Stationary 20s Hybrid Discharge in JET
In 2006, the hybrid scenario at JET has been extended to duration of 20s with good confinement properties (H98y2=1) and a fusion figure of merit G = H89.bN/q952 = 0.4. 186MJ of neutral beam energy has been injected in these discharges and more than 50% of the total current is driven non-inductively. The 3/2 Neoclassical Tearing Mode (NTM) is observed to degrade the confinement by typically 15% and its triggering depends closely on the q profile at the time when the main heating is applied. Boundary flux control has been applied for 15s during these discharges together with strike point sweeping for spreading the heat load on the divertor target. In addition this control has been coupled with total plasma current control by the neutral beam power for shorter times (10s). This experiment demonstrates the potential of the hybrid scenario to become a reference scenario for stationary long duration operation.