Study of the Synchronous Operation of an Annular Field Reversed Configuration Plasma Device.

Abstract

Field Reversed Configuration (FRC) plasmas are high-density, magnetized, pulsed plasmas with unique translational and effcient formation properties that lend themselves to many uses. This dissertation furthers the understanding and empirical investigations into a slow-formation FRC, the low-voltage Annular Field Reversed Configuration plasma (AFRC) by successfully operating with heavy gases, at low-voltages, and in a synchronous discharge configuration. The AFRC plasma is an evolution of the cylindrical shock compression driven FRC that aims to increase compression times well into diffusive timescales, thereby increasing overall plasma content, lifetime, and greatly simplifying pulsed switching and transmission hardware. AFRC plasmas have uses ranging from primary pulsed magnetic fusion, refueling for Tokamak plasmas, and advanced space propulsion. In this thesis it is shown that AFRCs operating in a synchronous discharge configuration generate effcient, high-density magnetized toroidal plasmas with clear transitional regimes and optimal discharge parameters. A 10-kJ pulsed power facility and discharge network was constructed to explore AFRC plasmas. An extensive array of pulsed diagnostics were developed to explore the operational characteristics of a 40-cm outer diameter annular theta pinch and its pre-ionization, compression, field reversal, and translation configurations. Twelve high-speed, 3-axis B-dot probes were used to show plasma magnetization and compression for various discharge geometries. A fast DICAM and wide-angle photometer examined overall plasma content, compression regimes, downstream translation, and plasma instabilities for argon and xenon discharges ranging from 3-20 mTorr, 500-1000 V, and 185-450 microsecond discharge periods. Downstream B-dot probes and collimated, amplified photometers examined downstream plasma translation and magnetization. An axially-scanning internal triple probe was utilized to measure temporal plasma temperature, density, and geometry evolution for the complete set of discharge conditions and geometries. Optimized pre-ionization conditions, neutral gas densities, and plasma transition energies were determined for the 40 cm annulus in both argon and xenon. Peak argon and xenon densities and temperatures were found to be 5E19 m-3, 11 eV and 2E20 m-3, 8 eV , respectively, for 250-J plasma discharges. Finally, a zero-dimensional energy analysis has been developed and compared to collected internal plasma data.