Beta induced Alfvén eigenmode driven by energetic ions on the HL-2A tokamak

Shi, P.W.; Chen, W.; Shi, Z.B.; Duan, Xuru; Yang, Z.C.; Ma, Rui; Zhong, W.L.; Jiang, Min; Yu, Lu; Liang, Anshu; Wen, Jie; Yu, D.L.; Liu, Y.; Yang, Qingwei

doi:10.1088/1741-4326/ab05ee

Cited by 21 publications

(19 citation statements)

References 32 publications

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“…The power of NBI (P N BI ) can reach up to 1.5 M W . Aboundant Alfvénic waves have been observed during the NBI heating discharges [26][27][28][29][30]. The evolution of mode numbers is confirmed by the phase shift of the waves from Mirnov probe arrays.…”

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confidence: 80%

Experimental Evidence of Nonlinear Avalanche Dynamics of Energetic Particle Modes

Yu,

Zonca,

Qiu

et al. 2021

Preprint

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Recent observations in HL-2A tokamak give new experimental evidences of energetic particle mode (EPM) avalanche. In a strong EPM burst, the mode structure propagates radially outward within two hundred Alfvén time, while the frequency of the dominant mode changes self-consistently to maximize wave-particle power exchange and mode growth. This suggests that significant energetic particle transport occurs in this avalanche phase, in agreement with theoretical framework of EPM convective amplification. A simplified relay runner model yields satisfactory interpretations of the measurements. The results can help understanding the nonlinear dynamics of energetic particle driven modes in future burning plasmas, such as ITER.

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confidence: 80%

Experimental Evidence of Nonlinear Avalanche Dynamics of Energetic Particle Modes

Yu,

Zonca,

Qiu

et al. 2021

Preprint

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“…Figure 5 presents a statical result about the mode frequencies of TAE, 𝑛 = 1 Alfvénic mode and BAE, and line-averaged electron densities where the three energetic particle driven instabilities are excited. Usually, the BAE frequency increases with increasing ion temperature [35] while the TAE frequency shows a reversed relation with the electron density. [36] Great changes have been found in both BAE and TAE frequencies, whereas the mode frequencies of 𝑛 = 1 Alfvénic modes vary slightly during multiple discharge environment.…”

Section: √︀mentioning

confidence: 99%

Observation and Simulation of n = 1 Reversed Shear Alfvén Eigenmode on the HL-2A Tokamak

Shi

Yang

Chen

et al. 2022

Chinese Phys. Lett.

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A branch of high frequency Alfvénic mode is observed on the HL-2A tokamak. The electromagnetic mode can be driven unstable in the plasma with an off-axis neutral beam heating. Its mode frequency keeps almost unchanged or presents a slow-sweeping behavior, depending on the detail current evolution. The poloidal and toroidal mode numbers are $m/n=1/1$. The mode has a quite short duration ($\leq20 $ ms) and usually appears 5-10 ms after the neutral beam being injected into the plasma. Hybrid simulations based on M3D-K have also been carried out. The result suggests that co-passing energetic particles are responsible for the mode excitation. The simulated mode structures are localized nearby location of minimum safety factor ($q_{min}$) and agree with the structures obtained through tomography of soft x-ray arrays. Further, the modes are localized in the continuum gap and their frequencies increase with variation of $q_{min}$ in a wide range. Last but not least, the characteristic of unchanged frequency on experiment is also reproduced by the nonlinear simulation with a fixed safety factor. All those evidences indicate that the $n=1$ high frequency mode may belong to a reversed shear Alfvén eigenmode (RSAE).

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“…The i-BAEs were firstly observed and found to cause large losses of fast ions on DIII-D. [39] Those modes are also driven in the HL-2A plasma. [40] The mode frequencies are around 60-95 kHz and the radial structures have been detected by a multi-channel microwave reflectometer. It is spectrum of microwave reflectometer with frequency of 40 GHz in Fig.…”

Section: Reviewmentioning

confidence: 99%

Energetic Particle Physics on the HL-2A Tokamak: A Review

Shi¹,

Chen²,

Duan³

2021

Chinese Phys. Lett.

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Interaction between shear Alfvén wave (SAW) and energetic particles (EPs) is one of major concerns in magnetically confined plasmas since it may lead to excitation of toroidal symmetry breaking collective instabilities, thus enhances loss of EPs and degrades plasma confinement. In the last few years, Alfvénic zoology has been constructed on HL-2A tokamak and series of EPs driven instabilities, such as toroidal Alfvén eigenmodes (TAEs), revered shear Alfvén eigenmodes (RSAEs), beta induced Alfvén eigenmodes (BAEs), Alfvénic ion temperature gradient (AITG) modes and fishbone modes, have been observed and investigated. Those Alfvénic fluctuations show frequency chirping behaviors through nonlinear wave-particle route, and contribute to generation of axisymmetric modes by nonlinear wave-wave resonance in the presence of strong tearing modes. It is proved that the plasma confinement is affected by Alfvénic activities from multiple aspects. The RSAEs resonate with thermal ions, and this results in an energy diffusive transport process while the nonlinear mode coupling between core-localized TAEs and tearing modes trigger avalanche electron heat transport events. Effective measures have been taken to control SAW fluctuations and the fishbone activities are suppressed by electron cyclotron resonance heating. Those experimental results will not only contribute to better understandings of energetic particles physics, but also provide technology bases for active control of Alfvénic modes on International Thermonuclear Experimental Reactor (ITER) and Chinese Fusion Engineering Testing Reactor (CFETR).

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Beta induced Alfvén eigenmode driven by energetic ions on the HL-2A tokamak

Cited by 21 publications

References 32 publications

Experimental Evidence of Nonlinear Avalanche Dynamics of Energetic Particle Modes

Experimental Evidence of Nonlinear Avalanche Dynamics of Energetic Particle Modes

Observation and Simulation of n = 1 Reversed Shear Alfvén Eigenmode on the HL-2A Tokamak

Energetic Particle Physics on the HL-2A Tokamak: A Review

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