Characterization of physics events in JET preceding disruptions

Abstract

The Sequence of Physics Events (SPE) that leads the plasma towards a disruption can be different in different discharges. An Event, in this framework, refers to the signature of a physical phenomenon (e.g. a peaked ne profile or bolometric peaking factor), whose duration may vary from few ms to several hundreds ms. The SPE have a direct influence on the evolution of the pulses. Then, it is reasonable to assume that their identification can provide relevant information to keep the discharges within a safe operational space. In this work, first, a set of Event detectors (each one targeting a distinctive disruption-related phenomenon) have been considered. These detectors have been applied to JET disruptive discharges in the range of #94152 to #97137 (June 2019 – March 2020, corresponding to Baseline scenario experiments). Each one of these disruptive shots has been characterized by its corresponding SPE. Once the main signatures of the disruptive behaviour have been determined, the last step of the work consists of the analysis of these SPEs. The objective is to identify which ones are more prone to occur and therefore useful to describe their impact on the discharge evolution. This first step opens the possibility of applying the method to a considerable larger database, including also non-disruptive discharges, in order to better understand when and why similar trajectories end (or not) in a disruption.