TY - JOUR
T1 - Density peaking in JET - determined by fuelling or transport?
JF - Nuclear Fusion
Y1 - 2019
A1 - Tala, T.
A1 - Nordman, H.
A1 - Salmi, A.
A1 - Bourdelle, C.
A1 - Citrin, J.
A1 - Czarnecka, A.
A1 - Eriksson, F.
A1 - Fransson, E.
A1 - Giroud, C.
A1 - Hillesheim, J.
A1 - Maggi, C.
A1 - Mantica, P.
A1 - Mariani, A.
A1 - Maslov, M.
A1 - Meneses, L.
A1 - Menmuir, S.
A1 - Mordijck, S.
A1 - Naulin, V.
A1 - Oberparleiter, M.
A1 - Sips, G.
A1 - Tegnered, D.
A1 - Tsalas, M.
A1 - Weisen, H.
A1 - JET Contributors
AB - Core density profile peaking and electron particle transport have been extensively studied by performing several dimensionless collisionality (υ *) scans with other matched dimensionless profiles in various plasma operation scenarios on the Joint European Torus (JET). This is the first time when electron particle transport coefficients in the H-mode have been measured on JET with high resolution diagnostics, and therefore we are in a position to distinguish between the neutral beam injection (NBI) source and inward electron particle pinch in contributing to core density peaking. The NBI particle source is found to contribute typically 50%–60% to the electron density peaking in JET H-mode plasmas where T e/T i ~ 1 or smaller and at υ * = 0.1–0.5 (averaged between r/a = 0.3–0.8), and being independent of υ * within that range. In these H-mode plasmas, the electron particle transport coefficients, D e and v e, are small, thus giving rise to the large influence of NBI fueling with respect to transport effect on peaking. In L-mode plasma conditions, the role of the NBI source is small, typically 10%–20%, and the electron particle transport coefficients are large. These dimensionless υ * scans give the best possible data for model validation. TGLF simulations are in good agreement with the experimental results with respect to the role of NBI particle source versus inward pinch in affecting density peaking, both for the H-mode and L-mode υ * scans. It predicts, similarly to experimental results, that typically about half of the peaking originates from the NBI fuelling in the H-mode and 10%–20% in the L-mode. GENE simulation results also support the key role of NBI fuelling in causing a peaked density profile in JET H-mode plasma (T e/T i ~ 1 and υ * = 0.1–0.5) and, in fact, give an even higher weight on NBI fuelling than that experimentally observed or predicted by TGLF. For the non-fuelled H-mode plasma at higher T e/T i = 1.5 and lower β N and υ *, both TGLF and GENE predict peaked density profiles, therefore agreeing well with experimental steady-state density peaking. Overall, the various modelling results give a fairly good confidence in using TGLF and GENE in predicting density peaking in quite a wide range of plasma conditions in JET.
VL - 59
IS - 12
U1 - FP
U2 - IMT
U5 - 082a12a8da2101f77aa3f00d71ab98a6
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 -