T. Fujita et al 1999 Nucl. Fusion 39 1627 doi:10.1088/0029-5515/39/11Y/302
T. Fujita, Y. Kamada, S. Ishida, Y. Neyatani, T. Oikawa, S. Ide, S. Takeji, Y. Koide, A. Isayama, T. Fukuda, T. Hatae, Y. Ishii, T. Ozeki, H. Shirai and JT-60 Team
Show affiliationsThe operation of JT-60U reversed shear discharges has been extended to a high plasma current, low q regime keeping a large radius of the internal transport barrier (ITB), and a record value of equivalent fusion multiplication factor in JT-60U, QDTeq = 1.25, has been achieved at 2.6 MA. Operational schemes to reach the low q regime with good reproducibility have been developed. The reduction of Zeff was obtained in the newly installed W shaped pumped divertor. The β limit in the low qmin 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 flow control with ITB degradation. Sustainment of the ITB and improved confinement for 5.5 s has been demonstrated in an ELMy H mode reversed shear discharge.
52.55.Fa Tokamaks, spherical tokamaks
52.55.Rk Power exhaust; divertors
52.40.Hf Plasma-material interactions; boundary layer effects
Issue 11Y (November 1999)
Received 7 December 1998, accepted for publication 7 June 1999
T. Fujita et al 1999 Nucl. Fusion 39 1627
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