A review of the denseZ-pinch

Abstract

The Z-pinch, perhaps the oldest subject in plasma physics, has achieved a remarkable renaissance in recent years, following a few decades of neglect due to its basically unstable MHD character. Using wire arrays, a significant transition at high wire number led to a great improvement in both compression and uniformity of the Z-pinch. Resulting from this the Z-accelerator at Sandia at 20 MA in 100 ns has produced a powerful, short pulse, soft x-ray source >230 TW for 4.5 ns) at a high efficiency of ∼15%. This has applications to inertial confinement fusion. Several hohlraum designs have been tested. The vacuum hohlraum has demonstrated the control of symmetry of irradiation on a capsule, while the dynamic hohlraum at a higher radiation temperature of 230 eV has compressed a capsule from 2 mm to 0.8 mm diameter with a neutron yield >3 × 10 11 thermal DD neutrons, a record for any capsule implosion. World record ion temperatures of >200 keV have recently been measured in a stainless-steel plasma designed for Kα emission at stagnation, due, it was predicted, to ion-viscous heating associated with the dissipation of fast-growing short wavelength nonlinear MHD instabilities. Direct fusion experiments using deuterium gas-puffs have yielded 3.9×10 13 neutrons with only 5% asymmetry, suggesting for the first time a mainly thermal source. The physics of wire-array implosions is a dominant theme. It is concerned with the transformation of wires to liquid-vapour expanding cores; then the generation of a surrounding plasma corona which carries most of the current, with inward flowing low magnetic Reynolds number jets correlated with axial instabilities on each wire; later an almost constant velocity, snowplough-like implosion occurs during which gaps appear in the cores, leading to stagnation on the axis, and the production of the main soft-x-ray pulse. These studies have been pursued also with smaller facilities in other laboratories around the world. At Imperial College, conical and radial wire arrays have led to highly collimated tungsten plasma jets with a Mach number of >20, allowing laboratory astrophysics experiments to be undertaken. These highlights will be underpinned in this review with the basic physics of Z-pinches including stability, kinetic effects, and finally its applications.

Shock-less interactions of ablation streams in tungsten wire array z-pinches

“…5 An up-to-date review of the physics of these sources was recently published by Haines. 6 The underlying dynamics of z-pinch implosions have been studied experimentally over a wide range of drive parameters. In general, their evolution can be divided into a sequence of four reasonably distinct phases; initiation, ablation, implosion, and stagnation.…”

Spaced resolved analysis of suprathermal electrons in dense plasma

“…An X-pinch principle is similar to those of the well known Z-pinch where plasma pressure is balanced by magnetic field pressure that is driven by a high current [6][7][8][9]. The X-pinch geometry is realized by crossing 2 or more wires - Fig.…”

Characterization of the COBRA triple-nozzle gas-puff valve using planar laser induced fluorescence

“…Improved performance of the gas-puff z-pinch (see, for example, review [1]) as an intense source of kilovolt Xray radiation, or as a driver for high energy density plasma experiments, depends on gaining a comprehensive understanding of the fluid instabilities that develop during the 'run-in' time between current initiation and maximum compression. Recent experiments [2] have confirmed the predictions of Velikovich [3] and others that these instabilities can be mitigated to some degree by multi-nozzle puff-valves.…”