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Neural networks for turbulent transport prediction in a simplified model of tokamak plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-23 L M Pomârjanschi
The method of using neural networks (NNs) for turbulent transport prediction in a simplified model of tokamak plasmas is explored. The NNs are trained on a database obtained via test-particle simulations of a transport model in the slab-geometrical approximation. It consists of a five-dimensional input of transport model parameters, and the radial diffusion coefficient as output. The NNs display fast
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Static performance prediction of long-pulse negative ion based neutral beam injection experiment Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-23 Yang Li, Chundong Hu, Yuanzhe Zhao, Yu Gu, Qinglong Cui, Yahong Xie
The mission of negative ion-based neutral beam injection (NNBI) is to conduct experiments with pulses lasting thousands of seconds. It is crucial to develop a simplified physical calculation model for the long-pulse negative ion source in the current NNBI device. This model will be used to evaluate the advantages and disadvantages of the selected parameters prior to the experiment, and to assist in
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Comparison of detachment in Ohmic plasmas with positive and negative triangularity Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-22 O Février, C K Tsui, G Durr-Legoupil-Nicoud, C Theiler, M Carpita, S Coda, C Colandrea, B P Duval, S Gorno, E Huett, B Linehan, A Perek, L Porte, H Reimerdes, O Sauter, E Tonello, M Zurita, T Bolzonella, F Sciortino, the TCV Team6, the EUROfusion Tokamak Exploitation Team7
In recent years, negative triangularity (NT) has emerged as a potential high-confinement L-mode reactor solution. In this work, detachment is investigated using core density ramps in lower single null Ohmic L-mode plasmas across a wide range of upper, lower, and average triangularity (the mean of upper and lower triangularity: δ) in the TCV tokamak. It is universally found that detachment is more difficult
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Effects of plasma resistivity in FELTOR simulations of three-dimensional full-F gyro-fluid turbulence Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-18 M Wiesenberger, M Held
A full-F, isothermal, electromagnetic, gyro-fluid model is used to simulate plasma turbulence in a COMPASS-sized, diverted tokamak. A parameter scan covering three orders of magnitude of plasma resistivity and two values for the ion to electron temperature ratio with otherwise fixed parameters is setup and analysed. Two transport regimes for high and low plasma resistivities are revealed. Beyond a
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Electron ITB formation in EAST high poloidal beta plasmas under dominant electron heating Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-18 Z H Wang, B Zhang, X Z Gong, J P Qian, P Li, Y C Hu, W Wang, T Q Jia, Y T Guo, Q Zang, S X Wang, D A Lu
Plasma confinement and transport in tokamaks play a crucial role in the development of high poloidal beta steady-state operation scenarios. Therefore, it is very important to study the relevant mechanism of internal transport barriers (ITBs), which can help plasmas to obtain better confinement in order to achieve higher fusion gain. This paper mainly introduces the analysis of the characteristics of
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Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-18 S Bannmann, O Ford, U Hoefel, P Zs Poloskei, A Pavone, S Kwak, J Svensson, S Lazerson, P McNeely, N Rust, D Hartmann, E Pasch, G Fuchert, A Langenberg, N Pablant, K J Brunner, R C Wolf, the W7-X Team3
By employing Bayesian inference techniques, the full electron density profile from the plasma core to the edge of Wendelstein 7-X (W7-X) is inferred solely from neutral hydrogen beam and halo Balmer-α (Hα) emission data. The halo is a cloud of neutrals forming in the vicinity of the injected neutral beam due to multiple charge exchange reactions. W7-X is equipped with several neutral hydrogen beam
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Study of ablation phase in double-wire Z-pinch based on optical Thomson scattering Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-18 Wei Wang, Jian Wu, Zhiyuan Jiang, Yuanbo Lu, Zhenyu Wang, Yiming Zhao, Huantong Shi, Li Chen, Xingwen Li, Aici Qiu
Measurement of plasma parameters during the ablation phase in the Z-pinch is crucial for investigating the dynamic behaviors. In this study, optical Thomson scattering was employed to measure the temperature and velocity of the ablation plasma in a double-wire Z-pinch. The scattering spectra profiles were fitted using a model that considered the velocity distribution. The experimental results revealed
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Modelling of power exhaust in TCV positive and negative triangularity L-mode plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-18 E Tonello, F Mombelli, O Février, G Alberti, T Bolzonella, G Durr-Legoupil-Nicoud, S Gorno, H Reimerdes, C Theiler, N Vianello, M Passoni, the TCV Team5, the WPTE Team6
L-mode negative triangularity (NT) operation is a promising alternative to the positive triangularity (PT) H-mode as a high-confinement edge localised mode-free operational regime. In this work, two TCV Ohmic L-mode core density ramps with opposite triangularity δ≃±0.3 are investigated using SOLPS-ITER modelling. This numerical study aims to investigate the power exhaust differences between NT and
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Radial drift of plasma blobs in a toroidal magnetic field with fully kinetic and reduced fluid models Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-16 Nathan Mackey, Sergey Blinov, Adam Stanier, Ari Le
In curved magnetic geometries, field-aligned regions of enhanced plasma pressure and density, termed ‘blobs,’ move as coherent filaments across the magnetic field lines. Coherent blobs account for a significant fraction of transport at the edges of magnetic fusion experiments and arise in naturally-occurring space plasmas. This work examines the dynamics of blobs with a fully kinetic electromagnetic
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Study on stray electrons ejecting from a long-pulse negative ion source for fusion Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-16 Yuwen Yang, Jianglong Wei, Yuming Gu, Yahong Xie, Chundong Hu
The negative ion based neutral beam injection is a desirable plasma heating and current drive method for the large-scale magnetic fusion devices. Due to the strict requirements and difficult development of the negative ion source for fusion, a long-pulse negative ion source has been developed under the framework of the Comprehensive Research Facility for Fusion Technology in China. This negative ion
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Impact of increasing plasma-wall gap on plasma response to RMP fields in ITER Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-15 X Bai, A Loarte, Y Q Liu, S D Pinches, F Koechl, L Li, M Dubrov, Y Gribov
The impact of increasing plasma-wall gap on controlling edge-localized modes (ELMs) is numerically evaluated for the ITER 5 MA/2.65 T H-mode scenarios with full tungsten wall, based on the MARS-F computed plasma response to the applied n= 3–5 (n is the toroidal mode number) resonant magnetic perturbation (RMP) fields. Three new scenarios, referred to as standard, clearance and outergap, are considered
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Influence of the magnetic configuration on the high-field side scrape-off layer at ASDEX Upgrade and the role of the secondary separatrix Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-12 D Hachmeister, C Silva, J Santos, G D Conway, L Gil, A Silva, U Stroth, J Vicente, E Wolfrum, R M McDermott, R Dux, D Brida, R Fischer, B Kurzan, the ASDEX Upgrade Team4, the EUROfusion MST1 Team5
In tokamaks, radial transport is ballooning, meaning it is enhanced at the low-field side (LFS). This work investigates the effect of the magnetic configuration on the high-field side (HFS) scrape-off layer. Our experiments involved L-mode and H-mode discharges at ASDEX Upgrade, in which we scanned the magnetic configuration from a lower to an upper single-null shape, thus varying the location of the
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Modelling of vertical displacement events in tokamaks: status and challenges ahead Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-04 F J Artola, N Schwarz, S Gerasimov, A Loarte, M Hoelzl, the JOREK Team4
In this paper, we revisit the physics of mitigated and unmitigated vertical displacement events (VDEs) and present a summary of present modelling efforts and code capabilities. While 3D MHD simulations of VDEs for AUG and JET are now approaching realistic plasma parameters (e.g. resistivity) and getting closer to experimental observations (e.g. CQ times and vessel forces), the time scales of ITER VDEs
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Identifying quantum effects in seeded QED cascades via laser-driven residual gas in vacuum Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-03 Yinlong Guo, Xuesong Geng, Liangliang Ji, Baifei Shen, Ruxin Li
The discrete and stochastic nature of the processes in the strong-field quantum electrodynamics (SF-QED) regime distinguishes them from classical ones. An important approach to identifying the SF-QED features is through the interaction of extremely intense lasers with plasma. Here, we investigate the seeded QED cascades driven by two counter-propagating laser pulses in the background of residual gases
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Multi-scale recurrent transformer model for predicting KSTAR PF superconducting coil temperature Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-03 Giil Kwon, Hyunjung Lee
Superconducting coils play a critical role in a superconducting-based nuclear fusion device. As the temperature of superconducting magnets increases with a change in current, it is important to predict their temperature to prevent excessive temperature rise of coils and operate them efficiently. We present multi-scale recurrent transformer system, a deep learning model for forecasting the temperature
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Real-time feedback control of β p based on deep reinforcement learning on EAST Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-02 Y C Zhang, S Wang, Q P Yuan, B J Xiao, Y Huang
Recently, with the advancement of the AI field, reinforcement learning (RL) has increasingly been applied to plasma control on tokamak devices. However, possibly due to the generally high training costs of reinforcement learning based on first-principle physical models and the uncertainty in ensuring simulation results align perfectly with tokamak experiments, feedback control experiments using reinforcement
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Ion flow and dust charging at the sheath boundary in dusty plasma with an electron-emitting surface: applications to laboratory and lunar dusty plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-04-02 Suresh Basnet, Amit Patel, Shiva Bikram Thapa, Raju Khanal
In laboratory and space plasmas, the emission of electrons from the surface significantly affects the characteristics of the plasma sheath that forms at that surface, which is crucial to understanding the overall plasma-wall interaction mechanism. In this work, the collisional fluid model is used for laboratory dusty plasma, whereas the collisionless model is used for lunar dusty plasma. We have extended
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On electromagnetic turbulence and transport in STEP Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-28 M Giacomin, D Kennedy, F J Casson, Ajay C J, D Dickinson, B S Patel, C M Roach
In this work, we present first-of-their-kind nonlinear local gyrokinetic (GK) simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-β, reactor-scale, tight-aspect-ratio tokamak Spherical Tokamak for Energy Production (STEP). A prior linear analysis in Kennedy et al (2023 Nucl. Fusion 63 126061) reveals the presence of unstable hybrid kinetic ballooning
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Statistical analysis of magnetic divertor configuration influence on H-mode transitions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-25 Y Andrew, J Dunsmore, T Ashton-Key, H Farre Kaga, E Kim, T L Rhodes, L Schmitz, Z Yan
DIII-D plasmas are compared for two upper divertor configurations: with the outer strike point on the small angle slot (SAS) divertor target and with the outer strike point on the horizontal divertor target (HT). Scanning the vertical distance between the magnetic null point and the divertor target over a range 0.10–0.16 m is shown to increase the threshold power, Pth , and edge plasma power, PLoss
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Performance of the improved tritium decanting facility in support of JET tritium operations Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-21 Alex Withycombe, Nathanya Hayes, David Kennedy, Xavier Lefebvre, the JET Contributors1
A Tritium fuel cycle must have the capability to import tritium inventory from transport storage containers to enable initial inventory stockpiling and future refresh of the inventory. The Joint European Torus (JET) Active Gas Handling System (AGHS) previously imported tritium inventory from Amersham uranium beds (U-beds) via a decanting system housed in the Analytical Make-up box secondary containment
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Validated edge and core predictions of tungsten erosion and transport in JET ELMy H-mode plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-20 H A Kumpulainen, M Groth, S Brezinsek, F Casson, G Corrigan, L Frassinetti, D Harting, J Romazanov, JET contributors5
Predictive edge and core simulations of tungsten (W) erosion and transport in JET ITER-like wall plasmas are shown to be consistent with the experimentally inferred W density in the main plasma, within the uncertainty inherited from the measurements of the deuterium plasma conditions and from the W density measurements. The ERO2.0 code is applied to predicting the W erosion and edge transport, whereas
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Decoupled magnetic control of spherical tokamak divertors via vacuum harmonic constraints Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-19 O P Bardsley, J L Baker, C Vincent
Power exhaust is a critical challenge for spherical tokamak reactors, making the design, optimisation and control of advanced divertor configurations crucial. These tasks are greatly simplified if the poloidal magnetic fields in the core and divertor regions can be varied independently. We present a novel method which facilitates decoupling of the core plasma equilibrium from the divertor geometry
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One-dimensional simulation and validation of divertor detachment induced through nitrogen seeding on HL-2A Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-15 Yulin Zhou, Benjamin Dudson, Ting Wu, Zhanhui Wang, Tianyang Xia, Cailai Zhong, Jinming Gao, Hailong Du, Dongmei Fan
Divertor detachment is a promising method to solve the power exhaust problem in tokamak devices or even in future magnetic fusion reactors. In this work, a detachment experiment (HL-2A shot #38008) with mixed gas seeding (60% nitrogen and 40% deuterium) is simulated using the SD1D module in BOUT++. In the process from attachment to detachment, the target electron temperature and the target ion saturation
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Multi-machine benchmark of the self-consistent 1D scrape-off layer model DIV1D from stagnation point to target with SOLPS-ITER Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-15 G L Derks, E Westerhof, M van Berkel, J H Jenneskens, J T W Koenders, S Mijin, D Moulton, H Reimerdes, H Wu
This paper extends a 1D dynamic physics-based model of the scrape-off layer (SOL) plasma, DIV1D, to include the core SOL and possibly a second target. The extended model is benchmarked on 1D mapped SOLPS-ITER simulations to find input settings for DIV1D that allow it to describe SOL plasmas from upstream to target—calibrating it on a scenario and device basis. The benchmark shows a quantitative match
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Spin-polarized 3He shock waves from a solid-gas composite target at high laser intensities Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-14 L Reichwein, X F Shen, M Büscher, A Pukhov
We investigate collisionless shock acceleration of spin-polarized 3 He for laser pulses with normalized vector potentials in the range a0=100−200 . The setup utilized in the 2D-particle-in-cell simulations consists of a solid carbon foil that is placed in front of the main Helium target. The foil is heated by the laser pulse and shields the Helium from the highly oscillating fields. In turn, a shock
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Modeling turbulent impurity transport in the SOL of DIII-D with a reduced model Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-14 S Zamperini, J H Nichols, T Odstrcil, T Abrams, J A Boedo, J D Elder, D L Rudakov, D C Donovan, J D Duran, A Huang
A novel impurity transport model that approximates SOL turbulence as a fluctuating poloidal electric field is shown to be an acceptable replacement for the traditional approach of assigning an arbitrary radial diffusion coefficient to the impurity ions. The model is implemented in the DIVIMP impurity transport code and applied to an L-Mode tungsten divertor experiment on DIII-D. The poloidal electric
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Coupling between the Alfvén eigenmode and edge-coherent mode on the experimental advanced superconducting tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-14 M Y Wang, A D Liu, C Zhou, G Zhuang, X Feng, J Zhang, X M Zhong, R B Zhang, Y H Wang, J X Yang, H Li, T Lan, J L Xie, H Q Liu, Z X Liu, W Z Mao, W X Ding, W D Liu
High-frequency electromagnetic fluctuations and edge-coherent modes (ECMs) have been detected by Doppler reflectometry (DR) in the pedestal region of the Experimental Advanced Superconducting Tokamak. The frequency of the electromagnetic fluctuations was proportional to the Alfvén velocity and localized in the ellipticity-induced Alfvén eigenmodes (EAEs) gap in the Alfvén continuum. Therefore, the
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Space-time dependent non-local thermal transport effects on laser ablation dynamics in inertial confinement fusion Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-13 W Q Yuan, Z H Zhao, S P Zhu, X T He, B Qiao
In inertial confinement fusion (ICF), electron thermal transport plays a key role in laser ablation and the subsequent implosion processes, which always exhibits intractable non-local effects. Simple modifications of the local Spitzer–Härm model with either an artificially-assumed constant flux limiter or a purely time-dependent one are applied to explain some experimental data, but fail to simultaneously
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Stability analysis of WEST L-mode discharges with improved confinement from boron powder injection Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-12 G Bodner, C Bourdelle, P Manas, A Gallo, K Afonin, A Diallo, R Lunsford, Ph Moreau, A Nagy, F Clairet, C Gil, E Tsitrone, L Vermare, the WEST Team4
WEST L-mode plasmas with dominant electron heating and no core torque source have observed improvements in confinement during boron (B) powder injection. These results are reminiscent of previous powder injection experiments on other devices and gaseous impurity seeding experiments on WEST. During powder injection, the stored energy increased up to 25% due to enhanced ion and electron heat and particle
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A neoclassical validation of balanced and unbalanced rotations on EAST H-mode discharges Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-11 Cheonho Bae, Yifei Jin, Bo Lyu, Baolong Hao, Yingying Li, Xinjun Zhang, Haiqing Liu, Hongming Zhang, Fudi Wang, Jia Fu, Jing Fu, Juan Huang, Long Zeng, Qing Zang, Yichao Li, Liang He, Dian Lu
Predicting residual stress (RS) contribution to intrinsic rotation is one of the major challenges in the study of momentum transport in tokamaks. One efficient experimental means of quantifying RS torque magnitude is to generate radially-flat and near-zero rotation profiles, termed ‘balanced rotations’ in this work, using counter-Ip Neutral Beam Injections (NBIs) to effectively cancel the torques from
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NBI optimization on SMART and implications for scenario development Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-11 M Podestà, D J Cruz-Zabala, F M Poli, J Dominguez-Palacios, J W Berkery, M Garcia-Muñoz, E Viezzer, A Mancini, J Segado, L Velarde, S M Kaye
The SMall Aspect Ratio Tokamak (SMART) under commissioning at the University of Seville, Spain, aims to explore confinement properties and possible advantages in confinement for compact/spherical tokamaks operating at negative vs. positive triangularity. This work explores the benefits of auxiliary heating through Neutral Beam Injection (NBI) for SMART scenarios beyond the initial Ohmic phase of operations
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Flow-shear destabilization of multiscale electron turbulence Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-07 E A Belli, J Candy, I Sfiligoi
The impact of sheared E×B flow on multiscale turbulence is studied with nonlinear gyrokinetic simulations. Simulations are based on DIII-D-like, high-confinement mode (H-mode) pedestal parameters in the regime of low ion temperature gradient drive, where there is a broad spectrum of electron temperature gradient (ETG)-driven turbulence. It is found that E×B shear can have a significant effect on ETG-driven
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Comparison of electron temperature and density measured by helium line intensity ratio and Thomson scattering methods in ECH spherical tokamak plasma Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-06 Takumi Komiyama, Taiichi Shikama, Kazuaki Hanada, Takeshi Ido, Takumi Onchi, Kaori Kono, Akira Ejiri, Makoto Hasegawa, Satoshi Inoue, Masahiro Hasuo, Hiroshi Idei, Qilin Yue, Kengo Kuroda, Aki Higashijima, Pakkapawn Prapan
The electron temperature and density profiles in the midplane of a spherical tokamak plasma produced by electron cyclotron heating (ECH) in Q-shu University experiment with steady-state spherical tokamak (QUEST) are measured by the helium line intensity ratio method. The measured profiles are compared with those obtained by the Thomson scattering method, and the measured temperatures and densities
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Magnetics only real-time equilibrium reconstruction on ASDEX Upgrade Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-05 L Giannone, M Weiland, R Fischer, O Kudlacek, T Lunt, M Maraschek, B Sieglin, W Suttrop, G Conway, M Dunne, E Fable, J C Fuchs, A Gude, V Igochine, P J McCarthy, R McDermott, the ASDEX Upgrade Team1
Real-time reconstruction of the magnetic equilibrium provides fundamental control of plasma shape and position in a tokamak. Details of the implementation of the equilibrium reconstruction code developed for the ASDEX Upgrade tokamak (JANET++) are summarized. Cubic Hermite splines are introduced as current density basis functions for solving the Grad–Shafranov equation. The choice of the optimal Tikhonov
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Theoretical analysis of perturbative high harmonic wave mixing from plasma surfaces Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-04 Fan Xia, Haocheng Tang, Weiqi Tang, Zihang Wen, Zhengyan Li
High harmonic generation modulated by a weakly perturbing laser field enables new wave mixing frequency components, thus allowing in-situ spatiotemporal measurements and wavefront control of attosecond optical pulses. However, perturbative high harmonic wave mixing from plasma surfaces has not been investigated extensively. In this study, we theoretically analyze the plasma high harmonic generation
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Observation of the low electron density and electron temperature in an unmagnetized cascaded arc helium plasma by laser Thomson scattering approach Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-01 Yong Wang, Lina Zhou, Jielin Shi, Yu Li, Cong Li, Chunlei Feng, Hongbin Ding
In this study, the electron density (ne ) and temperature (Te ) in an unmagnetized cascaded arc helium (He) plasma are precisely determined using cutting-edge laser Thomson scattering. In our experimental scope, ne is only 1018 m−3 and Te is less than 0.2 eV, both of which are substantially lower than in linear plasma devices (LPDs). The comparison of ne and Te values in He plasma with those in cascaded
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Simulations of tokamak edge plasma turbulent fluctuations based on a minimal 3D model Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-01 M V Umansky, B I Cohen, I Joseph
A new simulation model for tokamak boundary plasma, SOLT3D, is implemented in the BOUT++ framework (Dudson et al 2009 Comput. Phys. Commun. 180 1467). The simulation model includes a set of dynamic equations describing collisional boundary plasma and neutral gas in the tokamak scrape-off layer and divertor region. The model is verified against standard linear plasma instabilities and available nonlinear
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Hall physics during magnetic reconnection with collision effect Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-01 Yukang Shu, San Lu, Quanming Lu, Kai Huang, Rongsheng Wang, Weixing Ding
The Hall effect, decoupling between the ion and electron motions, is the core mechanism triggering fast reconnection. In plasmas with collision effects such as laboratory facilities, collision can suppress the Hall effect and influence the triggering of fast reconnection. Here, by conducting a series of kinetic simulations with varying collision parameters, we show that collisions can suppress the
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Reversed-direction 2-point modelling applied to divertor conditions in DIII-D * Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-01 J H Nichols, P C Stangeby, A G McLean, J M Canik, A L Moser, M W Shafer, H Q Wang
A predictive form of the extended 2-point model known as the ‘reverse 2-point model’, Rev2PM, is applied to a range of detachment levels in the open lower divertor of DIII-D, showing that the experimentally measured electron temperature (Te ) and pressure (pe ) at the divertor entrance can be calculated within 50% from target measurements, if and only if a posteriori corrections for convective heat
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First measurements with a Coherence Imaging Charge Exchange Recombination Spectroscopy (CICERS) diagnostic at Wendelstein 7-X Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-03-01 R Lopez-Cansino, V Perseo, E Viezzer, D M Kriete, O P Ford, T Romba, P Zs Poloskei, the W7-X Team4
In this work, the Coherence Imaging Spectroscopy technique is exploited for active charge exchange radiation measurements to infer high spatial resolution 2D ion temperature ( Ti ) maps in the core region of Wendelstein 7-X plasmas. A synthetic model of the diagnostic is developed and used for the optimization of the hardware components for the expected ion temperatures ( Ti∼2 keV) prioritizing Ti
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Testing validity of 1D models for impurity fraction scaling for divertor detachment with EDGE2D-EIRENE Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-29 A V Chankin, G Corrigan, A Huber, JET Contributors4
Predictions of the Huber–Chankin (HC) scaling for the upstream impurity fraction were verified in a series of EDGE2D-EIRENE (‘code’) runs for highly radiating plasmas with nitrogen injection. The main quantity extracted from the code was poloidally averaged, from X-point to X-point, separatrix impurity fraction cZ in the main scrape-off layer (SOL). Variation of the main working gas (H, D and T) revealed
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Experimental study of the effect of geodesic curvature on turbulent transport in magnetically confined plasma Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-29 S Nishimoto, K Nagaoka, M Nakata, S Yoshimura, K Tanaka, M Yokoyama, M Nunami, T Tokuzawa, C Suzuki, R Seki, M Yoshinuma, G Motojima, K Ida, Y Suzuki
An experimental study has demonstrated the impact of the geodesic curvature of the magnetic field line on turbulent ion-heat transport in magnetically confined plasma using the large helical device. Statistical analyses with corrected Akaike Information Criterion and multiple regression have revealed that the geodesic curvature indicates a dominant contribution to the ion-heat transport. Geodesic curvature
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Gyrokinetic simulation of pedestal degradation correlated with enhanced magnetic turbulence in a DIII-D ELMy H-mode discharge Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-29 X Jian, J Chen, C Holland, V S Chan, X R Zhang, G Yu, Z Yan
Gyrokinetic simulation of a dedicated pedestal density ramping-up discharge on DIII-D can reproduce the enhancement of magnetic turbulence in the pedestal, which is identified to be caused by micro-tearing modes (MTMs). An increase of MTM amplitude results in higher electron thermal diffusivity, consistent with experimentally observed lower electron temperature gradient and degraded pedestal height
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Effect of the rising edge of ultrashort laser pulse on the target normal sheath acceleration of ions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-27 J Psikal
Laser-driven ion acceleration is theoretically/numerically mostly studied with the assumption of an idealised main ultrashort pulse of the Gaussian temporal shape, where nanosecond/multi-picosecond pedestals and short prepulses preceding the main pulse can be incorporated in the form of modifications in the initial density profile of irradiated ionised targets. This paper shows that the relatively
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QScatter: numerical framework for fast prediction of particle distributions in electron-laser scattering Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-23 Óscar Amaro, Marija Vranic
The new generation of multi-PetaWatt laser facilities will allow tests of strong field quantum electrodynamics (QED), as well as provide an opportunity for novel photon and lepton sources. The first experiments are planned to study the (nearly) head-on scattering of intense, focused laser pulses with either relativistic electron beams or high-energy photon sources. In this work, we present a numerical
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A mixed Fourier-variational approach to solve differential or integro-differential wave equations for magnetised plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 Dirk Van Eester, E A Lerche
The All ORders Spectral Algorithm (AORSA) wave equation solver by Jaeger (Jaeger et al 2001 Phys. Plasmas 8 1573) solves the integro-differential wave equation relevant for the radio frequency (RF) domain and for fusion-relevant conditions in tokamaks or stellarators, retaining all finite Larmor radius corrections by substituting the continuous Fourier integrals by a sum over a discrete set of modes
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Investigations into penetration depth profiles of hydrogenic species in beryllium plasma-facing components via molecular dynamics simulations Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 A Liptak, K D Lawson, M I Hasan
During the operation of nuclear fusion reactors, plasma-facing components lining the reactor vessel are continually bombarded by plasma species. The penetration and subsequent trapping of these bombarding plasma ions has implications for component damage as well as in-vessel inventory. Accurately predicting the expected ion penetration depth profiles at a range of plasma ion and surface temperatures
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A new FILDSIM model for improved velocity-space sensitivity modelling and reconstructions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 Bo S Schmidt, Jesús Poley-Sanjuán, José Rueda-Rueda, Joaquín Galdon-Quíroga, Marcelo Baquero-Ruiz, Henrik Järleblad, Bernard C G Reman, Mads Rud, Andrea Valentini, Manuel García-Muñoz, Mirko Salewski
We present a new version of the FILDSIM code (Galdon-Quíroga et al 2018 Plasma Phys. Control. Fusion 60 105005), which significantly refines the modelling of the fast-ion loss detector (FILD) signal. We demonstrate that the FILD weight functions computed using this new version of FILDSIM are more accurate relative to synthetic benchmarks than those computed using the previous version. Thus, the new
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Effect of hyper-resistivity on ballooning modes with resonant magnetic perturbations Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 S Y Chen, M L Mou, T Q Liu, Y M Zhang, L K Dong, H Fan, X Lu, C J Tang
The impact of hyper-resistivity on non-ideal ballooning modes (BMs) is studied in the presence of resonant magnetic perturbation (RMP) through considering the hyper-resistivity, resistivity and diamagnetic effect in the BM model with an equilibrium distorted by RMP, which is stable for ideal BMs. Similar to the resistivity, the hyper-resistivity is also destabilizing for the BMs, but RMPs make the
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Stability and debris-mitigation of a solid tape target delivery system for intense laser-matter interactions towards high-repetition-rate Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 Michael Ehret, Diego de Luis, Jon Imanol Apiñaniz, Jose Luis Henares, Roberto Lera, José Antonio Pérez-Hernández, Pilar Puyuelo-Valdes, Luca Volpe, Giancarlo Gatti
The VEGA-3 laser system at the Centro de Láseres Pulsados delivers laser pulses up to 1 PW at 1 Hz repetition rate, focused to intensities up to 2.5×1020 W cm−2. A versatile and compact solid target suitable for up to 0.05 Hz is presented which can operate in the challenging petawatt laser environment close to the laser-plasma interaction. Strips are spooled in a tape target system to deliver a solid
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Reduction of fast ion drag in the presence of ‘hollow’ non-Maxwellian electron distributions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-13 A P L Robinson
It is argued that the electronic stopping power in a plasma should be expected to exhibit significant differences in the presence of effects that shift the electron distribution function away from a Maxwellian. This is potentially important for nuclear reactions produced by laser-driven ion beams, where non-Maxwellian effects may have to be considered. We have calculated the electronic stopping power
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Soft H-L back transitions by applying resonant magnetic perturbations in the low q 95 EAST plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-13 L M Shao, R Chen, Y W Sun, M F Wu, W Gao, K D Li, X Li, M N Jia, Q Ma, L Y Meng, H H Wang, M R Wang, G S Xu, Q Zang, L Zhang, C Zhou, the EAST Team3
Controlled ‘soft’ H-L transitions with a simultaneous ramp-down of plasma density and stored energy, generated by applying resonant magnetic perturbations (n = 2 RMPs), relevant to the control of ITER terminations, are achieved in the EAST tokamak. These H-mode plasmas are run at median electron densities and a low safety factor q 95 ( q95=3.5 –4.0) under neutral beam injection (NBI) dominant heating
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Metal evaporation dynamics in electron cyclotron resonance ion sources: plasma role in the atom diffusion, ionisation, and transport Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-13 A Pidatella, D Mascali, A Galatà, B Mishra, E Naselli, L Celona, R Lang, F Maimone, G S Mauro, D Santonocito, G Torrisi
We present a numerical study of metals dynamics evaporated through resistively heated ovens in electron cyclotron resonance (ECR) plasma traps, used as metal ion beam injectors for accelerators and multi-disciplinary research in plasma physics. We use complementary numerical methods to perform calculations in the framework of the PANDORA trap. The diffusion and deposition of metal vapours at the plasma
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Anomalous hot electron generation via stimulated Raman scattering in plasma with up-ramp density profiles Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-08 X Y Jiang, S M Weng, H H Ma, C F Wu, Z Liu, M Chen, B Eliasson, Z M Sheng
We investigate the evolution and propagation of the electron plasma waves (EPWs) excited by stimulated Raman scattering (SRS) in the inhomogeneous plasma theoretically and numerically with particle-in-cell (PIC) simulations. A theoretical model of EPWs in inhomogeneous plasmas is presented, which shows that the evolution of the EPW wavenumber is mainly related to the plasma density profile rather than
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Parametric analysis of electron beam quality in laser wakefield acceleration based on the truncated ionization injection mechanism Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-07 Srimanta Maity, Alamgir Mondal, Eugene Vishnyakov, Alexander Molodozhentsev
Laser wakefield acceleration (LWFA) in a gas cell target separating injection and acceleration section has been investigated to produce high-quality electron beams. A detailed study has been performed on controlling the quality of accelerated electron beams using a combination of truncated ionization and density downramp injection mechanisms. For this purpose, extensive two-dimensional particle-in-cell
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The fastVFP code for solution of the Vlasov–Fokker–Planck equation Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-07 A R Bell, M Sherlock
We describe the fastVFP code for solution of the Vlasov–Fokker–Planck equation for non-local electron transport and the generation of magnetic field, especially for application to laser-produced plasmas. We describe the essential features of the code that make it fast and robust and suitable for inclusion as a transport package in a fluid simulation. We present a few sample results that demonstrate
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Investigation of core transport changes in DIII-D discharges with off-axis T e profile peaks Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-07 R Xie, M E Austin, K Gentle, C C Petty
DIII-D discharges that transition to H-mode solely with off-axis electron cyclotron heating (ECH) often exhibit strong off-axis peaking of electron temperature profiles at the heating location. Electron heat transport properties near these off-axis temperature peaks have been studied using modulated ECH. The Fourier analyzed electron temperature data have been used to infer electron thermal diffusivity
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Investigation of γ-photon sources using near-critical density targets towards the optimization of the linear Breit–Wheeler process Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-06 Iuliana-Mariana Vladisavlevici, Xavier Ribeyre, Daniel Vizman, Emmanuel d’Humières
In this paper we analyze the production of high energy synchrotron gamma photons in laser-plasma interaction for a laser intensity in 1022– 5⋅1023Wcm−2 and a near-critical density target using two dimensional particle-in-cell simulations. In the optimum configuration to maximize the conversion efficiency of the laser energy to γ-photons, we studied the production of electron–positron pairs by the linear
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Adaptive low-temperature plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-06 Michael Keidar
This paper highlights the uniqueness of low-temperature plasma (LTP), that is its ability to change the chemical composition in situ. An adaptive LTP platform is a plasma device that can adjust the plasma composition to obtain optimal desirable outcomes through its interaction with a target. This approach relies on the ability of measuring the real time response of target to plasma action. In biological
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PROTO-SPHERA: a magnetic confinement experiment which emulates the jet + torus astrophysical plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-06 Franco Alladio, Paolo Micozzi, Luca Boncagni, Annamaria Pau, Shayesteh Naghinajad, Samanta Macera, Yacopo Damizia, Paolo Buratti, Francesco Filippi, Giuseppe Galatola Teka, Francesco Giammanco, Edmondo Giovannozzi, Matteo Iafrati, Alessandro Lampasi, Paolo Marsili
The PROTO-SPHERA experiment, built at the CR-ENEA laboratory in Frascati, was in part inspired by the jet + torus astrophysical plasmas, a rather common morphology in Astrophysics. This paper illustrates how the said plasma morphology can be reproduced in a laboratory with the setup of the PROTO-SPHERA experiment. The experiment as such displayed the appearance and sustainment of a plasma torus around