Preliminary Investigations of Equilibrium Reconstruction
Quality During ELMy and ELM-Free
Phases on JET
M. Gelfusa, A. Murari, E. Peluso, P. Gaudio, F.P. Orsitto, S.
and JET EFDA contributors
On JET the magnetic topology is normally derived from the code EFIT, which solves the
Grad-Shafranov equation with constraints imposed by the available measurements, typically the
pick-up coils. Both the code and the measurements are expected to perform worse during ELMs.
To assess this hypothesis, various statistical indicators, based on the values of the residuals
and their probability distribution, have been calculated. They all show that the quality of
EFIT reconstructions is clearly better in absence of ELMs. How the responsibility, for the lower
quality of the reconstructions, is shared between the
measurements, and EFIT and its constraints is a subject under investigation.
Preprint of Paper to be submitted for publication in Proceedings of the
2nd International Conference Frontiers in Diagnostic Technologies
(28th November 2011 - 30th November 2011)