On non existence of tokamak equilibria with purely poloidal flow
  It is proved that irrespective of compressibility tokamak steady states with purely poloidal mass flow can not exist in the framework of either magnetohydrodynamics (MHD) or Hall MHD models. Non-existence persists within single fluid plasma models with pressure anisotropy and incompressible flows. 
G. N. Throumoulopoulos, H. Weitzner, H. Tasso