Statistical study of TCV disruptivity and H-mode accessibility
Optimizing tokamak operation consists of finding a path, in a multidimensional parameter space, which leads to the desired plasma characteristics and avoids hazardous regions. Typically the desirable regions are the domain where an L-mode to H-mode transition can occur, and then, in the H-mode, where edge localized modes (ELM) and the required high density can be maintained. The regions to avoid are those with a high rate of disruptivity. This paper presents the results of a statistical analysis of the occurrence of disruptions in TCV. For the H-mode accessibility, it is usually admitted that a minimum auxiliary power is required, and that this power threshold depends on some plasma parameters. On TCV, since the H-mode was achieved with Ohmic heating only, such a power threshold can not be determined. Plasma shape, current and densities as well as the vacuum vessel conditioning are known to play a role in the H-mode accessibility. Discriminant analysis, has been used to estimate a probability of being close to an L-mode to H-mode (LH) transition, which could be used to guide the plasma discharge towards the LH transition, with the help of an advanced and intelligent control system.
Bibliographic Reference: Article: Proceedings of 24th EPS Conference on Controlled Fusion and Plasma Physics, Berchtesgaden 9-13 June 1997, pp. 521-524
Record Number: 199810023 / Last updated on: 1998-02-03
Original language: en
Available languages: en