Wednesday, April 30, 2025 - 3:30 p.m. to 4:30 p.m.
Morse Hall, rm 301 -OR- Zoom
Speakers:
Neha Srivastava and James McClung – University of New Hampshire graduate students
Full Titles:
(Srivastava): Dayside Magnetospheric Response to a Solar Wind Tangential Discontinuity: Global MHD Simulation Using OpenGGCM
(McClung): Two-Dimensional Bernstein–Greene–Kruskal Modes: Theory, Simulations, and Reality
Abstracts:
(Srivastava): Solar wind is abundant in discontinuities, such as tangential discontinuities, which, upon interacting with the bow shock and subsequently the magnetopause, lead to plethora of wave-discontinuity interaction within magnetosheath. These non-linear interactions generate substantial disturbances at the bow shock and, in turn, influence the magnetospheric dynamics. Studying such interactions is crucial to our understanding of the Solar Wind-Magnetosphere system. In this study, we investigate the interaction of such a discontinuity with the dayside magnetosphere that leads to pronounced perturbations in the magnetopause boundary, employing a global MHD simulation using Open Geospace Circulation Model (OpenGGCM).
(McClung): Bernstein–Greene–Kruskal (BGK) modes are exact, steady-state, nonlinear solutions to the Vlasov-Poisson system of equations. Their mathematical existence was first demonstrated in 1957 by the eponymous physicists using particles trapped in one-dimensional potential energy troughs. Their physical existence is an area of ongoing research, however. Being solutions to the Vlasov equation, BGK modes would require a collisionless plasma, but such plasmas are ubiquitous in nature. The more difficult demands of nature are dimensionality, stability, and formation. Following theoretical work that identified two- and three-dimensional BGK modes, I will present particle-in-cell (PIC) simulations of two-dimensional axisymmetric BGK modes that are stable in a collisionless, magnetically-dominated plasma (β ≤ 2×10-6), as well as evidence that similar plasma configurations exist at higher β. These configurations, which manifest primarily as electron density holes, exhibit similar behavior when extended to three dimensions. The PIC code used for these simulations was the Plasma Simulation Code (PSC), a fully electromagnetic code.
Check out the rest of this season's Space Science Seminar Series, as well as previous recordings.
