Compatibility of High Performance Operation with JET ILW
ABSTRACT As reported at the FEC 2012, operation with a Be/W wall (JET-ILW) at JET has an impact on plasma confinement and scenario development relative to the carbon wall (JET-C). The main differences observed are a degradation of confinement for low βN scenarios (typically H98(y,2)~0.8) and W accumulation in the plasma core at low fuelling gas rates, in some cases leading to an increased core radiation causing the triggering of MHD followed by a disruption. During the JET 2014 campaign, both high and low βN scenarios started to be successfully developed towards high plasma current where control of W accumulation in the plasma core and methods to reduce the plasma temperature near the target plates were successfully integrated in the scenarios. Plasma energy confinement has been improved at Ip < 3MA.