The development of safe high current operation in JET-ILW

Highlights: • JET is unique in its capability to operate in DT and at high plasma current. • Studies of high current H-mode are integral part of JET ITER-like Wall programme. • Focus is on safety wrt transient & steady-state heat loads on ILW components. • Early real-time detection of off-normal events and disruption effects mitigation. • This work successfully delivered H-mode scenario up to 4 MA. - Abstract: The JET tokamak is unique amongst present fusion devices in its capability to operate at high plasma current, providing the closest plasma parameters to ITER. The physics benefits of high current operation have to be balanced against the risks to the integrity of the machine due to high force disruptions. The installation of the ITER-Like Wall (ILW) has added risks due to the thermal characteristics of the metal Plasma Facing Components. This paper describes the operational aspects of the scientific development of high current H-mode plasmas with the ILW, focusing on disruption prediction, avoidance and amelioration. The development yielded baseline H-mode plasmas up to 4 MA/3.74 T, comparable to the maximum current achieved in JET in Carbon-Wall (CFC) conditions with similar divertor geometry.