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330 results on '"Xu, G. S."'

1. Impact of pedestal density gradient and collisionality on ELM dynamics

Author

Li, Nami, Xu, X. Q., Wang, Y. F., Lin, X., Yan, N., and Xu, G. S.

Subjects
Physics - Plasma Physics
Abstract

BOUT++ turbulence simulations are conducted to capture the underlying physics of the small ELM characteristics achieved by increasing separatrix density via controlling strike points from vertical to horizontal divertor plates for three EAST discharges. BOUT ++ linear simulations show that the most unstable modes change from high-n ideal ballooning modes to the intermediate-n peeling-ballooning modes and eventually to peeling-ballooning stable plasmas in the pedestal. Nonlinear simulations show that the fluctuation is saturated at a high level for the lowest separatrix density. The elm size decreases with increasing the separatrix density, until the fraction of this energy lost during the ELM crash becomes less than 1% of the pedestal stored energy, leading to small ELMs. Simulations indicate that small ELMs can be triggered either by the marginally peeling-ballooning instability near the peak pressure gradient position inside pedestal or by a local instability in the pedestal foot with a larger separatrix density gradient. The pedestal collisionality scan for type-I ELMs with steep pedestal density gradient shows that both linear growth rate and elm size decrease with collisionality increasing. While the pedestal collisionality and pedestal density width scan with a weak pedestal density gradient indicate small ELMs can either be triggered by high-n ballooning mode or by low-n peeling mode in low collisionality region 0.04~0.1. The simulations indicate the weaker the linear unstable modes near marginal stability with small linear growth rate, the lower nonlinearly saturated fluctuation intensity and the smaller turbulence spreading from the linear unstable zone to stable zone in the nonlinear saturation phase, leading to small ELMs.

Published
2022
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3. Gyro-kinetic simulations of trapped electron collision effects on low-frequency drift-wave instabilities in tokamak plasmas.

Author

Tao, Y Q, Wang, L, Xu, G S, Chen, R, Yan, N, Sun, P J, Yang, Q Q, Lin, X, and Ye, Y

Subjects
COLLISIONS (Nuclear physics), PLASMA instabilities, DISPERSION relations, ION temperature, ELECTRON temperature
Abstract

Low-frequency drift-wave instabilities play a crucial role in the radial transport of present-day tokamaks, and trapped electron collisions can significantly influence these instabilities. In this paper, the effects of trapped electron collisions on these instabilities are investigated based on linear gyro-kinetic simulations. The basic numerical techniques including dispersion relation integral method and orthogonal basis function expansion are presented in detail with necessary benchmark work. The results demonstrate that in medium gradients, the increase of trapped electron proportions promotes the growth rate and radial heat transport largely for quasi-linear trapped electron modes (TEMs) and ion temperature gradient (ITG) modes. Moreover, trapped electron collisions have strong stabilizing effects, especially for TEMs driven by electron temperature gradients. Two distinctive branches, namely Mode #1 and #2, are investigated in steep gradients. Both behave in a varied instability nature during different ranges of the normalized wave vector k ^ θ . Mode #1 mainly induces radial heat transport during k ^ θ < 0.5 and is significantly suppressed by the collisions. Mode #2 mainly induces radial heat transport during 0.4 < k ^ θ < 0.8 , and is largely enhanced by the collisions. When the collisionality is large enough, Mode #2 has stronger transport capacity than the other. Mode #2 at the medium wave vector, known as dissipative TEM, may provide the mechanism of the edge coherent mode observed in EAST H-mode plasmas, wherein collisionality plays an important role in the mode excitation. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Flux-driven simulations of self-generated radial electric fields and transition to improved confinement regime.

Author

Zhou, Zhenyu, Xu, G. S., Dong, Chao, Lu, Zhixin, Zhou, Tianchun, Jiang, Changzhi, Li, Bo, and Ernst, D. R.

Subjects
*ELECTRIC fields, *PLASMA boundary layers, *TURBULENT flow, *ENERGY transfer, *TOKAMAKS, *TURBULENCE
Abstract

The evolution of plasma profiles and radial electric fields in the edge of tokamaks during a transition to an improved confinement regime is explored in an unfavorable configuration based on self-consistent, flux-driven simulations of reduced Braginskii models with ion pressure dynamics. The edge plasma response to the heating power is explored by varying the heat source strength. The energy transfer from turbulent to mean flows is induced by the large-amplitude fluctuations as the power input becomes sufficiently strong. It is found that ion pressure fluctuations play an important role in the generation of the Reynolds power. Consequently, the plasma spontaneously forms radial electric fields localized at the edge, which reduces the radial correlation and amplitudes of edge fluctuations. An edge temperature pedestal also forms while the density profiles remain nearly unchanged, featuring an I-mode-like regime. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Simulation of transition dynamics to high confinement in fusion plasmas

Author

Nielsen, A H., Xu, G. S., Madsen, J., Naulin, V., Rasmussen, J. Juul, and Wan, B. N.

Subjects
Physics - Plasma Physics
Abstract

The transition dynamics from the low (L) to the high (H) confinement mode in magnetically confined plasmas is investigated using a first-principles four-field fluid model. Numerical results are in close agreement with measurements from the Experimental Advanced Superconducting Tokamak - EAST. Particularly, the slow transition with an intermediate dithering phase is well reproduced by the numerical solutions. Additionally, the model reproduces the experimentally determined L-H transition power threshold scaling that the ion power threshold increases with increasing particle density. The results hold promise for developing predictive models of the transition, essential for understanding and optimizing future fusion power reactors.

Published
2014

7. Observation of confined current ribbon in JET plasmas

Author

Solano, E. R., Lomas, P. J., Alper, B., Xu, G. S., Andrew, Y., Arnoux, G., Boboc, A., Barrera, L., Belo, P., Beurskens, M. N. A., Brix, M., Crombe, K., de la Luna, E., Devaux, S., Eich, T., Gerasimov, S., Giroud, C., Harting, D., Howell, D., Huber, A., Kocsis, G., Korotkov, A., Lopez-Fraguas, A., Nave, M. F. F., Rachlew, E., Rimini, F., Saarelma, S., Sirinelli, A., Thomsen, H., Zabeo, L., Zarzoso, D., and contributors, JET EFDA

Subjects
Physics - Plasma Physics
Abstract

we report the identification of a localised current structure inside the JET plasma. It is a field aligned closed helical ribbon, carrying current in the same direction as the background current profile (co-current), rotating toroidally with the ion velocity (co-rotating). It appears to be located at a flat spot in the plasma pressure profile, at the top of the pedestal. The structure appears spontaneously in low density, high rotation plasmas, and can last up to 1.4 s, a time comparable to a local resistive time. It considerably delays the appearance of the first ELM., Comment: 10 pages, 6 figures

Published
2009
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8. Progress of Divertor Heat and Particle Flux Control in EAST for Advanced Steady-State Operation in the Last 10 Years

Author

Wang, L., Xu, G. S., Hu, J. S., Li, K. D., Yuan, Q. P., Liu, J. B., Ding, F., Yu, Y. W., Luo, Z. P., Xu, J. C., Meng, L. Y., Wu, K., Zhang, B., Chen, M. W., Deng, G. Z., Liu, X. J., Yang, Z. S., Liu, X., Liu, S. C., Ding, R., Zuo, G. Z., Sun, Z., Wu, J. H., Cao, B., Zhang, Y., Duan, Y. M., Zhang, L., Qian, X. Y., Li, A., Chen, L., Jia, M. N., Si, H., Xia, T. Y., Sun, Y. W., Chen, Y. P., Li, Q., Luo, G. N., Yao, D. M., Xiao, B. J., Gong, X. Z., Zhang, X. D., Wan, B. N., Wang, H. Q., Guo, H. Y., Eldon, D., Garofalo, A. M., Liang, Y., Xu, S., Sang, C. F., Wang, D. Z., Dai, S. Y., Sun, J. Z., Ding, H. B., Maingi, R., Gan, K. F., Zou, X. L., and Du, H. L.

Published
2021
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10. Investigation and predict-first exploration of steady-state operation scenarios on EAST considering several upgrade options for RF heating and current drive.

Author

Zhai, X. M., Chen, J. L., Xiang, N., Gong, X. Z., Huang, J., Qian, J. P., Li, M. H., and Xu, G. S.

Subjects
HEATING, RADIO frequency, PLASMA waves, PLASMA density, TOKAMAKS
Abstract

How to utilize heating and current drive by different radio frequency (RF) waves to improve plasma performance is a critical issue in the development of steady-state operation scenarios on Experimental Advanced Superconducting Tokamak (EAST). The steady-state scenario with the highest thermal stored energy on EAST was obtained by combining the central heating and current drive by electron cyclotron (EC) waves, the efficient lower hybrid (LH) current drive at 4.6 GHz and high plasma density (∼80% of the Greenwald density limit [1]) in high poloidal beta experiments [2]. The integrated modeling for core plasmas at flat-top phase has been validated with the previous high poloidal beta experiments with the external heating dominated by LH and EC waves. Thus, it can and should be used to do 'predict-first' explorations for future development of high performance steady-state scenarios on EAST. In this paper a validation with a recent experiment with remarkable ICRF power is presented. Then a preliminary predictive modeling taking into account the replacement of the LH waves at 2.45 GHz by that at 4.6 GHz shows that an advanced steady-state scenario with reversed magnetic shear is sustained with only RF heating. The uncertainties in the modeling are briefly discussed. [ABSTRACT FROM AUTHOR]

Published
2023
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11. Hot spots of the main limiter induced by fast ions in experimental advanced superconducting tokamak (EAST).

Author

Li, Y. L., Xu, Y. F., Xu, X. Y., Xu, G. S., Liang, R. R., Ding, R., Liu, X., Geng, K. N., Zhang, T., Wang, S. X., Fan, H. C., Zhong, G. Q., Fu, S. Y., Lu, D. A., Mao, S. T., Fu, J., Zang, Q., Cao, L., Zhang, B., and Wang, L.

Subjects
FAST ions, TOKAMAKS, HEATING load, NEUTRAL beams, RADIO frequency, HEAT storage
Abstract

The main limiter in EAST was observed to endure a high heat load and was cracked near the midplane at the right side during the plasma operation. To explore the heat load carried by fast ion loss toward the main limiter, the neutral beam injection (NBI) and radio frequency power proportion experiment was conducted in EAST where the plasma stored energy and line integrated density were kept almost constant. The hot spot at the right side of the main limiter was observed to be enhanced by co-current perpendicular (co-perp) NBI. An NBI ion loss simulation was performed in the presence of the toroidal field ripple and the Coulomb collision by using the orbit code GYCAVA and the NBI code TGCO. The result indicates that the NBI ion loss by ripple and collision mainly causes a bright area below the midplane of the right side of the main limiter as observed in the EAST experiment. The peak heat load of lost fast ions generated by co-perp NBI is ∼0.5 MW/m2 as obtained by 1 MW of NBI deposited power and comparable with the heat load carried by fast electrons induced by lower hybrid current drive. In addition, increasing the gap between the separatrix and the first-wall limiters in the simulation is found to reduce this heat load. [ABSTRACT FROM AUTHOR]

Published
2023
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14. An innovative divertor concept, the fish tail divertor, for reducing the surface temperature on the divertor target plate in EAST tokamak experiments.

Author

Zhang, Y., Zhang, X. D., Qiu, Q. L., Zhang, J., Li, B., Chen, L., Luo, Z. P., Qian, J. P., Wang, L., Liu, H. Q., Meng, L. Y., Liu, X., Zhang, B., Shen, B., Yuan, Q. P., Xiao, B. J., Gong, X. Z., Xu, G. S., Hu, J. S., and Lu, K.

Subjects
SURFACE temperature, FUSION reactor divertors, TOKAMAKS, FUSION reactors, PLASMA currents, MAGNETIC fields
Abstract

An innovative divertor concept, the fish tail divertor, is proposed in this paper, aimed at reducing the surface temperature on the tokamak divertor plate as well as that due to the edge localized modes. This new concept has been implemented in experiments to demonstrate its capability of strike point sweeping on the plate at a frequency range from 10 to 100 Hz by using an oscillating magnetic field. A strike point movement of 5–6 cm is achieved by applying a coil current of several percent of plasma current, leading to a significant reduction of divertor surface temperature. The result indicates a possible application in a fusion reactor. [ABSTRACT FROM AUTHOR]

Published
2023
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17. Experimental investigation of electromagnetic GAMs under the influence of 3D magnetic topological structure in EAST

Author

Qu, H, primary, Kong, D F, additional, Xu, M, additional, Liu, A D, additional, Liang, Y F, additional, Zhang, S B, additional, Cai, H S, additional, Qiu, Z Y, additional, Chen, W, additional, Shi, T H, additional, Gu, S, additional, Duan, Y M, additional, Wang, H H, additional, Chu, N, additional, Zhao, H L, additional, Xiang, H M, additional, Wang, Y M, additional, Han, X, additional, Zhang, T, additional, Gao, X, additional, Feng, X, additional, Zhou, C, additional, Zhuang, G, additional, Hu, L Q, additional, Xu, G S, additional, and Gong, X Z, additional

Published
2022
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19. Dependence of upstream SOL density shoulder on divertor neutral pressure observed in L-mode and H-mode plasmas in the EAST superconducting tokamak

Author

Yan, N., Chen, L., Xu, G. S., Wu, X. Q., Liu, S. C., Wang, Y. F., Meng, L. Y., Hu, G. H., Zhao, N., Lan, H., Naulin, V., Nielsen, A. H., Juul Rasmussen, J., Li, K. D., Wang, L., Yang, Q. Q., Li, M. H., Ye, Y., Ding, R., Tao, Y. Q., Qian, Y. Z., Hou, J. L., Liu, X., Liu, J. B., Yan, N., Chen, L., Xu, G. S., Wu, X. Q., Liu, S. C., Wang, Y. F., Meng, L. Y., Hu, G. H., Zhao, N., Lan, H., Naulin, V., Nielsen, A. H., Juul Rasmussen, J., Li, K. D., Wang, L., Yang, Q. Q., Li, M. H., Ye, Y., Ding, R., Tao, Y. Q., Qian, Y. Z., Hou, J. L., Liu, X., and Liu, J. B.

Abstract

Upstream density profiles in the scrape-off layer (SOL) have been examined in low-confinement mode (L-mode) and high-confinement mode (H-mode) plasmas in the EAST superconducting tokamak. A weak density shoulder forms in the near SOL region in upper single-null configurations when the neutral pressure measured at the lower divertor exceeds a threshold value of 2 × 10-2 Pa in L-mode plasmas. When the neutral pressure is below this threshold, the weak density shoulder is absent and the sidebands of the lower hybrid waves associated with SOL parametric instabilities are reduced. Active detachment control with neon-deuterium seeding demonstrate that the weak density shoulder can form before the onset of the outer divertor detachment as long as the neutral pressure is above the threshold. Furthermore, no remarkable expansion of a shoulder is observed during divertor detachment, suggesting that divertor detachment is not a necessary condition for the formation or growth of a density shoulder. Through the increase in neutral pressure in the lower divertor by an order of magnitude, the weak shoulder was observed to expand into the far SOL and reach the leading edge of the limiter. The results in L-mode discharges identified the neutral pressure in the lower divertor as a primary factor for the formation of an SOL density shoulder in the upper single-null discharges. For the type-I ELMy H-mode plasmas, a similar density shoulder was detected during the inter-ELM phase when the neutral pressure in the lower divertor exceeded a threshold value of 4 × 10-2 Pa. On the other hand, the shoulder was absent when the divertor neutral pressure went below this threshold even though the plasma discharge was conducted with a higher core line-averaged density and divertor collisionality. This is consistent with the observations in L-mode plasmas. The neutral particle ionization of the working gas is thus believed to play a key role during the formation of the SOL density shoulder in th

Published
2021

20. Observation of fully detached divertor integrated with improved core confinement for tokamak fusion plasmas

Author

Wang, H. Q., primary, Wang, L., additional, Ding, S., additional, Garofalo, A. M., additional, Gong, X. Z., additional, Eldon, D., additional, Guo, H. Y., additional, Leonard, A. W., additional, Hyatt, A. W., additional, Qian, J. P., additional, Weisberg, D. B., additional, McClenaghan, J., additional, Fenstermacher, M. E., additional, Osborne, T. H., additional, Lasnier, C. J., additional, Watkins, J. G., additional, Shafer, M. W., additional, Grierson, B. A., additional, Xu, G. S., additional, Yan, Z., additional, Mckee, G. R., additional, Huang, J., additional, Ren, J., additional, Buttery, R. J., additional, Humphreys, D. A., additional, Thomas, D. M., additional, Zhang, B., additional, and Liu, J. B., additional

Published
2021
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22. Advances in physics understanding of high poloidal beta regime toward steady-state operation of CFETR

Author

Qian, J. P., primary, Garofalo, A. M., additional, Gong, X. Z., additional, Huang, J., additional, Ding, S. Y., additional, Holcomb, C. T., additional, Hyatt, A., additional, Ferron, J., additional, McClenaghan, J., additional, McKee, G., additional, Kotschenreuther, M., additional, Wu, M. Q., additional, Shi, S. Y., additional, Li, M. H., additional, Zhu, X., additional, Sun, Y. W., additional, Xu, G. S., additional, Wang, L., additional, Chen, J. L., additional, Zang, Q., additional, Zhang, B., additional, Zhang, L., additional, Liu, H. Q., additional, Lyu, B., additional, Guo, W. F., additional, Pan, C. K., additional, Ren, Q., additional, Li, G. Q., additional, Wang, H. Q., additional, Zhang, X. J., additional, Pinsker, R. I., additional, Staebler, G. M., additional, and Lao, L. L., additional

Published
2021
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23. First Evidence of Local E × B Drift in the Divertor Influencing the Structure and Stability of Confined Plasma near the Edge of Fusion Devices

Author

Wang, Huiqian, Guo, H. Y., Xu, G. S., Leonard, A. W., Wu, X. Q., Groth, M., Jaervinen, A. E., Watkins, J. G., Osborne, T. H., Thomas, D. M., Eldon, D., Stangeby, P. C., Turco, F., Xu, J. C., Wang, Liang, Wang, Y. F., Liu, J. B., Fusion and Plasma Physics, Chinese Academy of Sciences, Department of Applied Physics, Aalto-yliopisto, and Aalto University

Subjects
DYNAMICS, PEDESTAL, CONVECTION, Physics::Plasma Physics, FLOW, TRANSPORT
Abstract

The structure of the edge plasma in a magnetic confinement system has a strong impact on the overall plasma performance. We uncover for the first time a magnetic-field-direction dependent density shelf, i.e., local flattening of the density radial profile near the magnetic separatrix, in high confinement plasmas with low edge collisionality in the DIII-D tokamak. The density shelf is correlated with a doubly peaked density profile near the divertor target plate, which tends to occur for operation with the ion B×â‡B drift direction away from the X-point, as currently employed for DIII-D advanced tokamak scenarios. This double-peaked divertor plasma profile is connected via the E×B drifts, arising from a strong radial electric field induced by the radial electron temperature gradient near the divertor target. The drifts lead to the reversal of the poloidal flow above the divertor target, resulting in the formation of the density shelf. The edge density shelf can be further enhanced at higher heating power, preventing large, periodic bursts of the plasma, i.e., edge-localized modes, in the edge region, consistent with ideal magnetohydrodynamics calculations.

Published
2020

24. Statistical characteristics of the SOL turbulence in the first divertor plasma operation of W7-X using a reciprocating probe

Author

W7-X Team, Liu, S. C., Liang, Y., Wang, H. Q., Killer, C., Drews, P., Knieps, A., Han, X., Grulke, O., Krämer-Flecken, A., Xu, G. S., Yan, N., Höschen, D., Nicolai, D., Satheeswaran, G., Geiger, J., Henkel, M., Huang, Z., König, R., Li, Y., Neubauer, O., Rahbarnia, K., Sandri, N., Schweer, B., Wang, E. H., Wang, Y. M., Xu, S., Gao, X., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Technology, Cross-correlation, Field (physics), Turbulence, Divertor, Statistical parameter, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Computational physics, Normal field, Physics::Fluid Dynamics, Reciprocating motion, Condensed Matter::Materials Science, Computer Science::Emerging Technologies, Physics::Plasma Physics, 0103 physical sciences, ddc:530, 010306 general physics, ddc:600
Abstract

The statistical characteristics of the scrape-off layer (SOL) turbulence have been investigated in the first divertor plasma operation of W7-X using a reciprocating probe. The turbulence spectra, auto-correlation time and the statistical parameters are analyzed in three magnetic configurations. In standard and high mirror configurations, the SOL turbulence can be classified into four patterns from the outer SOL to the inner SOL, and each pattern is characterized by the poloidal cross correlation spectrum and the turbulence propagation property. A strong dependence of the SOL turbulence on the magnetic topology is demonstrated experimentally. In high iota configuration, the SOL island is relatively narrow and consequently the fluctuation level of turbulence is weak in the far SOL but enhanced significantly in the near SOL. In the reversed field case, the SOL turbulence reveals similar propagation properties and statistical parameters with those in the normal field case, demonstrating the same turbulence structure in both toroidal field directions.

Published
2020
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26. First Evidence of Local E×B Drift in the Divertor Influencing the Structure and Stability of Confined Plasma near the Edge of Fusion Devices

Author

Wang, H. Q., primary, Guo, H. Y., additional, Xu, G. S., additional, Leonard, A. W., additional, Wu, X. Q., additional, Groth, M., additional, Jaervinen, A. E., additional, Watkins, J. G., additional, Osborne, T. H., additional, Thomas, D. M., additional, Eldon, D., additional, Stangeby, P. C., additional, Turco, F., additional, Xu, J. C., additional, Wang, L., additional, Wang, Y. F., additional, and Liu, J. B., additional

Published
2020
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27. Experimental study of detachment density threshold in L-mode plasmas on EAST

Author

Meng, L Y, primary, Liu, J B, additional, Xu, J C, additional, Wang, L, additional, Xu, G S, additional, Guo, H Y, additional, Liu, X J, additional, Si, H, additional, Wang, H Q, additional, Ge, W D, additional, Lan, H, additional, Chen, L, additional, Qian, X Y, additional, Zhang, J Y, additional, Feng, W, additional, Yang, Q Q, additional, Long, F F, additional, Li, K D, additional, Gao, B F, additional, Tao, Y Q, additional, Luo, Y, additional, Li, A, additional, Yu, L, additional, Gao, S L, additional, Yuan, Q P, additional, Ding, F, additional, Yu, Y W, additional, Duan, Y M, additional, Zhang, B, additional, and Gao, W, additional

Published
2020
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29. Measurement of edge ion temperature in W7-X with island divertor by a retarding field analyzer probe

Author

Li, Y., Henkel, M., Liang, Y., Knieps, A., Drews, P., Killer, C., Nicolai, D., Cosfeld, J., Geiger, J., Feng, Y., Florian Effenberg, Zhang, D., Hacker, P., Höschen, D., Satheeswaran, G., Liu, S., Grulke, O., Jakubowski, M., Brezinsek, S., Otte, M., Neubauer, O., Schweer, B., Xu, G. S., Cai, J., Huang, Z., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2019

30. Study of power width scaling in scrape-off layer with 2D electrostatic turbulence code based on EAST L-mode discharges

Author

Liu, X., Nielsen, A. H., Rasmussen, J. J., Naulin, Volker, Olsen, J., Xia, T. Y., Wang, L., Deng, G. Z., Wu, X. Q., Liu, Y., Wang, Y. M., Li, Y. Y., Zhang, Q., Xu, G. S., Li, J., Liu, X., Nielsen, A. H., Rasmussen, J. J., Naulin, Volker, Olsen, J., Xia, T. Y., Wang, L., Deng, G. Z., Wu, X. Q., Liu, Y., Wang, Y. M., Li, Y. Y., Zhang, Q., Xu, G. S., and Li, J.

Abstract

The study of the power width in the scrape-off layer (SOL) is very important for the design and operation of ITER. In this paper, a 2D electrostatic turbulence code is employed to study the power width scaling in L-mode plasmas. It is found that the electron and ion turbulent transports dominate the radial heat fluxes, and the electron heat conduction and the ion heat advection dominate the parallel heat flux in the near and far SOL in L-mode plasmas. The simulated SOL power width agrees well with the Eich scaling [T. Eich et al., Nucl. Fusion 53, 093031 (2013)] and the predictions by the heuristic drift-based model [R. J. Goldston, Nucl. Fusion 52, 013009 (2012)] for selected EAST L-mode discharges. A numerical scaling has been performed based on one of these discharges. The scaling dependence on the safety factor is consistent with the Eich scaling and the scaling exponent of the edge electron temperature is close to that in the ASDEX-Upgrade L-mode scaling [B. Sieglin et al., Plasma Phys. Controlled Fusion 58, 055015 (2016)]. The investigation of the obtained numerical scaling for L-mode plasmas reveals that the SOL power width is influenced by the safety factor, the edge electron density, and the edge electron temperature through the parallel heat transports, the radial turbulent heat transports, and both the parallel and radial heat transports, respectively. The formulation of the turbulence model suggests that the scaling dependence on the poloidal magnetic field (or the plasma current) for the experimental scalings is essentially the scaling dependence on the ballooning length, q95R. Based on this idea, a further numerical scaling gives λ-q ∝ q951.30Bt−0.33R1.32 ∝ Bt−0.29(q95R)1.33, which has a strong scaling dependence on the major radius that is different from the Eich scaling.

Published
2019

31. Statistical study of particle flux footprint widths with tungsten divertor in EAST

Author

Liu, X., Naulin, V., Xu, J. C., Deng, G. Z., Rasmussen, J. J., Liu, J. B., Nielsen, A. H., Goldston, R. J., Maingi, R., Liu, Y., Xu, G. S., Wang, L., Li, J., Liu, X., Naulin, V., Xu, J. C., Deng, G. Z., Rasmussen, J. J., Liu, J. B., Nielsen, A. H., Goldston, R. J., Maingi, R., Liu, Y., Xu, G. S., Wang, L., and Li, J.

Abstract

The study of the divertor heat flux is of great importance for the operation of ITER and future fusion devices. In this paper, the behaviors of the widths of the particle flux footprints on the tungsten divertor in EAST have been statistically studied for the first time. A large number of divertor Langmuir probe (Div-LP) data from EAST general discharges in the 2016 campaign have been stepwise selected and analyzed for both L- and H-mode plasmas. It is found that the scaling dependences on poloidal magnetic field for the particle flux fall-off width at the inner tungsten divertor agree well with those at the outer graphite divertor in both L- and H-mode plasmas. The difficulty of extracting reliable footprint widths has been overcome by fitting data from two Div-LP arrays distributed toroidally. The nonlinear regressions of the particle flux fall-off width and particle flux spreading width at the inner tungsten divertor in H-mode plasmas have then been performed. A negative dependence on the plasma stored energy is found in the regression of the particle flux fall-off width and the exponent of the stored energy in the regression is consistent with previous experimental studies. The comparison between the particle flux fall-off width at the tungsten divertor with that at the graphite divertor indicates that statistically the divertor material and the direction of the toroidal magnetic field seem to have no significant influence on the particle flux fall-off width at the inner divertor. In addition, the similar particle flux fall-off width in L- and H-mode plasmas and the in-out asymmetry of the particle flux fall-off width at the graphite divertor have also been shown.

Published
2019

34. Promising High-Confinement Regime for Steady-State Fusion

Author

Xu, G. S., primary, Yang, Q. Q., additional, Yan, N., additional, Wang, Y. F., additional, Xu, X. Q., additional, Guo, H. Y., additional, Maingi, R., additional, Wang, L., additional, Qian, J. P., additional, Gong, X. Z., additional, Chan, V. S., additional, Zhang, T., additional, Zang, Q., additional, Li, Y. Y., additional, Zhang, L., additional, Hu, G. H., additional, and Wan, B. N., additional

Published
2019
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35. Pace making of edge localized modes with low-hybrid-wave power pulses in the EAST superconducting tokamak

Author

Yang, Q Q, primary, Xu, G S, additional, Wan, B N, additional, Wang, M, additional, Wang, Y F, additional, Guo, H Y, additional, Jia, M N, additional, Zhang, T, additional, Li, G Q, additional, Wang, H Q, additional, Gong, X Z, additional, Chen, R, additional, Xu, J C, additional, Li, Y L, additional, Lan, H, additional, Ye, Y, additional, Lin, X, additional, Yan, N, additional, Feng, W, additional, Lu, Z Y, additional, Liu, S C, additional, Shao, L M, additional, Chen, L, additional, Wu, X Q, additional, Wang, L, additional, Hu, G H, additional, and Zhang, W, additional

Published
2019
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37. Study of power width scaling in scrape-off layer with 2D electrostatic turbulence code based on EAST L-mode discharges

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Liu, X., primary, Nielsen, A. H., additional, Rasmussen, J. J., additional, Naulin, V., additional, Olsen, J., additional, Xia, T. Y., additional, Wang, L., additional, Deng, G. Z., additional, Wu, X. Q., additional, Liu, Y., additional, Wang, Y. M., additional, Li, Y. Y., additional, Zang, Q., additional, Xu, G. S., additional, and Li, J., additional

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2019
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39. Multi-machine scaling of the main SOL parallel heat flux width in tokamak limiter plasmas

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Horacek, J., Pitts, R. A., Adamek, J., Arnoux, G., Bak, J-G, Brezinsek, S., Dimitrova, M., Goldston, R. J., Gunn, J. P., Havlicek, J., Hong, S-H, Janky, F., LaBombard, B., Marsen, S., Maddaluno, G., Nie, L., Pericoli, V., Popov, Tsv, Panek, R., Rudakov, D., Seidl, J., Seo, D. S., Shimada, M., Silva, C., Stangeby, P. C., Viola, B., Vondracek, P., Wang, H., Xu, G. S., Xu, Y., Abhangi, M., Abreu, P., Aftanas, M., Afzal, M., Aggarwal, K. M., Aho-Mantila, L., Ahonen, E., Aints, M., Airila, M., Albanese, R., Alegre, D., Alessi, E., Aleynikov, P., Alfier, A., Alkseev, A., Allan, P., Almaviva, S., Alonso, A., Alper, B., Alsworth, I., Alves, D., Ambrosino, G., Ambrosino, R., Amosov, V., Andersson, F., Andersson Sunden, E., Angelone, M., Anghel, A., Anghel, M., Angioni, C., Appel, L., Apruzzese, G., Arena, P., Ariola, M., Arnich, Arshad, S., Ash, A., Asp, E., Asunta, O., Atanasiu, C. V., Austin, Y., Avotina, L., Axton, M. D., Ayres, C., Bachmann, C., Baciero, A., Baiao, D., Bailescu, V., Baiocchi, B., Baker, A., Baker, R. A., Balboa, I., Balden, M., Balshaw, N., Bament, R., Banks, J. W., Baranov, Y. F., Barlow, I. L., Barnard, M. A., Barnes, D., Barnsley, R., Baron Wiechec, A., Baruzzo, M., Basiuk, V., Bassan, M., Bastow, R., Batista, A., Batistoni, P., Bauer, R., Bauvir, B., Bazylev, B., Beal, J., Beaumont, P. S., Becoulet, A., Bednarczyk, P., Bekris, N., Beldishevski, M., Bell, K., Belli, F., Bellinger, M., Belo, J. K., Belo, P., Belonohy, E., Benterman, N. A., Bergsaker, H., Bernardo, J., Bernert, M., Berry, M., Bertalot, L., Beurskens, M. N. A., Bieg, B., Bielecki, J., Biewer, T., Bigi, M., Bilkova, P., Binda, F., Bizarro, J. P. S., Bjorkas, C., Blackman, K., Blackman, T. R., Blanchard, P., Blanco, E., Blatchford, P., Bobkov, V., Boboc, A., Bodnar, G., Bogar, O., Bolzonella, T., Boncagni, L., Bonham, R., Bonheure, G., Boom, J., Booth, J., Borba, D., Borodin, D., Botrugno, A., Boulbe, C., Boulting, P., Bovert, K. V., Bowden, M., Bower, C., Boyce, T., Boyer, H. J., Bradshaw, J. M. A., Braic, V., Breizman, B., Bremond, S., Brennan, P. D., Brett, A., Bright, M. D. J., Brix, M., Broeckx, W., Brombin, M., Brown, B. C., Brown, D. P. D., Brown, M., Bruno, E., Bucalossi, J., Buch, J., Buckley, M. A., Bucko, K., Budny, R., Buffer, Bulman, M., Bulmer, N., Bunting, P., Buratti, P., Burcea, G., Burckhart, A., Buscarino, A., Butcher, P. R., Butler, N. K., Bykov, I., Byrne, J., Byszuk, A., Cackett, A., Cahyna, P., Cain, G., Calabro, G., Callaghan, C. P., Campling, D. C., Cane, J., Cannas, B., Capel, A. J., Caputano, M., Card, P. J., Cardinali, A., Carman, P., Carralero, D., Carraro, L., Carvalho, B. B., Carvalho, I., Carvalho, P., Casson, F. J., Castaldo, C., Cavazzana, R., Cavinato, M., Cazzaniga, A., Cecconello, M., Cecil, E., Cenedese, A., Centioli, C., Cesario, R., Challis, C. D., ler, M., ra, D., Chang, C. S., Chankin, A., Chapman, I. T., Chapman, S. C., Chernyshova, M., Chiru, P., Chitarin, G., Chouli, B., Chung, N., Ciraolo, G., Ciric, D., Citrin, J., Clairet, F., Clark, E., Clatworthy, D., Clay, R., Clever, M., Coad, J. P., Coates, P. A., Coccorese, V., Cocilovo, V., Coda, S., Coelho, R., Coenen, J. W., Coffey, I., Colas, L., Collins, S., Conboy, J. E., Conroy, S., Cook, N., Coombs, D., Cooper, D., Cooper, S. R., Corre, Y., Corrigan, G., Cortes, S., Coster, D., Couchman, A. S., Cox, M., Cox, M. P., Cox, P., Craciunescu, T., Cramp, S., Crisanti, F., Cristescu, I., Croci, G., Croft, O., Crombe, K., Crowe, R., Cruz, N., Cseh, G., Cull, K., Cupido, L., Curran, D., Curuia, M., Czarnecka, A., Czarski, T., Dalley, S., Dalziel, A., Darrow, D., Davies, R., Davis, W., Day, C., Day, I. E., de la Cal, E., de la Luna, E., De Magistris, M., de Pablos, J. L., De Tommasi, G., de Vries, P. C., Deakin, K., Deane, J., Decker, J., Degli Agostini, F., Dejarnac, R., Delabie, E., den Harder, N., Dendy, R. O., Denner, P., Devaux, S., Devynck, P., Di Maio, F., Di Pace, L., Dittmar, T., Dodt, D., Donne, T., Dooley, P., Dorling, S. E., Dormido-Canto, S., Doswon, S., Douai, D., Doyle, P. T., Dreischuh, T., Drewelow, P., Drozdov, V., Drozdowicz, K., Dumont, R., Dumortier, P., Dunai, D., Dunne, M., Duran, I., Durodie, F., Dutta, P., Duval, B., Dux, R., Dylst, K., Dzysiuk, N., Edappala, P. V., Edwards, A. M., Eich, Th., Ekedahl, A., Elevant, T., El-Jorf, R., Elsmore, C. G., Ericsson, G., Eriksson, A., Eriksson, J., Eriksson, L. G., Esposito, B., Esser, H. G., Esteve, D., Evans, G. E., Evans, J., Ewart, G. D., Ewers, D. T., Fagan, D., Falie, D., Farthing, J. W., Fasoli, A., Fattorini, L., Faugeras, B., Faustin, J., Fawlk, N., Federici, G., Fedorczak, N., Felton, R. C., Fenzi, C., Fernades, A., Fern, es, H., Ferreira, J., Fessey, J. A., Figini, L., Figueiredo, A., Figueiredo, J., Fil, A., Finburg, P., Firdaouss, M., Fischer, U., Fittill, L., Fitzgerald, M., Flammini, D., Flanagan, J., Fleming, C., Flinders, K., Formisano, A., Forsythe, L., Fortuna, L., Fortune, M., Frasca, M., Frassinetti, L., Freisinger, M., Fresa, R., Frigione, D., Fuchs, V., Fyvie, J., Gadomska, M., Gal, K., Galperti, C., Galvao, R., Gao, X., Garavaglia, S., Garcia, J., Garcia-Carrasco, A., Garcia-Munoz, M., Gardner, M., Garzotti, L., Gaudio, P., Gauthier, E., Gaze, J. W., Gear, D. F., Gee, S. J., Gelfusa, M., Genangeli, E., Gerasimov, S., Gervasini, G., Ghate, M., Gherendi, M., Giacalone, J. C., Giacomelli, L., Gibson, C. S., Giegerich, T., Gin, D., Giovannozzi, E., Girardo, J. B., Giroud, C., Giruzzi, G., Gleason-Gonzalez, C., Godwin, J., Gohil, P., Gojska, A., Goloborod'ko, V., Gomes, R., Goncalves, B., Goniche, M., Gonzalez, S., Goodsell, B., Goodyear, A., Gorini, G., Goussarov, A., Graham, B., Graham, M. E., Graves, J., Grazier, N., Green, N. R., Greuner, H., Grigore, E., Griph, F. S., Grisolia, C., Grist, D., Groth, M., Grundy, C. N., Gryaznevich, M., Guard, D., Gubb, D., Guillemaut, C., Guo, Y., Utoh, H. H., Hackett, L. J., Hacquin, S., Hagar, A., Hakola, A., Halitovs, M., Hall, S. J., Hallworth Cook, S. P., Hammond, K., Hart, J., Harting, D., Hartmann, N., Haupt, T. D. V., Hawkes, N. C., Hawkins, J., Haydon, P. W., Hazel, S., Heesterman, P. J. L., Heinola, K., Hellesen, C., Hellsten, T., Helou, W., Hemming, O. N., Hender, T. C., Henderson, M., Henriques, R., Hepple, D., Hermon, G., Hidalgo, C., Highcock, E. G., Hill, J. W., Hill, M., Hillairet, J., Hillesheim, J., Hillis, D., Hjalmarsson, A., Hobirk, J., Hogben, C. H. A., Hogeweij, G. M. D., Homfray, D. A., Horton, A. R., Horton, L. D., Hotchin, S. P., Hough, M. R., Howarth, P. J., Huber, A., Huddleston, T. M., Hughes, M., Hunter, C. L., Hurzlmeier, H., Huygen, S., Huynh, P., Igitkhanov, J., Iglesias, D., Imrisek, M., Ivanova, D., Ivanova-Stanik, I., Ivings, E., Jachmich, S., Jacobsen, A. S., Jacquet, P., Jakubowska, K., James, J., Jarvinen, A., Jaulmes, F., Jednorog, S., Jenkins, C., Jenkins, I., Jesko, K., Joffrin, E., Johnson, R., Johnson, T., Joita, L., Jones, G., Jones, T. T. C., Joyce, L., Jupen, C., Hoshino, K. K., Kallenbach, A., Kalupin, D., Kamiya, K., Kaniewski, J., Kantor, A., Karhunen, J., Kasprowicz, G., Kaveney, G., Kazakov, Y., Keeling, D. L., Keep, J., Kempenaars, M., Kennedy, C., Kenny, D., Khilkevich, E., Kiisk, M., Kim, H. -T., Kim, H. S., King, C., King, D., King, R. F., Kinna, D. J., Kiptily, V., Kirov, K., Kirschner, A., Kizane, G., Klepper, C., Knaup, M., Knipe, S. J., Kobuchi, T., Kochl, F., Kocsis, G., Kogut, D., Koivuranta, S., Koppen, M., Koskela, T., Koslowski, H. R., Kotov, V., Kowalska-Strzeciwilk, E., Krasilnikov, A., Krasilnikov, V., Kreter, A., Krieger, K., Krivchenkov, Y., Krivska, A., Kruezi, U., Ksiazek, I., Kukushkin, A., Kundu, A., Kurki-Suonio, T., Kwon, O. T., Kyrytsya, V., Laan, M., Labate, C., Laguardia, L., Lam, N., Lane, C., Lang, P. T., Lapins, J., Lasa, A., Last, J. R., Lawson, A., Lawson, K. D., Lazaros, A., Lazzaro, E., Lee, S., Leggate, H. J., Lehnen, M., Leichtle, D., Leichuer, P., Leipold, F., Lengar, I., Lennholm, M., Lerche, E., Leyl, Leysen, W., Liang, Y., Likonen, J., Lindholm, V., Linke, J., Linsmeier, Ch., Lipschultz, B., Litaudon, X., Liu, G., Liu, Y., Lo Schiavo, V. P., Loarer, T., Loarte, A., Lobel, R. C., Lohr, N., Lomas, P. J., Lonnroth, J., Lopez, J., Lopez, J. M., Louche, F., Loving, A. B., Lowbridge, S., Lowry, C., Luce, T., Lucock, R. M. A., Lukin, A., Lungu, A. M., Lungu, C. P., Lupelli, I., Lyssoivan, A., Macheta, P., Mackenzie, A. S., Maddison, G. P., Magesh, B., Maget, P., Maggi, C. F., Maier, H., Mailloux, J., Maj, A., Makkonen, T., Makwana, R., Malaquias, A., Mansffield, F., Mansfield, M., Manso, M. E., Mantica, P., Mantsinen, M., Manzanares, A., Mar, et, Y., Marcenko, N., Marchetto, C., Marchuk, O., Marinelli, M., Marinucci, M., Markovic, T., Marocco, D., Marot, L., Marren, C. A., Marshal, R., Martin, A., Martin, D. L., Martin, Y., Martin de Aguilera, A., Martin-Solis, J. R., Masiello, A., Maslov, M., Maslova, V., Matejcik, S., Mattei, M., Matthews, G. F., Matveev, D., Matveev, M., Maviglia, F., Mayer, M., Mayoral, M. -L., Mazon, D., Mazzotta, C., McAdams, R., McCarthy, P. J., McClements, K. G., McCormick, K., McCullen, P. A., McDonald, D., Mcgregor, R., McKean, R., McKehon, J., McKinley, R., Meadows, I., Meadows, R. C., Medina, F., Medl, Medley, S., Meigh, S., Meigs, A. G., Meneses, L., Menmuir, S., Merrigan, I. R., Mertens, Ph., Meshchaninov, S., Messiaen, A., Meszaros, B., Meyer, H., Miano, G., Michling, R., Middleton-Gear, D., Miettunen, J., Migliucci, P., Militello-Asp, E., Minucci, S., Mirizzi, F., Miyoshi, Y., Mlynar, J., Monakhov, I., Monier-Garbet, P., Mooney, R., Moradi, S., Mordijck, S., Moreira, L., Moreno, R., Morgan, P. D., Morgan, R., Morley, L., Morlock, C., Morris, A. W., Morris, J., Moser, L., Moulton, D., Murari, A., Muraro, A., Mustata, I., Asakura, N. N., Nabais, F., Nakano, T., Nardon, E., Naulin, V., Nave, M. F. F., Nedzelski, I., Neethiraj, N., Nemtsev, G., Nespoli, F., Neto, A., Neu, R., Neubauer, O., Newman, M., Nicholls, K. J., Nicolai, D., Nicolas, T., Nieckchen, P., Nielsen, P., Nightingale, M. P. S., Nilsson, E., Nishijima, D., Noble, C., Nocente, M., Nodwell, D., Nordman, H., Nunes, I., O'Meara, B., Oberkofler, M., Obryk, B., Odupitan, T., Ogawa, M. T., O'Gorman, T., Okabayashi, M., Olariu, S., O'Mullane, M., Ongena, J., Orsitto, F., Oswuigwe, B. I., Pace, N., Pacella, D., Page, A., Paget, A., Pagett, D., Pajuste, E., Palazzo, S., Pamela, J., Pamela, S., Panin, A., Panja, S., Papp, P., Parail, V., Paris, P., Parish, S. C. W., Park, M., Parsloe, A., Pasqualotto, R., Pearson, I. J., Pedrosa, M. A., Pereira, R., Perelli Cippo, E., Perez von Thun, Ch., Perez-Von-Thun, C., Pericoli-Ridolfini, V., Perona, A., Peruzzo, S., Peschanyi, S., Peterka, M., Petersson, P., Petravich, G., Petrzilka, V., Pfefferle, D., Philipps, V., Pietropaolo, A., Pillon, M., Pintsuk, G., Piovesan, P., Pires dos Reis, A., Pironti, A., Pisano, F., Pitts, R., Plusczyk, C., Plyusnin, V., Pomaro, N., Pompilian, O., Pool, P. J., Popovichev, S., Porcelli, F., Porosnicu, C., Porton, M., Pospieszczyk, A., Possnert, G., Potzel, S., Powell, T., Pozniak, K., Pozzi, J., Prajapati, V., Prakash, R., Prestopino, G., Price, D., Price, R., Prior, P., Prokopowicz, R., Proudfoot, R., Puglia, P., Puiatti, M. E., Pulley, D., Purahoo, K., Putterich, T., Quercia, A., Rachlew, E., Rack, M., Raeder, J., Rainford, M. S. J., Ramogida, G., Ranjan, S., Rasmussen, J., Rasmussen, J. J., Rathod, K., Ratta, G., Rayner, C., Rebai, M., Reece, D., Reed, A., Refy, D., Regan, B., Regana, J., Reich, M., Reid, P., Reinelt, M., Reinke, M. L., Reinke, M., Reiser, D., Reiter, D., Rendell, D., Reux, C., Riccardo, V., Rimini, F. G., Riva, M., Roberts, J. E. C., Robins, R. J., Robinson, S. A., Robinson, T., Robson, D. W., Roddick, P., Rodionov, R., Rohde, V., Romanelli, F., Romanelli, M., Romanelli, S., Romano, A., Rowe, D., Rowe, S., Rowley, A., Rubel, M., Rubinacci, G., Ruchko, L., Ruiz, M., Ruset, C., Ryc, L., Rzadkiewicz, J., Saarelma, S., Sabot, R., Sadakov, S., Safi, E., Sagar, P., Saibene, G., Saint-Laurent, F., Salewski, M., Salmi, A., Salzedas, F., Samm, U., S, iford, D., quist, P., Santa, P., Santala, M. I. K., Sartori, F., Sartori, R., Saunders, R., Sauter, O., Scannell, R., Scarabosio, A., Schlummer, T., Schmidt, V., Schmitz, O., Schmuck, S., Schneider, M., Scholz, M., Schopf, K., Schweer, B., Sergienko, G., Serikov, A., Sertoli, M., Shabbir, A., Shannon, M., Shannon, M. M. J., Sharapov, S. E., Shaw, I., Shaw, S. R., Shepherd, A., Shevelev, A., Shumack, A., Sibbald, M., Sieglin, B., Simmons, P. A., Sinha, A., Sipila, S. K., Sips, A. C. C., Siren, P., Sirinelli, A., Sjostr, Skiba, M., Skilton, R., Slade, B., Smith, N., Smith, P. G., Smith, T. J., Snoj, L., Soare, S., Solano, E. R., Soldatov, S., Sonato, P., Sopplesa, A., Sousa, J., Sowden, C. B. C., Sozzi, C., Sparkes, A., Spelzini, T., Spineanu, F., Stables, G., Stamatelatos, I., Stamp, M. F., Stancalie, V., Stankiewicz, R., Stankunas, G., Stano, M., Stan-Sion, C., Starkey, D. E., Stead, M. J., Stejner, M., Stephen, A. V., Stephen, M., Stevens, B. 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M., Wojciech, D., Wojenski, A., Wood, D., Wood, S., Woodley, C., Woznicka, U., Wright, J., Wu, J., Yao, L., Yapp, D., Yavorskij, V., Yoo, M. G., Yorkshades, J., Young, C., Young, D., Young, I. D., Zabolotny, W., Zacks, J., Zagorski, R., Zaitsev, F. S., Zanino, R., Zaroschi, V., Zastrow, K. D., Zeidner, W., Ziolkowski, A., Zoita, V., Zoletnik, S., Zychor, I., JET Contributors, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla. RNM138: Física Nuclear Aplicada, JET Contributors, Viola, B., Pericoli, V., Maddaluno, G., Horacek, J., Pitts, R. A., Adamek, J., Arnoux, G., Bak, J-G, Brezinsek, S., Dimitrova, M., Goldston, R. J., Gunn, J. P., Havlicek, J., Hong, S-H, Janky, F., Labombard, B., Marsen, S., Nie, L., Popov, Tsv, Panek, R., Rudakov, D., Seidl, J., Seo, D. S., Shimada, M., Silva, C., Stangeby, P. C., Vondracek, P., Wang, H., Xu, G. S., Xu, Y., Abhangi, M., Abreu, P., Aftanas, M., Afzal, M., Aggarwal, K. M., Aho-Mantila, L., Ahonen, E., Aints, M., Airila, M., Albanese, R., Alegre, D., Alessi, E., Aleynikov, P., Alfier, A., Alkseev, A., Allan, P., Almaviva, S., Alonso, A., Alper, B., Alsworth, I., Alves, D., Ambrosino, G., Ambrosino, R., Amosov, V., Andersson, F., Andersson Sunden, E., Angelone, M., Anghel, A., Anghel, M., Angioni, C., Appel, L., Apruzzese, G., Arena, P., Ariola, M., Arnich, Arshad, S., Ash, A., Asp, E., Asunta, O., Atanasiu, C. V., Austin, Y., Avotina, L., Axton, M. D., Ayres, C., Bachmann, C., Baciero, A., Baiao, D., Bailescu, V., Baiocchi, B., Baker, A., Baker, R. A., Balboa, I., Balden, M., Balshaw, N., Bament, R., Banks, J. W., Baranov, Y. F., Barlow, I. L., Barnard, M. A., Barnes, D., Barnsley, R., Baron Wiechec, A., Baruzzo, M., Basiuk, V., Bassan, M., Bastow, R., Batista, A., Batistoni, P., Bauer, R., Bauvir, B., Bazylev, B., Beal, J., Beaumont, P. S., Becoulet, A., Bednarczyk, P., Bekris, N., Beldishevski, M., Bell, K., Belli, F., Bellinger, M., Belo, J. K., Belo, P., Belonohy, E., Benterman, N. A., Bergsaker, H., Bernardo, J., Bernert, M., Berry, M., Bertalot, L., Beurskens, M. N. A., Bieg, B., Bielecki, J., Biewer, T., Bigi, M., Bilkova, P., Binda, F., Bizarro, J. P. S., Bjorkas, C., Blackman, K., Blackman, T. R., Blanchard, P., Blanco, E., Blatchford, P., Bobkov, V., Boboc, A., Bodnar, G., Bogar, O., Bolzonella, T., Boncagni, L., Bonham, R., Bonheure, G., Boom, J., Booth, J., Borba, D., Borodin, D., Botrugno, A., Boulbe, C., Boulting, P., Bovert, K. V., Bowden, M., Bower, C., Boyce, T., Boyer, H. J., Bradshaw, J. M. A., Braic, V., Breizman, B., Bremond, S., Brennan, P. D., Brett, A., Bright, M. D. J., Brix, M., Broeckx, W., Brombin, M., Brown, B. C., Brown, D. P. D., Brown, M., Bruno, E., Bucalossi, J., Buch, J., Buckley, M. A., Bucko, K., Budny, R., Buffer, Bulman, M., Bulmer, N., Bunting, P., Buratti, P., Burcea, G., Burckhart, A., Buscarino, A., Butcher, P. R., Butler, N. 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C., Medina, F., Medl, Medley, S., Meigh, S., Meigs, A. G., Meneses, L., Menmuir, S., Merrigan, I. R., Mertens, Ph., Meshchaninov, S., Messiaen, A., Meszaros, B., Meyer, H., Miano, G., Michling, R., Middleton-Gear, D., Miettunen, J., Migliucci, P., Militello-Asp, E., Minucci, S., Mirizzi, F., Miyoshi, Y., Mlynar, J., Monakhov, I., Monier-Garbet, P., Mooney, R., Moradi, S., Mordijck, S., Moreira, L., Moreno, R., Morgan, P. D., Morgan, R., Morley, L., Morlock, C., Morris, A. W., Morris, J., Moser, L., Moulton, D., Murari, A., Muraro, A., Mustata, I., Asakura, N. N., Nabais, F., Nakano, T., Nardon, E., Naulin, V., Nave, M. F. F., Nedzelski, I., Neethiraj, N., Nemtsev, G., Nespoli, F., Neto, A., Neu, R., Neubauer, O., Newman, M., Nicholls, K. J., Nicolai, D., Nicolas, T., Nieckchen, P., Nielsen, P., Nightingale, M. P. S., Nilsson, E., Nishijima, D., Noble, C., Nocente, M., Nodwell, D., Nordman, H., Nunes, I., O'Meara, B., Oberkofler, M., Obryk, B., Odupitan, T., Ogawa, M. 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D., Whittington, P., Widdowson, A. M., Wiesen, S., Wilkes, D., Wilkinson, J., Williams, M., Wilson, A. R., Wilson, D. J., Wilson, H. R., Wischmeier, M., Withenshaw, G., Witts, D. M., Wojciech, D., Wojenski, A., Wood, D., Wood, S., Woodley, C., Woznicka, U., Wright, J., Wu, J., Yao, L., Yapp, D., Yavorskij, V., Yoo, M. G., Yorkshades, J., Young, C., Young, D., Young, I. D., Zabolotny, W., Zacks, J., Zagorski, R., Zaitsev, F. S., Zanino, R., Zaroschi, V., Zastrow, K. D., Zeidner, W., Ziolkowski, A., Zoita, V., Zoletnik, S., Zychor, I., and Jet, Contributors

Subjects
Materials science, Tokamak, SOL decay length, Nuclear engineering, chemistry.chemical_element, 01 natural sciences, 7. Clean energy, Scaling, 010305 fluids & plasmas, law.invention, law, ITER, 0103 physical sciences, Limiter, ddc:530, 010306 general physics, tokamak, scaling, Plasma, Condensed Matter Physics, Multi machine, Nuclear Energy and Engineering, Heat flux, chemistry, SOL width, Beryllium
Abstract

As in many of today's tokamaks, plasma start-up in ITER will be performed in limiter configuration on either the inner or outer midplane first wall (FW). The massive, beryllium armored ITER FW panels are toroidally shaped to protect panel-to-panel misalignments, increasing the deposited power flux density compared with a purely cylindrical surface. The chosen shaping should thus be optimized for a given radial profile of parallel heat flux, ${{q}_{||}}$ in the scrape-off layer (SOL) to ensure optimal power spreading. For plasmas limited on the outer wall in tokamaks, this profile is commonly observed to decay exponentially as ${{q}_{||}}={{q}_{0}}\text{exp} ~\left(-r/\lambda _{q}^{\text{omp}}\right)$ , or, for inner wall limiter plasmas with the double exponential decay comprising a sharp near-SOL feature and a broader main SOL width, $\lambda _{q}^{\text{omp}}$ . The initial choice of $\lambda _{q}^{\text{omp}}$ , which is critical in ensuring that current ramp-up or down will be possible as planned in the ITER scenario design, was made on the basis of an extremely restricted L-mode divertor dataset, using infra-red thermography measurements on the outer divertor target to extrapolate to a heat flux width at the main plasma midplane. This unsatisfactory situation has now been significantly improved by a dedicated multi-machine ohmic and L-mode limiter plasma study, conducted under the auspices of the International Tokamak Physics Activity, involving 11 tokamaks covering a wide parameter range with $R=\text{0}\text{.4--2}\text{.8}\,\text{m},\,{{B}_{0}}=\text{1}\text{.2--7}\text{.5}\,\text{T},\,{{I}_{\text{p}}}=\text{9--2500}\,\text{kA}.$ Measurements of $\lambda _{q}^{\text{omp}}$ in the database are made exclusively on all devices using a variety of fast reciprocating Langmuir probes entering the plasma at a variety of poloidal locations, but with the majority being on the low field side. Statistical analysis of the database reveals nine reasonable engineering and dimensionless scalings. All yield, however, similar predicted values of $\lambda _{q}^{\text{omp}}$ mapped to the outside midplane. The engineering scaling with the highest statistical significance, $\lambda _{q}^{\text{omp}}=10{{\left({{P}_{\text{tot}}}/V\,\left(\text{W}\,{{\text{m}}^{-3}}\right)\right)}^{-0.38}}{{\left(a/R/\kappa \right)}^{1.3}}$ , dependent on input power density, aspect ratio and elongation, yields $\lambda _{q}^{\text{omp}}$ = [7, 4, 5] cm for ${{I}_{\text{p}}}$ = [2.5, 5.0, 7.5] MA, the three reference limiter plasma currents specified in the ITER heat and nuclear load specifications. Mapped to the inboard midplane, the worst case (7.5 MA) corresponds to $\lambda _{q}^{\text{imp}}\sim 57\pm 14$ mm, thus consolidating the 50 mm width used to optimize the FW panel toroidal shape.

Published
2016

40. Effect of del B drift on the H-mode power threshold in upper single null plasmas with ITER-like tungsten divertor on EAST

Author

Chen, L., Xu, G. S., Yan, Ning, Nielsen, A. H., Liu, J. B., Gao, W., Chen, R., Qu, H., Ding, F., Mao, H. M., Sun, Zhenhua, Zhang, L., Li, M. H., Zhang, W., Hu, G. H., Shao, L. M., Wu, X. Q., Du, H. F., Xu, J. C., Li, Y. L., Zhao, N., Lan, H., Ye, Y., Zhang, H., Wang, H. Q., Ding, S. Y., Wang, L., Wan, B. N., Team, EAST, Chen, L., Xu, G. S., Yan, Ning, Nielsen, A. H., Liu, J. B., Gao, W., Chen, R., Qu, H., Ding, F., Mao, H. M., Sun, Zhenhua, Zhang, L., Li, M. H., Zhang, W., Hu, G. H., Shao, L. M., Wu, X. Q., Du, H. F., Xu, J. C., Li, Y. L., Zhao, N., Lan, H., Ye, Y., Zhang, H., Wang, H. Q., Ding, S. Y., Wang, L., Wan, B. N., and Team, EAST

Abstract

In this paper, we will experimentally investigate the power threshold (PL-H) in upper single null plasmas with an ITER-like tungsten divertor under different ∇B drift directions on EAST [F. Ding et al., Commissioning and PSI Behavior of the ITER-Like W/Cu Divertor in EAST 22nd PSI, Rome (2016)]. The power threshold for the low (L) to high (H) confinement mode has a clear and positive toroidal magnetic field, BT, dependence when the ∇ B drift points toward the primary X-point (Bx∇B↑). A factor of 2-3 increase in PL-H is observed for the ∇B drift away from the primary X-point (Bx∇B↓). The edge and core impurities quantified by spectroscopy measurements show comparable levels for the transitions for both drift directions. On the other hand, it is found that the divertor Dα emission just prior to the L-H transition is lower for Bx∇B↑, compared with that for Bx∇B↓. The upper in-out divertor asymmetry, as manifested by particle fluxes measured by the divertor triple Langmuir probe, is most marked for Bx∇B↓, and with significantly more particle flux to the outer divertor. The reversing field increases the particle flux into the upper inner and lower outer divertor, reducing the in-out asymmetry. One important distinction between the two field directions has been observed, with respect to the amplitude of the scrape-off layer (SOL) parallel flow. A dedicated experiment under similar target plasma conditions shows a lower SOL density and thus a steeper density gradient slightly inside the separatrix, where a lower PL-H is found for the Bx∇B↑, compared to that for Bx∇B↓. We, therefore, conclude that the fielddependent SOL plasma conditions play an important role in the transition physics.

Published
2018

41. Statistical characteristics of the SOL turbulence in the first divertor plasma operation of W7-X using a reciprocating probe.

Author

Liu, S. C., Liang, Y., Wang, H. Q., Killer, C., Drews, P., Knieps, A., Han, X., Grulke, O., Krämer-Flecken, A., Xu, G. S., Yan, N., Höschen, D., Nicolai, D., Satheeswaran, G., Geiger, J., Henkel, M., Huang, Z., König, R., Li, Y., and Neubauer, O.

Subjects
TURBULENCE, COLLOIDS, PLASMA turbulence, CROSS correlation
Abstract

The statistical characteristics of the scrape-off layer (SOL) turbulence have been investigated in the first divertor plasma operation of W7-X using a reciprocating probe. The turbulence spectra, auto-correlation time and the statistical parameters are analyzed in three magnetic configurations. In standard and high mirror configurations, the SOL turbulence can be classified into four patterns from the outer SOL to the inner SOL, and each pattern is characterized by the poloidal cross correlation spectrum and the turbulence propagation property. A strong dependence of the SOL turbulence on the magnetic topology is demonstrated experimentally. In high iota configuration, the SOL island is relatively narrow and consequently the fluctuation level of turbulence is weak in the far SOL but enhanced significantly in the near SOL. In the reversed field case, the SOL turbulence reveals similar propagation properties and statistical parameters with those in the normal field case, demonstrating the same turbulence structure in both toroidal field directions. [ABSTRACT FROM AUTHOR]

Published
2020
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42. Experimental observation of coexisting electromagnetic fluctuations correlating with the inter-ELM pedestal evolution on EAST.

Author

Lan, H., Chen, R., Xu, G. S., Yan, N., Chen, L., Zhang, H., Ye, Y., Lan, T., Sun, P. J., Xu, J. C., Lin, X., Wang, Y. F., Yang, Q. Q., Zhao, H. L., He, K. Y., Shi, T. H., Wang, Y. M., Zang, Q., Liu, H. Q., and Duan, Y. M.

Subjects
PEDESTALS, ELECTRON density, ELECTRON temperature, BIOLOGICAL evolution
Abstract

Correlations between the edge fluctuations and the pedestal evolution during the relatively large edge localized mode (ELM) cycles at high pedestal normalized electron collisionality ( ν e , ped * > 1) on the EAST tokamak are investigated. Not only the edge electrostatic coherent mode (ECM, ∼50 kHz) and the low frequency magnetic coherent mode (MCM, ∼32 kHz) but also a high frequency electromagnetic mode (HFM, >150 kHz) are observed to be coexisting between ELMs. After the ELM crash, the pedestal electron temperature recovered faster than the pedestal electron density. It is found that the saturation of the ECM coincides more with the saturation of the pedestal electron density, while the saturation of the HFM and MCM coincides more with the saturation of the pedestal electron temperature. In addition, the characteristics of the electromagnetic fluctuations (the HFM and MCM) are studied in detail: the HFM propagates in the electron diamagnetic drift direction in the laboratory frame with an average poloidal wave number of k ¯ θ HFM ≈ 0.17 cm − 1 , while the MCM propagates in the ion diamagnetic drift direction in the laboratory frame with k ¯ θ MCM ≈ 0.12 cm − 1 and the toroidal mode number of n = 1. Furthermore, both the HFM and MCM have inward average radial wave numbers of k ¯ R HFM ≈ 0.13 cm − 1 and k ¯ R MCM ≈ 4.64 cm − 1 . The bispectral analysis shows that the HFM and MCM have strong nonlinear interactions. The HFM is clearly observed on both low and high field side Mirnov coils, which might suggest a feature beyond a ballooning type instability, e.g., the kinetic ballooning mode. These studies may contribute to a better understanding of the pedestal evolution. [ABSTRACT FROM AUTHOR]

Published
2019
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45. Experimental study of heating scheme effect on the inner divertor power footprint widths in EAST lower single null discharges

Author

Deng, G Z, primary, Xu, J C, additional, Liu, X, additional, Liu, X J, additional, Liu, J B, additional, Zhang, H, additional, Liu, S C, additional, Chen, L, additional, Yan, N, additional, Feng, W, additional, Liu, H, additional, Xia, T Y, additional, Zhang, B, additional, Shao, L M, additional, Ming, T F, additional, Xu, G S, additional, Guo, H Y, additional, Xu, X Q, additional, Gao, X, additional, and Wang, L, additional

Published
2018
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47. Investigation of energy transport in DIII-D High-βPEAST-demonstration discharges with the TGLF turbulent and NEO neoclassical transport models

Author

Pan, C., primary, Staebler, G.M., additional, Lao, L.L., additional, Garofalo, A.M., additional, Gong, X., additional, Ren, Q., additional, McClenaghan, J., additional, Li, G., additional, Ding, S., additional, Qian, J., additional, Wan, B., additional, Xu, G. S., additional, Solomon, W., additional, Meneghini, O., additional, and Smith, S.P., additional

Published
2017
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48. Numerical simulations of blobs with ion dynamics

Author

Nielsen, A H, primary, Rasmussen, J Juul, additional, Madsen, J, additional, Xu, G S, additional, Naulin, V, additional, Olsen, J M B, additional, Løiten, M, additional, Hansen, S K, additional, Yan, N, additional, Tophøj, L, additional, and Wan, B N, additional

Published
2016
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49. Retarding field analyzer for the EAST plasma boundary

Author

Li, Y. L., primary, Xu, G. S., additional, Xiao, C., additional, Wang, H. Q., additional, Yan, N., additional, Wan, B. N., additional, Chen, L., additional, Liu, Y. L., additional, Zhang, H., additional, Zhang, W., additional, Wang, L., additional, Hu, G. H., additional, Chen, R., additional, Xu, J. C., additional, Ye, Y., additional, and Li, J., additional

Published
2016
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50. Numerical modeling of the transition from low to high confinement in magnetically confined plasma

Author

Rasmussen, Jens Juul, Nielsen, Anders Henry, Madsen, Jens, Naulin, Volker, Xu, G. S., Rasmussen, Jens Juul, Nielsen, Anders Henry, Madsen, Jens, Naulin, Volker, and Xu, G. S.

Abstract

The transition dynamics from low (L) to high (H) mode confinement in magnetically confined plasmas is investigated using a four-field drift fluid model—HESEL (Hot Edge-Sol-Electrostatic). The model includes profile evolution and is solved in a 2D domain at the out-board mid-plane of a tokamak including both open and closed field lines. The results reveal different types of L–H-like transitions in response to ramping up the input power by increasing the ion temperature in the edge region. For a fast rising input power we obtain an abrupt transition, and for a slow rising power we obtain a L–I–H transition with an intermediate I-phase displaying limit-cycle oscillations (LCO). The model recovers the power threshold for the L–H transition, the scaling of the threshold with the density and with the loss-rate in the SOL, indicating a decrease in power threshold when switching from single to double null configuration. The results hold promises for developing full predictive modeling of the L–H transition, which is an essential step in understanding and optimizing fusion devices.

Published
2016

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