Flux pumping and bifurcated relaxations of helical core in 3D magnetohydrodynamic modelling of ASDEX Upgrade plasmas
Max Planck Institute for Plasma Physics（马克斯·普朗克等离子体物理研究所）；Eindhoven University of Technology（埃因霍温理工大学）；Dutch Institute for Fundamental Energy Research（荷兰基础能源研究所）；Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA)（RFX联盟（意大利国家研究委员会、国家能源与新技术机构、国家核物理研究所、帕多瓦大学、威尼斯钢铁公司））；Istituto per la Scienza e la Tecnologia dei Plasmi, CNR（意大利国家研究委员会等离子体科学与技术研究所）；Proxima Fusion GmbH（Proxima Fusion有限公司）
H. Zhang, M. Hoelzl, I. Krebs, A. Burckhart, A. Bock, S. Guenter, V. Igochine, K. Lackner, D. Bonfiglio, E. Fable, F. Stefanelli, R. Ramasamy, H. Zohm, JOREK TE… 展开作者
H. Zhang, M. Hoelzl, I. Krebs, A. Burckhart, A. Bock, S. Guenter, V. Igochine, K. Lackner, D. Bonfiglio, E. Fable, F. Stefanelli, R. Ramasamy, H. Zohm, JOREK TEAM, ASDEX UPGRADE TEAM
Flux pumping was achieved in recent hybrid scenario experiments in the ASDEX Upgrade (AUG) tokamak, which is characterized by a sawtooth-free helical quiescent state and the anomalous radial redistribution of toroidal current density and poloidal magnetic flux. In this article, the self-regulation mechanism of the AUG core plasma during flux pumping is investigated at realistic parameters using the JOREK code based on the two-temperature, nonlinear, full magnetohydrodynamic (MHD) model. A key milestone in AUG flux pumping modelling is achieved by quantitatively reproducing the clamped current density and safety factor profiles in the plasma core, demonstrating the effectiveness of the dynamo effect in sustaining the flux pumping state. The dynamo term, that is of particular interest, is primarily generated by the pressure-gradient driven m/n = 1/1 quasi-interchange-like MHD instability. The work systematically extrapolates the parameter regimes of flux pumping from the above AUG base case by scanning dissipation coefficients and plasma beta. The simulation results reveal bifurcated plasma behaviours at different Hartmann numbers, including distinct states such as flux pumping (helical core with a flat current density), sawteeth (periodic kink-cycling), single crash (without subsequent cycle), and quasi-stationary magnetic island (peaked current density). Transitions from marginal flux pumping state to sawteeth are observed in long-term simulations. The relationships between system dissipation, plasma beta, and different plasma states are carefully analyzed. For practical purposes, the potential operational window for flux pumping, as determined by plasma density and temperature, is estimated. The modelling efforts advance the understanding of flux pumping and facilitate the development of a fast surrogate model for efficient evaluation of flux pumping.
Disruptions in tokamak plasmas may lead to the generation of runaway electrons that have the potential to damage plasma-facing components. Improved understanding of the runaway generation process requires interpretative modelling of experiments. In this work we simulate eight discharges in the ASDEX Upgrade and JET tokamaks, where argon gas was injected to trigger the disruption. We use a fluid modelling framework with the capability to model the generation of runaway electrons through the hot-tail, Dreicer and avalanche mechanisms, as well as runaway electron losses. Using experimentally base…
Microwave interferometer in the Limiter Shadow (MILS) is a new diagnostic, installed on ASDEX Upgrade for electron density measurements in the far Scrape-Off Layer (SOL). At the chosen frequency of 47 GHz the region of measurements varies within several centimeters before and after the limiter, depending on the density. 200 kHz data acquisition allows resolving transient events such as edge localised modes (ELMs) filaments and turbulence filaments. The measured quantities, phase shift and power decay of the microwave beam, which crosses the plasma, are directly connected to the density and do …
In the present paper, the evolution of the Alfvén modes is studied in a realistic ASDEX Upgrade equilibrium by analysing the results of simulations with the global, electromagnetic, gyrokinetic particle-in-cell code ORB5. The energetic particles are modelled both via the newly implemented isotropic slowing-down and with Maxwellian distribution functions. The comparison of the numerical results shows that modelling the energetic particles with the equivalent Maxwellian rather than with the slowing-down, does not affect the frequency of the driven Alfvén mode, while its growth rate appears to be…
An Imaging Neutral Particle Analyser (INPA) diagnostic has been designed for the ASDEX Upgrade (AUG) tokamak. The AUG INPA diagnostic will measure fast neutrals escaping the plasma after CX reactions. The neutrals will be ionised by a 20 nm carbon foil and deflected towards a scintillator by the local magnetic field. The use of a neutral beam injector (NBI) as active source of neutrals will provide radially resolved measurements while the use of a scintillator as active component will allow us to cover the whole plasma along the NBI line with unprecedented phase-space resolution ($ < $ 12 keV …
The theoretical investigation of relevant turbulent transport mechanisms in H-mode pedestals is a great scientific and numerical challenge. In this study, we address this challenge by global, nonlinear gyrokinetic simulations of a full pedestal up to the separatrix, supported by a detailed characterisation of gyrokinetic instabilities from just inside the pedestal top to pedestal centre and foot. We present ASDEX Upgrade pedestal simulations using an upgraded version of the gyrokinetic, Eulerian, delta-f code GENE (genecode.org) that enables stable global simulations at experimental plasma bet…
In some conditions, I-mode plasmas can feature pedestal relaxation events (PREs) that transiently enhance the energy reaching the divertor target plates. To shed light into their appearance, characteristics and energy reaching the divertor targets, a comparative study between two tokamaks $-$ Alcator C-Mod and ASDEX Upgrade $-$ is carried out. It is found that PREs appear only in a subset of I-mode discharges, mainly when the plasma is close to the H-mode transition. Also, the nature of the triggering instability is discussed by comparing measurements close to the separatrix in both devices. T…
An accurate description of turbulence up to the transport time scale is essential for predicting core plasma profiles and enabling reliable calculations for designing advanced scenarios and future devices. Here, we exploit the gap separation between turbulence and transport time scales and couple the global gyrokinetic code GENE to the transport-solver Tango, including kinetic electrons, collisions, realistic geometries, toroidal rotation and electromagnetic effects for the first time. This approach overcomes gyrokinetic codes' limitations and enables high-fidelity profile calculations in expe…
Nonlinear generation of global zonal structures in gyrokinetic simulations of TCV and ASDEX Upgrade magnetic configurations
Max-Planck-Institut für Plasmaphysik（马克斯·普朗克等离子体物理研究所）；De Vinci Higher Education, De Vinci Research Center（德芬奇高等教育，德芬奇研究中心）；Institute of Physics, University of Greifswald（格赖夫斯瓦尔德大学物理研究所）；École Polytechnique Fédérale de Lausanne, Swiss Plasma Center（洛桑联邦理工学院，瑞士等离子体中心）
The development of small- and no-ELM regimes for ITER is a high priority topic due to the risks associated to type-I ELMs. By considering non-linear extended MHD simulations of the ASDEX Upgrade tokamak with the JOREK code, we probe a regime that avoids type-I ELMs completely provided that the separatrix density is high enough. The dynamics of the pedestal in this regime are observed to be qualitatively similar to the so-called quasi-continuous exhaust (QCE) regime in several ways. Repetitive type-I ELMs are substituted by roughly constant levels of outwards transport caused by peeling-balloon…
Quantitative 3D non-linear simulations of shattered pellet injection in ASDEX Upgrade using JOREK
Max Planck Institute for Plasma Physics（马克斯·普朗克等离子体物理研究所）；Beihang University（北京航空航天大学）；ITER Organization（国际热核聚变实验堆组织）；Institute of Plasma Physics of the CAS（捷克科学院等离子体物理研究所）；CEA/IRFM（法国原子能和替代能源委员会/核聚变研究集成设施）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）
Hollow toroidal rotation profiles in strongly electron heated H-mode plasmas in the ASDEX Upgrade tokamak
Max Planck Institute for Plasma Physics（马克斯·普朗克等离子体物理研究所）；Department of Applied Physics and Applied Mathematics, Columbia University（哥伦比亚大学应用物理与应用数学系）；VTT（芬兰技术研究中心VTT）
AXUV synthetic diagnostic for ASDEX Upgrade and its application for SPI simulations
Budapest University of Technology and Economics（布达佩斯技术与经济大学）；Institute for Atomic Energy Research, HUN-REN Centre for Energy Research（原子能研究所，匈牙利研究网络能源研究中心）；Max Planck Institute for Plasma Physics（马克斯·普朗克等离子体物理研究所）；Chalmers University of Technology（查尔姆斯理工大学）；Institute of Plasma Physics, Czech Academy of Sciences（捷克科学院等离子体物理研究所）；ITER Organization（国际热核聚变实验堆组织）；Ecole Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）
Evolution of SPI-induced disruptions in ASDEX Upgrade
Max Planck Institute for Plasma Physics（马克斯·普朗克等离子体物理研究所）；Institute of Plasma Physics of the CAS（捷克科学院等离子体物理研究所）；Institute for Applied Physics（应用物理研究所）
