Stability analysis and numerical simulation of a hard-core diffusezpinch during compression with Atlas facility liner parameters

Abstract

In the ‘metal liner’ approach to magnetized target fusion (MTF), a preheated magnetized plasma target is compressed to thermonuclear temperature and high density by externally driving the implosion of a flux conserving metal enclosure, or liner, which contains the plasma target. As in inertial confinement fusion, the principal fusion fuel heating mechanism is pdV work by the imploding enclosure, called a pusher in ICF. One possible MTF target, the hard-core diffuse z pinch, has been studied in MAGO experiments at VNIIEF and is one possible target being considered for experiments on the Atlas pulsed power facility. Numerical MHD simulations show two intriguing and helpful features of the diffuse z pinch with respect to compressional heating. First, in two-dimensional simulations the m = 0 interchange modes, arising from an unstable pressure profile, result in turbulent motions and self-organization into a stable pressure profile. The turbulence also gives rise to convective thermal transport, but the level of turbulence saturates at a finite level, and simulations show substantial heating during liner compression despite the turbulence. The second helpful feature is that pressure profile evolution during compression tends towards improved stability rather than instability when analysed according to the Kadomtsev criteria. A liner experiment is planned for Atlas to study compression of magnetic flux without plasma, as a first step. The Atlas geometry is compatible with a diffuse z pinch, and simulations of possible future experiments show that kiloelectronvolt temperatures and useful neutron production for diagnostic purposes should be possible if a suitable plasma injector is added to the Atlas facility.

Burn phase calculations and one-dimensional optimization studies for an inversez-pinch magnetized target fusion system

“…The return path for this current is a cylindrical shell located outside the liner. One possible electric connection is illustrated in [5]. A detailed discussion of inverse z-pinches and the dynamics of their creation can be obtained from [22].…”

“…A variety of MTF configurations being studied around the world, and their relative merits, are summarized in [3]. Computational studies of various MTF configurations have been reported in [1,[3][4][5]. A brief summary of such work is given in [6], and is omitted here for the sake of brevity.…”

Stability of Plasma Configurations During Compression

“…If the compression occurs slowly enough that the plasma approximates an equilibrium at all times, this satisfies [11] …”

“…This example was chosen to match the parameters of a published MHD simulation intended to represent this case. [11] …”

Magnetized Target Fusion With Centimeter-Size Liners

“…An interesting MTF-related experiment has been proposed at University of Nevada (Reno) [17,18], where a high-beta plasma would be produced in the inversepinch geometry.…”