Fast tokamak plasma flux and electron density reconstruction technique

Abstract

Density profiles in TEXT-U are obtained using a vertical viewing far-infrared (FIR) interferometer. To obtain the local (inverted) density, we have developed a simple analytic model of the plasma equilibrium configuration which is faster than EFIT (a flux surface reconstruction program) and can be easily computed between discharges. This analytic solution of the Grad-Shafranov equation is valid as long as the pressure p is a function of poloidal flux ψ, i.e., p=p(ψ). The procedure incorporates both magnetic and FIR density data to solve the Grad-Shafranov equation, and provides a density profile which is self-consistent with the reconstructed equilibrium flux surfaces. Examples are presented. © 1997 American Institute of Physics.