A novel electron density reconstruction method for asymmetrical toroidal plasmas

Abstract

A novel reconstruction method is developed for acquiring the electron density profile from multi-channel interferometric measurements of strongly asymmetrical toroidal plasmas. It is based on a regularization technique, and a generalized cross-validation function is used to optimize the regularization parameter with the aid of singular value decomposition. The feasibility of method could be testified by simulated measurements based on a magnetic configuration of the flexible helical-axis heliotron device, Heliotron J, which has an asymmetrical poloidal cross section. And the successful reconstruction makes possible to construct a multi-channel Far-infrared laser interferometry on this device. The advantages of this method are demonstrated by comparison with a conventional method. The factors which may affect the accuracy of the results are investigated, and an error analysis is carried out. Based on the obtained results, the proposed method is highly promising for accurately reconstructing the electron density in the asymmetrical toroidal plasma.

APTWG: The 5th Asia-Pacific Transport Working Group Meeting

“…Zhang introduced preliminary results from particle transport studied by using modulated SMBI and fast sweep FMCW reflectometer on HL-2A. Shi and Liu reported the particle transport studies in a density modulation experiment by using polarimeter/ interferometer on EAST, where the singular value decomposition (SVD) together with the generalized cross-validation (GCV) reconstruction method [51] and the fast date processing method were introduced in these two presentations, respectively. Zhang reported the status of impurity transport studies on HL-2A by virtue of laser blow-off (LBO) and SMBI techniques for metal and gaseous impurity injection and impurity transport code STRAHL with a derivative χ 2 minimization method for analyzing.…”