Coupled spheromak-helicity injector in the sustained spheromak physics experiment, SSPX

The Sustained Spheromak Physics Experiment, now under construction at LLNL, will be sustained by helicity injected from a coaxial plasma source. The ideal MHD equilibrium of the coupled spheromak and source plasmas is calculated in this report, with the plasma in the injector treated in the force free approximation. The two regions are linked by a current-carrying edge plasma region, with field lines which end on the injector electrodes and a width determined by the ratio of the poloidal flux applied to the injector by external coils and that generated in the spheromak. The safety factor, q, on the magnetic axis and its profile within the spheromak separatrix are determined primarily by the ratio of the external and internal values of {lambda} =j{sub {vert_bar}{vert_bar}}/B and by the internal profile of {lambda}. The q-profile is expected to have significant effect on the operation of the experiment, particularly on the stability of the equilibrium and the associated magnetic dynamo.