Plasma Physics and Controlled Fusion最新文献

{"title":"Kinetic modeling of the plasma-wall interaction in the DTT divertor region","authors":"F. Cichocki, P. Innocente, V. Sciortino, P. Minelli, F. Taccogna","doi":"10.1088/1361-6587/ad1a41","DOIUrl":"https://doi.org/10.1088/1361-6587/ad1a41","url":null,"abstract":"\u0000 A precise estimate of the local energy fluxes and erosion profiles at the divertor monoblocks of a fusion reactor requires a kinetic modeling of the plasma-wall interaction. Here, a two-dimensional Particle-in-Cell code is used to quantify the particle and energy fluxes and ion impact distribution functions across the divertor monoblocks of the ``Divertor Tokamak Test'' reactor, focusing on poloidal gaps with toroidal beveling. The considered critical locations are close to the strike points at both Inner and Outer Vertical Targets. A worst-case scenario for particle fluxes corresponding to attached plasma conditions and featuring a single-null magnetic configuration is assumed. The separate and cumulative effects of including electron wall emission and ions/electrons collisions with a background neutral gas (recycled at the walls) are also assessed. It is found that a non-negligible energy flux affects the shadowed regions of the monoblocks, especially when accounting for collisions, and that the ion impact distribution functions are strongly influenced by the considered kinetic effects, with important implications on the induced sputtering yield.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"42 14","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139451740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Initial Fulcher band observations from high resolution spectroscopy in the MAST-U divertor","authors":"N Osborne, K Verhaegh, M D Bowden, T Wijkamp, N Lonigro, P Ryan, E Pawelec, B Lipschultz, V Soukhanovskii, T van den Biggelaar, the MAST-U Team2","doi":"10.1088/1361-6587/ad1654","DOIUrl":"https://doi.org/10.1088/1361-6587/ad1654","url":null,"abstract":"High resolution <inline-formula>\u0000<tex-math><?CDATA $textrm{D}^{*}_{2}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>∗</mml:mo></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"ppcfad1654ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and (shorter-legged) elongated divertor density ramps with <inline-formula>\u0000<tex-math><?CDATA $textrm{D}_{2}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"ppcfad1654ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> fuelling from the mid-plane high-field side. In the Super-X case, the upper divertor showed ground state rotational temperatures of the <inline-formula>\u0000<tex-math><?CDATA $textrm{D}_{2}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"ppcfad1654ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> molecules increasing from ~6000 K, starting at the detachment onset, to ~9000 K during deepening detachment. This was correlated with the movement of the Fulcher emission region towards the X-point, which is in turn correlated with the movement of the ionisation source. The increase in rotational temperature occurred throughout the divertor except near the divertor entrance, where ionisation was still the dominant process. Qualitative agreement was obtained between the lower and upper divertor. Similar rotational temperatures were obtained in the elongated divertor before the detachment onset, although the increase in rotational temperature during detachment was less clearly observed as less deep detachment was obtained. The measured vibrational distribution of the upper Fulcher state does not agree with a ground state Boltzmann distribution but shows a characteristically elevated population in the <italic toggle=\"yes\">ν</italic> = 2 and <italic toggle=\"yes\">ν</italic> = 3 bands in particular; which is strongly correlated to the <italic toggle=\"yes\">rotational</italic> temperature.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"7 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139095003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On scalable liquid-metal MHD solvers for fusion breeder blanket multiphysics applications","authors":"R W Eardley-Brunt, A J Dubas, A Davis","doi":"10.1088/1361-6587/ad100a","DOIUrl":"https://doi.org/10.1088/1361-6587/ad100a","url":null,"abstract":"While substantial research effort has been made recently in the development of computational liquid-metal magnetohydrodynamics (MHD) solvers, this has typically been confined to closed-source and commercial codes. This work aimed to investigate some open-source alternatives. Two OpenFOAM-based MHD solvers, <monospace>mhdFoam</monospace> and <monospace>epotFoam</monospace>, were found to show strong scaling profiles typical of fluid dynamics codes, while weak scaling was impeded by an increase in iterations per timestep with increasing resolution. Both were found to accurately solve the Shercliff and Hunt flow problems for Hartmann numbers from 20 to 1000, except for <monospace>mhdFoam</monospace> which failed in the Hunt flow <inline-formula>\u0000<tex-math><?CDATA $mathit{Ha} = 1000$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mi>H</mml:mi><mml:mi>a</mml:mi></mml:mrow><mml:mo>=</mml:mo><mml:mn>1000</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"ppcfad100aieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> case. A basic inductionless MHD solver was implemented in the Proteus MOOSE application as a proof of concept, using two methods referred to as the kernel method and material method. Future work will aim to build on these studies, exploring more advanced OpenFOAM MHD solvers as well as improving the Proteus MHD solver.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139054943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Moment tracking and their coordinate transformations for macroparticles with an application to plasmas around black holes","authors":"Alexander Warwick, Jonathan Gratus","doi":"10.1088/1361-6587/ad11fc","DOIUrl":"https://doi.org/10.1088/1361-6587/ad11fc","url":null,"abstract":"Particle-in-cell (PIC) codes usually represent large groups of particles as a single macroparticle. These codes are computationally efficient but lose information about the internal structure of the macroparticle. To improve the accuracy of these codes, this work presents a method in which, as well as tracking the macroparticle, the moments of the macroparticle are also tracked. Although the equations needed to track these moments are known, the coordinate transformations for moments where the space and time coordinates are mixed cannot be calculated using the standard method for representing moments. These coordinate transformations are important in astrophysical plasma, where there is no preferred coordinate system. This work uses the language of Schwartz distributions to calculate the coordinate transformations of moments. Both the moment tracking and coordinate transformation equations are tested by modelling the motion of uncharged particles in a circular orbit around a black hole in both Schwarzschild and Kruskal–Szekeres coordinates. Numerical testing shows that the error in tracking moments is small, and scales quadratically. This error can be improved by including higher order moments. By choosing an appropriate method for using these moments to deposit the charge back onto the grid, a full PIC code can be developed.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"13 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139054692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disruption avoidance and investigation of the H-Mode density limit in ASDEX Upgrade","authors":"B. Sieglin, M. Maraschek, Anja Gude, F. Klossek, Federico Felici, Matthias Bernert, O. Kudlacek, A. Pau, W. Treutterer","doi":"10.1088/1361-6587/ad163a","DOIUrl":"https://doi.org/10.1088/1361-6587/ad163a","url":null,"abstract":"\u0000 In recent years a strong effort has been made to investigate disruption avoidance schemes in order to aid the development of integrated operational scenarios for ITER. Within the EUROfusion programme the disruptive H-Mode density limit (HDL) has been studied on the WPTE (Work Package Tokamak Exploitation) devices ASDEX Upgrade, TCV and JET. Advanced real-time control coupled with improved real-time diagnostics has enabled the routine disruption avoidance of the HDL. This allowed the systematic study of the influence of various plasma parameters on the onset and behaviour of the HDL in regimes not easily accessible otherwise. The upper triangularity δ top is found to have a significant influence on the X-Point Radiator (XPR), which plays a major role for the evolution of the disruptive HDL. At high δ top the gas flow rate at which the onset of the XPR occurs is strongly reduced compared to low δ top . The reduction of δ top has proven to be an effective actuator for the HDL disruption avoidance on ASDEX Upgrade. It is observed that the occurrence of the XPR and the H-L transition at the density limit are two separate events, the order of which depends on the applied auxiliary heating power. At sufficiently high heating power the XPR occurs before the H-L transition. Impurity seeding, used for divertor detachment, influences the onset and the dynamics of the XPR and the behaviour of the HDL. The stable existence of the XPR, which is thought to be a requirement for detachment control in future devices, has also been observed without impurity seeding. The implementation of a robust and sustainable operational scenario, e.g. for ITER, requires the combination of continuous control and exception handling. For each disruption path the appropriate observers and actuators have to be validated in present devices. Automation of the dynamic pulse schedule has proven successful to scan the operational space of the HDL without disruption. Applying such a technique to ITER could reduce the machine risk induced by disruptions during commissioning. The methodology to develop physics-based observers, which indicate the entry into a disruption path well in time, and applying the appropriate action before the discharge becomes unstable has proven successful.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"21 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Safety factor influence on the edge E × B velocity establishment in tokamak plasmas","authors":"R. Varennes, L. Vermare, X. Garbet, P. Hennequin, G. Dif-Pradalier, Y. Sarazin, V. Grandgirard, O. Panico, P. Donnel, K. Obrejan","doi":"10.1088/1361-6587/ad1653","DOIUrl":"https://doi.org/10.1088/1361-6587/ad1653","url":null,"abstract":"This study is motivated by experiments on Tore Supra and WEST tokamaks where a deepening of the E × B velocity—governed by the radial electric field Er —near the edge is observed when the safety factor decreases in L-mode plasmas. Flux-driven global simulations of ion temperature gradient turbulence recover qualitatively the trend observed in the experiments, i.e. the E × B velocity increases when decreasing the safety factor. From these simulations, multiple clues point out the role of turbulence in the establishment of the radial electric field even though the turbulent intensity increases with the safety factor. The proposed mechanism to elucidate this phenomenon, backed up by a reduced model, is that the damping of the poloidal flow, governed by the neoclassical friction, increases more strongly with the safety factor than the turbulent drive for Er , due to the (r,θ) component of the Reynolds stress.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"264 26‐43","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies","authors":"R. Paddock, Tat Sang Li, Eugene Kim, Jordan Lee, Heath Martin, R. Ruskov, Stephen Hughes, Steven J Rose, C. Murphy, Robert Henry Hamilton Scott, Robert Bingham, Warren J Garbett, Vadim V Elisseev, Brian M. Haines, A. Zylstra, E. M. Campbell, Cliff A Thomas, T. Goffrey, T. Arber, R. Aboushelbaya, M. von der Leyen, Robin H. W. Wang, Abigail A James, I. Ouatu, R. Timmis, Sunny Howard, E. Atonga, P. Norreys","doi":"10.1088/1361-6587/ad15ee","DOIUrl":"https://doi.org/10.1088/1361-6587/ad15ee","url":null,"abstract":"\u0000 Low convergence ratio implosions (where wetted-foam layers are used to limit capsule convergence, achieving improved robustness to instability growth) and auxiliary heating (where electron beams are used to provide collisionless heating of a hotspot) are two promising techniques that are being explored for inertial fusion energy applications. In this paper, a new analytic study is presented to understand and predict the performance of these implosions. Firstly, conventional gain models are adapted to produce gain curves for fixed convergence ratios, which are shown to well-describe previously simulated results. Secondly, auxiliary heating is demonstrated to be well understood and interpreted through the burn-up fraction of the DT fuel, with the gradient of burn-up with respect to burn-averaged temperature shown to provide good qualitative predictions of the effectiveness of this technique for a given implosion. Simulations of auxiliary heating for a range of implosions are presented in support of this and demonstrate that this heating can have significant benefit for high gain implosions, being most effective when the burn-averaged temperature is between 5 and 20 keV.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"10 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138973115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High temporal resolution of pedestal dynamics via machine learning on density diagnostics","authors":"Diogo R Ferreira, A. Gillgren, A. Ludvig-Osipov, P. Strand","doi":"10.1088/1361-6587/ad15ef","DOIUrl":"https://doi.org/10.1088/1361-6587/ad15ef","url":null,"abstract":"At the Joint European Torus, the reference diagnostic to measure electron density is Thomson scattering. However, this diagnostic has a low sampling rate, which makes it impractical to study the temporal dynamics of fast processes, such as edge localized modes. In this work, we use machine learning to predict the density profile based on data from another diagnostic, namely reflectometry. By learning to transform reflectometry data into Thomson scattering profiles, the model is able to generate the density profile at a much higher sampling rate than Thomson scattering, and more accurately than reflectometry alone. This enables the study of pedestal dynamics, by analyzing the time evolution of the pedestal height, width, position and gradient. We also discuss the accuracy of the model when applied on experimental campaigns that are different from the one it was trained on.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"28 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138973048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validating the simulation of beam-ion charge exchange in MAST Upgrade","authors":"P. Ollus, Scott Allan, James R Harrison, Andrew R Jackson, T. Kurki-Suonio, K. G. McClements, Clive A Michael, David Moulton, B. Patel, Michael Robson, A. Snicker, J. Varje, Charles Vincent","doi":"10.1088/1361-6587/ad15ed","DOIUrl":"https://doi.org/10.1088/1361-6587/ad15ed","url":null,"abstract":"\u0000 Simulation of the impact of charge-exchange (CX) reactions on beam ions in the MAST Upgrade spherical tokamak was compared to measurements carried out with a fission chamber (neutron fluxes) and a Fast Ion Deuterium-Alpha (FIDA) diagnostic. A simple model was developed to reconstruct the outer-midplane neutral density based on measurements of deuterium-alpha emission from edge neutrals, and on Thomson scattering measurements of electron density and temperature. The main computational tools used were the ASCOT orbit-following code and the FIDASIM code for producing synthetic FIDA signals. The neutral density reconstruction agrees qualitatively with SOLPS-ITER modelling and yields a synthetic passive FIDA signal that is consistent with measurement. When CX losses of beam ions are accounted for, predicted neutron emission rates are quantitatively more consistent with measurement. It was necessary to account for CX losses of beam ions in simulations to reproduce the measured passive FIDA signal quantitatively and qualitatively. The results suggest that the neutral density reconstruction is a good approximation, that CX with edge neutrals causes significant beam-ion losses in MAST Upgrade, typically 20% of beam power, and that the ASCOT fast-ion CX model can be used to accurately predict the redistribution and loss of beam ions due to CX.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"23 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138971504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of hydrogen isotope species on ITG microturbulence in LHD","authors":"Y. Q. Qin, Yichao Chen, Guo-Ya Sun, J. Nicolau, Zhihong Lin","doi":"10.1088/1361-6587/ad15f0","DOIUrl":"https://doi.org/10.1088/1361-6587/ad15f0","url":null,"abstract":"\u0000 The linear and nonlinear effects of hydrogen isotope species on ion temperature gradient mode (ITG) in the Large Helical Device (LHD) stellarator are studied using radially global gyrokinetic simulation. We found that the coupling range of linear toroidal harmonics depends on the ion mass of the hydrogen isotope. The growth rate profiles of ITG mode are almost the same for H, D, and T plasmas, indicating a gyro-Bohm scaling of ion-mass dependence. The nonlinear electrostatic simulations show that the zonal flow breaks the radially elongated eigenmode structures and reduces the size of the turbulence eddies, which suppresses the turbulence and the ion heat transport in the LHD. The turbulence amplitude without the zonal flow is almost the same for H, D, and T plasmas, while it decreases with increasing the ion mass of the hydrogen isotope when the zonal flow is present. The reduction of the turbulent transport with larger ion mass is mostly due to the enhancement of zonal fows by larger ion mass. The ion heat conductivity deviates from the gyro-Bohm scaling for both cases with and without the zonal flow.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"15 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138974987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}