Nuclear Fusion最新文献

{"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}

{"title":"Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions","authors":"K. Ida, M. Yoshinuma, M. Kobayashi, T. Kobayashi, N. Kenmochi, F. Nespoli, R.M. Magee, F. Warmer, A. Dinklage, A. Matsuyama, R. Sakamoto, T. Nasu, T. Tokuzawa, T. Kinoshita, K. Tanaka, N. Tamura, K. Nagaoka, M. Nishiura, Y. Takemura, K. Ogawa, G. Motojima, T. Oishi, Y. Morishita, J. Varela, W.H.J. Hayashi, M. Markl, H. Bouvain, Y. Liang, M. Leconte, D. Moseev, V.E. Moiseenko, C.G. Albert, I. Allfrey, A. Alonso, F.J. Arellano, N. Ashikawa, A. Azegami, L. Bardoczi, M. van Berkel, M. Beurskens, M.W. Binderbaue, A. Bortolon, S. Brezinsek, R. Bussiahn, A. Cappa, D. Carralero, I.C. Chan, J. Cheng, X. Dai, D.J. Den Hartog, C.P. Dhard, F. Ding, A. Ejiri, S. Ertmer, T. Fornal, K. Fujita, Y. Fujiwara, H. Funaba, L. Garcia, J.M. Garcia-Regana, I. Garcia-Cortés, I.E. Garkusha, D.A. Gates, Y. Ghai, E.P. Gilson, H. Gota, M. Goto, E.M. Green, V. Haak, S. Hamaguchi, K. Hanada, H. Hara, D. Hartmann, Y. Hayashi, T. Henning, C. Hidalgo, J. Hillairet, R. Hutton, T. Ido, H. Igami, K. Ikeda, S. Inagaki, A. Ishizawa, S. Ito, M. Isobe, Y. Isobe, M. Ivkovic, Z. Jiang, J. Jo, S. Kamio, H. Kasahara, D. Kato, Y. Katoh, Y. Kawachi, Y. Kawamoto, G. Kawamura, T. Kawate, Ye.O. Kazakov, V. Klumper, A. Knieps, W.H. Ko, S. Kobayashi, F. Koike, Yu.V. Kovtun, M. Kubkowska, S. Kubo, S.S.H. Lam, A. Langenberg, H. Laqua, S. Lazerson, J. Lestz, B. Li, L. Liao, Z. Lin, R. Lunsford, S. Masuzaki, H. Matsuura, K.J. McCarthy, D. Medina-Roque, O. Mitarai, A. Mollen, C. Moon, Y. Mori, T. Morisaki, S. Morita, K. Mukai, I. Murakami12, S. Murakami, T. Murase, C.M. Muscatello, K. Nagasaki, D. Naujoks, H. Nakano, M. Nakata, Y. Narushima, A. Nagy, J.H. Nicolau, T. Nishizawa, S. Nishimoto, H. Nuga, M. Nunami, R. Ochoukov, S. Ohdachi, J. Ongena, M. Osakabe, N.A. Pablant, N. Panadero, B. Peterson, J. de la Riva Villén, J. Romazanov, J. Rosato, M. Rud, S. Sakakibara, H.A. Sakaue, H. Sakai, I. Sakon, M. Salewski, S. Sangaroon, S. Sereda, T. Stange, K. Saito, S. Satake, R. Seki, T. Seki, S. Sharapov, A. Shimizu, T. Shimozuma, G. Shivam, M. Shoji, D.A. Spong, H. Sugama, Z. Sun, C. Suzuki, Y. Suzuki, T. Tajima, E. Takada, H. Takahashi, K. Toi, Y. Tsuchibushi, N. Tsujii, K. Tsumori, T.I. Tsujimurai, G. Ueno, H. Uehara, J.L. Velasco, E. Wang, K.Y. Watanabe, T. Wauter, U. Wenzel, M. Yajima, H. Yamada, I. Yamada, K. Yanagihara, H. Yamaguchi, R. Yanai, R. Yasuhara, M. Yokoyama, Y. Yoshimura, M. Zarnstorff, M. Zhao, G.Q. Zhong, Q. Zhou, S. Ziaei, LHD Experiment Group1, the W7-X Teama","doi":"10.1088/1741-4326/ad3a7a","DOIUrl":"https://doi.org/10.1088/1741-4326/ad3a7a","url":null,"abstract":"Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues in burning plasma are: alpha-channeling (ion heating by alpha particles), turbulence and transport in electron dominant heating helium ash exhaust, reduction of the divertor heat load. To solve these problems, understanding the basic plasma physics of (1) wave–particle interaction through (inverse) Landau damping, (2) characteristics of electron-scale (high-<italic toggle=\"yes\">k</italic>) turbulence, (3) ion mixing and the isotope effect, and (4) turbulence spreading and detachment, is necessary. This overview discusses the experimental studies on these issues and turbulent transport in multi-ion plasma and other issues in the appendix.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"12 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211998","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":"Formation of high areal density core using an efficient and robust implosion method for fast ignition","authors":"H. Nagatomo, T. Johzaki, R. Takizawa, S. Fujioka","doi":"10.1088/1741-4326/ad6b38","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6b38","url":null,"abstract":"A new fuel compression method for a fast ignition scheme is discussed. To form a high areal density fuel plasma for the ignition condition, homogenous isentropic compression (HIC) with solid spherical target is effective. We improve a multi-step pulse shape method that uses progressive shockwaves and reflected shockwaves for the compression, where a precisely controlled step-pulse laser drives the shockwaves to compress the fuel and suppress entropy increase. Another advantage of this approach is the relatively smooth high dense fuel is distributed at maximum compression time, compared to our previous design based on Kidder’s HIC method. In addition, we insert a power dip as a preconditioning before the last pulse step to reduce the electron and ion temperature near critical density. As a result, an optimum implosion is designed using 245 kJ of implosion laser energy to meet the ignition condition.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"86 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212000","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":"Status and issues of high-temperature and high-pressure water corrosion research of fusion structural materials in Japanese DEMO reactor development","authors":"Motoki Nakajima, Takashi Nozawa","doi":"10.1088/1741-4326/ad6e04","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6e04","url":null,"abstract":"The activated corrosion product assessments of fusion structural materials are essential to designing components and evaluating workers’ radiation exposure. This paper first gives the R&amp;D status of the high-temperature pressurized water corrosion study of reduced activation ferritic/martensitic steels and chromium–zirconium–copper (CuCrZr) alloys, which are the leading candidate materials of fusion reactor in-vessel components such as breeding blanket and divertor, which are utilized in high-temperature and high-pressure water, and the recent progress of corrosion test apparatus simulating the unique environment of a fusion reactor will also be presented.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"12 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212063","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":"Validation study of RWM stability in DIII-D high-βN plasmas","authors":"Y.F. Zhao, L. Li, V. Chan, Y.Q. Liu, A.M. Garofalo, G.Z. Hao, Z.X. Wang, S.Y. Ding, S. Wang, G.Q. Dong","doi":"10.1088/1741-4326/ad6e01","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6e01","url":null,"abstract":"The <italic toggle=\"yes\">n</italic> = 1 (<italic toggle=\"yes\">n</italic> is the toroidal mode number) resistive wall mode (RWM) stability is numerically investigated for two DIII-D high-<italic toggle=\"yes\">β</italic>_{<italic toggle=\"yes\">N</italic>} discharges 176440 and 172461, utilizing the MARS-F (Liu <italic toggle=\"yes\">et al</italic> 2000 <italic toggle=\"yes\">Phys. Plasmas</italic> <bold>7</bold> 3681) and MARS-K (Liu <italic toggle=\"yes\">et al</italic> 2008 <italic toggle=\"yes\">Phys. Plasmas</italic> <bold>15</bold> 112503) codes. Systematic validation efforts are attempted, for the first time, for discharges with very slow or vanishing toroidal flow for a large fraction of the plasma volume. While gaining physics insights in accessing stable operation regime at <italic toggle=\"yes\">β</italic>_{<italic toggle=\"yes\">N</italic>} exceeding the Troyon no-wall limit in these slow-rotation experiments, the predictive capability of fluid and non-perturbative magnetohydrodynamic-kinetic hybrid models for the RWM is further confirmed. The MARS-F fluid model, with a strong but numerically tunable viscosity mimicking ion Landau damping of parallel sound waves, finds complete stabilization of the <italic toggle=\"yes\">n</italic> = 1 RWM in the considered DIII-D plasmas under the experimental flow conditions. Similarly, either full stabilization (for discharge 176440) or marginal stability (for discharge 172461) of the mode is computed by the MARS-K hybrid model, which is first-principle based without free model parameters. In particular, all drift kinetic resonances, including those of thermal and energetic particles, are found to synergistically act to marginally stabilize the RWM in discharge 172461. These MARS-F/K modeling results explain the experimentally observed stable operational regime in DIII-D, as far as the RWM stability is concerned. Extensive numerical sensitivity studies, with respect to the plasma toroidal flow speed as well as the radial location of the resistive wall, are also carried out to further support the validation study.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"263 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212001","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":"Bayesian modelling of multiple plasma diagnostics at Wendelstein 7-X","authors":"Sehyun Kwak, U. Hoefel, M. Krychowiak, A. Langenberg, J. Svensson, H. Trimino Mora, Y.-C. Ghim, the W7-X Teama","doi":"10.1088/1741-4326/ad6e02","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6e02","url":null,"abstract":"Inference of electron density and temperature has been performed using multiple, diverse sets of plasma diagnostic data at Wendelstein 7-X. Predictive models for the interferometer, Thomson scattering and helium beam emission spectroscopy (He-BES) systems have been developed within the Minerva framework and integrated into a unified model. Electron density and temperature profiles are modelled using Gaussian processes. Calibration factors for the Thomson scattering system and predictive uncertainties are considered as additional unknown parameters. The joint posterior probability distribution for the electron density and temperature profiles as well as Gaussian process hyperparameters and model parameters is explored through a Markov chain Monte Carlo algorithm. Samples from this distribution are numerically marginalised over the hyperparameters and model parameters to yield marginal posterior distributions for the electron density and temperature profiles. The profile inferences incorporate various data combinations from the interferometer and Thomson scattering as well as constraints at the limiter/divertor positions through <italic toggle=\"yes\">virtual observations</italic> or edge data from He-BES. Additionally, the integration of x-ray imaging crystal spectrometer data into the model for ion temperature profiles is presented. All profiles presented in this study are inferred with optimally selected hyperparameters and model parameters by exploring the joint posterior distribution, inherently applying Bayesian Occam’s razor.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"46 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212062","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":"Negative triangularity scenarios: from TCV and AUG experiments to DTT predictions","authors":"A. Mariani, L. Aucone, A. Balestri, P. Mantica, G. Merlo, R. Ambrosino, F. Bagnato, L. Balbinot, J. Ball, T. Bolzonella, D. Brioschi, I. Casiraghi, A. Castaldo, S. Coda, L. Frassinetti, V. Fusco, T. Happel, J. Hobirk, P. Innocente, R.M. McDermott, P. Muscente, T. Pütterich, O. Sauter, F. Sciortino, M. Vallar, B. Vanovac, N. Vianello, G. Vlad, C.F.B. Zimmermann, the EUROfusion Tokamak Exploitation teama, the TCV Teamb, the ASDEX Upgrade Teamc","doi":"10.1088/1741-4326/ad6ea0","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6ea0","url":null,"abstract":"Experiments, gyrokinetic simulations and transport predictions were performed to investigate if a negative triangularity (NT) L-mode option for the Divertor Tokamak Test (DTT) full-power scenario would perform similarly to the positive triangularity (PT) H-mode reference scenario, avoiding the harmful edge localized modes (ELMs). The simulations show that a beneficial effect of NT coming from the edge/scrape-off layer (SOL) region <inline-formula>\u0000<tex-math><?CDATA $rho_{mathrm{tor}} gt 0.9$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>ρ</mml:mi><mml:mrow><mml:mrow><mml:mi>tor</mml:mi></mml:mrow></mml:mrow></mml:msub><mml:mo>&gt;</mml:mo><mml:mn>0.9</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"nfad6ea0ieqn1.gif\"></inline-graphic></inline-formula> is needed to allow the actual NT L-mode option to perform like the PT H-mode. Dedicated experiments at TCV and AUG, with DTT-like shapes, show an optimistic picture. In TCV, experiments indicate that even with the relatively small triangularity of the DTT NT scenario, a large beneficial effect of NT comes from the plasma edge and SOL, allowing NT L-modes to outperform PT L-modes with the same power input, reaching the same central pressures as PT H-modes with twice as much applied heating power. For AUG, NT plasmas go into H-mode more easily than for TCV, but always present much smaller pedestals compared with PT plasmas with the same input power, showing a much weaker or absent ELM activity. However, NT has a smaller beneficial effect for AUG than for TCV, with NT pulses outperforming PT pulses with the same input power only for an ECRH-only case with relatively low input power. For the considered AUG cases, PT pulses perform better than NT ones at higher ECRH power or with mixed NBI and ECRH power. Based on this analysis, the NT option is a viable alternative for the DTT full power scenario, providing high performance plasmas with reduced or absent ELMs.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"27 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212064","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":"Electron cyclotron current start-up using a retarding electric field in the QUEST spherical tokamak","authors":"T. Onchi, H. Idei, K. Hanada, O. Watanabe, R. Miyata, Y. Zhang, Y. Koide, Y. Otsuka, T. Yamaguchi, A. Higashijima, T. Nagata, I. Sekiya, S. Shimabukuro, I. Niiya, K. Kono, F. Zennifa, K. Nakamura, R. Ikezoe, M. Hasegawa, K. Kuroda, Y. Nagashima, T. Ido, T. Kariya, A. Ejiri, S. Murakami, A. Fukuyama, Y. Kosuga","doi":"10.1088/1741-4326/ad6914","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6914","url":null,"abstract":"The plasma current start-up experiment is conducted through electron cyclotron (EC) heating in the QUEST spherical tokamak. During the EC heating, the application of a toroidal electric field in the opposite direction to the plasma current effectively inhibits the growth of energetic electrons. Observations show rapid increases in plasma current and hard x-ray count immediately following the cancellation of the retarding electric field. When a compact tokamak configuration maintains equilibrium on the high field side, along with the retarding field, it leads to effective bulk electron heating. This heating achieved an electron temperature of <italic toggle=\"yes\">T</italic>_e ≈ 1 keV at electron density <italic toggle=\"yes\">n</italic>_e &gt; 1.0 × 10¹⁸ m⁻³. Ray tracing of the EC wave verifies that more power absorption into plasma through a single-pass occurs around the second resonance layer with higher values of electron density and temperature.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"28 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212066","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":"Integrated modelling of tungsten accumulation control with wave heating: validation in ASDEX Upgrade and predictions for ITER","authors":"D. Fajardo, C. Angioni, E. Fable, G. Tardini, R. Bilato, T. Luda, R.M. McDermott, O. Samoylov, the ASDEX Upgrade Teama","doi":"10.1088/1741-4326/ad6f26","DOIUrl":"https://doi.org/10.1088/1741-4326/ad6f26","url":null,"abstract":"In present-day fusion devices, central wave heating is crucial to avoid core tungsten (W) accumulation. In this work, we present an integrated modelling framework that reproduces the reduction of core W peaking in ASDEX Upgrade experiments when multiple transport channels are self-consistently evolved, emphasizing the effects of wave heating on turbulent and neoclassical W transport. Predictions for the ITER 15 MA baseline are then provided. We show that the core of a reactor is in a different transport regime for W as compared to present-day tokamaks. The challenges introduced by W arise from global radiation losses that can hinder operation in H-mode, instead of local central accumulation.","PeriodicalId":19379,"journal":{"name":"Nuclear Fusion","volume":"30 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212065","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}