Real time control developments at JET in preparation for deuterium-tritium operation

Abstract

Robust high performance plasma scenarios are being developed to exploit the unique capability of JETto operate with Tritium and Deuterium. In this context, real time control schemes are used to guidethe plasma into the desired state and maintain it there. Other real time schemes detect undesirablebehaviour and trigger appropriate actions to assure the best experimental results without unnecessaryuse of the limited neutron and Tritium budget. This paper discusses continuously active controllers andevent/threshold detection algorithms triggering a variety of actions. Recent advances include: (i) Con-trol of the degree of plasma detachment via impurity injection; (ii) ELM frequency control via gas/Pelletinjection; (iii) Sawtooth pacing using ICRH modulation, (iv) control of the Hydrogen to Deuterium iso-tope ratio through gas injection and (v) the determination that a discharge is not evolving as desired,triggering a cascade of actions attempting to stop the plasma rapidly and safely, eventually triggering massive gas injection if a disruption is deemed unavoidable. For high power Deuterium-Tritium operation these control schemes need to be integrated into the plasma scenarios ensuring that they are mutually compatible,