Nuclear Fusion最新文献

{"title":"Analysis of the periodic variation of pellet ablation radiation intensity in ASDEX Upgrade","authors":"P.T. Lang, G.D. Conway, O.J.W.F. Kardaun, M. Maraschek, B. Pégourié, B. Ploeckl, R. Samulyak, the ASDEX Upgrade Teama","doi":"10.1088/1741-4326/ad6f27","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6f27","url":null,"abstract":"In a future fusion reactor, the main fuelling method will likely rely on the injection of solid hydrogen pellets. Current predictions assume that this goal can be achieved, since being based on a technology which is already largely developed. However, this belief is founded on modelling tools that are usually aligned to the observation made in existing devices and then extrapolated to reactor conditions. This approach needs a sound consideration of its intrinsic restrictions and any observed feature not reproduced by the utilised codes should be applied to check their validation and possibly contribute to their refinement. One specific feature still lacking an explanation of a reasonable and self-consistent mechanism in the current models is the appearance of a phenomenon called striations, which are high frequency variations in the radiation emitted during the pellet ablation process. In order to provide a sound and reliable database for further considerations, a dedicated analysis of this effect has been performed on the mid-size tokamak ASDEX Upgrade. Therefore, such cases have been selected with the relevant signal recorded with sufficient temporal resolution during experiments covering a wide variation of plasma and pellet parameters which are regarded to be potentially influential on the striation pattern. In addition, it was ensured that for any specific case the observed behaviour was reproducible for several individual ablation events under identical conditions. In all cases considered, the observed radiation-intensity variations appear with a typical pattern showing a broad peak of frequencies in the range 50<bold>–</bold>150 kHz. This characteristic unveils a notable resilience against any parameter variation. This new collection of data can now act as firm basis to corroborate future modelling code-validation efforts. In addition, the analysis method can provide a relatively simple way of reviewing future modelling predictions.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"21 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Recent advance progress of HL-3 experiments","authors":"X.R. Duan, M. Xu, W.L. Zhong, X.Q. Ji, W. Chen, Z.B. Shi, X.L. Liu, B. Lu, B. Li, Y.Q. Wang, J.Q. Li, G.Y. Zheng, Yong Liu, Q.W. Yang, L.W. Yan, L.J. Cai, Q. Li, Y. Liu, X.Y. Bai, Z. Cao, X. Chen, H.T. Chen, Y.H. Chen, G.Q. Dong, H.L. Du, D.M. Fan, J.M. Gao, S.F. Geng, G.Z. Hao, H.M. He, M. Huang, M. Jiang, R. Ke, A.S. Liang, J.X. Li, Qing Li, Yongge Li, L.C. Li, H.J. Li, W.B. Li, D.Q. Liu, T. Long, L.F. Lu, L. Nie, P.W. Shi, J.F. Peng, A.P. Sun, T.F. Sun, R.H. Tong, H.L. Wei, S. Wang, G.L. Xiao, X.P. Xiao, L. Xue, H.B. Xu, Z.Y. Yang, D.L. Yu, L.M. Yu, Y.P. Zhang, X. Zheng, L. Zhang, Y. Zhang, F. Zhang, X.L. Zhang, HL-3 Team & Collaborators2345678910111213141516171819","doi":"10.1088/1741-4326/ad6e9e","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6e9e","url":null,"abstract":"Since the first plasma realized in 2020, a series of key systems on HL-3 (known as HL-2M before) tokamak have been equipped/upgraded, including in-vessel components (the first wall, lower divertor, and toroidal cryogenic/water-cooling/baking/glow discharge systems, etc.), auxiliary heating system of 11 MW, and 28 diagnostic systems (to measure the plasma density, electron temperature, radiation, magnetic field, etc.). Magnet field systems were commissioned firstly for divertor plasma discharges. During the 2nd experimental campaign of HL-3 tokamak, several great progresses have been achieved. Firstly, the successful operation with plasma current larger than 1 MA was achieved under a divertor configuration. Secondly, the advanced divertor concept with two distinct snowflake configurations was realized. It is found that the distribution of ion saturation current and heat flux on bottom plate becomes wide due to magnetic surface expansion, demonstrating the advantage of such configuration in the heat flux mitigation. In addition, using the combination of NBI, ECRH and LHCD, the standard sawtoothing high confinement mode of megampere plasma was firstly accessed on the HL-3. The successful commissioning of HL-3 is beneficial for the initial operation of ITER.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"31 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"MHD flows through ferromagnetic rectangular ducts in liquid metal blankets","authors":"Xiujie Zhang, Yao Zhao, Zhenchao Sun, Lei Wang, Xinting Lv","doi":"10.1088/1741-4326/ad7159","DOIUrl":"https://doi.org/10.1088/1741-4326/ad7159","url":null,"abstract":"In most designs of liquid metal blankets, the reduced activation ferritic martensitic steel with high relative magnetic permeability is proposed as the structural wall material, which will have an obvious influence on the magnetic field distribution inside the duct and consequently modify the liquid metal magnetohydrodynamics (MHD) flow state. However, the MHD flow state considering the influence of the ferromagnetic wall is lack of systematic investigations especially under the relevant conditions of magnetic confinement fusion reactors. In this work, systematic investigations on the ferromagnetic MHD effect are conducted by experiments and numerical simulations considering the relevant condition of fusion reactors such as high magnetic fields up to 10 T and the actual magnetic permeability of ferromagnetic walls. It is found that magnetic field lines are mainly gathered through the side wall for ferromagnetic rectangular ducts, which will result in the overall magnetic shielding effect. As applied magnetic fields increase, the magnetic shielding effect weakens, increasing the aspect ratio and wall thickness of the duct is benefit to enhance the overall magnetic shielding effect. A slightly magnetic strengthening effect is firstly observed in our experimental and numerical investigations, which is characterized that the average magnetic flux intensity in the fluid region is slightly greater than applied magnetic fields and the pressure drop in ferromagnetic ducts is also higher than that in non-ferromagnetic ducts when the applied magnetic field is bigger than the threshold of transition. The dimensionless pressure gradient in ferromagnetic rectangular ducts usually increases firstly and then decreases with the increase of applied magnetic fields, the pressure drop estimated from the coefficient of the square of the average magnetic flux intensity in the fluid region is generally accurate with exceptions in some extreme conditions. These findings will provide a theoretical guidance for future liquid metal blanket designs.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"64 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Flat-top plasma operational space of the STEP power plant","authors":"E. Tholerus, F.J. Casson, S.P. Marsden, T. Wilson, D. Brunetti, P. Fox, S.J. Freethy, T.C. Hender, S.S. Henderson, A. Hudoba, K.K. Kirov, F. Koechl, H. Meyer, S.I. Muldrew, C. Olde, B.S. Patel, C.M. Roach, S. Saarelma, G. Xia, the STEP team1","doi":"10.1088/1741-4326/ad6ea2","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6ea2","url":null,"abstract":"STEP is a spherical tokamak prototype power plant that is being designed to demonstrate net electric power. The design phase involves the exploitation of plasma models to optimise fusion performance subject to satisfying various physics and engineering constraints. A modelling workflow, including integrated core plasma modelling, MHD stability analysis, SOL and pedestal modelling, coil set and free boundary equilibrium solvers, and whole plant design, has been developed to specify the design parameters and to develop viable scenarios. The integrated core plasma model JETTO is used to develop individual flat-top operating points that satisfy imposed criteria for fusion power performance within operational constraints. Key plasma parameters such as normalised beta, Greenwald density fraction, auxiliary power and radiated power have been scanned to scope the operational space and to derive a collection of candidate non-inductive flat-top points. The assumed auxiliary heating and current drive is either from electron cyclotron (EC) systems only or a combination of EC and electron Bernstein waves. At present stages of transport modelling, there is a large uncertainty in overall confinement for relevant parameter regimes. For each of the two auxiliary heating and current drive systems scenarios, two candidate flat-top points have been developed based on different confinement assumptions, totalling to four operating points. A lower confinement assumption generally suggests operating points in high-density, high auxiliary power regimes, whereas higher confinement would allow access to a broader parameter regime in density and power while maintaining target fusion power performance.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"21 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Multi-field coupling in the scrape-off layer of tokamak plasma","authors":"Xiaohui Ji, Zhibin Guo, Yi Zhang","doi":"10.1088/1741-4326/ad70ca","DOIUrl":"https://doi.org/10.1088/1741-4326/ad70ca","url":null,"abstract":"We study a reduced electrostatic fluid model for the tokamak scrape-off layer, which incorporates temperature gradient and vorticity gradient as two free energy fields. Two scenarios of field coupling are addressed: (1) sheath condition; (2) vortex wave coupling. For the sheath condition induced field coupling, the poloidal <inline-formula>\u0000<tex-math><?CDATA $mathbf{E} times mathbf{B}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mi mathvariant=\"bold\">E</mml:mi></mml:mrow><mml:mo>×</mml:mo><mml:mrow><mml:mi mathvariant=\"bold\">B</mml:mi></mml:mrow></mml:mrow></mml:math><inline-graphic xlink:href=\"nfad70caieqn1.gif\"></inline-graphic></inline-formula> flow shear is coupled with the temperature gradient. Combining an eigenmode analysis and the nonlinear phase dynamics approach, our findings indicate that in the absence of a vorticity gradient, the overall effect of the sheath condition induced flow shear can either stabilize or destabilize the interchange mode, depending on the competition between the flow shear suppression and the temperature gradient driving. This is different from the case where the gradient drive and shear damping are decoupled. When the field coupling is mediated by wave interactions, by setting an idealized step-like temperature and vorticity profiles, a joint mode forms through resonant interaction between the interfacial waves driven by the temperature and vorticity gradients, respectively. Near the phase locking condition, the joint mode can be more unstable than pure temperature gradient driven mode.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"78 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Semi-analytical modeling of prompt redeposition in a steady-state plasma","authors":"L. Cappelli, N. Fedorczak, E. Serre","doi":"10.1088/1741-4326/ad6c5e","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6c5e","url":null,"abstract":"A steady-state, 1D semi-analytical model for prompt redeposition based on the separation between redeposition caused by the electric field in the sheath and redeposition related to gyromotion is here described. The model allows for the estimation of not only the fraction of promptly redeposited flux but also the energy and angular distribution of the non-promptly redeposited population, along with their average charge state. Thus, the temperature and mean parallel-to-B velocity of the non-promptly redeposited flux are also available. The semi-analytical model was validated against equivalent Monte Carlo simulations across a broad range of input parameters. In this paper the eroded material under exam was tungsten (W) for which the code demonstrated consistent agreement with respect to numerical results, within its defined validity limits. The model can theoretically provide a solution for any material, temperature and electron density profile in the sheath, monotonic potential drop profile, and sputtered particles energy and angular distribution at the wall. As such, this code emerges as a potential tool for addressing the boundary redeposition phenomenon in fluid impurity transport simulations.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"64 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Expulsion of runaway electrons using ECRH in the TCV tokamak","authors":"J. Decker, M. Hoppe, U. Sheikh, B.P. Duval, G. Papp, L. Simons, T. Wijkamp, J. Cazabonne, S. Coda, E. Devlaminck, O. Ficker, R. Hellinga, U. Kumar, Y. Savoye-Peysson, L. Porte, C. Reux, C. Sommariva, A. Tema Biwolé, B. Vincent, L. Votta, the TCV Team, the EUROfusion Tokamak Exploitation Teamb","doi":"10.1088/1741-4326/ad6c61","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6c61","url":null,"abstract":"Runaway electrons (REs) are a concern for tokamak fusion reactors from discharge startup to termination. A sudden localized loss of a multi-megaampere RE beam can inflict severe damage to the first wall. Should a disruption occur, the existence of a RE seed may play a significant role in the formation of a RE beam and the magnitude of its current. The application of central electron cyclotron resonance heating (ECRH) in the Tokamak à Configuration Variable (TCV) reduces an existing RE seed population by up to three orders of magnitude within only a few hundred milliseconds. Applying ECRH before a disruption can also prevent the formation of a post-disruption RE beam in TCV where it would otherwise be expected. The RE expulsion rate and consequent RE current reduction are found to increase with applied ECRH power. Whereas central ECRH is effective in expelling REs, off-axis ECRH has a comparatively limited effect. A simple 0-D model for the evolution of the RE population is presented that explains how the effective ECRH-induced RE expulsion results from the combined effects of increased electron temperature and enhanced RE transport.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"178 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Overview of recent results from the ST40 compact high-field spherical tokamak","authors":"S.A.M. McNamara, A. Alieva, M.S. Anastopoulos Tzanis, O. Asunta, J. Bland, H. Bohlin, P.F. Buxton, C. Colgan, A. Dnestrovskii, E. du Toit, M. Fontana, M. Gemmell, M.P. Gryaznevich, J. Hakosalo, M.R. Hardman, D. Harryman, D. Hoffman, M. Iliasova, S. Janhunen, F. Janky, J.B. Lister, H.F. Lowe, E. Maartensson, C. Marsden, S.Y. Medvedev, S.R. Mirfayzi, M. Moscheni, G. Naylor, V. Nemytov, J. Njau, T. O’Gorman, D. Osin, T. Pyragius, A. Rengle, M. Romanelli, C. Romero, M. Sertoli, V. Shevchenko, J. Sinha, A. Sladkomedova, S. Sridhar, J. Stirling, Y. Takase, P.R. Thomas, J. Varje, E. Vekshina, B. Vincent, H.V. Willett, J. Wood, E. Wooldridge, D. Zakhar, X. Zhang, D. Battaglia, N. Bertelli, P.J. Bonofiglo, L.F. Delgado-Aparicio, V.N. Duarte, N.N. Gorelenkov, M. de Haas, S.M. Kaye, R. Maingi, D. Mueller, M. Ono, M. Podesta, Y. Ren, S. Trieu, E. Delabie, T.K. Gray, B. Lomanowski, E.A. Unterberg, O. Marchuk, the ST40 Team1","doi":"10.1088/1741-4326/ad6ba7","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6ba7","url":null,"abstract":"ST40 is a compact, high-field (<inline-formula>\u0000<tex-math><?CDATA $B_{mathrm{T0}}unicode{x2A7D} 2.1,,,textrm{T}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>B</mml:mi><mml:mrow><mml:mrow><mml:mi mathvariant=\"normal\">T</mml:mi><mml:mn>0</mml:mn></mml:mrow></mml:mrow></mml:msub><mml:mtext>⩽</mml:mtext><mml:mn>2.1</mml:mn><mml:mstyle scriptlevel=\"0\"></mml:mstyle><mml:mstyle scriptlevel=\"0\"></mml:mstyle><mml:mstyle scriptlevel=\"0\"></mml:mstyle><mml:mtext>T</mml:mtext></mml:mrow></mml:math><inline-graphic xlink:href=\"nfad6ba7ieqn1.gif\"></inline-graphic></inline-formula>) spherical tokamak (ST) with a mission to expand the physics and technology basis for the ST route to commercial fusion. The ST40 research programme covers confinement and stability; solenoid-free start-up; high-performance operating scenarios; and plasma exhaust. In 2022, ST40 obtained central deuterium ion temperatures of <inline-formula>\u0000<tex-math><?CDATA $9.6 pm 0.4 textrm{keV}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mn>9.6</mml:mn><mml:mo>±</mml:mo><mml:mn>0.4</mml:mn><mml:mtext> </mml:mtext><mml:mtext>keV</mml:mtext></mml:mrow></mml:math><inline-graphic xlink:href=\"nfad6ba7ieqn2.gif\"></inline-graphic></inline-formula>, demonstrating for the first time that pilot plant relevant ion temperatures can be reached in a compact, high-field ST. Analysis of these high-ion temperature plasmas is presented, including a summary of confinement, transport and microstability characteristics, and energetic particle instabilities. Recent scenario development activities have focused on establishing diverted H-mode plasmas across a range of toroidal fields and plasma currents, along with scenarios with high non-inductive current fractions. In future operations, beginning in 2025, a 1 MW dual frequency (104/137 GHz) electron cyclotron (EC) system will be installed to enable the study of EC and electron Bernstein wave plasma start-up and current drive. Predictive modelling of the potential performance of these systems is presented.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"46 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Overview of physics results from MAST upgrade towards core-pedestal-exhaust integration","authors":"J.R. Harrison, A. Aboutaleb, S. Ahmed, M. Aljunid, S.Y. Allan, H. Anand, Y. Andrew, L.C. Appel, A. Ash, J. Ashton, O. Bachmann, M. Barnes, B. Barrett, D. Baver, D. Beckett, J. Bennett, J. Berkery, M. Bernert, W. Boeglin, C. Bowman, J. Bradley, D. Brida, P.K. Browning, D. Brunetti, P. Bryant, J. Bryant, J. Buchanan, N. Bulmer, A. Carruthers, M. Cecconello, Z.P. Chen, J. Clark, C. Cowley, M. Coy, N. Crocker, G. Cunningham, I. Cziegler, T. Da Assuncao, Y. Damizia, P. Davies, I.E. Day, G.L. Derks, S. Dixon, R. Doyle, M. Dreval, M. Dunne, B.P. Duval, T. Eagles, J. Edmond, H. El-Haroun, S.D. Elmore, Y. Enters, M. Faitsch, F. Federici, N. Fedorczak, F. Felici, A.R. Field, M. Fitzgerald, I. Fitzgerald, R. Fitzpatrick, L. Frassinetti, W. Fuller, D. Gahle, J. Galdon-Quiroga, L. Garzotti, S. Gee, T. Gheorghiu, S. Gibson, K.J. Gibson, C. Giroud, D. Greenhouse, V.H. Hall-Chen, C.J. Ham, R. Harrison, S.S. Henderson, C. Hickling, B. Hnat, L. Howlett, J. Hughes, R. Hussain, K. Imada, P. Jacquet, P. Jepson, B. Kandan, I. Katramados, Y.O. Kazakov, D. King, R. King, A. Kirk, M. Knolker, M. Kochan, L. Kogan, B. Kool, M. Kotschenreuther, M. Lees, A.W. Leonard, G. Liddiard, B. Lipschultz, Y.Q. Liu, B.A. Lomanowski, N. Lonigro, J. Lore, J. Lovell, S. Mahajan, F. Maiden, C. Man-Friel, F. Mansfield, S. Marsden, R. Martin, S. Mazzi, R. McAdams, G. McArdle, K.G. McClements, J. McClenaghan, D. McConville, K. McKay, C. McKnight, P. McKnight, A. McLean, B.F. McMillan, A. McShee, J. Measures, N. Mehay, C.A. Michael, F. Militello, D. Morbey, S. Mordijck, D. Moulton, O. Myatra, A.O. Nelson, M. Nicassio, M.G. O’Mullane, H.J.C. Oliver, P. Ollus, T. Osborne, N. Osborne, E. Parr, B. Parry, B.S. Patel, D. Payne, C. Paz-Soldan, A. Phelps, L. Piron, C. Piron, G. Prechel, M. Price, B. Pritchard, R. Proudfoot, H. Reimerdes, T. Rhodes, P. Richardson, J. Riquezes, J.F. Rivero-Rodriguez, C.M. Roach, M. Robson, K. Ronald, E. Rose, P. Ryan, D. Ryan, S. Saarelma, S. Sabbagh, R. Sarwar, P. Saunders, O. Sauter, R. Scannell, T. Schuett, R. Seath, R. Sharma, P. Shi, B. Sieglin, M. Simmonds, J. Smith, A. Smith, V. A. Soukhanovskii, D. Speirs, G. Staebler, R. Stephen, P. Stevenson, J. Stobbs, M. Stott, C. Stroud, C. Tame, C. Theiler, N. Thomas-Davies, A.J. Thornton, M. Tobin, M. Vallar, R.G.L. Vann, L. Velarde, K. Verhaegh, E. Viezzer, C. Vincent, G. Voss, M. Warr, W. Wehner, S. Wiesen, T.A. Wijkamp, D. Wilkins, T. Williams, T. Wilson, H.R. Wilson, H. Wong, M. Wood, V. Zamkovska","doi":"10.1088/1741-4326/ad6011","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6011","url":null,"abstract":"Recent results from MAST Upgrade are presented, emphasising understanding the capabilities of this new device and deepening understanding of key physics issues for the operation of ITER and the design of future fusion power plants. The impact of MHD instabilities on fast ion confinement have been studied, including the first observation of fast ion losses correlated with Compressional and Global Alfvén Eigenmodes. High-performance plasma scenarios have been developed by tailoring the early plasma current ramp phase to avoid internal reconnection events, resulting in a more monotonic q profile with low central shear. The impact of <italic toggle=\"yes\">m</italic>/<italic toggle=\"yes\">n</italic> = 3/2, 2/1 and 1/1 modes on thermal plasma confinement and rotation profiles has been quantified, and scenarios optimised to avoid them have transiently reached values of normalised beta approaching 4.2. In pedestal and ELM physics, a maximum pedestal top temperature of ∼350 eV has been achieved, exceeding the value achieved on MAST at similar heating power. Mitigation of type-I ELMs with <italic toggle=\"yes\">n</italic> = 1 RMPs has been observed. Studies of plasma exhaust have concentrated on comparing conventional and Super-X divertor configurations, while X-point target, X-divertor and snowflake configurations have been developed and studied in parallel. In L-mode discharges, the separatrix density required to detach the outer divertors is approximately a factor 2 lower in the Super-X than the conventional configuration, in agreement with simulations. Detailed analysis of spectroscopy data from studies of the Super-X configuration reveal the importance of including plasma-molecule interactions and D₂ Fulcher band emission to properly quantify the rates of ionisation, plasma-molecule interactions and volumetric recombination processes governing divertor detachment. In H-mode with conventional and Super-X configurations, the outer divertors are attached in the former and detached in the latter with no impact on core or pedestal confinement.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"28 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Ripple-induced neoclassical toroidal viscous torque in Augmented-First Plasma operation phase in ITER","authors":"Yueqiang Liu, Xue Bai, Y. Gribov, F. Koechl, A. Loarte, S.D. Pinches, L. Schmitz","doi":"10.1088/1741-4326/ad70cb","DOIUrl":"https://doi.org/10.1088/1741-4326/ad70cb","url":null,"abstract":"A systematic calculation is performed on the ripple-induced neoclassical toroidal viscous (NTV) torque for new ITER scenarios designed for the Augmented-First Plasma (A-FP) operation phase with the full tungsten wall, where the plasma-wall gap is varied in view of mitigating the impact of tungsten wall-plasma interactions. The torque calculation includes drift kinetic response of the plasma thermal and energetic particles to the <italic toggle=\"yes\">n</italic> = 18 (<italic toggle=\"yes\">n</italic> is the toroidal harmonic number) ripple field. For the plasma scenario with ~45 cm plasma-wall gap at the outboard mid-plane and considering the corrected ripple level of 0.17% by the ferritic steel inserts, the computed net NTV torque acting on the plasma column is in the sub-Nm level. However, with decreasing the plasma-wall gap, the computed net NTV torque can reach a level comparable to that produced by the neutral-beam momentum injection in ITER. Ripple correction by ferritic inserts reduces the net torque by a factor of 3.3 for all the three A-FP scenarios considered. The <inline-formula>\u0000<tex-math><?CDATA $nomega_d = lomega_b$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>n</mml:mi><mml:msub><mml:mi>ω</mml:mi><mml:mi>d</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mi>l</mml:mi><mml:msub><mml:mi>ω</mml:mi><mml:mi>b</mml:mi></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"nfad70cbieqn1.gif\"></inline-graphic></inline-formula> (with <italic toggle=\"yes\">ω</italic>_{<italic toggle=\"yes\">d</italic>} and <italic toggle=\"yes\">ω</italic>_{<italic toggle=\"yes\">b</italic>} being the toroidal precession and bounce frequencies of trapped particles, respectively, and <italic toggle=\"yes\">l</italic> an integer number) type of resonance-enhancement of the NTV torque, due to thermal particles, is found to be weak in ITER despite high-<italic toggle=\"yes\">n</italic> of 18. The same also holds for the ITER 10 MA steady state scenario from the D-T operation phase, where the aforementioned resonance associated with fusion-born alphas is also included. The ripple-induced NTV torque is well below that produced by the resonant magnetic perturbation applied for controlling the type-I edge-localized mode in ITER.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"3 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}