High performance experiments in JT-60U reversed shear discharges

The operation of JT-60U reversed shear discharges has been extended to a hi gh plasma current, low q regime keeping a large radius of the internal tran sport barrier (ITB), and a record value of equivalent fusion multiplication factor in JT-60U, Q(DT)(eq) = 1.25. has been achieved at 2.6 MA. Operation al schemes to reach the low q regime with good reproducibility have been de veloped. The reduction of Z(eff) was obtained in the newly installed W shap ed pumped divertor. The beta limit in the low q(min) regime, which limited the performance of L mode edge discharges, has been improved in H mode edge discharges with a broader pressure profile, which was obtained by power fl ow control with ITB degradation. Sustainment of the ITB and improved confin ement for 5.5 s has been demonstrated in an ELMy H mode reversed shear disc harge.