Steady state beam driven field-reversed mirror

A method is presented for sustaining a current in a beam driven field reversed mirror. It has been shown that attempts to drive steady state field reversed configurations (or Tokamaks, Spheromaks) with neutral beams may be foiled by electron currents. The plasma electrons are accelerated by collisional interaction with the beam-produced ion current, causing the net current to vanish asymptotically in time. We show that the current cancellation can be avoided by weakly breaking the toroidal symmetry of the device, for instance by the addition of quadrupole magnetic fields. The symmetry breaking allows angular momentum transfer between the electrons and the external coil structures, without having plasma in contact with material surfaces