Seminars
Lecturer: Mark E Dieckmann
Date: 2024-11-14 10:00
Place: Aniara
Boundary oscillations of subcritical fast magnetosonic shocks in collisionless plasmaMark Eric Dieckmann, Docent,
Media and Information Technology (MIT),
Department of Science and Technology, Linköping University
We compare the evolution of a deformed subcritical fast magnetosonic shock front in two two-dimensional PIC simulations with different orientations of the magnetic field relative to the simulation box. All other initial and simulation conditions are identical. Shock boundary oscillations are observed in the simulation where the magnetic field direction is resolved. These oscillations result from the reformation of the shock front, where one part of the front behaves as a shock while the other acts as a magnetic piston. These two sections alternate their states in antiphase. The oscillation period corresponds to the time required for the new shock wave to form while the other collapses. In the second simulation, where the magnetic field points out of the simulation plane, the corrugated fast magnetosonic shock does not oscillate. This indicates that the shock oscillations are driven by magnetic tension, which is only effective in the first simulation. In both simulations, the shock perturbations do not grow over time, suggesting that the shocks are stable. We discuss the potential relevance of these findings for the Alfvénic oscillations observed in the Earth's supercritical bow shock, as detected by the MMS multi-spacecraft mission.
The seminar is also online. See emails for connection details.
Created 2024-10-01 09:00:54 by Mats HolmströmLast changed 2024-10-08 13:26:22 by Mats Holmström
