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We present a detailed characterization of the structure and evolution of differentially rotating plasmas driven on the MAGPIE pulsed-power generator (1.4 MA peak current, 240 ns rise-time). The experiments were designed to simulate physics relevant to accretion discs and jets on laboratory scales. A cylindrical aluminium wire array Z pinch enclosed by return posts with an overall azimuthal off-set angle was driven to produce ablation plasma flows that propagate inwards in a slightly off-radial trajectory, injecting mass, angular momentum, and confining ram pressure to a rotating plasma column on the axis. However, the plasma is free to expand axially, forming a collimated, differentially rotating axial jet that propagates at $\approx 100$ km/s. The density profile of the jet corresponds to a dense shell surrounding a low-density core, which is consistent with the centrifugal barrier effect being sustained along the jet's propagation. We show analytically that, as the rotating plasma accretes mass, conservation of mass and momentum implies plasma radial growth scaling as $r \propto t^{1/3}$. As the characteristic moment of inertia increases, the rotation velocity is predicted to decrease and settle on a characteristic value $\approx 20$ km/s. We find that both predictions are in agreement with Thomson scattering and optical self-emission imaging measurements., Comment: Final Production Files accepted by the Journal of Plasma Physics on 18th May 2024. 9 figures

Recent pulsed-power experiments have demonstrated the formation of astrophysically-relevant, differentially rotating plasmas [1]. Key features of the plasma flows are the discovery of a quasi-Keplerian rotation curve, the launching of highly-collimated angular-momentum-transporting axial jets, and a hollow density structure sustained by the centrifugal barrier effect. In this communication we discuss several features of the plasma structure in these experiments through order-of-magnitude models. First, we show that the observed rotation velocity would produce a centrifugal force strong enough to support the hollow density profile. Second, we show that the axial jet should diverge much faster than what was observed, were it not for a magnetized halo with 3T which surrounds the jet and exerts pressure on the interface.Finally, we discuss the temperature structure in the axial jet and plasma halo.We show that a 3T magnetic field would also suppress electron heat conduction,leading to the flat profile observed experimentally. We also find that the axial jet is efficiently radiatively cooled,whereas the halo is not, which would explain the thermal decoupling between the two regions., Comment: Second version with clarifications on text and figures, and explicit calculations regarding the omega-effect. Manuscript re-submitted to IEEE Transactions On Plasma Science. 4 Figures

We present results from pulsed-power driven differentially rotating plasma experiments designed to simulate physics relevant to astrophysical disks and jets. In these experiments, angular momentum is injected by the ram pressure of the ablation flows from a wire array Z pinch. In contrast to previous liquid metal and plasma experiments, rotation is not driven by boundary forces. Axial pressure gradients launch a rotating plasma jet upwards, which is confined by a combination of ram, thermal, and magnetic pressure of a surrounding plasma halo. The jet has subsonic rotation, with a maximum rotation velocity $23 \pm 3$ km/s. The rotational velocity profile is quasi-Keplerian with a positive Rayleigh discriminant $\kappa^2 \propto r^{-2.8\pm0.8}$ rad$^2$/s$^2$. The plasma completes $0.5 - 2$ full rotations in the experimental time frame ($\sim 150$ ns)., Comment: 4 figures

The cross-magnetic-field (i.e., perpendicular) profile of ion temperature and the perpendicular profile of the magnetic-field-aligned (parallel) plasma flow are sometimes inhomogeneous for space and laboratory plasma. Instability caused by a gradient in either the ion-temperature profile or by shear in the parallel flow has been discussed extensively in the literature. In this paper, hydrodynamic plasma stability is investigated, real and imaginary frequency are quantified over a range of the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths, and the role of inverse Landau damping is illustrated for the case of combined ion-temperature gradient and parallel-flow shear. We find that increasing the ion-temperature gradient reduces the instability threshold for the hydrodynamic parallel-flow shear instability, also known as the parallel Kelvin-Helmholtz instability or the D'Angelo instability. We also find that a kinetic instability arises from the coupled, reinforcing action of both free-energy sources. For the case of comparable electron and ion temperature, we illustrate analytically the transition of the D'Angelo instability to the kinetic instability as the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths are varied and we attribute the changes in stability to changes in the amount of inverse ion Landau damping. We show that, near a normalized wavenumber $k_{\perp} \rho_{i}$ of order unity, the real and imaginary values of frequency become comparable and the growth rate maximizes., Comment: 9 pages, 6 figures

The linear non-modal kinetic theory of the kinetic drift-Alfven instability of plasma shear flows reveals the temporal non-modal growth with growing with time growth rate. The turbulent scattering of the sheared modes on ions accelerates this growth. The instability ceases its growth when the coupling of the drift and Alfven waves violates due to the changing with time frequencies of the drift and Alfven waves in shear flow., Comment: 18 pages. arXiv admin note: text overlap with arXiv:1208.6183

If a magnetized-orbit-charged grain encounters any abrupt inhomogeneity in plasma conditions during a gyro-orbit, such that the resulting in-situ equilibrium charge is significantly different between these regions (q(sub1)/q(sub 2) approximately 2, where q(sub 1) is the in-situ equilibrium charge on one side of the inhomogeneity, q(sub 2) is the in-situ equilibrium charge on the other side, and q(sub1) less than q(sub 2) less than 0), then the capacitive effects of charging and discharging of the dust grain can result in a modification to the orbit-averaged grain trajectory, i.e. gyro-phase drift. The special case of q(sub 1)/q(sub 2) is notioned for the purpose of illustrating the utility of the method. An analytical expression is derived for the grain velocity, assuming a capacitor approximation to the OML charging model. For cases in which a strong electric field suddenly appears in the wake or at the space-plasma-to-crater interface from solar wind and/or ultraviolet illumination and in which a magnetic field permeates an asteroid, comet, or moon, this model could contribute to the interpretation of the distribution of fields and particles.