Momentum and thermal transport in neutral-beam-heated tokamaks

Abstract
The relation between momentum and thermal transport in neutral‐beam‐heated tokamaks with subsonic toroidal rotation velocity has been investigated. A theory of diffusive momentum transport driven by ion‐temperature‐gradient‐driven turbulence (ηi turbulence) is presented. In addition, the level of ηi turbulence is enhanced by radially sheared toroidal rotation. The resulting ion shear viscosity is χφ=1.3{(1+ηi)/τ+[(Ln/2cs) (dV0/dr)]2}22scs/ Ls). The associated ion thermal diffusivity, χi, is identical to χφ. Thus a scenario based on velocity‐shear‐enhanced ηi turbulence is consistent with the experimentally observed relationship between thermal and momentum confinement.