Magnetospheres are a ubiquitous feature of magnetized bodies embedded in a plasma flow. While large planetary magnetospheres have been studied for decades by spacecraft, ionscale “mini” magnetospheres can provide a unique environment to study kineticscale, collisionless plasma physics in the laboratory to help validate models of larger systems. In this work, we present preliminary experiments of ionscale magnetospheres performed on a unique highrepetitionrate platform developed for the Large Plasma Device at the University of California, Los Angeles. The experiments utilize a highrepetitionrate laser to drive a fast plasma flow into a pulsed dipole magnetic field embedded in a uniform magnetized background plasma. 2D maps of the magnetic field with high spatial and temporal resolution are measured with magnetic flux probes to examine the evolution of magnetosphere and current density structures for a range of dipole and upstream parameters. The results are further compared to 2D particleincell simulations to identify key observational signatures of the kineticscale structures and dynamics of the laserdriven plasma. We find that distinct 2D kineticscale magnetopause and diamagnetic current structures are formed at higher dipole moments, and their locations are consistent with predictions based on pressure balances and energy conservation.
This content will become publicly available on April 21, 2023
Pressure–Strain Interaction as the Energy Dissipation Estimate in Collisionless Plasma
The dissipative mechanism in weakly collisional plasma is a topic that pervades decades of studies without a
consensus solution. We compare several energy dissipation estimates based on energy transfer processes in plasma
turbulence and provide justification for the pressure–strain interaction as a direct estimate of the energy dissipation
rate. The global and scalebyscale energy balances are examined in 2.5D and 3D kinetic simulations. We show
that the global internal energy increase and the temperature enhancement of each species are directly tracked by the
pressure–strain interaction. The incompressive part of the pressure–strain interaction dominates over its
compressive part in all simulations considered. The scalebyscale energy balance is quantified by scale filtered
Vlasov–Maxwell equations, a kinetic plasma approach, and the lag dependent von Kármán–Howarth equation, an
approach based on fluid models. We find that the energy balance is exactly satisfied across all scales, but the lack of
a welldefined inertial range influences the distribution of the energy budget among different terms in the inertial
range. Therefore, the widespread use of the Yaglom relation in estimating the dissipation rate is questionable in
some cases, especially when the scale separation in the system is not clearly defined. In contrast, the pressure–
strain interaction balances exactly the dissipation rate at kinetic scales regardless of the scale separation
 Award ID(s):
 2108834
 Publication Date:
 NSFPAR ID:
 10329562
 Journal Name:
 The Astrophysical journal
 Volume:
 929
 Page Range or eLocationID:
 142
 ISSN:
 0004637X
 Sponsoring Org:
 National Science Foundation
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