Wall shape effects on straight doublet equilibria

The effect on magnetohydrodynamic equilibria of conducting wall shape in a straight plasma current multipole, or doublet, is studied by examination of two extreme longitudinal current models. For the first of these models, the current is concentrated in two filaments which are symmetrically located in the cross section of the device. In the second model, the current density is uniform over the cross section. If the neck size is appropriately chosen, the two-filament case is excluded and the proper doublet equilibrium is obtained. For a neck size which allows both models, the poloidal magnetic fields at the wall are compared.