Scenario Development at JET with the New ITER-like Wall
In the recent JET experimental campaigns with the new ITER-like-Wall (ILW), major progress has been achieved in the characterisation of the H-mode regime in a metallic first wall: i) plasma breakdown and L-mode operation have been recovered in a few days of operation. ii) Stable type I ELMy H-modes with bN ~1.4 have been achieved in low and high triangularity ITER­like shape plasmas and their operational domain at H = 1 is significantly reduced with the ILW for equivalent amount of deuterium gas injection than with the carbon wall. iii) Deuterium gas injection (1022D/s) are needed to control the core radiation. iii) In contrast, the hybrid H-mode scenario has reached H factor close to 1.3 at bN of 3 for 2 to 3s. iv) In comparison to carbon equivalent discharges, total radiation is similar but the edge radiation is lower and Zeff of the order of 1.3-1.4. It appears that at low gas fuelling (0.5 1022D/s), impurity transport plays a key role in the behaviour of the H-mode discharges. This paper reviews the major physics and operational achievements and challenges that JET has to face to produce stable plasma scenarios with maximised performance in an ITER-like wall.