Development and application of real-time magnetic coordinate mapping system in the Large Helical Device

Abstract

We have newly developed a large-scale equilibrium database for real-time magnetic coordinate mapping system in the Large Helical Device. Thousands of free-boundary equilibria for each vacuum configuration have been calculated under wide ranges of central beta, pressure peaking factor, toroidal current and current peaking factor. We have also prepared a line of sight database which tabulates pre-calculated mapping results for all equilibria along several selected lines of sight to accelerate the mapping procedure. A user library has been developed to retrieve results of the inverse mapping as well as additional equilibrium parameters from the databases. A mapping program iteratively searches for the best-fitted equilibrium so as to minimize the discrepancy between inboard and outboard side of an electron temperature profile measured by the Thomson scattering diagnostic. Real-time mapping of all the time slices of the Thomson data enables us to provide time evolutions of equilibrium parameters and electron temperature/density profiles as functions of effective minor radius, which can be applied specifically for subsequent analyses of transport phenomena based on experiments.