Field-reversal experiments in a neutral-beam-injected mirror machine

Data on field-reversal experiments in the neutral-beam-injected 2XIIB mirror machine area reported. The best result is an estimated field-reversal parameter zeta=ΔB/Bsub(vac)=0.9+-0.2 with vacuum field strength Bsub(vac)=4.35kG. Experiments at higher field strength Bsub(vac)=6.7kG achieved zeta=0.6+-0.1. Ion energy confinement average value of ntausub(Ei) for the Bsub(vac)=6.7kG experiment is less than that predicted by classical Spitzer electron drag. Ion-cyclotron oscillations increasing with injected neutral-beam current suggest that ion-cyclotron losses are present and that ΔB/Bsub(vac) could be increased by improving stabilization of the ion-cyclotron oscillations. (author)