Semi-Empirical Approach to Determine the Plasma Boundary of Toroidal Helical Equilibria in LHD

A new semi-empirical technique of 3-D equilibrium reconstruction using the extended virtual magnetic surface coordinate is adopted to determine the plasma boundary surface fitted to experimental data in the Large Helical Device (LHD). The plasma radius is defined by nearly zero plasma pressure, and the core and edge magnetic surfaces are iteratively calculated to fit experimental kinetic pressure.