Operation at high performance in optimized shear plasmas in JET

Heating during the early part of the current rise phase gives a low or negative magnetic shear (= 0741-3335/40/6/020/img27(dq/dr)) in the centre of JET plasmas. Under these conditions the confinement improves with high additional heating power heating during the current ramp-up phase of the discharge. The reduction in the transport manifests itself as a peaking of the profiles with a large gradient region near 0741-3335/40/6/020/img28 = 0.55. The best discharges have no transport barrier at the edge of the plasma (L-mode). This allows central power deposition by the neutral beams in JET. A control of the plasma pressure, using feedback of the additional heating power in real-time, minimizes the impact of magnetohydrodynamic instabilities. As a result, these discharges achieve the highest D-D neutron rates in JET; 0741-3335/40/6/020/img29, with 0741-3335/40/6/020/img30, 0741-3335/40/6/020/img31 and 0741-3335/40/6/020/img32