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Role of turbulent separatrix tangle in the improvement of the integrated pedestal and heat exhaust issue for stationary-operation tokamak fusion reactors Nucl. Fusion (IF 3.3) Pub Date : 2024-04-16 C.S. Chang, S. Ku, R. Hager, J. Choi, D. Pugmire, S. Klasky, A. Loarte, R.A Pitts
The magnetic separatrix surface is designed to provide the final and critical confinement to the hot stationary-operation core plasma in modern tokamak reactors in the absence of an external magnetic perturbation (MP) or transient magneto-hydrodynamic perturbation, while diverting the exhaust heat to divertor plates. All the stationary operational boundary plasma studies and reactor designs have been
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Analysis and design of fast flow liquid Li divertor for fusion nuclear science facility (FNSF) using coupled plasma boundary and LM MHD/heat transfer codes * Nucl. Fusion (IF 3.3) Pub Date : 2024-04-12 M.S. Islam, J.D. Lore, S. Smolentsev, C.E. Kessel, R. Maingi
The SOLPS-ITER code is utilized to analyze the boundary plasma associated with a fast-flow lithium (Li) divertor configuration in the fusion nuclear science facility (FNSF) tokamak and identify operational regimes with acceptable divertor and core conditions. Plasma transport from the SOLPS-ITER code has been coupled with a liquid metal (LM) MHD/heat transfer code to model a Li open-surface divertor
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Effects of magnetic helicity on 3D equilibria and self-organized states in KTX reversed field pinch Nucl. Fusion (IF 3.3) Pub Date : 2024-04-12 Ke Liu, Guodong Yu, Yuhua Huang, Wenzhe Mao, Yidong Xie, Xianyi Nie, Hong Li, Tao Lan, Jinlin Xie, Weixing Ding, Wandong Liu, Ge Zhuang, Caoxiang Zhu
The reversed field pinch (RFP) is a toroidal magnetic configuration in which plasmas can spontaneously transform into different self-organized states. Among various states, the ‘quasi-single-helical’ (QSH) state has a dominant component for the magnetic field and significantly improves confinement. Many theoretical and experimental efforts have investigated the transitions among different states. This
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Preliminary accident analysis of the loss of vacuum in vacuum vessel for the European DEMO HCPB blanket concept Nucl. Fusion (IF 3.3) Pub Date : 2024-04-12 Xue Zhou Jin, Wolfgang Raskob
Design basis accidents are investigated continuously for the European DEMO reactor accompanying its development. One selected postulated initial event (PIE) is a loss of vacuum (LOVA) in vacuum vessel (VV) with large ingress of air induced by rupture in a VV penetration. It has been investigated for the helium cooled pebble bed (HCPB) blanket concept according to the DEMO baseline 2017. The associated
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Temperature-dependent bubble growth under synergistic interactions of hydrogen and helium in tungsten Nucl. Fusion (IF 3.3) Pub Date : 2024-04-12 Chunjie Niu, Wentao Qin, Siddharth Suman, Weiyuan Ni, Weifeng Liu, Hongyu Fan, Guangjiu Lei, Dongping Liu
A novel theoretical model based on modified diffusion rate equations is proposed to simulate the retention of hydrogen isotopes and the dynamics of bubble growth in tungsten (W) when exposed to simultaneous hydrogen (H) and helium (He) plasma irradiations. Simulation is conducted to assess the influence of temperature as well as simultaneous H and He irradiation at an increasing fluence. Not only to
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Kinetic-ballooning-limited pedestals in spherical tokamak plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-04-11 J.F. Parisi, W. Guttenfelder, A.O. Nelson, R. Gaur, A. Kleiner, M. Lampert, G. Avdeeva, J.W. Berkery, C. Clauser, M. Curie, A. Diallo, W. Dorland, S.M. Kaye, J. McClenaghan, F.I. Parra
A theoretical model is presented that for the first time matches experimental measurements of the pedestal width-height Diallo scaling in the low-aspect-ratio high-β tokamak NSTX. Combining linear gyrokinetics with self-consistent pedestal equilibrium variation, kinetic-ballooning, rather than ideal-ballooning plasma instability, is shown to limit achievable confinement in spherical tokamak pedestals
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Reducing transport via extreme flux-surface triangularity Nucl. Fusion (IF 3.3) Pub Date : 2024-04-10 M.J. Pueschel, S. Coda, A. Balestri, J. Ball, R.J.J. Mackenbach, J.M. Duff, G. Snoep, the TCV Teama
Based on a gyrokinetic analysis of and extrapolation from TCV discharges with large negative and positive triangularity δ, the potential of extreme |δ| in reducing turbulent transport is assessed. Linearly, both positive and negative δ can exert a stabilizing influence, with substantial sensitivity to the radial wavenumber kx . Nonlinear fluxes are reduced at extreme δ in a trapped-electron-mode regime
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Isotope impact on Alfvén eigenmodes and fast ion transport in DIII-D Nucl. Fusion (IF 3.3) Pub Date : 2024-04-10 M.A. Van Zeeland, E. Bass, X.D. Du, W.W. Heidbrink, C. Chrystal, C. Crocker, G. DeGrandchamp, S. Haskey, D. Liu, J. Gonzalez-Martin, K.E. Thome, G. Yu, Y. Zhu
Measurements of beam driven Alfvén Eigenmode (AE) activity in matched deuterium (D) and hydrogen (H) DIII-D plasmas show a dramatic difference in unstable mode activity and fast ion transport for a given injected beam power. The dependence of the unstable AE spectrum in reversed magnetic shear plasmas on beam and thermal species is investigated in the current ramp by varying beam power in a sequence
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Correlation of source parameters and beam properties in the early operation of the full size ITER negative ion beam source Nucl. Fusion (IF 3.3) Pub Date : 2024-04-10 M. Ugoletti, M. Agostini, C. Poggi, E. Sartori, G. Serianni, B. Zaniol
One of the requirements of Heating and current drive Neutral Beam injectors for ITER is a beam homogeneity greater than 90%, to achieve an optimal beam transmission while keeping the heat load consistently low on the acceleration electrodes. The large size and complexity of ITER negative ion source play a key role in determining the homogeneity of the negative ion current of each of the 1280 beamlets
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Transport and stability in sustained high qmin , high βN discharges on DIII-D Nucl. Fusion (IF 3.3) Pub Date : 2024-04-10 J. Huang, X.Z. Gong, X. Jian, J.P. Qian, X.J. Zhang, P.J. Sun, Y.X. Sun, Q.L. Ren, L. Wang, R. Ding, A.M. Garofalo, E.J. Strait, S.Y. Ding, H.Q. Wang, X. Chen, C. Chrystal, R. I. Pinsker, J.M. Lohr, W. Choi, R.J. Hong, T. Rhodes, Q.M. Hu, Z. Yan, G.R. Mckee, C.T. Holcomb
To address the needs for a fusion pilot plan design, DIII-D/EAST joint experiments on DIII-D have demonstrated high normalized beta β N ∼ 4.2, toroidal beta β T ∼ 3.3% with q min > 2, q 95 ⩽ 8 sustained for more than six energy confinement times in high poloidal beta regime. The excellent energy confinement quality (H 98y2 ∼ 1.8) is achieved with an internal transport barrier at high line-averaged
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Plasma surrogate modelling using Fourier neural operators Nucl. Fusion (IF 3.3) Pub Date : 2024-04-09 Vignesh Gopakumar, Stanislas Pamela, Lorenzo Zanisi, Zongyi Li, Ander Gray, Daniel Brennand, Nitesh Bhatia, Gregory Stathopoulos, Matt Kusner, Marc Peter Deisenroth, Anima Anandkumar, the JOREK Teama, MAST Teamb
Predicting plasma evolution within a Tokamak reactor is crucial to realizing the goal of sustainable fusion. Capabilities in forecasting the spatio-temporal evolution of plasma rapidly and accurately allow us to quickly iterate over design and control strategies on current Tokamak devices and future reactors. Modelling plasma evolution using numerical solvers is often expensive, consuming many hours
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Dynamic characteristics of edge plasma profiles during the opening of edge islands on the J-TEXT tokamak Nucl. Fusion (IF 3.3) Pub Date : 2024-04-09 J. Yang, Y. Liang, P. Shi, N.C. Wang, S. Zhou, Z.P. Chen, Z.H. Jiang, F.Y. Mao, Q.H. Yang, J.K. Hua, D. Li, Z.Y. Chen, Y.H. Ding, P. Drews, A. Knieps, E. Wang, S. Xu, H.M. Xiang, J.Q. Cai, J. Huang, Y.C. Gao, J.W. Liu, Y. Luo, L. Liao, the J-TEXT team1a
On the J-TEXT tokamak, the dynamics of edge magnetic topology during the opening of the edge magnetic islands induced by the external Resonant Magnetic Perturbation (RMP) are investigated. The edge island chain is pushed outward by increasing plasma toroidal current to intersect the poloidally and toroidally localized divertor plate, forming an open magnetic island in the Scrape-Off Layer (SOL). The
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Progress in design and experimental activities for the development of an advanced breeding blanket Nucl. Fusion (IF 3.3) Pub Date : 2024-04-09 I. Fernández-Berceruelo, I. Palermo, F.R. Urgorri, D. Rapisarda, M. González, J. Alguacil, J.P. Catalán, J.M. García, J. Kekrt, M. Kordač, I. Krastiņš, T. Melichar, J.Á. Noguerón, E. Platacis, R. Petráš, M. Roldán, A. Rueda, J. Serna, D. Sosa, D. Suàrez
There is no doubt about the interest of achieving as fast as possible the capability to build and operate high performance reactors that finally allow fusion competing in the electricity market. An advanced breeding blanket based on the Dual Coolant Lithium Lead concept with single module segment architecture, designed for the European DEMO, is certainly aligned with such objective. This work describes
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Kinetic plasma-wall interaction using immersed boundary conditions Nucl. Fusion (IF 3.3) Pub Date : 2024-04-09 Yann Munschy, Emily Bourne, Guilhem Dif-Pradalier, Peter Donnel, Philippe Ghendrih, Virginie Grandgirard, Yanick Sarazin
The interaction between a plasma and a solid surface is studied in a (1D-1V) kinetic approach using immersed boundary conditions and penalization to model the wall. Two solutions for the penalized wall region are investigated that either allow currents to flow within the material boundary or not. Essential kinetic aspects of sheath physics are recovered in both cases and their parametric dependencies
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A new type of resonant magnetic perturbation for controlling edge localized modes Nucl. Fusion (IF 3.3) Pub Date : 2024-04-08 Xu Yang, Yueqiang Liu, Xuan Sun, Wei Xu, Li Li, Yuling He, Guoliang Xia, Hanqing Hu, Lina Zhou
A new type of resonant magnetic perturbation (RMP), generated by helical coils, is proposed for controlling the edge localized mode (ELM) in H-mode tokamak plasmas. The helical coil optimization utilizes the MARS-F code (Liu et al 2000 Phys. Plasmas 7 3681) computed linear resistive fluid response of the plasma to the applied RMP field. The optimal helical coils are found to be located near the outboard
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Equilibrium reconstruction constrained by the consistency of current simulation on EAST Nucl. Fusion (IF 3.3) Pub Date : 2024-04-08 Z.H. Qian, N. Xiang, Y.H. Huang, J.L. Chen, X.M. Zhai, L.H. Ma, X.M. Wu, G. Li, G.Q. Li, J.P. Qian, G.L. Lin, Y.F. Jin, H.L. Zhao, K.X. Ye, H.Q. Liu, B. Lyu, Q. Zang
The attainment of a reliable equilibrium is a critical aspect of tokamak experiments and physics analysis. A common method for establishing a reliable equilibrium current involves reconstructing it from indirect measurements, such as those obtained from polarimeter-interferometers (POINT) and motional Stark effect (MSE) systems. However, uncertainties still exist in the reconstruction results. For
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Structure of pellet cloud emission and relation with the local ablation rate Nucl. Fusion (IF 3.3) Pub Date : 2024-04-08 B. Pégourié, E. Geulin, M. Goto, A. Matsuyama, G. Motojima, R. Sakamoto
The experimental reproduction of the conditions of pellet injection expected in future large devices being not possible in present day machines, it is mandatory to validate as thoroughly as possible the available ablation models. Among the different points still under discussion, there is the relation between the spectroscopic measurement of the ablation clouds and the local ablation rate. This relation
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Characterization of SOL profiles and turbulence in ICRF-heated plasmas in EAST Nucl. Fusion (IF 3.3) Pub Date : 2024-04-03 You Li, Ning Yan, Guosheng Xu, Shaocheng Liu, Hua Zhou, Hua Yang, Binfu Gao, Ziqiang Zhou, Nami Li, Qingquan Yang, Miaohui Li, Yifeng Wang, Xin Lin, Panjun Tang, Yufei Zhang, Nannan Wang, the EAST Teama
Scrape-off layer (SOL) profiles and turbulence in ion cyclotron range of frequency (ICRF)-heated plasmas are investigated by the reciprocating probe diagnostic system (FRPs) and gas puff imaging (GPI) diagnostic in EAST. A radio-frequency (RF) sheath potential reaching up to 100 V is identified proximate to the ICRF antennas. Notably, the amplitude of this RF sheath potential escalates in response
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Plasma profile reconstruction supported by kinetic modeling Nucl. Fusion (IF 3.3) Pub Date : 2024-04-03 M. Bergmann, R. Fischer, C. Angioni, K. Höfler, P. Molina Cabrera, T. Görler, T. Luda, R. Bilato, G. Tardini, F. Jenko, the ASDEX Upgrade teama
Combining the analysis of multiple diagnostics and well-chosen prior information in the framework of Bayesian probability theory, the Integrated Data Analysis code (IDA Fischer et al 2010 Fusion Sci. Technol. 58 675–84) can provide density and temperature radial profiles of fusion plasmas. These IDA-fitted measurements are then used for further analysis, such as discharge simulations and other experimental
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Deuterium retention in cyclic transient heat loaded tungsten with increasing cycle numbers Nucl. Fusion (IF 3.3) Pub Date : 2024-04-02 Meng-Chong Ren, Yue Yuan, Fan Feng, Long Cheng, You-Yun Lian, Hai-Shan Zhou, Guang-Hong Lu
Surface damage and microscopic defect evolution of tungsten (W) armor under transient heat loads are key factors for fuel retention in fusion reactors. In this work, experiments were conducted to investigate the effects of cyclic thermal shocks on deuterium (D) retention and surface blistering in W. Thermal shock experiments were conducted on recrystallized W using an electron beam with a power density
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Predicting ion cyclotron emission from neutral beam heated plasmas in Wendelstein7-X stellarator Nucl. Fusion (IF 3.3) Pub Date : 2024-04-02 O. Samant, R.O. Dendy, S.C. Chapman, D. Moseev, R. Ochoukov
Measurements of ion cyclotron emission (ICE) are planned for magnetically confined fusion plasmas heated by neutral beam injection (NBI) in the Wendelstein 7-X stellarator (W7-X). Freshly injected NBI ions in the edge region, whose velocity-space distribution function approximates a delta-function, are potentially unstable against the magnetoacoustic cyclotron instability (MCI), which could drive a
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Machine learning-enhanced model-based scenario optimization for DIII-D Nucl. Fusion (IF 3.3) Pub Date : 2024-03-28 S. Morosohk, B. Leard, T. Rafiq, E. Schuster
Scenario development in tokamaks is an open area of investigation that can be approached in a variety of different ways. Experimental trial and error has been the traditional method, but this required a massive amount of experimental time and resources. As high fidelity predictive models have become available, offline development and testing of proposed scenarios has become an option to reduce the
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Simulations of stand-off runaway electron beam termination by tungsten particulates for tokamak disruption mitigation Nucl. Fusion (IF 3.3) Pub Date : 2024-03-28 Michael A. Lively, Danny Perez, Blas P. Uberuaga, Yanzeng Zhang, Xian-Zhu Tang
Stand-off runaway electron termination by injected tungsten particulates offers a plausible option in the toolbox of disruption mitigation. Tungsten is an attractive material choice for this application due to large electron stopping power and high melting point. To assess the feasibility of this scheme, we simulate runaway collisions with tungsten particulates using the MCNP program for incident runaway
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Reduced model for H-mode sustainment in unfavorable ∇B drift configuration in ASDEX Upgrade Nucl. Fusion (IF 3.3) Pub Date : 2024-03-28 O. Grover, T. Eich, P. Manz, W. Zholobenko, T. Happel, T. Body, U. Plank, P. Ulbl, the ASDEX Upgrade Teama
A recently developed reduced model of H-mode sustainment based on interchange-drift-Alfvén turbulence description in the vicinity of the separatrix matching experimental observations in ASDEX Upgrade has been extended to experiments with the unfavorable ∇B drift. The combination with the theory of the magnetic-shear-induced Reynolds stress offers a possibility to quantitatively explain the phenomena
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High-frequency fluctuation and EHO-like mode in the H-mode pedestal on the EAST tokamak Nucl. Fusion (IF 3.3) Pub Date : 2024-03-28 K.N. Geng, T. Zhang, G.S. Li, W.H. Ye, K.X. Ye, F.B. Zhong, Y. Chao, S.Q. Yang, Lin Yu, Z.Q. Zhou, T.F. Tang, X.X. Zhang, Y.J. Yang, A. Ti, J.B. Liu, N. Yan, G.Q. Li, X. Gao, the EAST Teama
In the pedestal region of the Experimental Advanced Superconducting Tokamak (EAST) during high confinement mode plasma operations with radio-frequency heating, two distinct fluctuations are observed: high-frequency fluctuations (HFFs) and edge harmonic oscillation-like (EHO-like) modes. The HFFs are characterized by intermittent fluctuations with a broadband frequency range of 1−3 MHz and a poloidal
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3D modeling of a double-driver ion source considering ion magnetization: an investigation of plasma symmetry modulation methods Nucl. Fusion (IF 3.3) Pub Date : 2024-03-27 Si-Yu Xing, Fei Gao, Yu-Ru Zhang, Miao Zhao, Guang-Jiu Lei, You-Nian Wang
A three-dimensional fluid model of a double-driver negative hydrogen ion source for China Fusion Engineering Test Reactor (CFETR) neutral beam injection is developed. In this model, the magnetic filter field is generated by 16 permanent magnets, which are surrounded by a soft iron. In order to accurately describe the transportation of charged species in the presence of strong magnetic field, both the
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Effect of resonant magnetic perturbation on edge–core turbulence spreading in a tokamak plasma Nucl. Fusion (IF 3.3) Pub Date : 2024-03-27 Guangzhi Ren, Lai Wei, Jiquan Li, Zheng-Xiong Wang
Turbulence spreading from the edge to the core region of a tokamak with a resonant magnetic perturbation (RMP) is investigated using an electromagnetic Landau-fluid model in a toroidal geometry. As a RMP field with an appropriate amplitude is applied, long-wavelength fluctuations around the resonance surface can be excited due to forced magnetic reconnection. Strong shear flow at the magnetic island
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A package to bridge experimental tokamak data to modelling workflows for heating and transport Nucl. Fusion (IF 3.3) Pub Date : 2024-03-26 G. Tardini, T. Odstrcil, E. Poli, M. Weiland, the ASDEX Upgrade Teama
The comprehensive visual tool TRVIEW is presented, a software to read and fit experimental measurements and equilibrium reconstruction in the frame of nuclear fusion research. At the same time, TRVIEW provides a framework to setup physics workflows, especially those related to heating and transport. The TRVIEW package was originally created in order to provide file input to transport codes such as
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Integral analysis of the effect of material dimension and composition on tokamak neutronics * Nucl. Fusion (IF 3.3) Pub Date : 2024-03-26 Jin Whan Bae, Davin Young, Katarzyna Borowiec, Vittorio Badalassi
The neutronics performance of a tokamak has been identified as an important factor in designing a fusion power plant. The design of the tokamak should not only meet operational parameters such as sufficient tritium breeding, but also safety parameters such as low structural material activation. This paper investigates the impacts of the neutronics metrics for the ARC-class tokamak, a compact tokamak
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Shear Alfvén waves within magnetic islands Nucl. Fusion (IF 3.3) Pub Date : 2024-03-26 Axel Könies, Jinjia Cao, Ralf Kleiber
We calculate Alfvén eigenmodes within a magnetic island (MiAE) which have been conjectured over a decade ago. Starting from a cylindrical plasma equilibrium, we calculate the complete metric of the island interior assuming an iota profile with a constant shear for Wendelstein 7-X parameters. Then, we solve the resulting Magneto-Hydrodynamic equations inside the island optionally considering Finite
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Overview of advances in ASDEX Upgrade plasma control to support critical physics research for ITER and beyond Nucl. Fusion (IF 3.3) Pub Date : 2024-03-26 O. Kudlacek, P. David, I. Gomez, A. Gräter, B. Sieglin, W. Treutterer, M. Weiland, T. Zehetbauer, M. Van Berkel, M. Bernert, T. Bosman, F. Felici, L. Giannone, J. Illerhaus, D. Kropackova, P.T. Lang, M. Maraschek, B. Ploeckl, M. Reich, A. Vedl Kubincova, the ASDEX Upgrade Teama, EUROfusion Tokamak Exploitation Teamb
The successful operation of fusion reactors requires plasma scenarios with good core confinement and acceptable first wall heat loads that are stable and robust to external perturbations. This poses both physical and technological challenges. One of the technologies that addresses these challenges is a complex feedback control system that supports advances in physical understanding and helps to ensure
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Development and validation of fully open-source R2S shutdown dose rate capabilities in OpenMC * Nucl. Fusion (IF 3.3) Pub Date : 2024-03-22 Ethan E. Peterson, Paul K. Romano, Patrick C. Shriwise, Patrick A. Myers
We present the first fully open-source capabilities for shutdown dose rate (SDR) calculations of fusion energy facilities based on the Rigorous 2-Step (R2S) methodology. These capabilities have been implemented in the OpenMC Monte Carlo particle transport code, building on its existing capabilities while also leveraging new features that have been added to the code to support SDR calculations, such
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Influence of AR injection on shielding layer properties and surface protection from transient high heat loads under the QSPA plasma exposures Nucl. Fusion (IF 3.3) Pub Date : 2024-03-22 I.E. Garkusha, V.A. Makhlai, S.S. Herashchenko, M.S. Ladygina, N.N. Aksenov, O.V. Byrka, Yu.V. Petrov, Y.E. Volkova, N.V. Kulik, V.V. Staltsov, D.V. Yelisyeyev
The paper presents experimental studies of a shielding plasma layer formation in front of a tungsten surface exposed with hydrogen plasma in the QSPA-M test-bed facility under the conditions of additional seeding of argon (Ar) along the target surface into the zone of plasma-surface interaction. A pulsed gas injector on the base of a fast electromagnetic valve has been developed for the local injection
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Determination of the mean energy of fast electron losses and anisotropies through thick-target emission on WEST Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 T. Barbui, L.F. Delgado-Aparicio, B. Stratton, O. Chellaï, R. Dumont, K.W. Hill, N.A. Pablant, Y. Savoye-Peysson, the WEST Teama
A new method to obtain the mean energy of fast electron losses in fusion plasmas using a versatile multi-energy hard x-ray (HXR) detector is presented. The method is based on measuring the thick-target emission of tungsten in the divertor region produced by fast electron losses interacting with the target and modeling the tungsten spectra by a Monte Carlo code which simulates the interaction between
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Micro-particle injection experiments in ADITYA-U tokamak using an inductively driven pellet injector Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 Sambaran Pahari, Rahulnath P.P., Aditya Nandan Savita, Pradeep Kumar Maurya, Saroj Kumar Jha, Neeraj Shiv, Raghavendra K., Harsh Hemani, Belli Nagaraju, Sukantam Mahar, Manmadha Rao, I.V.V. Suryaprasad, U.D. Malshe, J. Ghosh, B.R. Doshi, Prabal Kumar Chattopadhyay, R.L. Tanna, K.A. Jadeja, K.M. Patel, Rohit Kumar, Tanmay Macwan, Harshita Raj, S. Aich, Kaushlender Singh, Suman Dolui, D. Kumawat, M.N
A first-of-its-kind, inductively driven micro-particle (Pellet) accelerator and injector have been developed and operated successfully in ADITYA-U circular plasma operations, which may ably address the critical need for a suitable disruption control mechanism in ITER and future tokamak. The device combines the principles of electromagnetic induction, pulse power technology, impact, and fracture dynamics
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Defect production in tungsten under sub-threshold energy irradiation: role of hydrogen and surface effects Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 Hao-Xuan Huang, Yu-Hao Li, Jin-Liang Li, Fang-Fei Ma, Qing-Yuan Ren, Li-Min Liu, Hong-Bo Zhou, Guang-Hong Lu
Despite the low solubility of hydrogen isotopes (HIs) in tungsten (W), their concentration can reach up to ∼10 at.% after low-energy plasma irradiation. This is generally attributed to the vacancies that may accommodate excessive HIs. However, the kinetic energy of incident HIs transferred to W is far below the energy threshold to create a Frenkel pair, the underlying mechanism of defect production
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Studies on the impacts of the pore size and shape on deuterium retention in tungsten fuzzy nanostructures Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 J.Y. Chen, S.Y. Dai, K.R. Yang, C.R. Zu, D.P. Liu, W.Y. Ni, S.G. Liu
Tritium retention in plasma-facing materials is a critical issue that can significantly impact the long-term and steady-state operation of fusion devices. The experiments conducted in the laboratory device MIES have confirmed that the presence of the tungsten (W) nanostructure (called ‘fuzz’) leads to a substantial retention of hydrogen isotopes within W fuzz layer. This observation motivates us to
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Divertor enrichment of recycling impurity species (He, N2, Ne, Ar, Kr) in ASDEX Upgrade H-modes Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 A. Kallenbach, R. Dux, S.S. Henderson, C. Tantos, M. Bernert, C. Day, R.M. McDermott, V. Rohde, A. Zito, the ASDEX Upgrade Teama
Particle balance calculations are done for the seeding species N2, Ne, Ar, Kr as well as He with the aim of obtaining a realistic description of the divertor and core plasma impurity content. Experimental time traces of main plasma impurity densities are fitted by a single, time-independent parameter v z,ineff . This parameter represents the product of the impurity inward pinch in the pedestal, used
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Surface modification of ZrC dispersion-strengthened W under low energy He plasma irradiation Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 Long Li, Zhe Liu, Ze Chen, Chao Yin, Shifeng Mao, Xuebang Wu, Noriyasu Ohno, Minyou Ye
ZrC dispersion-strengthened W exhibits high strength/ductility, low ductile-to-brittle transition temperature, and excellent thermal shock resistance, making it a promising candidate plasma-facing material for future fusion devices. In this study, surface modification of 0.5 wt.% ZrC dispersion-strengthened W (WZrC) under low energy and high fluence He plasma irradiation at high temperature was presented
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MARS-F/K modeling of plasma response and fast ion losses due to RMP in KSTAR Nucl. Fusion (IF 3.3) Pub Date : 2024-03-15 Yueqiang Liu, S.M. Yang, J.S. Kang, J. Van Blarcum, M.J. Choi, H. Frerichs, S.K. Kim
The toroidal single-fluid magnetohydrodynamic (MHD) code MARS-F (Liu et al 2000 Phys. Plasmas 7 3681) and the MHD-kinetic hybrid code MARS-K (Liu et al 2008 Phys. Plasmas 15 112503) are utilized to study the plasma response to the n = 1 (n is the toroidal mode number) resonant magnetic perturbation (RMP), applied to suppress the type-I edge localized mode (ELM) in a KSTAR discharge. Both the resistive-rotating
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Real-time control of NBI fast ions, current-drive and heating properties Nucl. Fusion (IF 3.3) Pub Date : 2024-03-14 M. Weiland, O. Kudlacek, B. Sieglin, R. Bilato, U. Plank, W. Treutterer, the ASDEX Upgrade Team, EUROfusion Tokamak Exploitation Teamb
Conventionally, neutral beam injection (NBI) in tokamaks is controlled via engineering parameters such as injection voltage and power. Recently, the high-fidelity real-time NBI code RABBIT has been coupled to the discharge control system of ASDEX Upgrade. It allows to calculate the NBI fast-ion distribution and hence the properties of NBI in real-time, making it possible to control them directly. We
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Finite element models for radiation effects in nuclear fusion applications Nucl. Fusion (IF 3.3) Pub Date : 2024-03-13 Luca Reali, Sergei L. Dudarev
Deuterium-tritium fusion reactions produce energy in the form of 14.1 MeV neutrons, and hence fusion reactor components will be exposed to high energy neutron irradiation while also being subjected to thermal, mechanical and magnetic loads. Exposure to neutron irradiation has numerous consequences, including swelling and dimensional changes, comparable in magnitude to the peak transient thermal deformations
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Effects of edge-localized electron cyclotron current drive on edge-localized mode suppression by resonant magnetic perturbations in DIII-D Nucl. Fusion (IF 3.3) Pub Date : 2024-03-13 Q.M. Hu, N.C. Logan, Q. Yu, A. Bortolon
According to recent DIII-D experiments (Logan et al 2024 Nucl. Fusion 64 014003), injecting edge localized electron cyclotron current drive (ECCD) in the counter-plasma-current (counter-I p) direction reduces the n = 3 resonant magnetic perturbation (RMP) current threshold for edge-localized mode (ELM) suppression, while co-I p ECCD during the suppressed ELM phase causes a back transition to ELMing
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Investigating the role of edge neutrals in exciting tearing mode activity and achieving flat temperature profiles in LTX-β Nucl. Fusion (IF 3.3) Pub Date : 2024-03-08 Santanu Banerjee, D.P. Boyle, A. Maan, N. Ferraro, G. Wilkie, R. Majeski, M. Podesta, R. Bell, C. Hansen, W. Capecchi, D. Elliott
We present observations, numerical simulations, and analysis from experiments in the Lithium Tokamak Experiment-Beta (LTX-β) in which the electron temperature profile (Te (r)) shifts from flat to peaked and a tearing mode is also destabilized when the average density (ne ave ) exceeds ∼1019 m−3. Flat Te (r) is obtained routinely in LTX-β, with a lithium coated, low-recycling first wall, once the external
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Formation, propagation and conversion of transport barriers triggered by dynamical critical gradient in tokamak plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-03-08 Xiaobo Li, Zhibin Guo, Patrick H. Diamond
In this work, we propose a reduced model with a dynamical critical gradient to study the formation, propagation, and conversion of the transport barriers. In contrast to the commonly adopted static critical gradient, an evolving critical gradient self-consistently softens the profile stiffness, so as to facilitate the generation of transport barriers. This is especially crucial to the internal transport
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Development of water-cooled cylindrical blanket in JA DEMO Nucl. Fusion (IF 3.3) Pub Date : 2024-03-06 Someya Youji, Tanigawa Hiroyasu, Sakamoto Yoshiteru, the Joint Special Design Team for Fusion DEMO
The concept of the tritium breeding blanket for Japan’s DEMOnstration fusion reactor (JA DEMO) has been developed with pressure tightness against in-box loss-of-coolant accidents based on a water-cooled solid breeder concept. The cooling conditions are designed on the pressurized-water reactor water conditions which are the coolant temperature of 290 °C–325 °C and the operating pressure of 15.5 MPa
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Self-consistent, global, neoclassical radial-electric-field calculations of electron-ion-root transitions in the W7-X stellarator Nucl. Fusion (IF 3.3) Pub Date : 2024-03-06 M.D. Kuczyński, R. Kleiber, H.M. Smith, C.D. Beidler, M. Borchardt, J. Geiger, P. Helander
The radial electric field in the Wendelstein 7-X stellarator is computed by means of self-consistent, global, neoclassical simulations using the gyrokinetic particle-in-cell code EUTERPE. The simulation results are compared with local predictions obtained from a transport code using locally computed neoclassical transport coefficients. The analysis focuses on ion-electron-root transitions and investigates
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Observation of fast electron redistribution during saturated kink mode in high βp H-mode discharge with central heating in EAST tokamak Nucl. Fusion (IF 3.3) Pub Date : 2024-03-06 Liqing Xu, Shiyao Lin, Chaowei Mai, Yan Chao, Tianfu Zhou, Wei Wang, Yueheng Huang, Tianqi Jia, Yuqi Chu, Yifeng Wang, Yanmin Duan, Jianwen Liu, the EAST Teama
In the EAST tokamak, we have developed an internal transport barrier (ITB) high-confinement mode (H-mode) scenario characterized by dominant electron heating and centrally peaked electron temperature profiles, facilitated primarily through the combustion of lower hybrid current drive and electron cyclotron radio heating (ECRH). Hard x-ray diagnostics reveal a marked increase in the population of fast
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Deuterium uptake, desorption and sputtering from W(110) surface covered with oxygen Nucl. Fusion (IF 3.3) Pub Date : 2024-03-05 E.A. Hodille, B. Pavec, J. Denis, A. Dunand, Y. Ferro, M. Minissale, T. Angot, C. Grisolia, R. Bisson
Rate equation modelling is performed to simulate D2 and D2+D2+ exposure of the W(110) surface with varying coverage of oxygen atoms (O) from the clean surface up to 0.75 monolayer of O. Density Functional Theory (DFT) calculated energetics are used as inputs for the surface processes and desorption energies are optimized to best reproduce the Thermal Desorption Spectrometry (TDS) experiments obtained
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Full-radius integrated modelling of ASDEX Upgrade L-modes including impurity transport and radiation Nucl. Fusion (IF 3.3) Pub Date : 2024-02-29 D. Fajardo, C. Angioni, R. Dux, E. Fable, U. Plank, O. Samoylov, G. Tardini, the ASDEX Upgrade Teama
An integrated framework that demonstrates multi-species, multi-channel modelling capabilities for the prediction of impurity density profiles and their feedback on the main plasma through radiative cooling and fuel dilution is presented. It combines all presently known theoretical elements in the local description of quasilinear turbulent and neoclassical impurity transport, using the models TGLF-SAT2
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Sawtooth suppression by flux pumping on HBT-EP Nucl. Fusion (IF 3.3) Pub Date : 2024-02-29 Boting Li, J.P. Levesque, G.A. Navratil, M.E. Mauel
This study examines the mechanisms underlying sawtooth suppression in the High Beta Tokamak-Extended Pulse (HBT-EP) device. It is observed that strong-intensity sawtooth activities correlate with reduced-amplitude magnetohydrodynamics (MHD) edge modes which are identified as m/n=3/1 external kink modes, while sawtooth suppression correlates with larger and saturated edge mode amplitudes. To further
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Kinetic plasma-sheath self-organization Nucl. Fusion (IF 3.3) Pub Date : 2024-02-28 Yann Munschy, Emily Bourne, Guilhem Dif-Pradalier, Peter Donnel, Philippe Ghendrih, Virginie Grandgirard, Yanick Sarazin
The interaction between a plasma and a solid surface is studied in a (1D–1V) kinetic framework using a localized particle and convective energy source. Matching the quasineutral plasma region and sheath horizon is addressed in the fluid framework with a zero heat flux closure. It highlights non-polytropic nature of the physics of parallel transport. Shortfalls of this approach compared to a reference
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First-principle based predictions of the effects of negative triangularity on DTT scenarios Nucl. Fusion (IF 3.3) Pub Date : 2024-02-28 A. Mariani, A. Balestri, P. Mantica, G. Merlo, R. Ambrosino, L. Balbinot, D. Brioschi, I. Casiraghi, A. Castaldo, L. Frassinetti, V. Fusco, P. Innocente, O. Sauter, G. Vlad
Plasmas with negative triangularity (NT) shape have been recently shown to be able to achieve H-mode levels of confinement in L-mode, avoiding detrimental edge localised modes. Therefore, this plasma geometry is now studied as a possible viable option for a future fusion reactor. Within this framework, an NT option is under investigation for the full power scenario of the Divertor Tokamak Test (DTT)
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Parallel flows as a key component to interpret Super-X divertor experiments Nucl. Fusion (IF 3.3) Pub Date : 2024-02-28 M. Carpita, O. Février, H. Reimerdes, C. Theiler, B.P. Duval, C. Colandrea, G. Durr-Legoupil-Nicoud, D. Galassi, S. Gorno, E. Huett, J. Loizu, L. Martinelli, A. Perek, L. Simons, G. Sun, E. Tonello, C. Wüthrich, the TCV Teama
The Super-X Divertor (SXD) is an alternative divertor configuration leveraging total flux expansion at the Outer Strike Point (OSP). While the extended 2-Point Model (2PM) predicts facilitated detachment access and control in the SXD configuration, these attractive features are not always retrieved experimentally. These discrepancies are at least partially explained by the effect of parallel flows
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Water activation products generation and transport in DEMO divertor Nucl. Fusion (IF 3.3) Pub Date : 2024-02-27 P. Chiovaro, A. Quartararo, P. Avona, G. Bongiovì, P.A. Di Maio, S. Giambrone, I. Moscato, E. Vallone
In water-cooled nuclear reactors, the issue of neutron-activated products transport along the primary heat transfer system (PHTS) is very demanding, as it is a coupled neutronic/fluid-dynamic problem requiring a challenging balance between accuracy and reasonable computational time. This work addresses the transport of water activation products in large hydraulic circuits. Regarding the nuclear calculations
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A hybrid physics/data-driven logic to detect, classify, and predict anomalies and disruptions in tokamak plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-02-27 R. Rossi, M. Gelfusa, T. Craciunescu, I. Wyss, J. Vega, 0000-0002-3932-3865A. Murari on behalf of JET Contributors56a
Disruptions are abrupt collapses of the configuration that have afflicted all tokamaks ever operated. Reliable observers are a prerequisite to the definition and the deployment of any realistic strategy of countermeasures to avoid or mitigate disruptions. Lacking first principle models of the dynamics leading to disruptions, in the past decades empirical predictors have been extensively studied and
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Small resonant magnetic perturbations result in three-dimensional material transport in the fusion plasma edge Nucl. Fusion (IF 3.3) Pub Date : 2024-02-27 Marcos Navarro, Juri Romazanov, Andreas Kirschner, Jonathan Van Blarcum, Edward Hinson, Tyler Abrams, Oliver Schmitz
Erosion patterns in a 3D magnetic topology are significantly altered when compared to an axisymmetric scenario due to differences in the impurity transport in a plasma environment. When resonant magnetic perturbations are applied in L-Mode discharges, eroded impurities can buildup in regions where an axisymmetric plasma would otherwise lead to zones of net erosion across the full toroidal length of
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Automated experimental design of safe rampdowns via probabilistic machine learning Nucl. Fusion (IF 3.3) Pub Date : 2024-02-23 Viraj Mehta, Jayson Barr, Joseph Abbate, Mark D Boyer, Ian Char, Willie Neiswanger, Egemen Kolemen, Jeff Schneider
Typically the rampdown phase of a shot consists of a decrease in current and injected power and optionally a change in shape, but there is considerable flexibility in the rate, sequencing, and duration of these changes. On the next generation of tokamaks it is essential that this is done safely as the device could be damaged by the stored thermal and electromagnetic energy present in the plasma. This
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Drifts effect on the divertor W leakage mechanisms under different dissipative divertor conditions of EAST Nucl. Fusion (IF 3.3) Pub Date : 2024-02-23 Hui Wang, Guoliang Xu, Rui Ding, Hang Si, Guozhang Jia, Hai Xie, Ran Hai, Zhibin Wang, Dahuan Zhu, Rong Yan, Junling Chen
A new drift module has been developed in the DIVIMP code, enabling two-dimensional simulations of tungsten (W) transport in the edge plasma with full drifts included. By using the SOLPS-DIVIMP code package, the impact of drifts on W transport and screening has been investigated for various levels of dissipative divertor conditions and different divertor geometric configurations in EAST. Simulation
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Mechanism of hydrogen isotope exchange for tritium removal in plasma-facing materials: a multi-scale investigation Nucl. Fusion (IF 3.3) Pub Date : 2024-02-23 F. Sun, C. Hao, D.Y. Chen, H.S. Zhou, Y. Oya, J.P. Zhu, J. Tang, H. Zong, L.M. Luo, Y.C. Wu
The safety of future fusion reactors is critically dependent on the tritium (T) retention in plasma-facing materials. Hydrogen isotope (HI) exchange offers a method to redistribute HIs within solid materials, presenting a feasible approach for removing T from bulk materials and trapped by strong trapping sites. Nonetheless, unraveling the intricate mechanism behind HI exchange remains an urgent yet