  In Hybrid plasma operation in JET with its ITER-like wall (JET-ILW) it is
found that n>1 tearing activity can significantly enhance the rate of on-axis
peaking of tungsten impurities, which in turn significantly degrades discharge
performance. Core n=1 instabilities can be beneficial in removing tungsten
impurities from the plasma core (e.g. sawteeth or fishbones), but can
conversely also degrade core confinement (particularly in combination with
simultaneous n=3 activity). The nature of MHD instabilities in JET Hybrid
discharges, with both its previous Carbon wall and subsequent JET-ILW, is
surveyed statistically and the character of the instabilities is examined.
Possible qualitative models for how the n>1 islands can enhance on-axis
tungsten transport accumulation processes are presented.
