Initial results from the Coaxial Slow Source FRC device

Abstract

The Coaxial Slow Source (CSS) is a device in which 'annular' FRCs, i.e. small aspect ratio, highly elongated plasmas with poloidal fields only, are formed in the annular space between concentric coils carrying toroidal currents. The device is constructed so that the plasma can be translated into a simple cylindrical chamber and re-formed as a true FRC. The goal of the investigation is to form FRCs on slow (diffusive) time-scales and at low voltage. Initial operation shows that the desired configurations are formed over a wide range of coil voltages and fill pressures. The radial plasma position can be controlled. Configuration lifetimes are 30-60 μs, with flux lifetimes of 15-20 μs. Flux is built up over 25 μs, at loop voltages of 1-2 kV, in comparison with 2.5 μs and 100 kV for comparably sized field reversed theta pinches conventionally employed for FRC generation.