Plasma equilibria for the case of a strong coupling of parallel and E×B flows

It is shown that the plasma of a tokamak can adopt equilibria with large pressure and electric potential variations along a magnetic flux surface, due to the strong coupling between parallel and perpendicular flows. Different types of solutions to the equilibrium two-fluid equations are found that describe actual plasma states. In particular, one of the equilibria is such that some plasma parameters, like the plasma pressure, can have maximum values in the vicinity of the X point of the separatrix, in agreement with the recent observations in DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)].