Effect of impurity ions on the coupling between zonal flow and local turbulent transport in HL-2A plasmas

Zou, Qian; Cheng, J.; Xu, Yuhong; Yan, L.W.; Huang, Z.H.; Wang, Weice; Wu, Na; Xu, Jianqiang; Shen, Yong; Liu, Liang; Dong, Chengli; Fang, Qian; Tang, C. J.; Nie, Lin; Shi, Z.B.; Zhong, Weizhi; Xu, M.

doi:10.1088/1741-4326/ac65a0

Cited by 3 publications

(2 citation statements)

References 43 publications

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“…, σ k is the averaged wavenumber broadening [46]. It is found that both L cθ and L cr increase significantly in the positive bias case, but change little in the negative bias case, revealing that the spatial dimensions of the turbulent eddies are enlarged in the positive bias case.…”

Section: Effects Of Different Bias Voltages On Spatial Structures Of ...mentioning

confidence: 93%

Effects of negative and positive bias voltages on turbulence characteristics in J-TEXT tokamak

Zhang¹,

Liu²,

Xu³

et al. 2022

Plasma Phys. Control. Fusion

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The effects of positive and negative bias voltages on the turbulence characteristics in edge plasmas of J-TEXT are studied using Langmuir probe arrays. The experimental results illustrate that the turbulent particle transport fluxes are suppressed in both positive and negative bias cases, while the suppression mechanisms are quite different. For the positive bias (+300 V), the long-range correlation (LRC) structures with frequencies of about 10 ~ 30 kHz are generated, which are beneficial for the turbulent transport suppression. In the -300 V bias case, no LRCs appear, while a strong mean flow shear exists which can reduce the amplitudes of potential and density fluctuations and thus decreases the turbulent transport.

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Section: Effects Of Different Bias Voltages On Spatial Structures Of ...mentioning

confidence: 93%

Effects of negative and positive bias voltages on turbulence characteristics in J-TEXT tokamak

Zhang¹,

Liu²,

Xu³

et al. 2022

Plasma Phys. Control. Fusion

Self Cite

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“…Recently, studies of the role played by impurity ions on turbulence and plasma confinement have been extensively carried out, such as, neon seeding in DIII-D [10], nitrogen seeding in AUG [11], helium seeding in T-10 [12], boron injection in EAST [13] and LHD [14], and carbon and tungsten injection in HL-2A [15,16]. A study that has attracted great attention is the one on tungsten, mainly because tungsten has been chosen as the plasma-facing material in ITER due to its high erosion resistance and good thermal conductivity [17].…”

Section: Introductionmentioning

confidence: 99%

Observation of reduced-turbulence regime with tungsten injection in HL-2A edge plasmas

Zou,

Cheng,

Shi

et al. 2023

Nucl. Fusion

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A reduced-turbulence regime has been observed in HL-2A NBI-heated deuterium plasmas. The transition to this regime was achieved by injecting certain amount of tungsten into plasma based on the laser blow-off (LBO) technique. It has been found that the amplitude of geodesic acoustic mode (GAM) zonal flow, turbulent vortex sizes together with eddy tilting angle are all significantly increased in the edge region after the tungsten injection, but the frequency of GAM zonal flow keeps nearly unchanged. Measurement shows the nonlinear coupling degree of turbulence dramatically increases, meanwhile the collisional damping of GAM zonal flow has slight drop, concluding that the increased nonlinear coupling is the main cause for the excitation of GAM zonal flow, which consequently results in the reduction of turbulent transport as observed in this experiment. These results given here indicate that the tungsten ions play an active role in turbulence-GAM dynamics through symmetry-breaking mechanism, which could help us to better understand the inherent physical mechanism governing turbulent transport in the presence of high-Z impurity ions in fusion plasmas.

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Reduction of turbulence by enhanced low-frequency zonal flow-like structures in HL-2A edge plasmas

Chen,

Cheng,

et al. 2024

Nucl. Fusion

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A low frequency zonal flow-like (LFZF-like) structure peaking at f~2.0 kHz has been observed in HL-2A ohmically-heated deuterium plasmas by using the combined Langmuir probe array. This time-varying potential structure, which has axisymmetric characteristic (n=0) and a finite radial correlation length (less than 1 cm), is identified to be generated by the three-wave interaction among small-scale turbulence. Results illustrate that the amplitude of LFZF-like structure dramatically increases with the influence of impurity ions, which is mainly due to the increased strength in the nonlinear energy transfer by the turbulence vortex symmetry-breaking process. Consequently, the enhanced LFZF-like structure has the ability to stabilize the local turbulence by the shearing decorrelation mechanism as demonstrated in this experiment. These observed results given here reveal the essential role played by the LFZF-like structure in the reduction of turbulent level, which could advance the understanding of multi-scale physics governing turbulence and the resulting transport in magnetically confined plasmas.

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Effect of impurity ions on the coupling between zonal flow and local turbulent transport in HL-2A plasmas

Cited by 3 publications

References 43 publications

Effects of negative and positive bias voltages on turbulence characteristics in J-TEXT tokamak

Effects of negative and positive bias voltages on turbulence characteristics in J-TEXT tokamak

Observation of reduced-turbulence regime with tungsten injection in HL-2A edge plasmas

Reduction of turbulence by enhanced low-frequency zonal flow-like structures in HL-2A edge plasmas

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