Particle-in-cell simulations of laser-driven, ion-scale magnetospheres in laboratory plasmas

Ion-scale "mini" magnetospheres provide a unique environment for studying kinetic-scale plasma physics, and have been observed around comets, weakly-magnetized asteroids, and localized regions of the moon. In this work, we present collisionless particle-in-cell (PIC) simulations of ion-scale magnetospheres that reproduce recent laboratory experiments performed on the Large Plasma Device (LAPD) at UCLA. In the PIC simulations, a super-Alfvènic plasma flow is driven into a dipole magnetic field that is embedded in a uniform background magnetic field. The simulations show how the magnetosphere structures evolves, the location of the magnetopause, and kinetic-scale structures of the plasma current distribution. Different dipole and upstream plasma parameters are exploited to interpret their effect on these systems. The coupling between the driver and background plasmas is characterized using both simulations and semi-analytical models.