Maintaining the closed magnetic-field-line topology of a field-reversed configuration with the addition of static transverse magnetic fields

The effects on magnetic-field-line structure of adding various static trans verse magnetic fields to a Solov'ev-equilibrium field-reversed configuratio n are examined. It is shown that adding fields that are antisymmetric about the axial midplane maintains the closed field-line structure, while adding fields with planar or helical symmetry opens the field structure. Antisymm etric modes also introduce pronounced shear. (C) 2000 American Institute of Physics. [S1070-664X(00)03705-8].