Article
Physics, Fluids & Plasmas
Javier H. Nicolau, Gyungjin Choi, Jingyuan Fu, Pengfei Liu, Xishuo Wei, Zhihong Lin
Summary: The helical components of the equilibrium magnetic field have significant impacts on zonal flow, while kinetic electrons can reduce zonal flow residue and increase the frequency of low frequency oscillation. Additionally, linear toroidal coupling of multiple toroidal n-harmonics barely affects zonal flows but can generate long wavelength toroidal harmonics with the same toroidal number as the helical magnetic field.
Article
Physics, Fluids & Plasmas
J. Smoniewski, E. Sanchez, I. Calvo, M. J. Pueschel, J. N. Talmadge
Summary: The linear collisionless damping of zonal flows in quasi-symmetric stellarator equilibria was investigated, revealing the impact of zonal flow oscillations and long-time damping on zonal flow evolution, with the zonal flow residual tending to zero for small radial wave-number. The oscillation frequency and damping rate depend on the bounce-averaged radial particle drift, with calculations accurately reproducing the full-volume long-time residual for moderate k(x).
PHYSICS OF PLASMAS
(2021)
Article
Physics, Fluids & Plasmas
Baoyi Xie, Lei Ye, Yang Chen, Pengfei Zhao, Yang Ye, Xin Lin, Heng Lan, Wenfeng Guo, Nong Xiang
Summary: Linear and nonlinear simulations have been conducted for the edge coherent mode (ECM) using the global gyrokinetic code GEM based on experimental parameters from the EAST tokamak. The simulations have shown that ECM is an electrostatic mode with dominant toroidal mode number n=18 and frequency around 48 kHz, propagating along the direction of electron diamagnetic drift, consistent with experimental observations. The nonlinear simulations have further revealed that ECM induces saturated particle and heat fluxes primarily through perturbed electrostatic ExB drift, with roughly equal fluxes of electrons and ions. ECM drives outward particle and heat fluxes, facilitating the maintenance of long pulse H-mode by promoting turbulence.
Article
Physics, Fluids & Plasmas
Jingchun Li, J. Q. Xu, Y. R. Qu, Z. Lin, J. Q. Dong, X. D. Peng, J. Q. Li
Summary: The effect of island width on the interactions between magnetic island and ion temperature gradient turbulence is investigated using the global gyrokinetic approach. It is observed that the coupling between the island and turbulence is strengthened with larger island width. Vortex flow, sensitive to the island width, triggers a potent E x B shear flow and reduces turbulent transport. The shearing rate is minimum at the O-point and maximum at the X-points of the island, regardless of the island width. The relationship between zonal flow amplitude and island width is nonmonotonic, with medium-sized islands partially suppressing it and large islands enhancing it. Larger islands damage the ITG mode structure, increasing turbulent transport at the X-point and decreasing it at the O-point. However, at very small island widths, the turbulence near the X-point is hardly affected while still suppressed inside the island. The influence of different island sizes on turbulence transport is also discussed.
Article
Computer Science, Interdisciplinary Applications
R. Kleiber, M. Borchardt, R. Hatzky, A. Koenies, H. Leyh, A. Mishchenko, J. Riemann, C. Slaby, J. M. Garcia-Regana, E. Sanchez, M. Cole
Summary: This paper describes the current state of the EUTERPE code, focusing on the implemented models and their numerical implementation. The code is capable of solving the multi-species electromagnetic gyrokinetic equations in a three-dimensional domain. It utilizes noise reduction techniques and grid resolution transformation for efficient computation. Additionally, various hybrid models are implemented for comparison and the study of plasma-particle interactions. The code is parallelized for high scalability on multiple CPUs.
COMPUTER PHYSICS COMMUNICATIONS
(2024)
Article
Physics, Fluids & Plasmas
Tajinder Singh, Deepti Sharma, Tanmay Macwan, Sarveshwar Sharma, Joydeep Ghosh, Abhijit Sen, Zhihong Lin, Animesh Kuley
Summary: Global gyrokinetic simulations are conducted to study the electrostatic microturbulence driven by pressure gradients of thermal ions and electrons in the ADITYA-U tokamak geometry. Collisional effects are taken into account. The dominant instability is identified as trapped electron mode (TEM) based on its linear eigenmode structure and propagation in the electron diamagnetic direction. Turbulence and transport are suppressed to some extent by collisional effects. Zonal flow does not play a critical role in TEM saturation, with the inverse cascade dominating. The frequency spectrum of electrostatic fluctuations is in broad agreement with experimentally recorded spectrum in ADITYA-U, ranging from approximately 0 to 50 kHz.
Article
Physics, Fluids & Plasmas
P. Costello, J. H. E. Proll, G. G. Plunk, M. J. Pueschel, J. A. Alcuson
Summary: In tokamaks and neoclassically optimised stellarators, turbulent transport is expected to be the dominant transport mechanism. The trapped-electron mode (TEM), which drives turbulence, has been shown to be absent over large parameter space in quasi-isodynamic stellarator configurations. It is proposed that the passing-electron-driven universal instability may become the fastest-growing instability in these configurations. Gyrokinetic simulations using the Gene code show that the universal instability is dominant in a variety of stellarator geometries, particularly in devices like W7-X that have beneficial TEM stability properties.
JOURNAL OF PLASMA PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
N. Nikulsin, R. Ramasamy, M. Hoelzl, F. Hindenlang, E. Strumberger, K. Lackner, S. Guenter, JOREK Team
Summary: This study reports on the extension of the JOREK code to 3D geometries and the first stellarator simulations carried out with it. The results demonstrate that stable full MHD equilibria are preserved in the reduced model, and the linear growth rates measured in JOREK are in reasonable agreement with the growth rates from the CASTOR3D linear MHD code.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
C. D. Stephens, X. Garbet, J. Citrin, C. Bourdelle, K. L. van de Plassche, F. Jenko
Summary: The tutorial presents a derivation of the QuaLiKiz code, a quasilinear gyrokinetic transport code, aiming to provide a self-contained and complete description of its underlying physics and mathematics from first principles. This work serves as both a comprehensive overview of QuaLiKiz specifically and an illustration for deriving quasilinear models in general.
JOURNAL OF PLASMA PHYSICS
(2021)
Article
Physics, Fluids & Plasmas
P. Trivedi, J. Dominski, C. S. Chang, S. Ku
Summary: This study investigates the differences between core coupled simplified Delta-f and total-f gyrokinetic models and performs large-scale gyrokinetic 3D turbulence simulations. The results show that the radial electric field and its drive must be consistently considered when coupling different models together.
PHYSICS OF PLASMAS
(2022)
Article
Computer Science, Interdisciplinary Applications
Gahyung Jo, Jae-Min Kwon, Janghoon Seo, Eisung Yoon
Summary: A hyperbolic solver is developed for the gyrokinetic equation in tokamak geometry. The effects of basis functions on the numerical solutions and the conservation of physical quantities are investigated. The weighted basis functions show better performance in resolving small scale structures in velocity space.
COMPUTER PHYSICS COMMUNICATIONS
(2022)
Article
Computer Science, Interdisciplinary Applications
PengFei Zhao, Lei Ye, Nong Xiang
Summary: A new method based on time diffusion technique is developed to mitigate numerical instability caused by high frequency electrostatic shear Alfven wave in gyrokinetic simulation of electrostatic turbulence. It fully preserves drift-kinetic electron effects and can be efficiently incorporated with explicit time integration scheme, successfully applied to linear and nonlinear ITG/TEM turbulence simulations, improving numerical stability and enlarging time step size in electrostatic turbulence simulation in tokamaks.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Engineering, Multidisciplinary
Shuaijun Lv, Daolun Li, Wenshu Zha, Luhang Shen, Yan Xing
Summary: This paper proposes a physics-informed residual network (PIResNet) to solve the single-phase seepage equation without labeled data. It adds physical constraints to the neural network, constructs the loss function based on the residuals of the discretized seepage equation, and embeds the boundary conditions as hard constraints. PIResNet has a simple network structure, fast convergence, and easy optimization.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2024)
Article
Physics, Fluids & Plasmas
G. J. Choi, P. Liu, X. S. Wei, J. H. Nicolau, G. Dong, W. L. Zhang, Z. Lin, W. W. Heidbrink, T. S. Hahm
Summary: Global gyrokinetic simulations have found a beta-induced Alfven eigenmode and a low-frequency mode co-existing in the DIII-D tokamak experiments. The low-frequency mode can be excited without fast ions, has a structure consistent with experimental observations, and is not the conventional Alfven-acoustic eigenmode as shown by an antenna scan. The simulated mode structures and parametric dependencies are in agreement with experimental findings.
Article
Physics, Fluids & Plasmas
Tajinder Singh, Javier H. Nicolau, Zhihong Lin, Sarveshwar Sharma, Abhijit Sen, Animesh Kuley
Summary: In this study, global gyrokinetic simulations are conducted to investigate the ion temperature gradient (ITG) and trapped electron mode (TEM) in the LHD stellarator. The simulations reveal that kinetic electron effects significantly enhance the growth rate and turbulent transport levels. Zonal flow is found to dominate the saturation mechanism in ITG turbulence, while the inverse cascade of toroidal harmonics plays a crucial role in the saturation of TEM turbulence. Furthermore, the simulations indicate that ITG turbulence is more effective in driving heat conductivity, while TEM turbulence is more efficient for particle diffusivity.
Article
Physics, Fluids & Plasmas
D. Kennedy, A. Mishchenko, P. Xanthopoulos, P. Helander, A. Banon Navarro, T. Goerler
JOURNAL OF PLASMA PHYSICS
(2020)
Article
Physics, Fluids & Plasmas
M. D. J. Cole, A. Mishchenko, A. Bottino, C. S. Chang
Summary: In this paper, global gyrokinetic simulation of the ion temperature gradient-driven mode-kinetic ballooning mode transition in a toroidal fusion plasma test case was successfully demonstrated using the MV/PT scheme with the particle-in-cell codes XGC and ORB5. The MV/PT scheme combines explicit time integration with mitigation of the electromagnetic gyrokinetic cancelation problem, showing good agreement with results from a conventional continuum code.
PHYSICS OF PLASMAS
(2021)
Article
Physics, Fluids & Plasmas
A. Biancalani, A. Bottino, A. Di Siena, O. Gurcan, T. Hayward-Schneider, F. Jenko, P. Lauber, A. Mishchenko, P. Morel, I Novikau, F. Vannini, L. Villard, A. Zocco
Summary: Nonlinear dynamics of beta-induced Alfven eigenmodes (BAEs) driven by energetic particles (EPs) in the presence of ion-temperature-gradient turbulence were investigated through selfconsistent global gyrokinetic simulations and analytical theory. It was found that EPs modify heat fluxes by introducing energy at large spatial scales, mainly at the toroidal mode number of the dominant BAE and its harmonics. The study also discussed the feedback of global relaxation in temperature profiles induced by BAEs and on turbulence dynamics.
PLASMA PHYSICS AND CONTROLLED FUSION
(2021)
Article
Physics, Fluids & Plasmas
Alessandro Zocco, Alexey Mishchenko, Carolin Nuehrenberg, Axel Koenies, Ralf Kleiber, Matthias Borchardt, Christoph Slaby, Marco Zanini, Torsten Stange, Heinrich Peter Laqua, Kian Rahbarnia, Henning Thomsen, R. C. Wolf, Per Helander, Roman Hatzky, Michael D. J. Cole
Summary: This study investigates magnetic reconnection in W7-X through global numerical simulations, focusing on the destabilization of reconnecting modes by equilibrium current density gradients. The results show that ideal MHD stable W7-X plasmas can be driven towards non-ideal marginality by ECCD, and gyrokinetic ions have a stabilizing effect on these modes. The growth rate of instabilities is dependent on plasma resistivity and electron skin depth for W7-X relevant collisionalities.
Article
Physics, Fluids & Plasmas
F. Vannini, A. Biancalani, A. Bottino, T. Hayward-Schneider, Ph Lauber, A. Mishchenko, E. Poli, G. Vlad
Summary: This study investigates the interaction between Alfven modes and zonal structures using gyrokinetic simulations with the ORB5 code, showing different instability and mode interactions under varying energetic particle concentrations, with three-wave coupling as a possible theoretical explanation.
PHYSICS OF PLASMAS
(2021)
Article
Physics, Fluids & Plasmas
A. Mishchenko, A. Biancalani, A. Bottino, T. Hayward-Schneider, Ph Lauber, E. Lanti, L. Villard, R. Kleiber, A. Koenies, M. Borchardt
Summary: The study examines electromagnetic turbulence in tokamak and stellarator plasmas using global gyrokinetic particle-in-cell codes, with a focus on increasing plasma beta, machine size, ion-to-electron mass ratio, and realistic-geometry features. Investigated are the numerical requirements and computational cost for simulations on computer systems with massive GPU deployments, aiming to enable electromagnetic turbulence simulations in future reactor plasmas.
PLASMA PHYSICS AND CONTROLLED FUSION
(2021)
Article
Physics, Fluids & Plasmas
T. Hayward-Schneider, Ph Lauber, A. Bottino, A. Mishchenko
Summary: Global electromagnetic gyrokinetic simulations are performed using the particle-in-cell code ORB5 for an ITER pre-fusion-power-operation plasma scenario. The analysis reveals the presence of eigenmodes and instabilities at different scale lengths, as well as the observation of unusual modes.
Article
Physics, Fluids & Plasmas
Mohsen Sadr, Alexey Mishchenko, Thomas Hayward-Schneider, Axel Koenies, Alberto Bottino, Alessandro Biancalani, Peter Donnel, Emmanuel Lanti, Laurent Villard
Summary: This study investigates the excitation of toroidicity-induced Alfven eigenmodes (TAEs) and their nonlinear couplings to other modes in a confined toroidal plasma using prescribed external electromagnetic perturbations (antenna). Numerically stable long-time linear simulations are conducted to evaluate the frequencies, growth/damping rates, and the interaction of antenna-driven modes with fast particles.
PLASMA PHYSICS AND CONTROLLED FUSION
(2022)
Article
Physics, Fluids & Plasmas
F. Vannini, A. Biancalani, A. Bottino, T. Hayward-Schneider, P. Lauber, A. Mishchenko, E. Poli, B. Rettino, G. Vlad, X. Wang
Summary: In this study, the evolution of Alfven modes (AMs) in a realistic ASDEX Upgrade equilibrium is investigated using the ORB5 code. The results show that modeling the energetic particles (EPs) with an equivalent Maxwellian distribution does not significantly affect the AM frequency, but underestimates its growth rate by almost 30%. The isotropic slowing-down model allows for a better description of the nonlinear modification of the dominant AM frequency.
Article
Physics, Fluids & Plasmas
A. Mishchenko, A. Bottino, T. Hayward-Schneider, E. Poli, X. Wang, R. Kleiber, M. Borchardt, C. Nuehrenberg, A. Biancalani, A. Koenies, E. Lanti, Ph Lauber, R. Hatzky, F. Vannini, L. Villard, F. Widmer
Summary: Global simulations of electromagnetic turbulence in circular-flux-surface tokamak and ASDEX-Upgrade geometry, tearing instabilities and their combination with the electromagnetic turbulence, nonlinear Alfvenic modes in the presence of fast particles and their combination with the electromagnetic turbulence and global electromagnetic turbulence in Wendelstein 7-X stellarator geometry were carried out using the gyrokinetic particle-in-cell code ORB5 and EUTERPE, demonstrating the computational feasibility of simulating such complex coupled systems.
PLASMA PHYSICS AND CONTROLLED FUSION
(2022)
Article
Physics, Fluids & Plasmas
A. Y. Sharma, M. D. J. Cole, T. Goerler, Y. Chen, D. R. Hatch, W. Guttenfelder, R. Hager, B. J. Sturdevant, S. Ku, A. Mishchenko, C. S. Chang
Summary: The effects of plasma shaping on the global, ion-scale electromagnetic modes are studied, and it is found that the growth rates of these modes are significantly reduced in high elongation and high triangularity geometries.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
Alessandro Zocco, Alexey Mishchenko, Axel Koenies, Matteo Falessi, Fulvio Zonca
Summary: We propose a theoretical scheme for studying the nonlinear interaction of drift-wave-like turbulence and energetic particles in stellarators. The scheme is based on gyrokinetics and separates time and scales for electromagnetic fluctuations using linear ballooning theory. The main equations of the system are derived from two specific moments of the gyrokinetic equation, which are then solved iteratively for a full kinetic nonlinear solution. Our analysis is valid for neoclassically optimized stellarators, and we discuss the resummation of all iterative and perturbative nonlinear kinetic solutions using Feynman diagrams, with emphasis on collisionlessly undamped large-scale structures and wave-like fluctuations generated by energetic particles.
JOURNAL OF PLASMA PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Alexey Mishchenko, Matthias Borchardt, Roman Hatzky, Ralf Kleiber, Axel Koenies, Carolin Nuehrenberg, Pavlos Xanthopoulos, Gareth Roberg-Clark, Gabriel G. G. Plunk
Summary: Global electromagnetic turbulence is simulated in stellarator geometry using the gyrokinetic particle-in-cell code EUTERPE. The evolution of the turbulent electromagnetic field and the plasma profiles is considered. It is found that turbulence is linearly driven at high toroidal mode numbers and lower mode numbers result in a quench of the linear instability drive. The turbulent heat flux is outward and leads to the nonlinear relaxation of the plasma temperature profile.
JOURNAL OF PLASMA PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
A. Mishchenko, A. Biancalani, M. Borchardt, A. Bottino, S. Briguglio, R. Dumont, J. Ferreira, J. P. Graves, T. Hayward-Schneider, R. Kleiber, A. Koenies, E. Lanti, Ph Lauber, H. Leyh, Z. X. Lu, H. Lutjens, B. McMillan, M. Campos Pinto, E. Poli, B. Rettino, B. Rofman, J. N. Sama, C. Slaby, F. Vannini, L. Villard, G. Vlad, X. Wang, F. Widmer, F. Zonca
Summary: This article introduces a software stack being developed as part of a European coordinated effort on tools for burning plasma modelling. The project is organized under the E-TASC initiative and is supported by the Advanced Computing Hubs. It aims to develop codes and release the software stack to the EUROfusion community.
PLASMA PHYSICS AND CONTROLLED FUSION
(2023)
Article
Physics, Fluids & Plasmas
X. Wang, S. Briguglio, A. Bottino, M. Falessi, T. Hayward-Schneider, Ph Lauber, A. Mishchenko, L. Villard, F. Zonca
Summary: In this study, we investigate the nonlinear dynamics of non-adiabatic frequency chirping energetic particle modes using the global gyrokinetic code ORB5. Our results reveal the non-perturbative features of these modes and confirm the linear relationship between the frequency chirping rate and mode saturation amplitude.
PLASMA PHYSICS AND CONTROLLED FUSION
(2023)
