Configuration and Perturbation Dependence of the Neutral Point in JET

Previously the existence of a Neutral Point was clearly demonstrated for plasma disruptions following radiative collapses in JET. This paper extends such studies to different configurations and different perturbations (ELMs). The result is that a Neutral Point for ELM-type perturbations does not exists in the explored range. Nevertheless, a spatial dependence of the excitation of the unstable mode can be found in the experimental data. This feature can give useful information about simplified ELM modelling for control purposes.