Time Domain Structures Driven by Whistler and Kinetic Alfven Waves in a Laboratory Plasma

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Observations of the Earth’s outer radiation belts uncovered intense electric field spikes called “time domain structures” (TDSs). They occur in plasma boundaries, where the energetics and dynamics are poorly understood. This project will use laboratory experiments, simulations, and analysis of satellite data to understand the plasma physics resulting in TDSs. This is an important process to understand how particles gain and lose energy within the radiation belts with applications towards space weather impacts, such as creation of detrimental effects to satellite operations. The project supports two early career scientists, a graduate student, and undergraduate students. The project will test the hypothesis that TDSs are excited by secondary electron beams trapped in the parallel electric fields of kinetic Alfven waves and whistler waves. Experiments will be conducted with the UCLA Large Plasma Device (LAPD) to generate TDSs by launching a large amplitude whistler or kinetic Alfven wave into a plasma. The laboratory data will be used in conjunction with data from particle-in-cell simulations. Field and particle measurements from NASA satellites will be compared to the laboratory and simulation results. The following science questions will be addressed: (1) What plasma parameters determine the type of TDS that will be generated? (2) What are the characteristics of TDSs? (3) How does the amplitude of whistler waves and kinetic Alfven waves affect the excitation of TDSs?This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.