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E. B. Hooper, R. H. Bulmer, B. I. Cohen,
D. N. Hill, L. D. Pearlstein, K. I. Thomassen,
R. D. Wood
Lawrence Livermore National Laboratory Livermore, CA 94551 USA
General Atomics San Diego CA 92121 USA
* Present address: Department of Physics, University of Wisconsin
Madison, WI 53706, USA
University of Washington Seattle, WA 98195 USA
University of California at Davis Davis, CA 95616 USA
Abstract. The Sustained Spheromak Physics Experiment, SSPX, will study
spheromak physics with particular attention to energy confinement and magnetic
fluctuations in a spheromak sustained by electrostatic helicity injection. In
order to operate in a low collisionality mode, requiring Te > 100 eV,
vacuum techniques developed for tokamaks will be applied, and a divertor will
be used for the first time in a spheromak. The discharge will operate for
pulse lengths of several milliseconds, long compared to the time to establish
a steady-state equilibrium but short compared to the L/R time of the flux
conserver. The spheromak and helicity injector (``gun'') are closely coupled,
as shown by an ideal MHD model with force-free injector and edge plasmas. The
current from the gun passes along the symmetry axis of the spheromak, and the
resulting toroidal magnetic field causes the safety factor, q, to
diverge on the separatrix. The q-profile depends on the ratio of the
injector current to spheromak current and on the magnetic flux coupling the
injector to the spheromak. New diagnostics include magnetic field measurements
by a reflectometer operating in combined O- and X-modes and by a transient
internal probe (TIP).
IAEA 2001
