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Fluid simulations of resistive drift-wave turbulence with diamagnetic flow in ZPED experiments
2024-05-22
聚变理论与模拟中心
Fluid simulations of resistive drift-wave turbulencewith diamagnetic flow in ZPED experimentsCite as: Phys. Plasmas 31, 052108 (2024); Submitted: 3 December 2023 . Accepted: 23 April 2024 .Published Online: 7 May 2024H. J. Zhao, Y. Mao, Z. Y. Wang, W. W. Xiao,a) and Y. Xiaoa)AFFILIATIONSInstitute for Fusion Theory and Simulation, School of Physics, Zhejiang University, Hangzhou 310027, Chinaa)Authors to whom correspondence should be addressed: wwxiao@zju.edu.cn and yxiao@zju.edu.cnABSTRACTWe derive a diamagnetic resistive fluid model (DRF) and develop an associated two-dimensional fluid simulation code (DRF-2D) to explore the dynamics of resistive drift modes within the plasmas of the Zheda Plasma Experiment Device (ZPED). The validation of the linear dispersion relation for the DRF-2D code revealed a harmonious agreement between analytical theory and linear numerical simulations. Leveraging plasma parameters obtained from the ZPED experiments, we conducted a comprehensive series of nonlinear simulations using the DRF-2D code. Our simulations successfully replicate the nonlinear trends in turbulent fluctuations and transport observed in the ZPED experiments, particularly demonstrating a remarkably accurate alignment of the turning point in the magnetic field. Notably, the DRF model sheds light on the observed frequency sign reversal from the electron diamagnetic direction to the ion diamagnetic direction in the ZPED experiments. This is demonstrated through well-matched turning points in the confining magnetic field between the nonlinear simulations and ZPED experiments. The fidelity of our model in capturing these phenomena underscores its efficacy in providing valuable insights and predictive capabilities for the intricate dynamics observed in the ZPED plasmas. FIG. 4. Density mode structures obtained from nonlinear simulations. The m-spectra are presented in (a)–(c), respectively. Corresponding 2D mode structures are depicted in (d)–(f).Fluid simulations of resistive drift-wave turbulence with diamagnetic flow in ZPED experiments.pdf
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A simple model for internal transport barrier induced by fishbone in tokamak plasmas
2024-05-22
聚变理论与模拟中心
J. Plasma Phys. (2023), vol. 89, 905890612 A simple model for internal transport barrierinduced by fishbone in tokamak plasmasZhaoyang Liu 1 and Guoyong Fu 1,†1Institute for Fusion Theory and Simulation and School of Physics, Zhejiang University,Hangzhou 310027, PR China(Received 17 July 2023; revised 24 November 2023; accepted 24 November 2023)Fishbone bursts have been observed to strongly correlate to internal transport barrier (ITB)formation in a number of tokamak devices. A simple model incorporating the fishbonedynamics and ion pressure gradient evolution is proposed in order to investigate the keyphysics parameters assisting the triggering of ITB. The time evolution of fishbone isdescribed by the well-known predator–prey model. For each burst cycle, the energeticparticles (EPs) resonantly interact with fishbone and are radially expelled from innerregion leading to a radial current. A compensating bulk plasma return current and, hence,poloidal flow can be induced if the fishbone cycle frequency is greater than the poloidalflow damping rate. When the shear of the poloidal flow exceeds a critical value, theturbulent fluctuations are suppressed and the bulk ion pressure gradient transits to thehigh-confinement state. It is shown that this process is only sensitive to the depositionrate of the trapped EPs within the q = 1 surface, but not sensitive to other parameters. Aquantitative formula for the shearing rate of poloidal flow induced by fishbone bursts isderived and verified numerically. FIGURE 2. Poloidal flow (a) and flow shear (b) driven by a single burst of fishbone (dashed line) and multiple bursts of fishbone (solid line). A simple model for internal transport barrier induced by fishbone in tokamak plasmas.pdf
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大尺度动理学模拟揭示对撞等离子体电磁湍流非线性演化与离子随机加热机制
2024-05-20
聚变理论与模拟中心
在天体物理中，常会出现高速等离子体的对撞，如超新星爆发的喷射物和太阳风与星际介质之间的相互作用。此类过程中等离子体速度和温度存在各项异性，宇宙中的种子磁场会在韦伯型不稳定性（Weibel-type instabilities）等作用下被放大成为电磁湍流并产生冲激波，继而产生极强的自生磁场。因此强磁场产生、无碰撞冲激波及其驱动的带电粒子加速等科学问题的研究是当前实验室天体物理领域的关注焦点，而且利用高功率激光装置（如美国的NIF，OMEGA以及中国的神光）已经成功产生了类似于天体中的对撞等离子体环境。浙江大学聚变理论与模拟中心团队，联合上海交通大学和中国科学院国家天文台相关团队，利用吴栋副教授开发的动理学模拟程序LAPINS，定量研究了磁化和非磁化碳氘与碳氢对撞等离子体系统中电磁湍流的非线性演化及其对离子动理学等过程的影响。研究表明：1）在成丝不稳定性和双流不稳定性的协同驱动下会产生电磁湍流；2）在外加横向磁场（垂直于对撞方向）作用下，等离子体自组织效应导致湍流场的剧烈放大，可以产生数十倍于外加磁场的自生磁场；3）离子在湍流场随机加速和碰撞热化的共同作用下，其分布函数会呈现超高斯分布，其中的高能离子会使得系统中氘氘聚变反应产额增加5～6倍。研究结果很好地解释了已有的实验结果。该成果以“Ion Kinetics and Neutron Generation Associated with Electromagnetic Turbulence in Laboratory-Scale Counterstreaming Plasmas” 为题于2024年4月11日发表在Physical Review Letters期刊。浙江大学物理学院博士生刘鹏为该文的第一作者，上海交通大学吴栋副教授、浙江大学聚变理论与模拟中心盛正卯教授为共同通讯作者。 文章信息P. Liu, D. Wu*， T. X. Hu , D. W. Yuan, G. Zhao, Z. M. Sheng*，X. T. He, and J. Zhang，Ion Kinetics and Neutron Generation Associated with Electromagnetic Turbulence in Laboratory-Scale Counterstreaming Plasmas，Phys. Rev. Lett. 132, 155103 (2024), PhysRevLett.132.155103 (aps.org)在激光驱动对流等离子体系统中（a），大尺度动理学模拟得到的非磁化（b）和磁化（c）对流等离子体中自生湍流磁场的空间分布。Ion Kinetics and Neutron Generation Associated with Electromagnetic Turbulence in Laboratory-Scale Counterstreaming Plasmas.pdf
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Magnetic field topology modeling under resonant magnetic perturbations on EAST
2024-03-04
聚变理论与模拟中心
Kinetic infernal mode (KIM) is an electromagnetic instability driven by thermal ions in weak magnetic shear region with a frequency similar to the kinetic ballooning mode (KBM). Gyrokinetic simulations of KIM using Gyrokinetic Toroidal Code (GTC) found that the electromagnetic instability shows a smooth transition from KBM to KIM in both frequency and growth rate when magnetic shear varies from strong to weak, which suggests that KIM and KBM may belong to the same mode physically. The mode structure analysis reveals that the mode transition is induced by the change in distance between adjacent mode rational surfaces. The magnetic shear and driving source effects are investigated in detail. The simulation results show that KIM prefers to grow on the mode rational surface nearest to the minimum magnetic shear, i.e., where the shear stabilizing effect is weakest, instead of at the maximum of density gradient or temperature gradient. However, the magnitude of the growth rate is determined by magnetic shear and temperature gradient simultaneously. These findings suggest that KIM can be effectively regulated by modifying the strength and position of magnetic shear, as well as pressure gradients.122.Linear gyrokinetic simulatioin of kinetic infernal mode.pdf
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Gyrokinetic theory of toroidal Alfvén eigenmode saturation via nonlinear wave-wave coupling
2023-07-03
聚变理论与模拟中心
Nonlinear wave-wave coupling constitutes an important route for the turbulence spectrum evolution in both space and laboratory plasmas. For example, in a reactor relevant fusion plasma, a rich spectrum of symmetry breaking shear Alfvén wave (SAW) instabilities are expected to be excited by energetic fusion alpha particles, and self-consistently determine the anomalous alpha particle transport rate by the saturated electromagnetic perturbations. In this work, we will show that the nonlinear gyrokinetic theory is a necessary and powerful tool in qualitatively and quantitatively investigating the nonlinear wave-wave coupling processes. More specifically, one needs to employ the gyrokinetic approach in order to account for the breaking of the “pure Alfvénic state” in the short wavelength kinetic regime, due to the short wavelength structures associated with nonuniformity intrinsic to magnetically confined plasmas. Using well-known toroidal Alfvén eigenmode (TAE) as a paradigm case, three nonlinear wave-wave coupling channels expected to significantly influence the TAE nonlinear dynamics are investigated to demonstrate the strength and necessity of nonlinear gyrokinetic theory in predicting crucial processes in a future reactor burning plasma. These are: 1.the nonlinear excitation of meso-scale zonal field structures via modulational instability and TAE scattering into short-wavelength stable domain; 2. the TAE frequency cascading due to nonlinear ion induced scattering and the resulting saturated TAE spectrum; and 3. the crossscale coupling of TAE with micro-scale ambient drift wave turbulence and its effect on TAE regulation and anomalous electron heating.108.Gyrokinetic theory of toroidal Alfvén eigenmode saturation via nonlinear wave-wave coupling.pdf
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Observation of turbulence energy transfer in a cylindrical laboratory plasma
2023-07-03
聚变理论与模拟中心
We report the experimental results on the turbulence energy transfer in a cylindrical laboratory plasma based on the data obtained by a set of Quadruple Langmuir Probe (QLP) on Zheda Plasma Experiment Device (ZPED). The turbulence energy transfer is directly embodied in the alternating change of the fluctuation amplitudes between the low frequency shear flow (LFSF) at ∼ 0.2kHz and the drift wave (DW) turbulence at ∼ 1 − 2kHz. The estimation of radial electric field and bispectral analysis of the experiments suggest that the DW turbulence gains the energy from the low frequency turbulence. The energy transport due to the interaction between the LFSF ant the DW turbulence with the magnetic field increase is a possible reason to drive the turbulence energy transfer in the laboratory plasma. 107.Observation of turbulence energy transfer in a cylindrical laboratory plasma.pdf
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On Nonlinear Scattering of Drift Wave by Toroidal Alfvén Eigenmode in Tokamak Plasmas
2023-07-03
聚变理论与模拟中心
106.On Nonlinear Scattering of Drift Wave by Toroidal Alfvén Eigenmode in Tokamak Plasmas.pdf
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Studies of the electron kinetics in capacitively coupled Ar/ 𝐎𝟐 mixture plasma generated by A.C power discharge
2023-07-03
聚变理论与模拟中心
105.Studies of the electron kinetics in capacitively coupled Ar-O2 mixture plasma generated by AC power discharge.pdf
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Machine Learning to Classify Electrostatic Plasma Turbulence in Tokamaks
2022-11-30
聚变理论与模拟中心
104.Machine Learning to Classify Electrostatic Plasma Turbulence in Tokamaks.pdf
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Elongation Effect on Beta-induced Alfvén Eigenmodes
2022-11-30
聚变理论与模拟中心
103.Elongation Effect on Beta-induced Alfvén Eigenmodes.pdf
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Intrinsic Evolution on the Decoupling-Coupling-Decoupling of the plasma Density and Temperature profiles in a Cylindrical Laboratory Plasma Device
2022-11-30
聚变理论与模拟中心
102.Intrinsic Evolution on the Decoupling-Coupling-Decoupling of the plasma Density and Temperature profiles in a Cylindrical Laboratory Plasma Device.pdf
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On scattering and damping of Toroidal Alfvén eigenmode by drift wave turbulence
2022-11-30
聚变理论与模拟中心
101.On scattering and damping of Toroidal Alfvén eigenmode by drift wave turbulence.pdf
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Kinetic investigations of nonlinear electrostatic excitations in quantum plasmas
2022-11-30
聚变理论与模拟中心
100.Kinetic investigations of nonlinear electrostatic excitations in quantum plasmas.pdf
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Effects of dynamic magnetic islands on bootstrap current in toroidal plasmas
2022-11-30
聚变理论与模拟中心
99.Effects of dynamic magnetic islands on bootstrap current in toroidal plasmas.pdf
