Integrated operation of steady-state long-pulse H-mode in Experimental Advanced Superconducting Tokamak. (1st July 2019)

• Record Type: Journal Article
• Authors: Gong, X.; Garofalo, A.M.; Huang, J.; Qian, J.; Holcomb, C.T.; Ekedah, A.; Maingi, R.; Li, E.; Zeng, L.; Zhang, B.; Chen, J.; Wu, M.; Du, H.; Li, M.; Zhu, X.; Sun, Y.; Xu, G.; Zang, Q.; Wang, L.; Zhang, L.; Liu, H.; Lyu, B.; Sun, P.; Ding, S.; Zhang, X.; Liu, F.; Zhao, Y.; Xiao, B.; Hu, J.; Hu, C.; Hu, L.; Li, J.; Wan, B.;
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 59:Number 8(2019:Aug.)
• Publication Date: 2019-07-01
• Subjects: long pulse -- high βP -- high bootstrap current -- tokamak; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ab1c7b
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Recent Experimental Advanced Superconducting Tokamak (EAST) experiments have successfully demonstrated a long-pulse steady-state scenario with improved plasma performance through integrated operation since the last IAEA FEC in 2016. A discharge with a duration over 100 s using pure radio frequency (RF) power heating and current drive has been obtained with the required characteristics for future long-pulse tokamak reactors such as good energy confinement quality (H98y2 ~ 1.1) with electron internal transport barrier inside ρ < 0.4, small ELMs (frequency ~100–200 Hz), and good control of impurity and heat exhaust with the tungsten divertor. The optimization of X -point, plasma shape, the outer gap and local gas puffing near the low hybrid wave (LHW) antenna were integrated with global parameters of B T and line-averaged electron density for higher current drive efficiency of LHW and on-axis deposition of electron cyclotron heating in the long-pulse operation. More recently, a high β P RF-only discharge ( β P ~ 1.9 and β N ~ 1.5, / n GW ~ 0.80, f bs ~ 45% at q 95 ~ 6.8) was successfully maintained over 24 s with improved hardware capabilities, demonstrating performance levels needed for the China Fusion Engineering Test Reactor steady-state operation. A higher energy confinement is observed at higher β P and with favorable toroidal field direction. Towards the next goal (⩾400 s long-pulse H-mode operations with ~50% bootstrap current fraction) on EAST, an integrated control of the current density profile, pressure profile and radiated divertor will be addressed in the near future.