Title: Foreshock Transients: Formation Mechanism and Particle Acceleration

Speaker: Dr. Zixu Liu (UCAR and University of Alaska at Fairbanks)

Time: 10:00am, Jan. 14, 2021

Location: Tencent Conference, ID: 821 105 936

Abstract: Foreshock transients are ion kinetic structures in the ion foreshock. Due to their dynamic pressure perturbations, they can disturb the bow shock, magnetosheath, magnetopause, and magnetosphere-ionosphere system. Recent studies found that they can also accelerate particles. Acceleration mechanisms including shock drift acceleration, Fermi acceleration, betatron acceleration, and magnetic reconnection have been identified from observations and simulations. Our results suggest that foreshock transients could play a role in particle acceleration at the parent bow shock. Although they are important, how they form is still unclear. Using particle-in-cell simulations and MMS observations, we propose a physical formation process that the positive feedback of foreshock ions on the varying magnetic field caused by the foreshock ion Hall current enables an “instability” and the growth of the structure.