Effect of a Toroidal Field on Plasma Transport in a Magnetically Perturbed Multipole

Field errors have been observed to cause anomalous loss to an internal hoop and produce convection patterns which have potentials $\sim \frac{k{T}_e}{e}$. A simple model of plasma flowing along field lines accounts semiquantitatively for the observed anomalous loss and the production of convection patterns. The addition of a small (5%) toroidal field reduces the anomalous loss by a factor of 60 to the level given by classical ion-neutral diffusion across the field.