The EqRV code for sensitivity analysis of equilibrium reconstruction in LTX-β and tokamaks in general.

The EqRV code, developed in 2008 for promoting MSE-LP (Line Polarization) and MSE-LS (Line Shift) to ITER, is made compatible with tokamak data on magnetic, MSE (-LP, -LS), Faraday rotation signals, and the use of transport code profiles as additional signals. The technique is based on calculation of perturbations of signals from solutions of linearised Grad-Shafranov equation in which the perturbations (variances) of plasma boundary, and pressure and current density profiles are considered as the source of perturbated signals. The application of SVD to the responce matrix, which relates signals and variances, results in determination of eigen values and eigen vectors of variances, which allows to classify the variances and visible, barely visible, and undetectable given the specific diagnostics. In its turn, this allows to judge on accuracy of reconstracted plasma shape, plasma paramenters, e.g., beta, li, or pressure and q-profiles. The number of visible variances inicates is a measure of quality of the diagnostics used. The EqRV code exposes the most and least valuable signals for reconstructions, thus, allowing to optimize the measurements on the device. The results of application of EqRV to LTX-β will be presented.