Partially Relaxed Minimum Energy States of Reversed-Field-Pinch Plasma

Abstract

An energy principle is formulated for construction of toroidal equilibria in partially relaxed minimum energy states. It is shown that additional global constraint yields an additional condition on the force-free current term of the MHD equilibrium equation. It is clarified that the partially relaxed state model (PRSM) for toroidal plasmas, such as the tokamak plasma and the reversed-field-pinch plasma (RFP plasma), represents the minimum-energy states with finite β-values under global invariants. Comparisons of numerical results by the PRSM for the RFP plasma with two typical experimental data indicate that RFP configurations close to the PRSM are realized in the two RFP experiments. The most advanced partially relaxed state with finite β-values is also discussed.