Predictability of burning plasmas is a key issue for designing and building credible future fusion devices. In this context, an important effort of physics understanding and guidance is being carried out in parallel to the on-going JET experimental campaigns in H, D and T by performing analyses and modelling towards an improvement of the understanding of DT physics for the optimization of the JET-DT neutron yield and fusion born alpha particle physics. Extrapolations to JET-DT from recent experiments using the maximum power available have been performed including some of the most sophisticated codes and a broad selection of models. There is a general agreement that 11-15MW of fusion power can be expected in DT for the hybrid and baseline scenarios. On the other hand, in high beta, torque and fast ion fraction conditions, isotope effects could be favourable leading to higher fusion yield. It is shown that alpha particles related physics, such as TAE destabilization or fusion power electron heating, could be studied in ITER relevant JET-DT plasmas.

PB - Tegenlicht Meet Up 040 CY - Eindhoven, Netherlands VL - 59 IS - 8 U1 -FP

U2 -IMT

U5 - 979e9d36956a6fb000f8d9e5060d8989 ER - TY - JOUR T1 - Control of the hydrogen:deuterium isotope mixture using pellets in JET JF - Nuclear Fusion Y1 - 2019 A1 - Valovic, M. A1 - Baranov, Y. A1 - Boboc, A. A1 - Buchanan, J. A1 - Citrin, J. A1 - Delabie, E. A1 - Frassinetti, L. A1 - Fontdecaba, J. A1 - Garzotti, L. A1 - Giroud, C. A1 - McKean, R. A1 - Lerche, E. A1 - Kiptily, V. A1 - Kochl, F. A1 - Marin, M. A1 - Maslov, M. A1 - Menmuir, S. A1 - Tvalashvili, G. A1 - Weisen, H. A1 - JET Contributors AB - Deuterium pellets are injected into an initially pure hydrogen H-mode plasma in order to control the hydrogen:deuterium (H:D) isotope mixture. The pellets are deposited in the outer 20% of the minor radius, similar to that expected in ITER, creating transiently hollow electron density profiles. A H:D isotope mixture of approximately 45%:55% is obtained in the core with a pellet fuelling throughput of @pel = 0.045 P aux / T e.ped similar to previous pellet fuelling experiments in pure deuterium. Evolution of the H:D mix in the core is reproduced using a simple model, although deuterium transport could be higher at the beginning of the pellet train compared with the flat-top phase. VL - 59 IS - 10 U1 - FP U2 - IMT U5 - 4e740b87f1a943a47d0fb40534bcfcce ER - TY - JOUR T1 - First principle integrated modeling of multi-channel transport including Tungsten in JET JF - Nuclear Fusion Y1 - 2018 A1 - Breton, S. A1 - Casson, F. A1 - Bourdelle, C. A1 - Citrin, J. A1 - Baranov, Y. A1 - Camenen, Y. A1 - Challis, C. A1 - Corrigan, G. A1 - J. Garcia A1 - Garzotti, L. A1 - Henderson, S. A1 - Koechl, F. A1 - Militello-Asp, E. A1 - O'Mulane, M. A1 - Putterich, T. A1 - Sertoli, M. A1 - Valisa, M. AB -For the first time, over five confinement times, the self-consistent flux driven time evolution of heat, momentum transport and particle fluxes of electrons and multiple ions including Tungsten (W) is modeled within the integrated modeling platform JETTO [Romanelli M et al PFR 2014], using first principle-based codes: namely, QuaLiKiz [Bourdelle C. et al. PPCF 2016] for turbulent transport and NEO [Belli E A and Candy J PPCF 2008] for neoclassical transport. For a JET-ILW pulse, the evolution of measured temperatures, rotation and density profiles are successfully predicted and the observed W central core accumulation is obtained. The poloidal asymmetries of the W density modfying its neoclassical and turbulent transport are accounted for. Actuators of the W core accumulation are studied: removing the central particle source annihilates the central W accumulation whereas the suppression of the torque reduces significantly the W central accumulation. Finally, the presence of W slightly reduces main ion heat turbulent transport through complex nonlinear interplays involving radiation, effective charge impact on ITG and collisionality.

VL - 58 IS - 9 U1 -FP

U2 -IMT

U5 - 8b217fe93b83353631a28ae3b1981d0a ER - TY - JOUR T1 - Tractable flux-driven temperature, density, and rotation profile evolution with the quasilinear gyrokinetic transport model QuaLiKiz JF - Plasma Physics and Controlled Fusion Y1 - 2017 A1 - Citrin, J. A1 - Bourdelle, C. A1 - Casson, F. J. A1 - Angioni, C. A1 - Bonanomi, N. A1 - Camenen, Y. A1 - Garbet, X. A1 - Garzotti, L. A1 - Gorler, T. A1 - Gurcan, O. D. A1 - Koechl, F. A1 - Imbeaux, F. A1 - Linder, O. A1 - van de Plassche, K. A1 - Strand, P. A1 - Szepesi, G. A1 - JET Contributors AB - Quasilinear turbulent transport models are a successful tool for prediction of core tokamak plasma profiles in many regimes. Their success hinges on the reproduction of local nonlinear gyrokinetic fluxes. We focus on significant progress in the quasilinear gyrokinetic transport model QuaLiKiz (Bourdelle et al 2016 Plasma Phys. Control. Fusion 58 014036), which employs an approximated solution of the mode structures to significantly speed up computation time compared to full linear gyrokinetic solvers. Optimisation of the dispersion relation solution algorithm within integrated modelling applications leads to flux calculations x10 6-7 faster than local nonlinear simulations. This allows tractable simulation of flux-driven dynamic profile evolution including all transport channels: ion and electron heat, main particles, impurities, and momentum. Furthermore, QuaLiKiz now includes the impact of rotation and temperature anisotropy induced poloidal asymmetry on heavy impurity transport, important for W-transport applications. Application within the JETTO integrated modelling code results in 1 s of JET plasma simulation within 10 h using 10 CPUs. Simultaneous predictions of core density, temperature, and toroidal rotation profiles for both JET hybrid and baseline experiments are presented, covering both ion and electron turbulence scales. The simulations are successfully compared to measured profiles, with agreement mostly in the 5%–25% range according to standard figures of merit. QuaLiKiz is now open source and available at www.qualikiz.com. VL - 59 UR - https://arxiv.org/abs/1708.01224 IS - 12 U1 - FP U2 - IMT U5 - 5234d3fadaa3c4d0ad98a555a43c362c ER - TY - JOUR T1 - Real-time control of ELM and sawtooth frequencies: similarities and differences JF - Nuclear Fusion Y1 - 2016 A1 - Lennholm, M. A1 - Frigione, D. A1 - Graves, J. P. A1 - Beaumont, P. S. A1 - Blackman, T. A1 - Carvalho, I. S. A1 - Chapman, I. A1 - Dumont, R. A1 - Felton, R. A1 - Tsalas, M. A1 - Garzotti, L. A1 - Goniche, M. A1 - Goodyear, A. A1 - Grist, D. A1 - Jachmich, S. A1 - Johnson, T. A1 - Lang, P. A1 - Lerche, E. A1 - de la Luna, E. A1 - Monakhov, I. A1 - Mooney, R. A1 - Morris, J. A1 - M F F Nave A1 - Reich, M. A1 - Rimini, F. A1 - Sips, G. A1 - H Sheikh A1 - Sozzi, C. A1 - JET Contributors AB -ELMs and Sawteeth, located in different parts of the plasma, are similar from a control engineering point of view. Both manifest themselves through quiescent periods interrupted by periodic collapses. For both, large collapses, following long quiescent periods, have detrimental effects while short periods are associated with decreased confinement. Following the installation of the all metal ‘ITER like wall’ on JET, sawteeth and ELMs also play an important role by expelling tungsten from the core and edge of the plasma respectively. Control of tungsten has therefore been added to divertor heat load reduction, NTM avoidance and helium ash removal as reasons for requiring ELM and sawtooth control. It is therefore of interest to implement control systems to maintain the sawtooth and ELM frequencies in the desired ranges. On JET, ELM frequency control uses radial field ‘kicks’ and pellet and gas injection as actuators, while sawtooth control uses ion cyclotron resonance heating (ICRH). JET experiments have, for the first time, established feedback control of the ELM frequency, via real time variation of the injected gas flow [1]. Using this controller in conjunction with pellet injection allows the ELM frequency to be kept as required despite variations in pellet ELM triggering efficiency. JET Sawtooth control experiments have, for the first time, demonstrated that low field side ICRH, as foreseen for ITER, can shorten sawteeth lengthened by central fast ions [2]. The development of ELM and sawtooth control could be key to achieve stable high performance JET discharges with minimal tungsten content. Integrating such schemes into an overall control strategy will be required in future tokamaks and gaining experience on current tokamaks is essential.

VL - 56 UR - http://www.euro-fusionscipub.org/wp-content/uploads/2015/05/WPJET1PR1501.pdf IS - 1 U1 -FP

U2 -PDG

U5 - 49c8929abb0e88d6ddf1d8e1ddde5233 ER - TY - JOUR T1 - JET experiments with tritium and deuterium–tritium mixtures JF - Fusion Engineering and Design Y1 - 2016 A1 - Horton, L. A1 - Batistoni, P. A1 - Boyer, H. A1 - Challis, C. A1 - Ciric, D. A1 - Donne, A. J. H. A1 - Eriksson, L. G. A1 - J. Garcia A1 - Garzotti, L. A1 - Gee, S. A1 - Hobirk, J. A1 - Joffrin, E. A1 - Jones, T. A1 - King, D. B. A1 - Knipe, S. A1 - X. Litaudon A1 - Matthews, G. F. A1 - Monakhov, I. A1 - Murari, A. A1 - Nunes, I. A1 - Riccardo, V. A1 - Sips, A. C. C. A1 - Warren, R. A1 - Weisen, H. A1 - Zastrow, K. D. KW - deuterium KW - Fusion performance KW - JET KW - plasma-wall interactions KW - Tritium AB - Extensive preparations are now underway for an experiment in the Joint European Torus (JET) using tritium and deuterium–tritium mixtures. The goals of this experiment are described as well as the progress that has been made in developing plasma operational scenarios and physics reference pulses for use in deuterium–tritium and full tritium plasmas. At present, the high performance plasmas to be tested with tritium are based on either a conventional ELMy H-mode at high plasma current and magnetic field (operation at up to 4 MA and 4 T is being prepared) or the so-called improved H-mode or hybrid regime of operation in which high normalised plasma pressure at somewhat reduced plasma current results in enhanced energy confinement. Both of these regimes are being re-developed in conjunction with JET's ITER-like Wall (ILW) of beryllium and tungsten. The influence of the ILW on plasma operation and performance has been substantial. Considerable progress has been made on optimising performance with the all-metal wall. Indeed, operation at the (normalised) ITER reference confinement and pressure has been re-established in JET albeit not yet at high current. In parallel with the physics development, extensive technical preparations are being made to operate JET with tritium. The state and scope of these preparations is reviewed, including the work being done on the safety case for DT operation and on upgrading machine infrastructure and diagnostics. A specific example of the latter is the planned calibration at 14 MeV of JET neutron diagnostics. VL - 109–111, Part A IS - 11 N1 - Proceedings of the 12th International Symposium on Fusion Nuclear Technology-12 (ISFNT-12) U1 - FP U2 - TP U3 - FP120 U5 - 919ea07aae93a82b6fd7640a977cd6c7 ER - TY - JOUR T1 - Integrated core–SOL–divertor modelling for ITER including impurity: effect of tungsten on fusion performance in H-mode and hybrid scenario JF - Nuclear Fusion Y1 - 2015 A1 - Zagorski, R. A1 - Voitsekhovitch, I. A1 - Ivanova-Stanik, I. A1 - Kochl, F. A1 - da Silva Aresta Belo, P. A1 - Fable, E. A1 - J. Garcia A1 - Garzotti, L. A1 - Hobirk, J. A1 - Hogeweij, G. M. D. A1 - Joffrin, E. A1 - X. Litaudon A1 - Polevoi, A. R. A1 - Telesca, G. A1 - JET Contributors AB -The compatibility of two operational constraints—operation above the L–H power threshold and at low power to divertor—is examined for ITER long pulse H-mode and hybrid scenarios in integrated core–scrape off layer (SOL)–divertor modelling including impurities (intrinsic Be, He, W and seeded Ne). The core thermal, particle and momentum transport is simulated with the GLF23 transport model tested in the self-consistent simulations of temperatures, density and toroidal rotation velocity in JET hybrid discharges and extrapolated to ITER. The beneficial effect of toroidal rotation velocity on fusion gain is shown. The sensitivity studies with respect to operational (separatrix and pedestal density, Ne gas puff) and unknown physics (W convective velocity and perpendicular diffusion in SOL as well as W prompt re-deposition) parameters are performed to determine their influence on the operational window and fusion gain.

VL - 55 IS - 5 U1 -FP

U2 -CPP-HT

U5 - 88a082ba90add46139f1b78733b8692b ER - TY - JOUR T1 - Progress at JET in integrating ITER-relevant core and edge plasmas within the constraints of an ITER-like wall JF - Plasma Physics and Controlled Fusion Y1 - 2015 A1 - Giroud, C. A1 - Jachmich, S. A1 - Jacquet, P. A1 - Jarvinen, A. A1 - Lerche, E. A1 - Rimini, F. A1 - Aho-Mantila, L. A1 - Aiba, N. A1 - Balboa, I. A1 - da Silva Aresta Belo, P. A1 - Angioni, C. A1 - Beurskens, M. A1 - Brezinsek, S. A1 - Casson, F. J. A1 - Coffey, I. A1 - Cunningham, G. A1 - Delabie, E. A1 - Devaux, S. A1 - Drewelow, P. A1 - Frassinetti, L. A1 - Figueiredo, A. A1 - Huber, A. A1 - Hillesheim, J. A1 - Garzotti, L. A1 - Goniche, M. A1 - Groth, M. A1 - Hyun-Tae Kim A1 - Leyland, M. A1 - Lomas, P. A1 - Maddison, G. A1 - Marsen, S. A1 - Matthews, G. A1 - Meigs, A. A1 - Menmuir, S. A1 - Putterich, T. A1 - G. van Rooij A1 - Saarelma, S. A1 - Stamp, M. A1 - Urano, H. A1 - Webster, A. A1 - JET-EFDA Contributors AB - This paper reports the progress made at JET-ILW on integrating the requirements of the reference ITER baseline scenario with normalized confinement factor of 1, at a normalized pressure of 1.8 together with partially detached divertor whilst maintaining these conditions over many energy confinement times. The 2.5 MA high triangularity ELMy H-modes are studied with two different divertor configurations with D-gas injection and nitrogen seeding. The power load reduction with N seeding is reported. The relationship between an increase in energy confinement and pedestal pressure with triangularity is investigated. The operational space of both plasma configurations is studied together with the ELM energy losses and stability of the pedestal of unseeded and seeded plasmas. The achievement of stationary plasma conditions over many energy confinement times is also reported. VL - 57 UR - http://www.iop.org/Jet/fulltext/EFDP14021.pdf IS - 3 U1 - FP U2 - PDG U5 - 4b7265a10a94f029cf4f14cd047251e2 ER - TY - JOUR T1 - ELM frequency feedback control on JET JF - Nuclear Fusion Y1 - 2015 A1 - Lennholm, M. A1 - Beaumont, P. S. A1 - Carvalho, I. S. A1 - Chapman, I.T. A1 - Felton, R. A1 - Frigione, D. A1 - Garzotti, L. A1 - Goodyear, A. A1 - Graves, J. A1 - Tsalas, M. A1 - Grist, D. A1 - Jachmich, S. A1 - Lang, P. A1 - Lerche, E. A1 - de la Luna, E. A1 - Mooney, R. A1 - Morris, J. A1 - M F F Nave A1 - Rimini, F. A1 - Sips, G. A1 - Solano, E. A1 - JET-EFDA Contributors AB - This paper describes the first development and implementation of a closed loop edge localized mode (ELM) frequency controller using gas injection as the actuator. The controller has been extensively used in recent experiments on JET and it has proved to work well at ELM frequencies in the 15–40 Hz range. The controller responds effectively to a variety of disturbances, generally recovering the requested ELM frequency within approximately 500 ms. Controlling the ELM frequency has become of prime importance in the new JET configuration with all metal walls, where insufficient ELM frequency is associated with excessive tungsten influx. The controller has allowed successful operation near the minimum acceptable ELM frequency where the best plasma confinement can be achieved. Use of the ELM frequency controller in conjunction with pellet injection has enabled investigations of ELM triggering by pellets while maintaining the desired ELM frequency even when pellets fail to trigger ELMs. VL - 55 U1 - FP U2 - PDG U5 - 3bda42d1e65385a69f8f1e4ab2b8220b ER - TY - JOUR T1 - Overview of MAST results JF - Nuclear Fusion Y1 - 2015 A1 - Chapman, I.T. A1 - Adamek, J. A1 - Akers, R. J. A1 - Allan, S. A1 - Appel, L. A1 - Asunta, O. A1 - Barnes, M. A1 - N. Ben Ayed A1 - Hawke, J. A1 - Bigelow, T. A1 - Boeglin, W. A1 - Bradley, J. A1 - Brünner, J. A1 - Cahyna, P. A1 - Carr, M. A1 - Caughman, J. A1 - Cecconello, M. A1 - Challis, C. A1 - Chapman, S. A1 - Chorley, J. A1 - Colyer, G. A1 - Conway, N. A1 - Cooper, W. A. A1 - Cox, M. A1 - Crocker, N. A1 - Crowley, B. A1 - Cunningham, G. A1 - Danilov, A. A1 - Darrow, D. A1 - Dendy, R. A1 - Diallo, A. A1 - Dickinson, D. A1 - Diem, S. A1 - Dorland, W. A1 - Dudson, B. A1 - Dunai, D. A1 - Easy, L. A1 - Elmore, S. A1 - Field, A. A1 - Fishpool, G. A1 - Fox, M. A1 - Fredrickson, E. A1 - Freethy, S. A1 - Garzotti, L. A1 - Ghim, Y. C. A1 - Gibson, K. A1 - Graves, J. A1 - Gurl, C. A1 - Guttenfelder, W. A1 - Ham, C. A1 - Harrison, J. A1 - Harting, D. A1 - Havlickova, E. A1 - Hawkes, N. A1 - Hender, T. A1 - Henderson, S. A1 - Highcock, E. A1 - Hillesheim, J. A1 - Hnat, B. A1 - Holgate, J. A1 - Horacek, J. A1 - Howard, J. A1 - Huang, B. A1 - Imada, K. A1 - Jones, O. A1 - S. Kaye A1 - Keeling, D. A1 - Kirk, A. A1 - Klimek, I. A1 - Kocan, M. A1 - Leggate, H. A1 - Lilley, M. A1 - Lipschultz, B. A1 - Lisgo, S. A1 - Liu, Y. Q. A1 - Lloyd, B. A1 - Lomanowski, B. A1 - Lupelli, I. A1 - Maddison, G. A1 - J. Mailloux A1 - Martin, R. A1 - McArdle, G. A1 - McClements, K. A1 - McMillan, B. A1 - Meakins, A. A1 - Meyer, H. A1 - Michael, C. A1 - Militello, F. A1 - Milnes, J. A1 - Morris, A. W. A1 - Motojima, G. A1 - Muir, D. A1 - Nardon, E. A1 - Naulin, V. A1 - Naylor, G. A1 - Nielsen, A. A1 - O'Brien, M. A1 - O'Gorman, T. A1 - Ono, Y. A1 - Oliver, H. A1 - Pamela, S. A1 - Pangioni, L. A1 - Parra, F. A1 - Patel, A. A1 - Peebles, W. A1 - Peng, M. A1 - Perez, R. A1 - Pinches, S. A1 - Piron, L. A1 - Podesta, M. A1 - Price, M. A1 - Reinke, M. A1 - Ren, Y. A1 - Roach, C. A1 - Robinson, J. A1 - Romanelli, M. A1 - Rozhansky, V. A1 - Saarelma, S. A1 - Sangaroon, S. A1 - Saveliev, A. A1 - Scannell, R. A1 - Schekochihin, A. A1 - Sharapov, S. A1 - Sharples, R. A1 - Shevchenko, V. A1 - Silburn, S. A1 - J. Simpson A1 - Storrs, J. A1 - Takase, Y. A1 - Tanabe, H. A1 - Tanaka, H. A1 - Taylor, D. A1 - Taylor, G. A1 - Thomas, D. A1 - Thomas-Davies, N. A1 - Thornton, A. A1 - Turnyanskiy, M. A1 - Valovic, M. A1 - Vann, R. A1 - Walkden, N. A1 - Wilson, H. A1 - Wyk, L. V. A1 - Yamada, T. A1 - Zoletnik, S. A1 - MAST Team A1 - MAST Upgrade Teams VL - 55 IS - 10 U1 - FP U2 - TP U5 - 9d7b191e90422e8ed8bcf2078b75987f ER - TY - JOUR T1 - Modelling of JET hybrid scenarios with GLF23 transport model: E × B shear stabilization of anomalous transport JF - Nuclear Fusion Y1 - 2014 A1 - Voitsekhovitch, I. A1 - da Silva Aresta Belo, P. A1 - Citrin, J. A1 - Fable, E. A1 - Ferreira, J. A1 - J. Garcia A1 - Garzotti, L. A1 - Hobirk, J. A1 - Hogeweij, G. M. D. A1 - Joffrin, E. A1 - Kochl, F. A1 - X. Litaudon A1 - Moradi, S. A1 - Nabais, F. A1 - JET-EFDA Contributors A1 - EU-ITM ITER Scenario Modelling group KW - E x B shear stabilization KW - hybrid scenario KW - transport modelling AB -The E × B shear stabilization of anomalous transport in JET hybrid discharges is studied via self-consistent predictive modelling of electron and ion temperature, ion density and toroidal rotation velocity performed with the GLF23 model. The E × B shear stabilization factor (parameter α E in the GLF23 model) is adjusted to predict accurately the four simulated quantities under different experimental conditions, and the uncertainty in α E determined by 15% deviation between simulated and measured quantities is estimated. A correlation of α E with toroidal rotation velocity and E × B shearing rate is found in the low density plasmas, suggesting that the turbulence quench rule may be more complicated than assumed in the GLF23 model with constant α E . For the selected discharges the best predictive accuracy is obtained by using weak/no E × B shear stabilization (i.e. α E ≈ 0) at low toroidal angular frequency (Ω < 60 krad s −1 ), even in the scenarios with the current overshoot, and α E = 0.9 at high frequency (Ω > 100 krad s −1 ). Interestingly, a weak E × B shear stabilization of anomalous transport is found in the medium density strongly rotating discharge. An importance of linear β e stabilization in this discharge is estimated and compared to the low density discharge with equally high β e . The toroidal rotation velocity is well predicted here by assuming that the momentum diffusion coefficient is a fraction of thermal ion diffusivity. Taking into account the α E and Prandtl number with their uncertainties determined in the modelling of JET hybrid discharges, the performance of ITER hybrid scenario with optimized heat mix (33 MW of NBI and 20 MW of ECCD) is estimated showing the importance of toroidal rotation for achieving Q > 5.

VL - 54 UR - http://www.iop.org/Jet/article?EFDP13041&EFDP13048 IS - 9 U1 -FP

U2 -CPP-HT

U5 - da2cf17455ede8d649edf343a88bdd87 ER - TY - JOUR T1 - Contrasting H-mode behaviour with deuterium fuelling and nitrogen seeding in the all-carbon and metallic versions of JET JF - Nuclear Fusion Y1 - 2014 A1 - G. P. Maddison A1 - Giroud, C. A1 - Alper, B. A1 - Arnoux, G. A1 - Balboa, I. A1 - Beurskens, M. N. A. A1 - Boboc, A. A1 - Brezinsek, S. A1 - Brix, M. A1 - Clever, M. A1 - Coelho, R. A1 - Coenen, J. W. A1 - Coffey, I. A1 - da Silva Aresta Belo, P. A1 - Devaux, S. A1 - Devynck, P. A1 - Eich, T. A1 - Felton, R. C. A1 - Flanagan, J. A1 - Frassinetti, L. A1 - Garzotti, L. A1 - Groth, M. A1 - Jachmich, S. A1 - Jarvinen, A. A1 - Joffrin, E. A1 - Kempenaars, M. A1 - Kruezi, U. A1 - Lawson, K. D. A1 - Lehnen, M. A1 - Leyland, M. J. A1 - Liu, Y. A1 - Lomas, P. J. A1 - Lowry, C. G. A1 - Marsen, S. A1 - Matthews, G. F. A1 - McCormick, G. K. A1 - Meigs, A. G. A1 - Morris, A. W. A1 - Neu, R. A1 - Nunes, I. M. A1 - Oberkofler, M. A1 - Rimini, F. G. A1 - Saarelma, S. A1 - Sieglin, B. A1 - Sips, A.C.C. A1 - Sirinelli, A. A1 - Stamp, M. F. A1 - G. J. van Rooij A1 - Ward, D. J. A1 - Wischmeier, M. A1 - JET-EFDA Contributors AB - The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between type I H-mode characteristics in each design by examining respective scans over deuterium fuelling and impurity seeding, required to ameliorate exhaust loads both in JET at full capability and in ITER. Attention is focused upon a common high-triangularity, single-null divertor configuration at 2.5 MA, q 95 ≈ 3.5 yielding the most robust all-C performance. Contrasting results between the alternative linings are found firstly in unseeded plasmas, for which purity is improved and intrinsic radiation reduced in the ITER-like wall (ILW) but normalized energy confinement is ≈30% lower than in all-C counterparts, owing to a commensurately lower (electron) pedestal temperature. Divertor recycling is also radically altered, with slower, inboard/outboard asymmetric transients at ELMs and spontaneous oscillations in between them. Secondly, nitrogen seeding elicits opposite responses in the ILW to all-C experience, tending to raise plasma density, reduce ELM frequency, and above all to recover (electron) pedestal pressure, hence global confinement, almost back to previous levels. A hitherto unrecognized role of light impurities in pedestal stability and dynamics is consequently suggested. Thirdly, while heat loads on the divertor outboard target between ELMs are successfully reduced in proportion to the radiative cooling and ELM frequency effects of N in both wall environments, more surprisingly, average power ejected by ELMs also declines in the same proportion for the ILW. Detachment between transients is simultaneously promoted. Finally, inter-ELM W sources in the ILW divertor tend to fall with N input, although core accumulation possibly due to increased particle confinement still leads to significantly less steady conditions than in all-C plasmas. This limitation of ILW H-modes so far will be readdressed in future campaigns to continue progress towards a fully integrated scenario suitable for D T experiments on JET and for ‘baseline’ operation on ITER. The diverse changes in behaviour between all-C and ILW contexts demonstrate essentially the strong impact which boundary conditions and intrinsic impurities can have on tokamak-plasma states. VL - 54 UR - http://www.iop.org/Jet/article?EFDP13011&EFDP13018 U1 - MaSF U2 - MaSF-E U5 - f14366e6d4de5a085217627f6a96a779 ER - TY - JOUR T1 - Modelling of hybrid scenario: from present-day experiments towards ITER JF - Nuclear Fusion Y1 - 2013 A1 - X. Litaudon A1 - Voitsekhovitch, I. A1 - Artaud, J. F. A1 - Belo, P. A1 - Bizarro, J. P. S. A1 - Casper, T. A1 - Citrin, J. A1 - Fable, E. A1 - Ferreira, J. A1 - J. Garcia A1 - Garzotti, L. A1 - Giruzzi, G. A1 - Hobirk, J. A1 - Hogeweij, G. M. D. A1 - Imbeaux, F. A1 - Joffrin, E. A1 - Koechl, F. A1 - Liu, F. A1 - Lonnroth, J. A1 - Moreau, D. A1 - Parail, V. A1 - Schneider, M. A1 - Snyder, P. B. A1 - ASDEX Upgrade Team A1 - JET-EFDA Contributors A1 - EU-ITM ITER Scenario Modelling group AB -The ‘hybrid’ scenario is an attractive operating scenario for ITER since it combines long plasma duration with the reliability of the reference H-mode regime. We review the recent European modelling effort carried out within the Integrated Scenario Modelling group which aims at (i) understanding the underlying physics of the hybrid regime in ASDEX-Upgrade and JET and (ii) extrapolating them towards ITER. JET and ASDEX-Upgrade hybrid scenarios performed under different experimental conditions have been simulated in an interpretative and predictive way in order to address the current profile dynamics and its link with core confinement, the relative importance of magnetic shear, s , and E × B flow shear on the core turbulence, pedestal stability and H–L transition. The correlation of the improved confinement with an increased s / q at outer radii observed in JET and ASDEX-Upgrade discharges is consistent with the predictions based on the GLF23 model applied in the simulations of the ion and electron kinetic profiles. Projections to ITER hybrid scenarios have been carried out focusing on optimization of the heating/current drive schemes to reach and ultimately control the desired plasma equilibrium using ITER actuators. Firstly, access condition to the hybrid-like q -profiles during the current ramp–up phase has been investigated. Secondly, from the interpreted role of the s / q ratio, ITER hybrid scenario flat-top performance has been optimized through tailoring the q -profile shape and pedestal conditions. EPED predictions of pedestal pressure and width have been used as constraints in the interpretative modelling while the core heat transport is predicted by GLF23. Finally, model-based approach for real-time control of advanced tokamak scenarios has been applied to ITER hybrid regime for simultaneous magnetic and kinetic profile control.

VL - 53 U1 -FP

U2 -CPP-HT

U5 - 1e865efa4611fccf9bfb441bffcf216a ER - TY - JOUR T1 - Overview of physics results from MAST towards ITER/DEMO and the MAST Upgrade JF - Nuclear Fusion Y1 - 2013 A1 - Meyer, H. A1 - Abel, I. G. A1 - Akers, R. J. A1 - Allan, A. A1 - Allan, S. Y. A1 - Appel, L. C. A1 - Asunta, O. A1 - Barnes, M. A1 - Barratt, N. C. A1 - N. Ben Ayed A1 - Bradley, J. W. A1 - Canik, J. A1 - Cahyna, P. A1 - Cecconello, M. A1 - Challis, C. D. A1 - Chapman, I.T. A1 - Ciric, D. A1 - Colyer, G. A1 - Conway, N. J. A1 - Cox, M. A1 - Crowley, B. J. A1 - Cowley, S. C. A1 - Cunningham, G. A1 - Danilov, A. A1 - Darke, A. A1 - de Bock, M. F. M. A1 - De Temmerman, G. A1 - Dendy, R. O. A1 - Denner, P. A1 - Dickinson, D. A1 - Dnestrovskij, A. Y. A1 - Dnestrovsky, Y. A1 - Driscoll, M. D. A1 - Dudson, B. A1 - Dunai, D. A1 - Dunstan, M. A1 - Dura, P. A1 - Elmore, S. A1 - Field, A. R. A1 - Fishpool, G. A1 - Freethy, S. A1 - Fundamenski, W. A1 - Garzotti, L. A1 - Ghim, Y. C. A1 - Gibson, K. J. A1 - Gryaznevich, M. P. A1 - Harrison, J. A1 - E. Havlíčková A1 - Hawkes, N. C. A1 - Heidbrink, W. W. A1 - Hender, T. C. A1 - Highcock, E. A1 - Higgins, D. A1 - Hill, P. A1 - Hnat, B. A1 - Hole, M. J. A1 - J. Horáček A1 - Howell, D. F. A1 - Imada, K. A1 - Jones, O. A1 - Kaveeva, E. A1 - Keeling, D. A1 - Kirk, A. A1 - M. Kočan A1 - Lake, R. J. A1 - Lehnen, M. A1 - Leggate, H. J. A1 - Liang, Y. A1 - Lilley, M. K. A1 - Lisgo, S. W. A1 - Liu, Y. Q. A1 - Lloyd, B. A1 - G. P. Maddison A1 - J. Mailloux A1 - Martin, R. A1 - McArdle, G. J. A1 - McClements, K. G. A1 - McMillan, B. A1 - Michael, C. A1 - Militello, F. A1 - Molchanov, P. A1 - Mordijck, S. A1 - Morgan, T. A1 - Morris, A. W. A1 - Muir, D. G. A1 - Nardon, E. A1 - Naulin, V. A1 - Naylor, G. A1 - Nielsen, A. H. A1 - O'Brien, M. R. A1 - O'Gorman, T. A1 - Pamela, S. A1 - Parra, F. I. A1 - Patel, A. A1 - Pinches, S. D. A1 - Price, M. N. A1 - Roach, C. M. A1 - Robinson, J. R. A1 - Romanelli, M. A1 - Rozhansky, V. A1 - Saarelma, S. A1 - Sangaroon, S. A1 - Saveliev, A. A1 - Scannell, R. A1 - Seidl, J. A1 - Sharapov, S. E. A1 - Schekochihin, A. A. A1 - Shevchenko, V. A1 - Shibaev, S. A1 - Stork, D. A1 - Storrs, J. A1 - Sykes, A. A1 - Tallents, G. J. A1 - Tamain, P. A1 - Taylor, D. A1 - Temple, D. A1 - Thomas-Davies, N. A1 - Thornton, A. A1 - Turnyanskiy, M. R. A1 - M. Valovič A1 - Vann, R. G. L. A1 - Verwichte, E. A1 - Voskoboynikov, P. A1 - Voss, G. A1 - Warder, S. E. V. A1 - Wilson, H. R. A1 - Wodniak, I. A1 - Zoletnik, S. A1 - Zagorski, R. A1 - MAST Team A1 - NBI Team AB - New diagnostic, modelling and plant capability on the Mega Ampère Spherical Tokamak (MAST) have delivered important results in key areas for ITER/DEMO and the upcoming MAST Upgrade, a step towards future ST devices on the path to fusion currently under procurement. Micro-stability analysis of the pedestal highlights the potential roles of micro-tearing modes and kinetic ballooning modes for the pedestal formation. Mitigation of edge localized modes (ELM) using resonant magnetic perturbation has been demonstrated for toroidal mode numbers n = 3, 4, 6 with an ELM frequency increase by up to a factor of 9, compatible with pellet fuelling. The peak heat flux of mitigated and natural ELMs follows the same linear trend with ELM energy loss and the first ELM-resolved T i measurements in the divertor region are shown. Measurements of flow shear and turbulence dynamics during L–H transitions show filaments erupting from the plasma edge whilst the full flow shear is still present. Off-axis neutral beam injection helps to strongly reduce the redistribution of fast-ions due to fishbone modes when compared to on-axis injection. Low- k ion-scale turbulence has been measured in L-mode and compared to global gyro-kinetic simulations. A statistical analysis of principal turbulence time scales shows them to be of comparable magnitude and reasonably correlated with turbulence decorrelation time. T e inside the island of a neoclassical tearing mode allow the analysis of the island evolution without assuming specific models for the heat flux. Other results include the discrepancy of the current profile evolution during the current ramp-up with solutions of the poloidal field diffusion equation, studies of the anomalous Doppler resonance compressional Alfvén eigenmodes, disruption mitigation studies and modelling of the new divertor design for MAST Upgrade. The novel 3D electron Bernstein synthetic imaging shows promising first data sensitive to the edge current profile and flows. VL - 53 UR - http://stacks.iop.org/0029-5515/53/i=10/a=104008 U1 - PSI U2 - PSI-E U5 - fee6f536ea06c1003255446f71a039bd ER - TY - JOUR T1 - Overview of physics results from MAST JF - Nuclear Fusion Y1 - 2011 A1 - Lloyd, B. A1 - Akers, R. J. A1 - Alladio, F. A1 - Allan, S. A1 - Appel, L. C. A1 - Barnes, M. A1 - Barratt, N. C. A1 - N. Ben Ayed A1 - Breizman, B. N. A1 - Cecconello, M. A1 - Challis, C. D. A1 - Chapman, I.T. A1 - Ciric, D. A1 - Colyer, G. A1 - Connor, J. W. A1 - Conway, N. J. A1 - Cox, M. A1 - Cowley, S. C. A1 - Cunningham, G. A1 - Darke, A. A1 - De Bock, M. A1 - Delchambre, E. A1 - De Temmerman, G. A1 - Dendy, R. O. A1 - Denner, P. A1 - Driscoll, M. D. A1 - Dudson, B. A1 - Dunai, D. A1 - Dunstan, M. A1 - Elmore, S. A1 - Field, A. R. A1 - Fishpool, G. A1 - Freethy, S. A1 - Garzotti, L. A1 - Gibson, K. J. A1 - Gryaznevich, M. P. A1 - Guttenfelder, W. A1 - Harrison, J. A1 - Hastie, R. J. A1 - Hawkes, N. C. A1 - Hender, T. C. A1 - Hnat, B. A1 - Howell, D. F. A1 - Hua, M. D. A1 - Hubbard, A. A1 - Huysmans, G. A1 - Keeling, D. A1 - Kim, Y. C. A1 - Kirk, A. A1 - Liang, Y. A1 - Lilley, M. K. A1 - Lisak, M. A1 - Lisgo, S. A1 - Liu, Y. Q. A1 - G. P. Maddison A1 - Maingi, R. A1 - Manhood, S. J. A1 - Martin, R. A1 - McArdle, G. J. A1 - McCone, J. A1 - Meyer, H. A1 - Michael, C. A1 - Mordijck, S. A1 - Morgan, T. A1 - Morris, A. W. A1 - Muir, D. G. A1 - Nardon, E. A1 - Naylor, G. A1 - O'Brien, M. R. A1 - O'Gorman, T. A1 - Palenik, J. A1 - Patel, A. A1 - Pinches, S. D. A1 - Price, M. N. A1 - Roach, C. M. A1 - Rozhansky, V. A1 - Saarelma, S. A1 - Sabbagh, S. A. A1 - Saveliev, A. A1 - Scannell, R. A1 - Sharapov, S. E. A1 - Shevchenko, V. A1 - Shibaev, S. A1 - Stork, D. A1 - Storrs, J. A1 - Suttrop, W. A1 - Sykes, A. A1 - Tamain, P. A1 - Taylor, D. A1 - Temple, D. A1 - Thomas-Davies, N. A1 - Thornton, A. A1 - Turnyanskiy, M. R. A1 - Valovic, M. A1 - Vann, R. G. L. A1 - Voss, G. A1 - Walsh, M. J. A1 - Warder, S. E. V. A1 - Wilson, H. R. A1 - Windridge, M. A1 - Wisse, M. A1 - Zoletnik, S. KW - MODEL KW - TRANSPORT AB -Major developments on the Mega Amp Spherical Tokamak (MAST) have enabled important advances in support of ITER and the physics basis of a spherical tokamak (ST) based component test facility (CTF), as well as providing new insight into underlying tokamak physics. For example, L-H transition studies benefit from high spatial and temporal resolution measurements of pedestal profile evolution (temperature, density and radial electric field) and in support of pedestal stability studies the edge current density profile has been inferred from motional Stark effect measurements. The influence of the q-profile and E x B flow shear on transport has been studied in MAST and equilibrium flow shear has been included in gyro-kinetic codes, improving comparisons with the experimental data. H-modes exhibit a weaker q and stronger collisionality dependence of heat diffusivity than implied by IPB98(gamma, 2) scaling, which may have important implications for the design of an ST-based CTF. ELM mitigation, an important issue for ITER, has been demonstrated by applying resonant magnetic perturbations (RMPs) using both internal and external coils, but full stabilization of type-I ELMs has not been observed. Modelling shows the importance of including the plasma response to the RMP fields. MAST plasmas with q > 1 and weak central magnetic shear regularly exhibit a long-lived saturated ideal internal mode. Measured plasma braking in the presence of this mode compares well with neo-classical toroidal viscosity theory. In support of basic physics understanding, high resolution Thomson scattering measurements are providing new insight into sawtooth crash dynamics and neo-classical tearing mode critical island widths. Retarding field analyser measurements show elevated ion temperatures in the scrape-off layer of L-mode plasmas and, in the presence of type-I ELMs, ions with energy greater than 500 eV are detected 20 cm outside the separatrix. Disruption mitigation by massive gas injection has reduced divertor heat loads by up to 70%.

VL - 51 SN - 0029-5515 IS - 9 N1 - ISI Document Delivery No.: 818DPTimes Cited: 0Cited Reference Count: 60SI U1 -PSI

U2 -PSI-E

U5 - 9e9434147fddee9a0003e22469980e60 ER - TY - JOUR T1 - ELM pacing investigations at JET with the new pellet launcher JF - Nuclear Fusion Y1 - 2011 A1 - Lang, P. T. A1 - Alonso, A. A1 - Alper, B. A1 - Belonohy, E. A1 - Boboc, A. A1 - Devaux, S. A1 - Eich, T. A1 - Frigione, D. A1 - Gal, K. A1 - Garzotti, L. A1 - Geraud, A. A1 - Kocsis, G. A1 - Kochl, F. A1 - Lackner, K. A1 - Loarte, A. A1 - Lomas, P. J. A1 - Maraschek, M. A1 - Muller, H. W. A1 - Neu, R. A1 - Neuhauser, J. A1 - Petravich, G. A1 - Saibene, G. A1 - Schweinzer, J. A1 - Thomsen, H. A1 - Tsalas, M. A1 - Wenninger, R. A1 - Zohm, H. KW - ASDEX UPGRADE KW - ENERGY KW - INJECTION KW - ITER KW - LOSSES KW - MODE AB -A new pellet injection system was installed at JET designed for both fuelling and ELM pacing. The purpose of the pacing section was to validate pellet ELM pacing as a suitable tool for ELM mitigation in ITER. Pellet pacing was confirmed at the large size scale of JET. The dynamics of triggered ELMs was investigated with respect to their spontaneous counterparts. Triggered ELMs show features also typical for spontaneous ELMs in several operational regimes. Since none of these regimes was unsettled by the pellets this is a strong hint for compatibility with other plasma control tools. Observations and modelling results indicate the ELM triggering occurs by the evolution of the pellet ablation plasmoid into the first ELM filament followed by a poloidal spread of the instability. An ELM obviously can be forced by a pellet due to the strong local perturbation imposed already under unusual onset conditions but then evolves like any ELM typical for the corresponding plasma regime. For tool optimization the pellet mass and hence the convective confinement losses imposed have to be minimized. In our experiments, a lower mass threshold was observed for the first time. It has been found that to reliably trigger an ELM the pellet needs to be sufficiently large (and fast) to penetrate close to the pedestal top. Recent investigations are clear steps forward to validate the pellet pacing approach for ITER.

VL - 51 SN - 0029-5515 IS - 3 N1 - ISI Document Delivery No.: 729AETimes Cited: 4Cited Reference Count: 38 U1 -FP

U2 -PDG

U5 - 506bca96c5637433dac75b877a0bcc14 ER - TY - JOUR T1 - Metal impurity transport control in JET H-mode plasmas with central ion cyclotron radiofrequency power injection JF - Nuclear Fusion Y1 - 2011 A1 - Valisa, M. A1 - Carraro, L. A1 - Predebon, I. A1 - M. E. Puiatti A1 - Angioni, C. A1 - Coffey, I. A1 - Giroud, C. A1 - Taroni, L. L. A1 - Alper, B. A1 - Baruzzo, M. A1 - da Silva, P. B. A1 - Buratti, P. A1 - Garzotti, L. A1 - Van Eester, D. A1 - Lerche, E. A1 - Mantica, P. A1 - Naulin, V. A1 - Tala, T. A1 - Tsalas, M. KW - ASDEX UPGRADE KW - BARRIER KW - BEHAVIOR KW - CONFINEMENT KW - DISCHARGES KW - divertor KW - FUSION DEVICES KW - NM REGION KW - TOKAMAK KW - Tungsten AB -The scan of ion cyclotron resonant heating (ICRH) power has been used to systematically study the pump out effect of central electron heating on impurities such as Ni and Mo in H-mode low collisionality discharges in JET. The transport parameters of Ni and Mo have been measured by introducing a transient perturbation on their densities via the laser blow off technique. Without ICRH Ni and Mo density profiles are typically peaked. The application of ICRH induces on Ni and Mo in the plasma centre (at normalized poloidal flux rho = 0.2) an outward drift approximately proportional to the amount of injected power. Above a threshold of ICRH power of about 3 MW in the specific case the radial flow of Ni and Mo changes from inwards to outwards and the impurity profiles, extrapolated to stationary conditions, become hollow. At mid-radius the impurity profiles become flat or only slightly hollow. In the plasma centre the variation of the convection-to-diffusivity ratio upsilon/D of Ni is particularly well correlated with the change in the ion temperature gradient in qualitative agreement with the neoclassical theory. However, the experimental radial velocity is larger than the neoclassical one by up to one order of magnitude. Gyrokinetic simulations of the radial impurity fluxes induced by electrostatic turbulence do not foresee a flow reversal in the analysed discharges.

VL - 51 SN - 0029-5515 IS - 3 N1 - ISI Document Delivery No.: 729AETimes Cited: 1Cited Reference Count: 34 U1 -FP

U2 -PDG

U5 - dc8bc3592b534a570ec367324f31bd67 ER - TY - JOUR T1 - Integrated modelling of ITER reference scenarios JF - Nuclear Fusion Y1 - 2009 A1 - Parail, V. A1 - Belo, P. A1 - Boerner, P. A1 - Bonnin, X. A1 - Corrigan, G. A1 - Coster, D. A1 - Ferreira, J. A1 - Foster, A. A1 - Garzotti, L. A1 - Hogeweij, G. M. D. A1 - Houlberg, W. A1 - Imbeaux, F. A1 - Johner, J. A1 - Kochl, F. A1 - Kotov, V. A1 - Lauro-Taroni, L. A1 - X. Litaudon A1 - Lonnroth, J. A1 - Pereverzev, G. A1 - Peysson, Y. A1 - Saibene, G. A1 - Sartori, R. A1 - Schneider, M. A1 - Sips, G. A1 - Strand, P. A1 - Tardini, G. A1 - Valovic, M. A1 - Wiesen, S. A1 - Wischmeier, M. A1 - Zagorski, R. KW - CONFINEMENT KW - MODES KW - TOKAMAKS KW - TRANSPORT AB - The ITER Scenario Modelling Working Group (ISM WG) is organized within the European Task Force on Integrated Tokamak Modelling (ITM-TF). The main responsibility of the WG is to advance a pan-European approach to integrated predictive modelling of ITER plasmas with the emphasis on urgent issues, identified during the ITER Design Review. Three major topics are discussed, which are considered as urgent and where the WG has the best possible expertize. These are modelling of current profile control, modelling of density control and impurity control in ITER (the last two topics involve modelling of both core and SOL plasma). Different methods of heating and current drive are tested as controllers for the current profile tailoring during the current ramp-up in ITER. These include Ohmic, NBI, ECRH and LHCD methods. Simulation results elucidate the available operational margins and rank different methods according to their ability to meet different requirements. A range of 'ITER-relevant' plasmas from existing tokamaks were modelled. Simulations confirmed that the theory-based transport model, GLF23, reproduces the density profile reasonably well and can be used to assess ITER profiles with both pellet injection and gas puffing. In addition, simulations of the SOL plasma were launched using both H-mode and L-mode models for perpendicular transport within the edge barrier and in the SOL. Finally, an integrated approach was also used for the predictive modelling of impurity accumulation in ITER. This includes helium ash, extrinsic impurities (such as argon) and impurities coming from the wall (including tungsten). The relative importance of anomalous and neo-classical pinch contributions towards impurity penetration through the edge transport barrier and further accumulation in the core was assessed. VL - 49 SN - 0029-5515 UR -