Determination of Spatial Distribution of Plasma Current Density by Multibeam FIR Interferometry/Polarimetry

A method is derived for inferring the point-wise current density given the shape of the outer plasma boundary ¿i neds and ¿i neB¿d¿s, where ne is the electron density, d¿s is an increment of path length, and B¿ is the magnetic field strength. The i is an index for the several integral traverses that are required. The integral quantities are assumed to be obtainable from far infrared (FIR) interferometer/polarimeter measurements [1], and the outer plasma boundary shape could be obtained from plasma loop probe measurements [2]. The method obtains a current density distribution that is consistent with ¿ . B¿ = 0, ¿ × B¿ = ¿ j¿, assuming that the ne contour lines follow the B-field lines [3], [4], as well as the measured line integrals, and the measured outer plasma boundary shape. If they are available, other experimental data can also be incorporated into the analysis method. A set of data from the TEXTOR tokamak reported by Soltwisch [3] is analyzed by the method, and the results are discussed.