A Preshaping Transition Coil for a Small Minimum-B Magnetic Mirror

An additional coil between the plasma source and the mirror cell prefans incoming plasma to map it directly into the well-known twisted bow-tie shape and thus avoids reshaping drifts generated in conventional min-B mirror machines. This reduces vacuum chamber size requirements and eliminates any drift reshaping delay. Wound in series with the standard quadrupole loffe bar set, this dual-coil system features end connections which contribute no field on axis.