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Mini-magnetospheres are ion-scale structures that are ideal for studying the kinetic-scale physics of collisionless space plasmas. Such ion-scale magnetospheres can be found on local regions of the Moon, associated with the interaction of the solar wind with the lunar crustal magnetic field. In this work, we report on the experimental study of magnetic reconnection in laser-driven lunar-like ion-scale magnetospheres on the Large Plasma Device (LAPD) at UCLA. In our experiment, we use a high-repetition rate (1 Hz), nanosecond laser to drive a fast moving plasma that expands into the field generated by a pulsed magnetic dipole embedded into a background plasma and magnetic field [1]. The dipole and background fields are oriented to be anti-parallel, allowing a magnetic reconnection geometry. The high-repetition rate enables the acquisition of time-resolved volumetric data of the magnetic and electric fields to characterize magnetic reconnection and calculate the reconnection rate. We notably observe the formation of Hall fields associated with reconnection. Particle-in-cell simulations reproducing the experimental results were performed to study the micro-physics of the interaction. We carry out a generalized Ohm's law terms analysis and find that the electron-only reconnection is mostly driven by kinetic effects, through the electron pressure anisotropy [2].
[1] D. B. Schaeffer et al. Physics of Plasmas 29, 042901 (2022)
[2] L. Rovige et al. arXiv:2402.05043 (2024)
