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The Role of Mesoscale Plasmasheet Dynamics in the Ring Current Formation

Presentation #101.06 in the session Universality of Mesoscale Processes in Space and Solar Physics.

Published onOct 20, 2022
The Role of Mesoscale Plasmasheet Dynamics in the Ring Current Formation

During geomagnetically active periods ions are transported from the magnetotail into the inner magnetosphere and accelerated to energies of tens to hundreds of keV. These energetic ions, of mixed composition with the most important species being H+ and O+, become the dominant source of plasma pressure in the inner magnetosphere. Ion transport and acceleration can occur at different spatial and temporal scales ranging from global quasi-steady convection to localized impulsive injection events and may depend on the ion gyroradius. Here we present the results of a study undertaken to better understand the relative importance of mesoscale flow structures and the role of finite gyroradius effects on the produced ring currents. To this end we utilize: global magnetohydrodynamic (MHD) simulations to generate self-consistent electromagnetic fields under typical driving conditions which exhibit bursty bulk flows (BBFs); and injected test particles, initialized to match the plasma moments of the MHD simulation, and subsequently evolved according to the kinetic equations of motion.

From this simulation we show that the BBFs produced by our simulation reproduce thermodynamic and magnetic statistics from in situ measurements and are numerically robust. Mining the simulation data we create a data set, over a billion points, connecting particle transport to characteristics of the MHD flow. These statistics demonstrate the critical role of mesoscale bubbles, localized depleted entropy regions, and energy-dependent particle drifts in ion transport from the plasma sheet into the inner magnetosphere.

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