introduces considerable risk into the success of the project but if successful, the rewards are high.