Coaxial helicity injection is used to produce low-aspect-ratio tokamak
s with toroidal currents reaching 150 kA (highest value yet attained b
y helicity injection current drive) and sustained over 100 kA for many
resistive diffusion times, without a current drive transformer. Curre
nt drive power efficiency, assuming no anomalous helicity dissipation,
is 40% that of Ohmic. These tokamaks have a rotating n = 1 toroidal d
istortion, with poloidal distortions only on the outer bad-curvature r
egion. Equilibrium reconstruction suggests these plasmas have up to 11
2 kA of closed-field toroidal current, an aspect ratio A = 1.69, a tok
amak q profile, and a hollow toroidal current profile.