Experimental observation of reverse-sheared Alfvén eigenmodes (RSAEs) in ELMy H-mode plasma on the EAST tokamak

Zhang, Tao; Liu, Yong; Li, Guoqiang

doi:10.1088/2058-6272/aac9b5

Cited by 18 publications

(29 citation statements)

References 39 publications

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“…[26] As shown in Figs. 13(a)-13(c), the pressure gradient is steep but the |s| is large in the negative magnetic shear region, which does not trap the αTAEs. [41] is obtained by the bootstrap current model [42] (V : the particle collision parameter, B θ : the poloidal magnetic, p: plasma pressure).…”

Section: αTaes In the Negative Off-axis Magnetic Shear Scenariomentioning

confidence: 99%

“…[4] The Alfvén wave has played a crucial part in the magnetic confinement fusion field. Various Alfvén eigenmodes (AEs) [5][6][7][8] have been explored, such as the toroidicityinduced Alfvén eigenmode (TAE), [9][10][11] the reversed shear Alfvén eigenmode (RSAE), [12][13][14] and the α-induced toroidal Alfvén eigenmode (αTAE). [15,16] Here, α = −q 2 Rdβ /dr, q is the safety factor, R and r are the major and minor radii in tokamaks, respectively, and β is the ratio between thermal and magnetic pressures.…”

Section: Introductionmentioning

confidence: 99%

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Discrete Alfvén eigenmodes in the CFETR steady-state scenario

Lan¹,

Hu²,

Ouyang³

et al. 2023

Chinese Phys. B

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In this paper, the stability features of discrete Alfvén eigenmodes (αTAEs) trapped by the α-induced potential wells are explored in CFETR (China Fusion Engineering Test Reactor) advanced steady-state operation, where α denotes a measure of the pressure gradient. For the reversed magnetic shear (RS) H-mode scenario with enhanced internal transport barrier (ITB), the αTAEs are trapped in the electron cyclotron (EC) power deposition region and effects of different pedestals on αTAEs are analysed. For the negative off-axis magnetic shear scenario, the αTAEs are discussed, and the effect of different magnetic shears on the αTAEs is presented. Finally, the effect of beam energies and pitch-angle distributions on αTAE stability is also presented.

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Section: αTaes In the Negative Off-axis Magnetic Shear Scenariomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Discrete Alfvén eigenmodes in the CFETR steady-state scenario

Lan¹,

Hu²,

Ouyang³

et al. 2023

Chinese Phys. B

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“…(Experimental Advanced Superconducting Tokamak)上观测到环效应引起的阿尔芬本征模(Toroidicity-Induced Alfvén Eigenmodes, TAEs) [10,11] 、比压阿尔芬本征模(Beta-Induced Alfvén Eigenmodes, BAEs) [12,13] 以及反磁剪切阿尔芬本征模(Reverse Shear Alfvén Eigenmodes, RSAEs) [14,15] 等. 这些模式在不同装置的不同放电条件下呈现出不同特性, 如在HL-2A上高能离子激发的BAE具有频率啁啾特性 [16] , 而在EAST上BAE的存在依赖于低杂波功率, 并且磁重联对其有很大影响等 [11] .…”

Section: 引言unclassified

Discrete Alfvén eigenmodes excited by energetic particles in China Fusion Engineering Test Reactor

Zhao¹,

Hu²,

He³

et al. 2020

Sci. Sin.-Phys. Mech. Astron.

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In burning plasmas, discrete Alfvén eigenmodes (αTAEs, where α denotes a parameter of plasma pressure gradient) can be readily destabilized by energetic particles under the wave-particle resonance condition. In this study, we theoretically analyze the physical features of αTAEs in the China Fusion Engineering Test Reactor (CFETR), which is viewed as the next generation device in the Chinese magnetic confinement fusion program. One of the scientific objectives of the device is to achieve steady-state operation. There are three reference schemes for baseline steady-state operation, namely Case 1: NB+EC, Case 2: NB+EC+LH, and Case 3: EC+LH, where NB, EC, and LH represent neutral beam, electron cyclotron wave, and lower hybrid wave, respectively. Within the ideal magnetohydrodynamic (MHD) description, we focus on the physical characteristics of αTAEs and correlation between the radial profile of total current density and αTAEs for the three scenarios of CFETR operation with the help of a MHD eigenvalue code. The numerical results indicated that multiple branches of αTAEs can be trapped in potential wells of the ballooning drive under the CFETR operation condition. In the inner region, the bootstrap current density is large, and the total current density profile, defined by the peak of the radial profile of total plasma current density is relatively flat. Therefore, there are abundant αTAEs in this region. However, in the outer region, the bootstrap current is relatively small, and the total current density decreases gradually. So, αTAEs are hardly seen in this region. The αTAEs in the inner region are quasi-marginally stable within the ideal MHD description. In the CFETR operations, the energetic particles generated can destablize the MHD αTAEs under the wave-particle resonance conditions. We study the stability features of αTAEs interacting with energetic particles by employing linear gyrokinetic-MHD hybrid eigenvalue codes. The multiple branches of αTAEs are excited under the various resonance conditions. Moreover, the multiple branches of αTAEs can also be excited by energetic particles with virial energy. Furthermore, higher-frequency αTAEs may be destabilized by energetic particles with higher energy. These αTAEs could change the distribution of energetic particles in phase space and cause the loss of a large number of particles, which may affect the plasma confinement.

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“…The other one is the hybrid scenario developed by neutron beam injection (NBI) and lower hybrid wave (LHW) with lower magnetic field (B T ) and higher normalized beta (β N ) than the former scenario [58]. The ITBs in the channels of n e , T e , T i and V t can been observed simultaneously [40,58,59]. This paper will focus on the ITB study in the hybrid scenario.…”

Section: Introductionmentioning

confidence: 99%

Predictive multi-channel integrated modeling of a reversed magnetic shear H-mode discharge with internal transport barrier in EAST

et al. 2021

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A reversed magnetic shear high plasma performance H-mode discharge with internal transport barrier (ITB) has been realized and modeled on experimental advanced superconducting tokamak (EAST) in deuterium (D) plasmas with an ITER-like tungsten (W) upper divertor. In this shot (#71326), the dimensionless parameter G ( H 89 β N / q 95 2 ) can reach to 0.25 (H 89 ⩽ 2, β N ⩽ 2, q 95 ∼ 4, I p ⩽ 450 kA, B T ⩽ 1.6 T). The ITB has been observed in the channels of particle (electron density n e), electron and ion temperature (T e and T i) and toroidal rotation velocity (V t). However, in the formation process of V t and n e ITBs, the heavy impurities accumulate in the core plasmas, which may be one of the most important reasons for the limitation of the improvement of plasma performance. A time slice (t = 4.65 s) of the high plasma performance phase with n e, T i and V t ITBs has been analyzed. It is found that the position of minimum safety factor (q min) is at about normalized radius ρ = 0.4 where may be the location of ion ITB foot, during equilibrium reconstruction from EFIT using external magnetic and internal polarimeter-INTferometer (POINT) measurement constraints. Based on this equilibrium, the source is self-consistently calculated by ONETWO and NUBEAM. Then the n e, T e, T i and V t have been modeled predictively and simultaneously by TGYRO utilizing the reconstructed equilibrium, the self-consistent source and the experimental radiated power for the first time in EAST. This modeling well reproduces the experimental n e and T i profiles in the reversed magnetic shear plasmas. In addition, it is shown that reversed magnetic shear rather than shear of radial electric field (E r) mainly produced by V t plays a key role to the formation of n e and T i ITBs. The reasons for central accumulation of W impurity are also clarified by computing both neoclassical and turbulent transport components of W. It turns out that the neoclassical transport dominates over turbulent transport for W and neoclassical pinch of W causes its central accumulation.

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Experimental observation of reverse-sheared Alfvén eigenmodes (RSAEs) in ELMy H-mode plasma on the EAST tokamak

Cited by 18 publications

References 39 publications

Discrete Alfvén eigenmodes in the CFETR steady-state scenario

Discrete Alfvén eigenmodes in the CFETR steady-state scenario

Discrete Alfvén eigenmodes excited by energetic particles in China Fusion Engineering Test Reactor

Predictive multi-channel integrated modeling of a reversed magnetic shear H-mode discharge with internal transport barrier in EAST

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Experimental observation of reverse-sheared Alfvén eigenmodes (RSAEs) in ELMy H-mode plasma on the EAST tokamak

Cited by 18 publications

References 39 publications

Discrete Alfvén eigenmodes in the CFETR steady-state scenario

Discrete Alfvén eigenmodes in the CFETR steady-state scenario

Discrete Alfv&eacute;n eigenmodes excited by energetic particles in China Fusion Engineering Test Reactor

Predictive multi-channel integrated modeling of a reversed magnetic shear H-mode discharge with internal transport barrier in EAST

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Discrete Alfvén eigenmodes excited by energetic particles in China Fusion Engineering Test Reactor