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Magnetic reconnection changes the topology of magnetic field lines to a lower-energy state. This process can liberate stored magnetic field energy and accelerate particles during unsteady, explosive events. This is one of the most important processes in astrophysical, space and laboratory plasmas. The abrupt onset and cessation has been a long-standing puzzle. We show the first three-dimensional (3D) laboratory example of the onset and stagnation of magnetic reconnection between magnetized and parallel current channels (flux ropes) driven by magnetohydrodynamic (MHD) attraction and a 3D plasma-current-driven instability. Antiparallel magnetic field lines carried by these colliding flux ropes annihilate and drive an electric field. The inflow soon exceeds a threshold for the formation of a reconnection current layer. Magnetic flux and pressure pile up just outside this layer, and eventually become large enough to support MHD back-reaction forces that stall the inflow and stagnate the reconnection process. Magnetic reconnection—the process by which magnetic field-lines break and reform in a plasma—is believed to be an important part of many astrophysical phenomena, but is poorly understood. The recreation of 3D reconnection events in a laboratory plasma provides a powerful means of studying the parameters that govern the onset, evolution and decay of this process.

In this community white paper, we describe an approach to achieving fusion which employs a hybrid of elements from the traditional magnetic and inertial fusion concepts, called magneto-inertial fusion (MIF). The status of MIF research in North America at multiple institutions is summarized including recent progress, research opportunities, and future plans.

In this article, we discuss the idea of a hierarchy of instabilities that can rapidly couple the disparate scales of a turbulent plasma system. First, at the largest scale of the system, L , current carrying flux ropes can undergo a kink instability. Second, a kink instability in adjacent flux ropes can rapidly bring together bundles of magnetic flux and drive reconnection, introducing a new scale of the current sheet width, ℓ , perhaps several ion inertial lengths ( δ i ) across. Finally, intense current sheets driven by reconnection electric fields can destabilize kinetic waves such as ion cyclotron waves as long as the drift speed of the electrons is large compared to the ion thermal speed, v D ≫ v i . Instabilities such as these can couple MHD scales to kinetic scales, as small as the proton Larmor radius, ρ i .

After considerable design and construction, we describe the status of a physics exploration of magnetized target fusion (MTF) that will be carried out with the first flux conserving compression of a high pressure field-reversed configuration (FRC). The upgraded Los Alamos (LANL) high density FRC experiment FRXL has demonstrated that an appropriate FRC plasma target can be created and translated on a time scale fast enough to be useful for MTF. Compression to kilovolt temperature is expected to form a Mbar pressure, high energy density laboratory plasma (HEDLP). Integrated hardware on the new Field Reversed Compression and Heating Experiment (FRCHX) at the Air Force Research Laboratory Shiva Star facility, has formed initial FRC’s and will radially compress them within a cylindrically symmetric aluminum “liner”. FRXL has shown that time scales for FRC translation to the target region are significantly shorter than the typical FRC lifetime. The hardware, diagnostics, and design rationales are presented. Pre-compression plasma formation and trapping experimental data from FRXL and FRCHX are shown.

We describe a physics scaling model used to design the high density field reversed configuration (FRC) at LANL that will translate into a mirror bounded compression region, and undergo Magnetized Target Fusion compression to a high energy density plasma. At Kirtland AFRL the FRC will be compressed inside a flux conserving cylindrical shell. The theta pinch formed FRC will be expelled from inside a conical theta coil. Even though the ideal FRC has zero helicity and toroidal magnetic field, significant non-ideal properties follow from formation within a conical (not cylindrical) theta coil. The FRC stability and lifetime properties may improve. Several experimental features will also allow unique scientific investigations of this high Lundquist number but collisional plasma.

Two codes have been developed to model solid metal or wire-wound conductors. The calculations are based on the decomposition of the conductors into arrays of thin wires. The first code, EDDY, models cylindrically symmetric conductors with currents in the theta direction. This code accurately models eddy current induction and magnetic diffusion. It was created in order to aid the design of magnetic-field shields in the FRX-L experiment for Magnetized Target Fusion (MTF). EDDY uses fast, accurate elliptic integral subroutines from MATLAB to solve for the time-dependent current flowing through each wire loop and the resultant magnetic field configuration. The second code, INDIV, models arbitrarily shaped conductors with current flow in the z direction. It was designed to model current division in an inductive divider that would inject current into a liner cavity, for magnetic flux and magnetized-plasma compression experiments. An experiment has been performed to test the INDIV code and the inductive division concept. The numerical results compare well with those of the experiment.

Stochastic transport of a two-dimensional (2D) dusty plasma liquid with a perpendicular magnetic field is studied. Superdiffusion, which is a type of non-Fickian transport, is found to occur especially at higher magnetic fields with \\(\\beta\\) of order unity. Here, \\(\\beta = \\omega_c / \\omega_{pd}\\) is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement \\({\\rm {MSD}} = 4 D_\\alpha t^\\alpha\\) is found to have an exponent \\(\\alpha > 1\\), indicating superdiffusion, with \\(\\alpha\\) increasing monotonically to \\(1.1\\) as \\(\\beta\\) increases to unity. The 2D Langevin molecular dynamics simulation used here also reveals that another indicator of random particle motion, the velocity autocorrelation function (VACF), has a dominant peak frequency \\(\\omega_{peak}\\) that empirically obeys \\(\\omega_{peak}^2 = \\omega_c^2+ \\omega_{pd}^2/4\\).

First experimental measurements are presented for the kink instability in a linear plasma column which is insulated from an axial boundary by finite sheath resistivity. Instability threshold below the classical Kruskal-Shafranov threshold, axially asymmetric mode structure and rotation are observed. These are accurately reproduced by a recent kink theory, which includes axial plasma flow and one end of the plasma column that is free to move due to a non-line-tied boundary condition.

Many nursing homes operated at thin profit margins prior to the COVID-19 pandemic. This study examines the role of nursing homes’ financial performance and chain affiliation in shortages of personal protection equipment (PPE) during the first year of the COVID-19 pandemic. We constructed a longitudinal file of 79 868 nursing home-week observations from 10 872 unique facilities. We found that a positive profit margin was associated with a 21.0% lower probability of reporting PPE shortages in chain-affiliated nursing homes, but not in non-chain nursing homes. Having adequate financial resources may help nursing homes address future emergencies, especially those affiliated with a multi-facility chain.