Analytic approximation to resonant plateau transport coefficients for tandem mirrors

Analytic approximations to resonant plateau diffusion coefficients for ions in a tandem mirror solenoid are developed. These are obtained by assuming that the ∇B azimuthal drift is small compared to × contribution, and that the radial drift per bounce is determined by properties of the vacuum magnetic field. The resulting expressions are used to estimate radial transport life-times for the Lawrence Livermore Laboratory Tandem Mirror Experiment (TMX) and for a proposed future experiment, MFTF-B. These estimates indicate radial loss comparable to axial for TMX, but smaller than axial for most operating modes considered for MFTF-B.