Tokamak MHD equilibria with reversed magnetic shear and sheared flow**A preliminary version of this study was presented in the 29th EPS Conf. on Plasma Phys. and Control. Fusion (Montreux, Switzerland, 17–21 June 2002) [1

Abstract

Analytical solutions of the magnetohydrodynamic equilibrium equations for a cylindrically symmetric magnetically confined plasma with reversed magnetic shear, s < 0, and sheared flow are constructed by prescribing the safety factor, poloidal velocity and axial velocity profiles consistently with experimental ones. On the basis of the solutions obtained, in most of the cases considered, it turns out that an increase of |s| and of the velocity components result in larger absolute values for the radial electric field, Er, its shear, , and the E × B velocity shear, ωE × B = |(d/dr)(E × B/B2)|, which may play a role in the formation of internal transport barriers in tokamaks. In particular for a constant axial magnetic field, ωE × B at the point where is proportional to 1−s. Also, and ωE × B increase as the velocity shear takes larger values. The results clearly indicate that s < 0 and sheared flow acts synergetically in an increase of ωE × B with the impact of the flow, in particular the poloidal one being stronger than that of s < 0.