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

GEM：KH 涡旋附近和低纬边界层等离子体“混合”区域等离子体波模式的实验识别

• 批准号: 1502774
• 负责人: Katariina Nykyri
• 金额: $ 17.97万
• 依托单位: Embry-Riddle Aeronautical University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-15 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1502774&HistoricalAwards=false
• 关键词: GEM; Experimental; Identification; Plasma; Wave

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.

空间不是空的，但充满了能量电子和离子，这些电子带有太阳带有太阳磁场线向外吹。 在这种媒介中包含的危险能量和动量水平不断轰炸地球。 尽管地球的磁场充当了地球周围大部分介质的盾牌，但某些小部分可以穿过地球的磁性屏蔽（称为磁磁磁带），即使这幅少量也可以为地球周围空间的高海拔地区的高度驱动空间。 发生这种情况是一个重要的问题，因为严重的太空风暴会对我们相互联系的社会所依赖的各种技术产生负面影响。最近，极端太空天气事件的潜力破坏了全球尺度上的电网，层叠的各种批判性社会基础设施的破坏一直是国家和国际关注的主题。 通常认为，将太阳能输送到磁层的主要机制是通过磁合并的过程将地球磁场线与太阳的连接在一起。 但是，尽管尚不清楚确切的细节和相对重要性，但最近揭露了另一条路线。 通常在加热和冷离子的混合种群和开尔文 - 霍尔莫尔兹波的混合种群的磁性内观察到大幅度低频率血浆波。 开尔文 - 赫尔姆霍尔茨波是太阳风吹过去在磁磁表面产生的波。 当前的理论表明，这些表面波沿磁场线（称为动力学的Alfven波）沿着与磁粘着的磁场梯度和场梯度处的内部波。这些波能够在磁层内加热离子。 实际上，该过程将能量从太阳风传输到磁层内的离子种群中。 然而，尚无实验证实，即该区域中观察到的低频波确实是动力学的alfven波。 该建议引入了一种新型的数据分析技术，该技术能够识别观察到的等离子体波的模式。 如果成功，这代表了前进的重要一步。 这里解决的科学主题与太阳能冠状的问题相似。因此，太阳能和天体物理学群落也将引起进步。 研究生将在研究该项目时接受培训和指导，而REU本科生将在夏季参加该项目。 最终，PI本身就是一名早期职业女性物理学教授，由于该项目，他将能够继续在Embry-Riddle航空大学的研究计划。该项目使用新的新型技术来实验确定分散关系，从而确定在低纬度边界层中经常存在的大型等离子波的波浪模式。 该技术需要两个簇航天器，并具有适当的分离，以观察混合等离子体种群的区域或磁性附近的K-H波的等离子体波。 两种航天器对电场和磁场的观察用于分散关系的构建，这允许识别特定的等离子体波模式。 对于一种情况，该技术已成功。 确定大量此类事件，其中满足上述条件会给项目的成功带来很大的风险，但是如果成功，则奖励很高。