Superbanana plateau regime transport in a multiple-helicity torsatron and a bumpy torus

Abstract

An analytic expression for the neoclassical flux valid in both a multiple-helicity torsatron and a bumpy torus in the superbanana plateau regime is obtained. The expression is valid for arbitrary values of Φ′, the radial electric field, ∂εH/∂r with εH the effective helical modulation or bumpiness, and ∂εT/∂r with εT the effective toroidal modulation. When small mirror force terms are included in the flux, a nonlinear first-order ordinary differential equation in Φ′ is obtained from the ambipolarity relationship.