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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, A. Murari, on behalf of JET Contributorsa
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
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Influence of the far non-resonant components of high-n resonant magnetic perturbations on energetic passing ions loss Nucl. Fusion (IF 3.3) Pub Date : 2024-02-23 Yao-Ning Zhang, Kai-Yang He, You-Wen Sun, Bao-Nian Wan, Xue-Min Wu, Peng-Cheng Xie, Yue-Qiang Liu
The influence on the loss of energetic passing ions by the n = 4 resonant magnetic perturbation (RMP) is investigated through numerical simulations (here, n is the toroidal mode number of the RMP field). Dedicated efforts have been made to uncover how the plasma response modifies the loss fractions and underlying mechanisms. The stochastization of the drift surfaces and the particle loss fractions
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Real-time disruption prediction in multi-dimensional spaces leveraging diagnostic information not available at execution time Nucl. Fusion (IF 3.3) Pub Date : 2024-02-23 J. Vega, S. Dormido-Canto, R. Castro, J.D. Fernández, A. Murari, JET Contributorsa
This article describes the use of privileged information to train supervised classifiers, applied for the first time to the prediction of disruptions in tokamaks. The objective consists of making predictions with real-time signals during the discharges (as usual) but after training the predictor also with any kind of data at training time that is not available during discharge execution. The latter
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The role of isotope mass on neutral fueling and density pedestal structure in the DIII-D tokamak Nucl. Fusion (IF 3.3) Pub Date : 2024-02-22 R.A. Chaban, S. Mordijck, A.M. Rosenthal, A. Bortolon, J.W. Hughes, M. Knolker, F.M. Laggner, T.H. Osborne, L. Schmitz, K.E. Thome, T.M. Wilks
Experimental measurements on DIII-D of hydrogen neutral penetration lengths ( λn0 ) on the high field side (HFS) are longer by a factor of 2 than for deuterium consistent with the thermal velocity ratio for neutrals at the same temperature (vthH/vthD=2) . This ratio is constant for both low and high pedestal electron density. At low pedestal density (ne∼4×1019 m −3) , the neutral penetration length
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Thermal hydraulic assessment on the full banana model of COOL blanket for CFETR Nucl. Fusion (IF 3.3) Pub Date : 2024-02-22 Kecheng Jiang, Lei Chen, Long Chen, Xuebin Ma, Qiuran Wu, Xiaoman Cheng, Juancheng Yang, Xuan Zheng, Nianmei Zhang, Mingjiu Ni, Songlin Liu
The Supercritical Carbon Dioxide (S-CO2) cOoled Lithium-Lead (COOL) blanket is under development for Chinese Fusion Engineering and Test Reactor. The thermal hydraulic assessment plays an important role for the comprehensive performance evaluation on the fusion blanket among the multi-physics fields. As the fusion reactor will enter into the engineering construction stage, it is important to study
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Formation of small-scale modes via ECCD injection into KSTAR plasma core Nucl. Fusion (IF 3.3) Pub Date : 2024-02-20 Dong-Kwon Kim, Jaehyun Lee, Minjun J. Choi, Young Dae Yoon, Minho Woo, Minho Kim, Gunsu S. Yun
In KSTAR experiments exhibiting sawtooth instability, the formation of multiple flux tubes (MFTs) has been frequently observed when electron cyclotron resonance heating or a current drive is applied near the inversion radius of the sawtooth. On the global scale, these MFTs evolve into a single flux tube mode or dual modes. The modes are observed as multiple Fourier harmonics in the spectrogram. A comprehensive
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Global linear and nonlinear gyrokinetic simulations of tearing modes Nucl. Fusion (IF 3.3) Pub Date : 2024-02-20 T. Jitsuk, A. Di Siena, M.J. Pueschel, P.W. Terry, F. Widmer, E. Poli, J.S. Sarff
To better understand multi-scale interactions between global tearing modes and microturbulence in the Madison Symmetric Torus (MST) reversed-field pinch (RFP), the global gyrokinetic code Gene is modified to describe global tearing mode instability via a shifted Maxwellian (SM) distribution consistent with experimental equilibria. The implementation of the SM is tested and benchmarked by comparisons
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Observation of resonant tearing mode induced by energetic-ion redistribution due to sawtooth collapse in HL-2A NBI plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-02-20 L.M. Yu, X.L. Zhu, W. Chen, P.W. Shi, X.Q. Ji, Z.B. Shi, R.R. Ma, X.F. He, X.Y. Yan, X.X. He, Y.M. Hou, Y.G. Li, Y. Huang, W. Deng, W.P. Gou, J.Y. Cao, Y.P. Zhang, Yi Liu, D.L. Yu, Z.X. Wang, W.L. Zhong, M. Xu
Recent observations on the HL-2A tokamak give new experimental evidence of resonant tearing modes (r-TMs) caused by the redistribution of energetic ions (EIs) due to sawtooth collapses in neutral beam injection plasmas. The m/n=2/1 (m and n are the poloidal and toroidal mode numbers) r-TMs with frequencies chirping down rapidly are found after strong bursts of fishbone modes and closely followed strong
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Core ion measurements with collective Thomson scattering for DEMO burn control Nucl. Fusion (IF 3.3) Pub Date : 2024-02-20 J. Rasmussen, S.B. Korsholm
DEMO burn control will require measurements of a range of plasma parameters, but the suite of feasible diagnostics for this purpose is limited. Here we assess the accuracy with which a collective Thomson scattering (CTS) diagnostic can provide key measurements for burn control in the planned European DEMO (EU-DEMO). This is based on estimated signal-to-noise ratios for a conceptual diagnostic design
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Synergistic effects of W–Ta alloys exposed to various ELM-like fusion events Nucl. Fusion (IF 3.3) Pub Date : 2024-02-16 Tyler E Ray, Jitendra Kumar Tripathi, Ahmed Hassanein
Recently tungsten alloys have shown capabilities in suppressing morphological changes when exposed to harsh fusion conditions. Morphological changes due to He+ and D+ ions at high temperatures (1000–2000 K) can lead to easier erosion and sputtering of tungten (W) particles towards quenching the fusion plasma. This study investigated W–3Ta alloy as potential plasma facing materials (PFMs) exposed to
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The role of RF-induced E×B flows in the mitigation of scrape-off-layer convective transport during ion cyclotron resonance heating Nucl. Fusion (IF 3.3) Pub Date : 2024-02-16 R. Diab, G. Decristoforo, S. Ahmed, S.G. Baek, Y. Lin, E. Marmar, J.L. Terry, S.J. Wukitch
While multiple experiments have reported a decrease in intermittent fluctuations in the far Scrape-Off-Layer (SOL) during ion cyclotron resonance heating (Antar et al 2010 Phys. Rev. Lett. 105 165001, Li et al 2022 Nucl. Eng. Technol. 54 207–19, Antar et al 2012 Nucl. Fusion 52 103005), the physical mechanism behind this observation has not been fully established yet. In this work, we demonstrate,
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Relationship between magnetic field and tokamak size—a system engineering perspective and implications to fusion development Nucl. Fusion (IF 3.3) Pub Date : 2024-02-14 G. Federici, M. Siccinio, C. Bachmann, L. Giannini, C. Luongo, M. Lungaroni
High temperature superconductors (HTSs) offer the promise of operating at higher magnetic field and temperature. Recently, the use of high field magnets (by adopting HTS) has been promoted by several groups around the world, including new start-up entries, both to substantially reduce the size of a fusion power reactor system and as a breakthrough innovation that could dramatically accelerate fusion
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A new quasilinear model for turbulent momentum transport in tokamaks with flow shear and plasma shaping Nucl. Fusion (IF 3.3) Pub Date : 2024-02-14 Haomin Sun, Justin Ball, Stephan Brunner, Arnas Volčokas
In tokamak experiments, sufficiently strong E × B flow shear reduces turbulent transport, thereby improving the prospects for fusion power plants. It is therefore of great importance to efficiently explore parameter space to find where strong plasma flow can be achieved. To this end, we propose a new, physically motivated quasi-linear model for estimating momentum transport from turbulence in the presence
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First numerical analysis of runaway electron generation in tungsten-rich plasmas towards ITER Nucl. Fusion (IF 3.3) Pub Date : 2024-02-13 J. Walkowiak, M. Hoppe, I. Ekmark, A. Jardin, J. Bielecki, K. Król, Y. Savoye-Peysson, D. Mazon, D. Dworak, M. Scholz
The disruption and runaway electron analysis model code was extended to include tungsten impurities in disruption simulations with the aim of studying the runaway electron (RE) generation. This study investigates RE current sensitivity on the following plasma parameters and modelling choices: tungsten concentration, magnetic perturbation strength, electron modelling, thermal quench time and tokamak
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Efficient training sets for surrogate models of tokamak turbulence with Active Deep Ensembles Nucl. Fusion (IF 3.3) Pub Date : 2024-02-13 L. Zanisi, A. Ho, J. Barr, T. Madula, J. Citrin, S. Pamela, J. Buchanan, F.J. Casson, V. Gopakumar, JET Contributorsa
Model-based plasma scenario development lies at the heart of the design and operation of future fusion powerplants. Including turbulent transport in integrated models is essential for delivering a successful roadmap towards operation of ITER and the design of DEMO-class devices. Given the highly iterative nature of integrated models, fast machine-learning-based surrogates of turbulent transport are
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Isotope effects on transport characteristics of edge and core plasmas heated by neutral beam injection (NBI) in an inward shifted configuration at the Large Helical Device Nucl. Fusion (IF 3.3) Pub Date : 2024-02-13 H. Zhou, Y. Xu, M. Kobayashi, A. Shimizu, R. Seki, K. Tanaka, T. Tokuzawa, M. Yoshinuma, Y. Takemura, H. Takahashi, K. Ogawa, J. Cheng, W. Li, D.N. Wu, Y.J. Zhu, Y. Luo, Y.C. Li, J. Huang, X.Q. Wang, H.F. Liu, H. Liu, X. Zhang
Isotope effects have been investigated in Neutral Beam Injection (NBI) heated plasmas on the Large Helical Device with similar operational parameters between Hydrogen (H) and Deuterium (D) plasmas. Experimental results show that the global energy confinement has no significant dependence on the isotope mass under similar discharge conditions with nearly the same heating power, line-averaged density
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Bursting core-localized ellipticity-induced Alfvén eigenmodes driven by energetic electrons during EAST ohmic discharges Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 P. Su, H. Lan, C. Zhou, J. Bao, A. Liu, X. Zhu, M. Wu, C. Luo, J. Han, J. Wang, H. Liu, T. Zhang, R. Zhou, S. Lin, H. Zhao, Y. Sun, Z. Qiu, N. Chu, T. Tang, Y. Tan, L. Zeng, Z. Gao
A series of high-frequency ( 400∼1000 kHz ) bursting core-localized Alfvén instabilities have been observed during ohmic discharges in EAST tokamak. The instability trigger favours the discharge conditions of low toroidal magnetic field and low electron density. The toroidal mode numbers are mainly n=2∼3 and they propagate in the ion diamagnetic drift (co-current) direction. These modes are radially
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3D radiated power analysis of JET SPI discharges using the Emis3D forward modeling tool Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 B. Stein-Lubrano, R. Sweeney, D. Bonfiglio, J. Lovell, P. Carvalho, L. Baylor, R.S. Granetz, S. Jachmich, E. Joffrin, M. Kong, M. Lehnen, C. Maggi, E. Marmar, E. Nardon, P. Puglia, U. Sheikh, D. Shiraki, S. Silburn, JET Contributorsc
Precise values for radiated energy in tokamak disruption experiments are needed to validate disruption mitigation techniques for burning plasma tokamaks like ITER and SPARC. Control room analysis of radiated power (P rad) on JET assumes axisymmetry, since fitting 3D radiation structures with limited bolometry coverage is an under-determined problem. In mitigated disruptions, radiation is toroidally
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A Gaussian process guide for signal regression in magnetic fusion Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 Craig Michoski, Todd A. Oliver, David R. Hatch, Ahmed Diallo, Mike Kotschenreuther, David Eldon, Matthew Waller, Richard Groebner, Andrew Oakleigh Nelson
Extracting reliable information from diagnostic data in tokamaks is critical for understanding, analyzing, and controlling the behavior of fusion plasmas and validating models describing that behavior. Recent interest within the fusion community has focused on the use of principled statistical methods, such as Gaussian process regression (GPR), to attempt to develop sharper, more reliable, and more
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Ultrahigh neutral pressures in the sub-divertor of the Large Helical Device Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 U. Wenzel, G. Motojima, M. Kobayashi, M. Goto, Y. Hayashi, S. Masuzaki, G. Kawamura, B. Jagielski, V. Haak
In the Large Helical Device (LHD) a low temperature mode (LTM) of the helical divertor was discovered. It combines particle detachment and very large sub-divertor pressures up to 1.4 Pa. During the LTM, the electron temperature in the divertor was in the range from 0.25 to 0.42 eV so that volume recombination occurred. This result is remarkable because in the stellarators LHD and Wendelstein 7-X only
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Design and analysis of a PAM launcher at 4.6 GHz for a new LHCD system on EAST Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 M.H. Li, L. Liu, Y. Yang, L.M. Zhao, W.D. Ma, T.A. Zhou, M. Wang, W.Q. Ma, C.B. Wu, B.J. Ding, H. Jia, Z.G. Wu, W.Y. Zhou, X.L. Li, L. Yin, J. Hillairet, Y. Savoye-Peysson, M. Goniche, A. Ekedahl, X.Z. Gong
To improve the Current Drive (CD) capability in long-pulse (up to ∼1000 s) H-mode operation, it has been decided to develop a new Lower Hybrid Current Drive system at 4.6 GHz with an active cooling Passive Active Multijunction (PAM) launcher on EAST. In this paper, both the radio frequency (RF) and the physical properties of this PAM are studied numerically. The same nominal parallel refractive index
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Calorimetry measurement for energy balance and energy distribution in WEST for L-mode plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 J. Gaspar, J. Gerardin, Y. Corre, J. Daumas, N. Fedorczak, V. Lamaison, C. Bourdelle, G. Ciraolo, A. Ekedahl, A. Gallo, N. Rivals, E. Tsitrone, the WEST Teama
This paper presents the energy balance of 602 pulses from four different experimental campaigns for the WEST tokamak. Different magnetic configurations have been studied, with lower single null (LSN) and upper single null (USN) configuration with deuterium or helium plasmas. The energy balance is closed with an imbalance of about 5% of the total injected energy for most of the campaigns and for different
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Impact of breech geometry and propellant flow on the release of large pellets for the ITER disruption mitigation system Nucl. Fusion (IF 3.3) Pub Date : 2024-02-09 T.E. Gebhart, L.R. Baylor, M. Dibon, M.N. Ericson, E.J. Felske, S.S. Frank, W.L. Gardner, A.G. Ghiozzi, S. Jachmich, U. Kruezi, M. Lehnen, D.A. Velez
Studies have been performed on the release mechanism for large pellets using high pressure gas in a shattered pellet injector. Typically, pellets are dislodged from the cryogenic surface and accelerated down a barrel using high pressure gas delivered by a fast-acting propellant valve. The pellets impact an angled surface which shatters the pellet into many small fragments before entering the plasma
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Magnetic flutter effect on validated edge turbulence simulations Nucl. Fusion (IF 3.3) Pub Date : 2024-02-02 Kaiyu Zhang, Wladimir Zholobenko, Andreas Stegmeir, Konrad Eder, Frank Jenko
Small magnetic fluctuations ( B1/B0∼10−4 ) are intrinsically present in a magnetic confinement plasma due to turbulent currents. While the perpendicular transport of particles and heat is typically dominated by fluctuations of the electric field, the parallel stream of plasma is affected by fluttering magnetic field lines. In particular through electrons, this indirectly impacts the turbulence dynamics
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Multi-scale gyrokinetic simulations of JT-60U L-mode plasma: reduction of the ion scale energy loss due to the nonlinear coupling with the electron scale turbulence Nucl. Fusion (IF 3.3) Pub Date : 2024-02-02 Shaokang Xu, S. Maeyama, T.-H. Watanabe
We investigate the effect of the electron temperature gradient (ETG) driven turbulence on the energy transport in JT-60U L-mode plasma by means of the multi-scale gyrokinetic simulation. In the core region at r/a=0.5 , the instability in the ion scale is driven by the ion temperature gradient (ITG), meanwhile strong unstable ETG modes are found in the electron scale. The nonlinear multi-scale gyrokinetic
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Metallic melt transport across castellated tiles Nucl. Fusion (IF 3.3) Pub Date : 2024-02-02 S. Ratynskaia, K. Paschalidis, K. Krieger, L. Vignitchouk, P. Tolias, M. Balden, M. Faitsch, V. Rohde, Y. Corre, R.A. Pitts, the ASDEX Upgrade Teama, the EUROfusion MST1 Teamb
In future fusion reactors, extended melt pools in combination with strong plasma-induced accelerations, suggest that the metallic melt could reach the gaps between castellated plasma-facing components, potentially accompanied by profound changes in their mechanical response. The first results of a combined experimental and modelling effort to elucidate the physics of melt transport across gaps are
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Development and application of a predictive model for advanced tokamak scenario design Nucl. Fusion (IF 3.3) Pub Date : 2024-02-02 Raphael Schramm, Alexander Bock, Emiliano Fable, Jörg Stober, Marc Maraschek, Maximilian Reisner, Rainer Fischer, Hartmut Zohm, the ASDEX-Upgrade Teama
Advanced tokamak (AT) scenarios applying additional heating during the current ramp (early-heating) usually require many iterations if developed fully empirically. To reduce the required experimental time, a model has been developed in the ASTRA framework, capable of doing predictive simulations of the relevant parameters. As scenario development requires fast iterations and inter-discharge runs, a
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β-induced Alfvén eigenmodes and fishbone driven by energetic electrons in EAST electron heating dominant plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-02-02 Y. Chao, L.Q. Xu, C.W. Mai, M.Q. Wu, Y.M. Duan, S.Y. Lin, K.N Geng, C. Zhou, L.Q. Hu
β-induced Alfvén eigenmodes (e-BAE) and fishbone (e-fishbone) driven by the energetic electrons have been identified on the experimental advanced superconducting tokamak in electron cyclotron resonance heating (ECRH), low hybrid wave (LHW) together with neutral beam injection plasma and in pure radio frequency heating plasma, respectively. The e-BAE is predominantly located near the pedestal region
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On multiple solutions of the Grad–Shafranov equation Nucl. Fusion (IF 3.3) Pub Date : 2024-02-02 C.J. Ham, P.E. Farrell
The Grad–Shafranov equation (GSE) for axisymmetric MHD equilibria is a nonlinear, scalar PDE which in principle can have zero, one or more non-trivial solutions. The conditions for the existence of multiple solutions has been little explored in the literature so far. We develop a simple analytic model to calculate multiple solutions in the large aspect ratio limit. We compare the results to the recently
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Maximizing the ion temperature in an electron heated plasma: from WEST towards larger devices Nucl. Fusion (IF 3.3) Pub Date : 2024-01-30 P. Manas, J.F. Artaud, C. Bourdelle, V. Ostuni, J. Morales, J. Citrin, the WEST Teama
In electron heated plasmas, as the power increases, it is experimentally reported that the ion temperature (Ti ) saturates while the electron temperature (Te ) increases [Beurskens NF 2022]. As on AUG, W7X and elsewhere, Ti saturates around 1.5 keV in WEST L-mode electron heated plasmas while Te reaches 4 keV. Simulations within the integrated model METIS have been compared against a whole WEST campaign
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Comparison of partial and deep energy detachment behaviors with Ar seeding on EAST new corner slot divertor Nucl. Fusion (IF 3.3) Pub Date : 2024-01-30 Kedong Li, Rong Wang, Zhongshi Yang, Kai Wu, Tao He, Guozhang Jia, Xin Lin, Lingyi Meng, Lin Yu, Bin Zhang, Jinhua Wu, Yanmin Duan, Songtao Mao, Qing Zang, Ling Zhang, Tao Zhang, Fudi Wang, Shouxin Wang, Qiping Yuan, Liang Wang, Guang-Nan Luo
It is necessary for future fusion reactor to reduce the heat fluxes on the entire divertor target, especially if view of long pulse high performance operation. In recent EAST experiments, partial energy detachment without confinement degradation, and deep energy detachment with protection of the entire divertor target have both been confirmed on EAST corner slot divertor by argon (Ar) seeding, which
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Plasma elongation effects on energetic particle-induced geodesic acoustic modes in tokamaks Nucl. Fusion (IF 3.3) Pub Date : 2024-01-26 Zhe Chen, Haijun Ren, Colin M Roach
Plasma elongation effects on energetic particle-induced geodesic acoustic modes (EGAMs) are theoretically investigated by using gyro-kinetic equations and the Miller local equilibrium model. Including an arbitrary elongation κ and a finite radial derivative sκ=r∂rκ/κ , a general EGAM dispersion relation is obtained for an arbitrary energetic particle (EP) distribution. In particular, we obtain analytical
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Recommendations for the future regulation of fusion power plants Nucl. Fusion (IF 3.3) Pub Date : 2024-01-26 J. Elbez-Uzan, L. Williams, S. Forbes, A. Dodaro, R. Stieglitz, M.I. Airila, J. Holden, S. Rosanvallon
The discussion in the international community on how fusion power plants (FPPs) will be licenced and regulated is ongoing. As such, there is a concerted drive from the European stakeholders to understand the requirements from such a framework and how to best establish it with the aim of easing the licensing process of FPPs. Initiated by the EUROfusion consortium, a group of European experts were convened
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Impact of helium and hydrogen plasma exposure on surface damage and erosion of tungsten Nucl. Fusion (IF 3.3) Pub Date : 2024-01-26 Ryuichi Sakamoto, Elodie Bernard, Arkadi Kreter, Céline Martin
The impact of helium plasma exposure on the tungsten surface damage structure development and erosion has been investigated by comparing the impact of hydrogen plasma exposure. Crystal orientation dependence of the undulating surface structure formation and erosion rate is observed on the plasma-exposed tungsten surface independently from the plasma species. The top surface of the plasma exposed tungsten
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Diagnostic weight functions in constants-of-motion phase-space Nucl. Fusion (IF 3.3) Pub Date : 2024-01-26 M. Rud, D. Moseev, F. Jaulmes, K. Bogar, J. Eriksson, H. Järleblad, M. Nocente, G. Prechel, B.C.G. Reman, B.S. Schmidt, A. Snicker, L. Stagner, A. Valentini, M. Salewski
The fast-ion phase-space distribution function in axisymmetric tokamak plasmas is completely described by the three constants of motion: energy, magnetic moment and toroidal canonical angular momentum. In this work, the observable regions of constants-of-motion phase-space, given a diagnostic setup, are identified and explained using projected velocities of the fast ions along the diagnostic lines-of-sight
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Global Alfvénic modes excitation in ohmic tokamak plasmas following magnetic reconnection events Nucl. Fusion (IF 3.3) Pub Date : 2024-01-24 A. Kryzhanovskyy, D. Bonfiglio, S. Cappello, M. Veranda
A possible triggering mechanism of Alfvén waves (AWs) in tokamak plasmas, based on localized perturbations induced by magnetic reconnection events, is discussed in the framework of nonlinear viscoresistive 3D magnetohydrodynamics (MHD) modeling. Numerical simulations are performed with the SpeCyl code (Cappello and Biskamp 1996 Nucl. Fusion 36 571) that solves the equations of the viscoresistive MHD
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Modeling of frequency-sweeping Alfvén modes in the TJ-II stellarator Nucl. Fusion (IF 3.3) Pub Date : 2024-01-24 A.G. Ghiozzi, M.J. Mantsinen, P. Pastells, D.A. Spong, A.V. Melnikov, L.G. Eliseev, S.E. Sharapov
Alfvénic activity has been observed in the TJ-II stellarator which resembles the frequency sweeping demonstrated by Alfvén cascade modes in tokamaks. A numerical validation study was conducted using a reduced magnetohydrodynamic (MHD) model to show that such modes could only have been observed in discharges where the rotational transform profile was non-monotonic. During experiments, coil current was
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Pedestal main ion particle transport inference through gas puff modulation with experimental source measurements Nucl. Fusion (IF 3.3) Pub Date : 2024-01-24 A.M. Rosenthal, J.W. Hughes, F.M. Laggner, T. Odstrčil, A. Bortolon, T.M. Wilks, S. Mordijck, M.A. Miller, F. Sciortino
Transport in the DIII-D high confinement mode (H-mode) pedestal is investigated through a periodic edge gas puff modulation (GPM) which perturbs the deuterium density and source profiles. By using absolutely calibrated experimental edge ionization profile measurements, radial profiles of diffusion (D) and convection (v) are calculated into the pedestal region without depending on modeling the edge
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Quasi-mode evolution in a stochastic magnetic field Nucl. Fusion (IF 3.3) Pub Date : 2024-01-24 Mingyun Cao, P.H. Diamond
We present a multi-scale model of quasi-mode evolution in a stochastic magnetic field. The similarity between a quasi-mode and a ballooning mode enables us to address the challenges arising from the disparate geometries in the theories of ballooning modes in the presence of resonant magnetic perturbations. We obtain useful insights into our understanding of ballooning mode dynamics in a stochastic
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Impact of gas injection location and divertor surface material on ITER fusion power operation phase divertor performance assessed with SOLPS-ITER * Nucl. Fusion (IF 3.3) Pub Date : 2024-01-23 Jae-Sun Park, Xavier Bonnin, Richard Pitts, Jeremy Lore
The ITER divertor design and performance assessment, primarily based on the SOLPS-4.3 burning plasma database (Pitts R. et al 2019 Nucl. Mater. Energy 20 100696), assumes the use of beryllium (Be) as the divertor surface material and the injection of gas from the main chamber top. However, the current ITER baseline favors gas injection from the more toroidally symmetric sub-divertor region. This paper
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Enhancement of ECCD by the current condensation effect for stabilizing large magnetic islands caused by neoclassical tearing modes in tokamak plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-01-19 Tong Liu, Zheng-Xiong Wang, Lai Wei, Jialei Wang, Allan Reiman
The radio frequency current condensation effect reported in Reiman and Fisch (2018 Phys. Rev. Lett. 121 225001) is modeled in the nonlinear resistive magnetohydrodynamic code. A series of numerical investigations have been performed to investigate the enhancement of electron cyclotron current drive (ECCD) by the current condensation effect during the control of neoclassical tearing mode (NTM) in tokamak
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Graphene-based electrochemical system for tritium enrichment Nucl. Fusion (IF 3.3) Pub Date : 2024-01-16 R.J. Zabolockis, M. Sondars, G. Vaivars, I. Reinholds, V. Gostilo, V. Malgin, A. Kizilov, A. Lescinskis, A. Felsharuk, L. Avotina, A.S. Teimane, E. Sprugis, E. Pajuste
In this study, a tritium enrichment system in the water phase has been developed based on the combination of a proton exchange membrane (PEM) electrolysis cell and a fuel cell. As the PEM, NafionTM and laboratory-synthesized sulfonated poly(ether ether ketone) membranes modified with an additional graphene layer in order to enhance the tritium separation factor were used. Both differences in the kinetics
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Inter-discharge optimization for fast, reliable access to ASDEX Upgrade advanced tokamak scenario Nucl. Fusion (IF 3.3) Pub Date : 2024-01-16 S. Van Mulders, O. Sauter, A. Bock, A. Burckhart, C. Contré, F. Felici, R. Fischer, R. Schramm, J. Stober, H. Zohm, the ASDEX Upgrade Teamb
Rapid inter-discharge simulation and optimization using the RAPTOR code have allowed the development of a reliable and reproducible early heating strategy for an advanced tokamak (AT) scenario on ASDEX Upgrade. Solving for electron heat and current diffusion in RAPTOR with ad-hoc formulas for heat transport and electron cyclotron current drive (ECCD) efficiency is found to robustly recover the coupled
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Impact of microwave beam scattering by density fluctuations on the electron–cyclotron power deposition profile in tokamaks Nucl. Fusion (IF 3.3) Pub Date : 2024-01-16 J. Cazabonne, S. Coda, J. Decker, O. Krutkin, U. Kumar, Y. Peysson, the TCV Team1a
Electron–cyclotron waves are a tool commonly used in tokamaks, in particular to drive current. Their ability to drive current in a very localized manner renders them an optimal tool for MHD mode mitigation. However, such applications require high accuracy and good control of the power deposition location to efficiently target the magnetic islands. It has been indirectly observed that the suprathermal
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Current drive by using lower hybrid fast wave in VEST Nucl. Fusion (IF 3.3) Pub Date : 2024-01-16 S.H. Kim, J.G. Jo, J.I. Wang, S.B. Lim, S.C. Kim, Y.S. Hwang
An efficient central or off-axis current drive is necessary for the steady-state operation of tokamak fusion reactors. The fast wave branch in the frequency range above two times the lower hybrid resonance frequency at high density, the so-called lower hybrid fast wave (LHFW), could be such an efficient current drive scheme in high density and high temperature of reactor-grade tokamak plasmas. This
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An analytical model of how the negative triangularity cuts off the access to the second stable region in tokamak plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-01-16 Y. Zhang, Z.B. Guo, R.R. Ma, M. Xu
We present an analytical model to evaluate the triangularity-shaping effects in accessing the second stable region for the ideal ballooning mode. Our results indicate that if the triangularity is sufficiently negative, the path from the first to the second stable region will be closed. The reason is that negative triangularity can weaken the stabilizing effect of the ‘magnetic well’, and even convert
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Progress towards edge-localized mode suppression via magnetic perturbations in hydrogen plasmas Nucl. Fusion (IF 3.3) Pub Date : 2024-01-12 N. Leuthold, W. Suttrop, C. Paz-Soldan, M.G. Dunne, R. Fischer, E. Hinson, M. Knolker, F. Laggner, N.C. Logan, T. Osborne, D. Orlov, L. Schmitz, M. Shafer, M. Willensdorfer, the ASDEX Upgrade Teama, the EUROfusion MST1 Teamb
The suppression of edge-localized modes (ELMs) by applying resonant magnetic perturbations (RMPs) is well studied in low collisionality deuterium plasmas as a measure to reduce transient divertor heat loads. However, ELM suppression has yet to be demonstrated in non-nuclear fuels such as hydrogen and hydrogen + helium mixtures which are the main ion species to be used in the ITER pre-fusion power operation
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Fast-ion orbit origin of neutron emission spectroscopy measurements in the JET DT campaign Nucl. Fusion (IF 3.3) Pub Date : 2024-01-12 H. Järleblad, L. Stagner, J. Eriksson, M. Nocente, K. Kirov, M. Rud, B.S. Schmidt, M. Maslov, D. King, D. Keeling, C. Maggi, J. Garcia, E.A. Lerche, P. Mantica, Y. Dong, M. Salewski, JET Contributorsa
In the JET DTE2 deuterium-tritium campaign, neutron diagnostics were employed to measure 14 MeV neutrons originating from D(T,n)4He reactions. In discharge 99965, a diamond matrix detector (KM14) and a magnetic proton recoil (MPRu) detector with a vertical and an oblique line-of-sight were used, respectively. At the timepoints of interest, a significant decrease in the expected diagnostic signals can
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The effect of plasma shaping on high density H-mode SOL profiles and fluctuations in TCV Nucl. Fusion (IF 3.3) Pub Date : 2024-01-12 A. Stagni, N. Vianello, M. Agostini, C. Colandrea, S. Gorno, B. Labit, U. Sheikh, L. Simons, G. Sun, C.K. Tsui, M. Ugoletti, Y. Wang, C. Wüthrich, J.A. Boedo, H. Reimerdes, C. Theiler, the TCV Teama
The impact of plasma shaping on the properties of high density H-mode scrape-off layer (SOL) profiles and transport at the outer midplane has been investigated on Tokamakà configuration variable. The experimental dataset has been acquired by evolving the upper triangularity while keeping the other parameters constant. The scan comprises δup values between 0.0 and 0.6, excluding negative triangularity
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Predict the last closed-flux surface evolution without physical simulation Nucl. Fusion (IF 3.3) Pub Date : 2024-01-10 Chenguang Wan, Shuhang Bai, Zhi Yu, Qiping Yuan, Yao Huang, Xiaojuan Liu, Yemin Hu, Jiangang Li
One of the main challenges in developing effective control strategies for the magnetic control system in tokamaks has been the difficulty in obtaining the last closed-flux surface (LCFS) evolution results from control commands. We have developed a data-driven model that combines a predictive model and a surrogate model for physics simulation programs. This model is capable of predicting the LCFS without
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Deuterium retention in heavy-ion and helium-ion sequentially irradiated tungsten Nucl. Fusion (IF 3.3) Pub Date : 2024-01-09 Hong Zhang, Xuexi Zhang, Yuhong Li, Peng Wang, Li Qiao
Neutron irradiation as well as the presence of helium (He) significantly affects fuel inventory in plasma-facing materials. To investigate the synergistic effects of neutron and He irradiation on deuterium (D) retention behaviors in tungsten, heavy- and He-ion sequentially irradiation experiments were performed with various He fluence and/or heavy-ion damage levels, and then the samples were exposed
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Validation of short-pulse reflectometry turbulence measurements with a synthetic diagnostic Nucl. Fusion (IF 3.3) Pub Date : 2024-01-03 O. Krutkin, U. Kumar, S. Mazzi, S. Brunner, S. Coda, S. Rienäcker, M. van Rossem, the TCV Teama
Experimental measurements of the turbulence amplitude utilizing a short pulse reflectometry method are presented. Two discharges with shaped plasma possessing opposite signs of triangularity are considered and a higher turbulence amplitude is found in the positive triangularity case. To confirm this result, a synthetic short pulse reflectometry diagnostic is developed. Local gyrokinetic modeling with
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First observation of beta-induced Alfvén eigenmode inside the edge magnetic island on the J-TEXT tokamak Nucl. Fusion (IF 3.3) Pub Date : 2024-01-03 J. Yang, Y. Liang, N.C. Wang, P. Shi, S. Zhou, Z.P. Chen, Z.H. Jiang, F.Y. Mao, J.K. Hua, C.K. Li, Q.H. Yang, D. Li, 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, Y.T. Yang, W. Xie, Z.Y. Chen, Y.H. Ding, the J-TEXT Team1
Experiments conducted on the J-TEXT tokamak have provided the first evidence that the Beta-induced Alfvén Eigenmode (BAE) is localized inside the isolated helical flux tube of its edge m/n = 3/1 magnetic island. The observations show that the BAE forms a standing wave inside the magnetic island, with its nodes located at the X- and O-points of the magnetic island. When the island is cut open by contact