Reversed field pinch plasma equilibria with shear flow

The Grad-Shafranov equation with flow, which is derived by a variational me thod, involves unknown functions such as the dynamic pressure, P(Psi). Thes e functions are specified by minimizations of free energies under the const raints of constant P-'(Psi), magnetic helicity, flow helicity, and cross he licity in reversed field pinch (RFP) plasmas. New flow and cross helicities are introduced based on the analogy of the magnetic helicity, which are di fferent from those used in fluid mechanics. The constraint of constant flow helicity provides flow with profiles from high- to low-shear flow. The Suy dam-stable RFP equilibria obtained with flows are extremely different in be ta and beta (p) from RFP equilibria without flow. The high-shear flow can e xtend the Suydam limit, allowing higher beta and beta (p). (C) 2001 America n Institute of Physics.