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Warm dense matter is present at the heart of gas giants and large exo-planets. Yet, its most basic properties are unknown and limit our understanding of planetary formation and evolution. In this state, where pressure climbs above 1 Mbar, matter is strongly coupled and quantum degenerate. This combination invalidates most theories capable of predicting the equation of state, the viscosity or heat conductivity of the material. When such properties are missing, understanding planetary evolution becomes an arduous endeavor. Henceforth, research in this field is actively growing, using high power laser or heavy ion beams to produce samples dense enough to overcome the 1 Mbar limit. These samples are not actively confined and tend to expand rapidly, precluding the existence of any thermodynamically stable equilibrium. However, a mega-ampere-class pulsed-power generator can produce confined matter in the Mbar range, providing two conditions are being met. First, the sample needs to be compressed cylindrically, to maximize magnetic pressure (compared to slab compression). Second, a damper must be used to preclude the formation of a corona around the sample. This corona robs the main sample from valuable current and limits the homogeneity of the compression. According to numerical simulations, the setup proposed here, and called a magnetic anvil cell, can reach pressure on the order of 1 Mbar using a mega-ampere pulsed power driver. These samples span several millimeters in length. Unlike diamond anvil cell, which pressure is limited below 1 Mbar due to materials strength, the magnetic anvil cell has virtually no pressure limit. Further, the current heats the sample to several eV, a temperature well beyond diamond anvil cell capabilities.

MagLIF is a fairly new fusion concept using a puled-power generator as the main driver. This concept uses a Z-pinch configuration where the implosion is driven by the Z-machine using 27 MA of electrical current in 100 ns. Since the implosion time is long compared to the heat diffusion time of a non-magnetized plasma, MagLIF requires an initial axial magnetic of 30T to reduce heat losses to the liner wall. Since the field needs to penetrate the transmission lines of the pulsed-power generator, as well as the liner itself, the rise time must exceed tens of microseconds. Any coil capable of producing such field on that long a pulse-length is inevitably bulky. The space required to house the coil near the liner increase the inductance of the load, which becomes problematic since the voltage at the load cannot exceed what the driver can already provide. Yet, the enormous amount of current that the Z-machine can provide could be used to produce the required 30 T by tilting the current posts surrounding the liner. However, the field penetration is limited by the skin effect of the liner wall. This paper shows that when current densities are large enough, the material generate resistivity gradients which forces the current to diffusive across the liner wall much fast than the skin time. As a result, the 30T coil can be eliminated and replaced by return current posts with minimal helicity.

Warm dense matter is difficult to generate since it corresponds to a state of matter which pressure is order of magnitude larger than can be handled by natural materials. A diamond anvil can be used to pressurize matter up to one Gbar, this matter is at high density but at room temperature. High power lasers and heavy ion beams can generate warm dense matter but they cannot confine it long enough to allow measurements of quasi-static transport coefficients such as viscosity or heat conduction. We present here a third method to generate warm dense matter. It uses a pulsed-power driver which current rise time is substantially shortened by using a plasma opening switch, limiting the development of electrothermal instabilities. The switch relies on the implosion of a gas puff Z-pinch which carries most of the discharge current until the pinch reaches the sample. After that, the sample is compressed until it reaches the warm dense matter regime. Three-dimensional magnetohydrodynamics computations show that if the density of the gas is low enough no detectable instabilities (e.g. kinks and sausages modes) impede the remainder of the implosion.

Using a 1-MA, 100ns-rise-time pulsed power generator, radial foil configurations can produce strongly collimated plasma jets. The resulting jets have electron densities on the order of 10^20 cm^-3, temperatures above 50 eV and plasma velocities on the order of 100 km/s, giving Reynolds numbers of the order of 10^3, magnetic Reynolds and P\'eclet numbers on the order of 1. While Hall physics does not dominate jet dynamics due to the large particle density and flow inside, it strongly impacts flows in the jet periphery where plasma density is low. As a result, Hall physics affects indirectly the geometrical shape of the jet and its density profile. The comparison between experiments and numerical simulations demonstrates that the Hall term enhances the jet density when the plasma current flows away from the jet compared to the case where the plasma current flows towards it.

A fluid description of lower hybrid, whistler and magnetosonic waves is applied to study wave phenomena near the lower hybrid resonance associated with plasma density depletions. The goal is to understand the nature of lower hybrid cavitons and spikelets often associated with transverse ion acceleration events in the auroral ionosphere. Three-dimensional simulations show the ponderomotive force leads to the formation of a density cavity (caviton) in which lower hybrid wave energy is concentrated (spikelet) resulting in a three-dimensional collapse of the configuration. Plasma density depletions of the order of a few percent are shown to greatly modify the homogeneous linear properties of lower hybrid waves and account for many of the observed features of lower hybrid spikelets.

This paper investigates the properties of a one-dimensional fluid model of plasma convection in the equatorial F region ionosphere. The model equations are similar in form to Burgers equation except for additional higher-order spatial derivatives. Like Burgers equation, solution to the model have the form of propagating, shocklike structures. Numerical simulations of the model closely resemble the steepened structures observed by sounding rocket plasma density probes within equatorial spread F. Simulated denstiy power spectra, like the spectra computed from in situ data, seem to possess power law forms with a break at wavelengths of about 100 m. The precise wavenumber of the spectral break is determined by the ambipolar diffusion coefficient. The model predicts that electric field fluctuations perpendicular to the direction of plasma steepening should be proportional to the plasma density fluctuations. Electric field fluctuations parallel to the steepening will be due primarily to the ambipolar field and have a Boltzmann relationship with density (square of the absolute value of delta E) approximately equal to (K(exp 2))(square of the absolute value of (delta n/n)). At wavelengths less than about 300 m, the ambipolar field should be the dominant component of the total field intensity.

The self-consistent electron kinetics of Alfven waves on the electron inertial scale is studied using a 2D hybrid-kinetic description. The ions follow a fluid description for Alfven waves at frequencies below the ion cyclotron frequency. The parallel electron dynamics is treated kinetically using particle-in-cell techniques. In this model, the electron plasma mode is eliminated, and only the physics of the Alfven waves is retained. At sufficiently large amplitudes, it is found that oblique Alfven waves break due to finite electron inertia in a cold plasma. The consequence of wave breaking is the formation of an electron beam which can be unstable to the beam-plasma instability. The electrons supporting the parallel current thermalize into a non-Maxwellian distribution with an energetic tail up to several keV, assuming a reasonable magnetospheric Alfven speed. In hot plasma simulations, electron trapping is the principal mechanism of electron acceleration. It is proposed that wave breaking or electron trapping of oblique Alfven waves at 1 R(E) can result in electron acceleration and may explain some observed auroral phenomena.

A three dimensional fluid model which includes the dispersive effect of electron inertia is used to study the nonlinear macroscopic plasma dynamics of small scale discrete auroral arcs within the auroral acceleration zone and ionosphere. The motion of the Alfven wave source relative to the magnetospheric and ionospheric plasma forms an oblique Alfven wave which is reflected from the topside ionosphere by the negative density gradient. The superposition of the incident and reflected wave can be described by a steady state analytical solution of the model equations with the appropriate boundary conditions. This two dimensional discrete auroral arc equilibrium provides a simple explanation of auroral acceleration associated with the parallel electric field. Three dimensional fully nonlinear numerical simulations indicate that the equilibrium arc configuration evolves three dimensionally through collisionless tearing and reconnection of the current layer. The interaction of the perturbed flow and the transverse magnetic field produces complex transverse structure that may be the origin of the folds and curls observed to be associated with small scale discrete arcs.

The dynamical properties and spectral characteristics of the ionospheric interchange instability in the collisional and inertial regimes are investigated numerically and analytically, using a two-dimensional fluid model. This model, which describes the collisional and inertial dynamics of the F region ionosphere, is similar to the models of Ott (1978) and Kintner and Seyler (1985). By numerically integrating the model equations, the nonlinear evolution of three interchange unstable configurations in the collisional and inertial regimes are followed, and their dynamical and spectral properties are studied. The solutions indicate that the dynamical properties of a collision-dominated regime are distinctly different from those of an inertia-dominated regime. The qualitative characteristics of a plasma bubble in both regime-types are described.

A two-dimensional model applicable to F region ionosphere plasma instabilities has been developed and described in a companion paper. Here the model is applied to equatorial F region irregularities and is tested against rocket and satellite data. As a diagnostic, simulated data sets are created which are similar to the one-dimensional measurements of plasma density performed by space probes and the Fourier transform of these data is taken in the same manner and used by the space experimentors. Unlike previous simulations of this phenomenon, an inherent anisotropy is found in the instability development which is mirrored in the in situ data. Evidence that the shallow spectral slopes which often characterize spread F rocket spectra near the F peak may be due to a change in the angle between the rocket velocity vector and the characteristic directions in the medium is presented.