Reduction of impurity confinement time by combined heating of LHW and ECRH in EAST |
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Affiliation: | 1.Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, China;2.Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;3.Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China;4.University of Science & Technology of China, Hefei 230031, China |
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Abstract: | The core impurity confinement properties are experimentally investigated in the Experimental Advanced Superconducting Tokamak (EAST) plasma heated by lower hybrid wave (LHW) and electron cyclotron resonance heating (ECRH) (LHW+ECRH). It is shown that the impurity confinement time (τimp) in the L-mode plasma jointly heated by LHW and ECRH is weakly dependent on electron density but strongly dependent on the heating power, thus it is shorter than that in LHW-only heated L-mode plasma with the similar plasma parameters. The combined heating of LHW and ECRH can reduce the collisionality and indicates a more effective heating method for core τimp reduction and normalized poloidal beta (βP) improvement. It should be emphasized that in this high βP operation window the small ELM regime can be accessed, and an L-mode level τimp (40 ms-80 ms) and high βN (~1.7) can be obtained simultaneously. It means that this typical small ELMy H-mode regime has an advantage in avoiding the serious tungsten accumulation, and will be competitive in future long-pulse steady-state and high-performance operation with high-Z material plasma-facing components. |
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Keywords: | LHW and ECRH heating impurity confinement time tungsten small ELMs regime EAST |
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