Experimental studies of spheromak formation

Abstract

Studies in the PS-1 spheromak configuration can be effectively formed by a combined z- and θ-pinch technique on both a fast (τformation≂τAlfvén) and a much slower timescale. The gross tilt and shift instability of the toroid can be suppressed by a combination of conduction walls, shaping the separatrix by externally applied fields, and the use of ‘‘figure-eight’’ coils. Optimum stabilty is obtained for almost spherical toroids. Maximum field-reversal times for stable, well-confined toroids are ≥40 /μsec, consistent with resistive decay. Temperatures during the stable decay are 5–10 eV; impurity radiation is an important energy-loss mechanism.