Reproducible High Density Field-Reversed Configuration Plasma for Magnetized Target Fusion

Abstract

Summary form only given. Field-reversed configuration (FRC) plasma will be translated into an imploding metal liner in a magnetized target fusion (MTF) scenario. Field-reversed theta pinch technology is employed with programmed cusp fields at the theta coil ends to achieve non-tearing field line reconnection during FRC formation. In the field reversed configuration experiment with a liner (FRX-L), an optimum formation procedure is identified. The well-formed FRC plasma has volume-averaged density of 2-4times1022 m-3, T e+Ti of 300-500 eV, and plasma lifetime between 15-20 mus. These parameters are very close to the desired parameters of a target plasma for MTF, and they can be reproduced with standard deviation of less than 10% about the mean in consecutive discharges. The FRCs have reasonably good initial flux and particle trapping efficiencies compared with previous lower density experiments. The confinement properties are approximately in agreement with empirical scaling laws obtained from previous experiments with fill pressure mostly less than 20 mtorr. However, due to severe main field modulation, the confinement properties deteriorate quickly when the FRC expands to reach the theta coil ends. Recently, the redesigned crowbar switches have reduced the external main field modulation from 52% previously to 21% now. Better FRC performance is expected in on-going experimental campaigns