This paper describes ZEUS-MP, a multiphysics, massively parallel, message-passing implementation of the ZEUS code. ZEUS-MP differs significantly from thoroughly documented ZEUS-2D code, completely undocumented (in peer-reviewed literature) ZEUS-3D and marginally "version 1" first distributed publicly in 1999. offers an MHD algorithm that is better suited for multidimensional flows than module by virtue modifications to method characteristics scheme suggested Hawley & Stone. shown compare...

Abstract We report the first measurements of formation and structure a magnetized collisionless shock by laser‐driven magnetic piston in current‐free laboratory plasma. This new class experiments combines high‐energy laser system large plasma to transfer energy from plume ambient ions through coupling, until self‐sustained M A ∼ 2 magnetosonic separates piston. The is highly magnetized, current free, enough (17 m × 0.6 m) support Alfvén waves. Magnetic field evolution are consistent with...

The dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma was investigated with magnetic flux probes and Langmuir probes. Debris-ions expanding at super-Alfvénic velocity (up to MA=1.5) expel the field, creating (>20 cm) diamagnetic cavity. We observe field compression up B/B0=1.5 as well localized electron heating edge bubble. Two-dimensional hybrid simulations reproduce these measurements show that majority ions are energized by piston swept outside bubble...

Experiments, analytic modeling, and numerical simulations are presented to characterize carbon plasmas produced by high-intensity (109−1013 W cm−2) lasers relevant experimental laboratory astrophysics. In the large-scale limit, results agree well with a self-similar isentropic, adiabatic fluid model. Laser-target simulations, however, show small-scale structure in velocity distribution of different ion species, which is also seen experiments. These distributions indicate that most plasma...

Two-dimensional hybrid simulations of perpendicular collisionless shocks are modeled after potential laboratory conditions that attainable in the LArge Plasma Device (LAPD) at University California, Los Angeles Basic Science Facility. The kJ class 1053 nm Nd:Glass Raptor laser will be used to ablate carbon targets LAPD with on-target energies 100-500 J. ablated debris ions expand into ambient, partially ionized hydrogen or helium. A parameter study is performed via simulation determine...

Collisionless shocks are common phenomena in space and astrophysical systems, many cases, the can be modeled as result of expansion a magnetic piston though magnetized ambient plasma. Only recently, however, have laser facilities diagnostic capabilities evolved sufficiently to allow detailed study laboratory microphysics piston-driven shocks. We review experiments on collisionless driven by laser-produced undertaken with Phoenix Large Plasma Device at University California, Los Angeles. The...

The interaction of a laser-driven super-Alfvénic magnetic piston with large, preformed magnetized ambient plasma has been studied by utilizing unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to Large Plasma Device [Gekelman Rev. Sci. 62, 2875 (1991)] at University California, Los Angeles. This provides conditions relevance space and astrophysical collisionless shocks and, in particular, allows detailed study...

Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies shock formation relevant to space shocks. The characteristics these shocks are compared with data in which no or a pre-shock formed. results consistent theory and 2D hybrid simulations indicate that observed shock-like structures can be organized into distinct regimes by coupling strength. With additional on early time...

Topanga is a kinetic ion code developed for simulating large-scale plasma phenomena in the Earth's ionosphere on magnetohydrodynamic timescales. It domain-decomposed parallel that runs high-performance computing platforms. Features of include spherical geometry simplified boundary conditions and computational efficiency; hybrid model with inertia-less fluid electrons, ions, an electric field specified via Ohm's law; Maxwell-FDTD (finite difference time domain) which retains displacement...

The explosive expansion of a localized plasma cloud into relatively tenuous, magnetized, ambient characterizes variety astrophysical and space phenomena. In these rarified environments, collisionless electromagnetic processes rather than Coulomb collisions typically mediate the transfer momentum energy from expanding “debris” to surrounding plasma. an effort better understand detailed physics coupling mechanisms, compliment in situ measurements phenomena, provide validation previous...

Two-dimensional hybrid simulations of super-Alfv\'enic expanding debris plasma interacting with an inhomogeneous ambient are presented. The demonstrate improved collisionless coupling energy to the ions when encountering a density gradient. Simulations cylinder running into step function gradient performed and compared simple analytical theory. Magnetic flux probe data from laboratory shock experiment simulation more realistic expansion ion density. confirms that is formed propagates within...

Emission decay curves and time-resolved emission spectra have been measured as a function of temperature for 10 to 50 K in crystals the one-dimensional salt BaPt(CN)4·4H2O, both undoped with 1 : 650 65 doping by Ni(CN)2–4. The lowest-frequency (18 400 cm–1 at K) are least-squares fitted obtain variation longest-lifetime component temperature. ratio intensities 18 20 100 bands short (50 ns) varies level. results interpreted three-level model, including radiationless passage from lowest...

Planar laser induced fluorescence (PLIF) imaging can potentially assess ion distributions and coupling in the context of super-Alfvénic ablation plasma expansions into magnetized background plasmas. In this feasibility study, we consider application PLIF to rapidly expanding carbon plasmas generated via energetic graphite. By utilizing hydrodynamic collisional-radiative simulations, identify schemes accessible commercially available tunable lasers for C I atom, II ion, V ion. We then...

The collision-less transfer of momentum and energy from explosive debris plasma to magnetized background is a salient feature various astrophysical space environments. While much theoretical computational work has investigated coupling mechanisms relevant parameters, an experimental validation the results demands measurement complex, collective electric fields associated with debris-background interaction. Emission spectroscopy offers non-interfering diagnostic via Stark effect. A unique...

The dynamics of an argon plasma in the gap a thermionic diode is investigated using particle-in-cell (PIC) simulations. time-averaged current, as function relative electrical potential between electrodes, studied while density depletes due to recombination on electrode surfaces. Simulations were performed both one and two dimensions, significant differences observed decay cases. Specifically, dimensions it was found that electrostatic gradually changes decays, dimension fluctuations led...

Paramagnetic Faraday rotator glass (rare-earth doped borosilicate) with a high Verdet constant will be used to measure the magnetic field inside of low density Helium plasmas (Te ∼ 5 eV, Ti 1 eV) n 1012 cm−3. Linearly polarized light is sent through such that plane polarization rotated by an angle depends on strength in direction propagation and length crystal (6 mm). The then passed into analyzer photo-detector setup determine change angle. This can detect fields up kG resolution <5...

The effect of various electron pressure models on the debris-ambient coupling in a magnetized collisionless shock is demonstrated with 2-D hybrid code. simulation specifically regime laboratory shocks launched by laser ablation into ambient plasma. A two-electron-fluid model employed different polytropic coefficients to vary temperature and gradients investigate their effects dynamics, electric field, between debris ions. simulations show significant variation radial field ion dynamics index.

We used photolithography to fabricate nanoscale grids in proximity a metal electrode. Such can be mitigate the space charges inter-electrode region of thermionic converter. The dimensions together with low fill factor grid led electron absorption, which was measured experimentally. further demonstrated charge mitigation using such grid-anode device under Ba dispenser cathode.

Summary form only given. The Raptor kJ class 1053 nm Nd:Glass laser in the Phoenix laboratory at UCLA is used to ablate a dense debris plasma from carbon or plastic target, which embedded relatively tenuous, uniform, and quiescent ambient magnetized Large Plasma Device (LAPD). LAPD provides peak density of n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ~ 10 <sup xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm...

The effect of various electron pressure models on the debris-ambient coupling in a magnetized collisionless shock is demonstrated with two-dimensional hybrid code. simulation specifically regime laboratory shocks launched by laser-ablation into ambient plasma. A two-electron-fluid model employed different polytropic coefficients to vary temperature and gradients investigate their dynamics, electric field, between debris ions. simulations show significant variation radial field ion dynamics index.