Plasma Physics and Controlled Fusion最新文献

{"title":"Cold ion effects in density-asymmetric collisionless magnetic reconnection","authors":"Mengmeng Sun, A. Mao, Xianglei He, A. Divin, Jitong Zou, Zhibin Wang, Tianchun Zhou, Xiaogang Wang","doi":"10.1088/1361-6587/ad670b","DOIUrl":"https://doi.org/10.1088/1361-6587/ad670b","url":null,"abstract":"\u0000 The coexistence of low-energy (cold) ions and thermal (warm) ions is commonly observed in space and laboratory plasmas, such as those in magnetopause and fusion fueling processes. In certain events, the cold ion proportion may play a crucial role in plasma processes, especially magnetic reconnection. In this paper, magnetic reconnection with density-asymmetric cold ions is investigated in implicit particle-in-cell (iPIC) simulations. It is found that in such events the reconnection rate decreases as the cold ion distribution depth into the current sheet increases, mainly due to the mass-loading effect. Particularly, a density-peak structure of cold ions is developed in the reconnection region owing to the bounce motion of cold ions entering from the opposite inflow region. In the y-vy phase space where the y-direction is normal to the current sheet, a cold ion ring structure related to the bounce motion is formed and amplified by the Hall electric field. Furthermore, the cold ions become a notable current carrier due to its shorter inertial scale than the warm ions. Consequently, the asymmetry of the cold ion distribution significantly breaks the symmetry in the Hall magnetic field, eventually leading to asymmetric cold ion density peak structure. Such structures can be taken as significant signals of cold ion existence in in situ spacecraft observations.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"36 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel identification algorithm for plasma boundary gap based on visible endoscope diagnostic on EAST tokamak","authors":"Jiahui Hu, Jiancheng Hou, Xiaofeng Han, Jianhua Yang, Teng Wang, Jianwen Liu, N. Yan, Yi-feng Wang, P. Sun, M. Ren, S. Xiao, Qing Zang","doi":"10.1088/1361-6587/ad6709","DOIUrl":"https://doi.org/10.1088/1361-6587/ad6709","url":null,"abstract":"\u0000 The precise plasma boundary gap identification at the midplane is a prerequisite for achieving controlled plasma positioning and holds a significant importance for the stable operation of tokamak devices. This study proposes a plasma boundary gap at the midplane recognition algorithm based on visual endoscopy diagnostic. The model is an end-to-end one that uses a convolutional neural network that does not require manual data labeling. The model performance is improved by experimentally comparing different convolutional layers and input image sizes. The model is validated using a testing dataset comprising 400 plasma discharge moments. The model has average errors of 3.7 and 4 mm for gap-in and -out, respectively, when compared to those obtained by equilibrium fitting. The proposed approach offers a convenient and effective means of obtaining the boundary gap value and is particularly suited for future fusion experimental devices, such as BEST and ITER tokamak.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"58 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parsimonious statistical techniques for the detection of drifts toward dangerous operational conditions in tokamaks","authors":"T. Craciunescu, Andrea Murari","doi":"10.1088/1361-6587/ad670a","DOIUrl":"https://doi.org/10.1088/1361-6587/ad670a","url":null,"abstract":"\u0000 The approaching initial operation of major new tokomaks is rendering more pressing the need for effective disruption prediction techniques. The required tools should be not only accurate but also capable of operating with a minimum number of signals, because in the first campaigns of new devices typically only a very limited number of diagnostics is available. The present work reports the results obtained with two advanced statistical techniques, chaos onset and concept drift. These methods are capable of detecting the plasma drifting towards dangerous regions of the operational space using only global signals such as the plasma current or the locked mode amplitude. The obtained performances meet the requirements of mitigation in devices such as JT60-SA and ITER at the beginning of their operation. The computational times of the chaos onset approach are already of the order of 1 ms on laptop computers, whereas the concept drift technique requires implementation on FPGAs or GPUs to be compatible with real time requirements","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"61 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MANTA: A Negative-Triangularity NASEM-compliant fusion pilot plant","authors":"Grant Rutherford, H. S. Wilson, A. Saltzman, D. Arnold, J. Ball, S. Benjamin, R. Bielajew, Nikolai de Boucaud, Miguel Calvo Carrera, R. Chandra, H. Choudhury, C. Cummings, L. Corsaro, N. DaSilva, R. Diab, A. Devitre, S. Ferry, S. Frank, C. Hansen, J. Jerkins, Jamal D Johnson, Priyansh Lunia, Jacob van de Lindt, S. Mackie, A. Maris, N. Mandell, Marco Andres Miller, Theodore Mouratidis, A. O. Nelson, M. Pharr, E. Peterson, Pablo Rodriguez-Fernandez, Stefano Segatin, M. Tobin, A. Velberg, Allen Wang, M. Wigram, J. Witham, C. Paz-Soldan, D. G. Whyte","doi":"10.1088/1361-6587/ad6708","DOIUrl":"https://doi.org/10.1088/1361-6587/ad6708","url":null,"abstract":"\u0000 The MANTA (Modular Adjustable Negative Triangularity ARC-class) design study investigated how negative-triangularity (NT) may be leveraged in a compact, fusion pilot plant (FPP) to take a \"power-handling first\" approach. The result is a pulsed, radiative, ELM-free tokamak that satisfies and exceeds the FPP requirements described in the 2021 National Academies of Sciences, Engineering, and Medicine report \"Bringing Fusion to the U.S. Grid\"[1]. A self-consistent integrated modeling workflow predicts a fusion power of 450 MW and a plasma gain of 11.5 with only 23.5 MW of power to the scrape-off layer (SOL). This low PSOL together with impurity seeding and high density at the separatrix results in a peak heat flux of just 2.8 MW/m2. MANTA's high aspect ratio provides space for a large central solenoid (CS), resulting in ~15 minute inductive pulses. In spite of the high B fields on the CS and the other REBCO-based magnets, the electromagnetic stresses remain below structural and critical current density limits. Iterative optimization of neutron shielding and tritium breeding blanket yield tritium self-sufficiency with a breeding ratio of 1.15, a blanket power multiplication factor of 1.11, toroidal field coil lifetimes of 3100 ± 400 MW-yr, and poloidal field coil lifetimes of at least 890 ± 40 MW-yr. Following balance of plant modeling, MANTA is projected to generate 90 MW of net electricity at an engineering fusion gain of ~2.4. Systems-level economic analysis estimates an overnight cost of US$3.4 billion, meeting the NASEM FPP requirement that this first-of-a-kind be less than US$5 billion. The toroidal field coil cost and replacement time are the most critical upfront and lifetime cost drivers, respectively.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141808481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From minimum-viable-products to full models: a step-wise development of diagnostic forward models in support of design, analysis and modelling on the ST40 tokamak","authors":"M. Sertoli, A. Alieva, P. F. Buxton, Aleksei Dnestrovskii, Michael Gemmell, Hazel Lowe, Thomas O'Gorman, Dmitry Osin, A. Sladkomedova, J. Varje, H. Willett, Jonathan Wood, B. Lomanowski, Ephrem Delabie, Oleksandr Marchuk, E. Litherland-Smith, Kingsley Collie, Sanket Gadgil","doi":"10.1088/1361-6587/ad668f","DOIUrl":"https://doi.org/10.1088/1361-6587/ad668f","url":null,"abstract":"\u0000 Like most magnetic confined fusion experiments, the ST40 tokamak started off with a small subset of diagnostics and gradually increased the diagnostic set to include more complex and comprehensive systems. To make the most of each operational phase, forward models of various diagnostics are used and developed to aid design, provide consistency-checks during commissioning, test analysis methods, and build workflows to constrain high-level parameters to inform interpretation, theory and modelling. For new models and new analysis workflows, minimum-viable-products (MVP) are released early, and their complexity is increased in a step-wise manner, facilitating the support of all programme phases on multiple parallel applications, while enabling learning opportunities and feedback loops. In this contribution we review the philosophy, scope and architecture of the framework under development. We discuss the details of some forward models, with examples on how they are used to aid diagnostic design, to investigate analysis methodologies through synthetic data, and how they are embedded in experimental analysis workflows. We compare previously published experimental results with new, more advanced analysis workflows employing more recent, detailed models and new diagnostic data, providing confirmation of the published material from the 2021-22 experimental campaign.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"124 42","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141811373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasma properties in the vicinity of the last closed flux surface in hydrogen and helium fusion plasma discharges","authors":"M. Dimitrova, D. Lopez-Bruna, James Paul Gunn, J. Kovačič, Vojtech Svoboda, Jan Stockel, P. Ivanova, Elmira Vasileva, Embie Hasan, R. Dejarnac, Ulises Losada, Carlos Hidalgo, T. Popov","doi":"10.1088/1361-6587/ad5377","DOIUrl":"https://doi.org/10.1088/1361-6587/ad5377","url":null,"abstract":"\u0000 The origin of the bi-Maxwellian electron energy distribution function (EEDF) observed in the scrape-off layer (SOL) of tokamak plasmas by means of Langmuir probes is still under discussion. It has been assumed that the ionization of hydrogen and deuterium neutrals by thermal electrons penetrating the SOL from the bulk plasma is the main reason for the appearance of a second Maxwellian. To validate this assumption, radial measurements of the electron temperatures and densities, or the plasma properties in helium plasmas in the GOLEM tokamak and the TJ-II stellarator were performed. The radial profiles of the low-temperature electron group densities follow the trend of the calculated radial profiles of the electron sources arising from the ionization of neutrals in both deuterium and helium plasmas in TJ-II. The difference in the radial location where the bi-Maxwellian EEDF appears can be explained by the difference in the rate coefficients for ionization of deuterium and helium. The results of probe measurements in GOLEM and the WEST tokamak divertor, at one radial location in the SOL, are compatible with the hypothesis concerning the ionization of neutral atoms and the type of the EEDF.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"45 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conceptual design of Visible Spectroscopy diagnostics for DTT","authors":"Andrea Belpane, Lorella Carraro, Alessandro Fassina, M. Cavedon, Luca Senni","doi":"10.1088/1361-6587/ad5378","DOIUrl":"https://doi.org/10.1088/1361-6587/ad5378","url":null,"abstract":"\u0000 The project of the Visible Spectroscopy diagnostics for the Zeff radial profile measurement and for the divertor visible imaging spectroscopy, designed for the new tokamak DTT (Divertor Tokamak Test), is presented. To deal with the geometrical constrains of DTT and to minimize the diagnostics volume inside the access port, an integrated and compact solution hosting the two systems has been proposed. The Zeff radial profile will be evaluated from the Bremsstrahlung radiation measurement in the visible spectral range, acquiring light along ten Lines of Sight (LoS) in the upper part of the poloidal plane. The plasma emission will be focused on optical fibers, which will carry it to the spectroscopy laboratory. A second equipment, with a single toroidal LoS crossing the plasma centre and laying on the equatorial plane, will measure the average Zeff on a longer path, minimizing the incidental continuum spectrum contaminations by lines/bands emitted from the plasma edge. The divertor imaging system is designed to measure impurity and main gas influxes, to monitor the plasma position and kinetics of impurities, and to follow the plasma detachment evolution. The project aims at obtaining the maximum coverage of the divertor region. The collected light can be shared among different spectrometers and interferential filter devices placed outside the torus hall to easily change their setup. The system is composed of two telescopes, an upper and a lower one, allowing both a perpendicular and a tangential view of the DTT divertor region. This diagnostic offers a unique and compact solution designed to cope, the demanding constraints of this next-generation tokamak fusion devices, integrating essential tools for wide-ranging impurity characterization and versatile invesitgation of divertor physics.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"JET Far Infrared (FIR) interferometer/polarimeter diagnostic system – 40 years of lessons-learned","authors":"A. Boboc, James Macdonald, Robert Felton, Mark J Brown, W. Studholme, Simon Cramp","doi":"10.1088/1361-6587/ad5376","DOIUrl":"https://doi.org/10.1088/1361-6587/ad5376","url":null,"abstract":"\u0000 Originally designed for five years of plasma operations, the JET Far Infrared (FIR) interferometer/polarimeter diagnostic system was still operating at its full capabilities nearly forty years later in ITER relevant conditions (eg. metal-wall, tungsten divertor) for multiple D-T campaigns, albeit with significantly lower neutron fluences. The original design had to adapt substantially over the years due to machine changes, leading to reduced signal and access to mirrors etc, and the diagnostic still worked due to the excellent dynamic range of the detectors. This paper will discuss invaluable lessons learned designing, operating, optimising, and enhancing such a complex system and how these can be used for developing the new class of laser-based diagnostics for the next generation reactor grade machines.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"52 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141269562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of prepulse on hot electron emission from mesoscopic particles","authors":"Ratul Sabui, Rakesh Y. Kumar, Rahul SV, A. Mondal, Ram Gopal, Vandana Sharma, Manchikanti Krishnamurthy","doi":"10.1088/1361-6587/ad5046","DOIUrl":"https://doi.org/10.1088/1361-6587/ad5046","url":null,"abstract":"\u0000 In this paper we make an attempt to study the effect of a nanosecond prepulse on electron acceleration from microscopic solid particles. While standard scaling laws predict temperatures of $sim 50keV$, our investigations showed an anomalous enhancement ($sim 200keV$) in electron temperatures from microscopic solids subjected to intense laser fields. Conventional isotropic expansion of the plasma target as a result of pre-pulse interaction is unable to explain the enhancement, prompting an experimental inquiry into the expansion form. Tentacle-like structures emerging from the spherical plasma are detected as an outcome of the pre-pulse interaction, with the region between the tentacles being targeted by the main laser pulse. We resort to PIC simulations to understand and predict the exact plasma condition that exists in this region. In this paper, we study a series of approximate pre-plasma conditions, particle shapes and electron densities, examining them for their role in electron acceleration from this extended over-critical plasma target","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"4 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141100098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast ion confinement in the presence of core magnetic islands in Wendelstein 7-X","authors":"S. Lazerson, Joachim Geiger, David Kulla, A. LeViness, S. Bozhenkov, C. Killer, Kunihiro Ogawa, Mitsutaka Isobe, P. McNeely, N. Rust, D. Hartmann","doi":"10.1088/1361-6587/ad4f11","DOIUrl":"https://doi.org/10.1088/1361-6587/ad4f11","url":null,"abstract":"\u0000 The effect of magnetic islands in the core region of Wendelstein 7-X (W7-X) on fast ion confinement is explored through simulations with the BEAMS3D code. A magnetic configuration where the n/m = 5/5 island chain is shifted to r/a ∼ 0.7 allows the exploration of core island physics in W7-X. The control coil system on W7-X allows the tuning of the island size either increasing the island width or decreasing it. A coupling of the BEAMS3D code to the FIELDLINES code provides a versatile mechanism for incorporating magnetic islands and stochastic regions into the BEAMS3D code. Collisionless simulations suggest that the presence of core islands degrade the confinement of passing particles in the region of the island chain. Full neutral beam simulations of W7-X show a similar behavior with confinement decreasing as the island width is increased. Comparisons between a vacuum magnetic field and low beta HINT2 simulation are made showing similar fast ion behavior. Measurements of lost fast ions in W7-X confirm this trend with the control coil suppressed island configuration showing lower losses than that with no control coils applied. Simulations of fast ion wall loads are performed suggesting no drastic change in loss pattern and a slight reduction in losses with minimized islands.","PeriodicalId":510623,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"79 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141111782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}