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

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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.