Effect of ∇<i>B drift</i> on the H-mode power threshold in upper single null plasmas with ITER-like tungsten divertor on EAST

Chen, L.; Xu, G. S.; Niu, Y.; Nielsen, A. H.; Liu, J. B.; Gao, Wei; Chen, R.; Qu, Hao; Ding, Fang; Mao, Haiyang; Sun, Zhuo; Zhang, L.; Li, M. H.; Zhang, W.; Hu, G.H.; Shao, L. M.; Wu, Xiaoxiao; Du, Haifeng; Xu, Jichan; Li, Y. L.; Zhao, Nan; Lan, H.; Ye, Y.; Zhang, H.; Wang, H. Q.; Ding, Siye; Wang, Li; Wan, Baonian; Team, East

doi:10.1063/1.5033983

Cited by 16 publications

(23 citation statements)

References 48 publications

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“…These findings suggest that the divertor neutral particle density or recycling, which correlated with the field-dependent SOL flow, plays an important role in the transition physics. The parallel flow at LFS midplane measured by a fast reciprocating probe exhibits a considerable asymmetry for the two field directions in USN plasmas on EAST [14]. This different flow pattern may lead to results of the field-dependent power threshold.…”

Section: Effect Of Ion ∇B Drift On L-h Transitionmentioning

confidence: 95%

“…Fuel recycling strongly affects plasma density and confinement performance, especially in high power long pulse plasma operation [14,15]. Increasing first wall temperature and gradually accumulated fuel retention on the wall surface leads to enhanced fuel recycling during long pulse operation, and which deteriorates plasma confinement and makes plasma density uncontrollable, and eventually the plasma would be terminated by a disruption.…”

Section: Recycling and Particle Exhaustmentioning

confidence: 99%

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Recent advances in EAST physics experiments in support of steady-state operation for ITER and CFETR

et al. 2019

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The recent EAST experimental progress since the last IAEA FEC in 2016 is presented. First demonstration of >100 seconds time scale long-pulse steady-state scenario with a good plasma performance (H98(y2) ~ 1.1) and a good control of impurity and heat exhaust with the tungsten divertor has been successfully achieved on EAST using the pure RF power heating and current drive. The extended operation regimes have been obtained (βP~2.5 & βN~1.9 of using RF&NB and βP~1.9 & βN~1.5). High bootstrap current fraction up to 47% was achieved with q95~6.0-7.0. The interaction effect between the ECH and two LHW systems has been investigated for enhanced current drive and improved confinement quality. ELM suppression using the n= 2 RMPs has been achieved at q95 (≈ 3.2-3.7) with standard type-I ELMy H-mode operational window in EAST. Reduction of the peak heat flux on the divertor was demonstrated using the active radiation feedback control. An increase in the total heating power and improvement of the plasma confinement are expected using a 0-D model prediction for higher bootstrap fraction. Towards long pulse, high bootstrap current fraction operation, a new lower ITER-like tungsten divertor with active watercooling will be installed, together with further increase and improvement of heating and current drive capability.

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Section: Effect Of Ion ∇B Drift On L-h Transitionmentioning

confidence: 95%

Section: Recycling and Particle Exhaustmentioning

confidence: 99%

Recent advances in EAST physics experiments in support of steady-state operation for ITER and CFETR

et al. 2019

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“…Here, P heat is the sum of Ohmic and auxiliary heating powers after subtracting the unabsorbed parts of the injected powers, and W is the plasma stored energy which is calculated in the usual way from the magnetic equilibrium (W MHD ). The calculation of the absorbed auxiliary heating power for different heating methods (LHW, ECCD, NBI) in EAST can be seen in references [16,21,22]. The scaling of the L-H transition power threshold P scale is evaluated according to the latest version of threshold scaling for deuterium plasmas [23] as,…”

Section: Reduced P L-h By LI Wall Conditioningmentioning

confidence: 99%

“…Because the first wall still can be regarded as a non-metallic wall or carbon wall, and because all plasmas in table 1 were run in phase III of wall recycling during lithium accumulation in the vessel, we can neglect the impacts of wall materials and wall recycling [27,32] on P L-H /P scale . And, because these plasmas were run in favourable configurations, the roles of plasma ion B × ∇B drift direction [21,33,34] on P L-H /P scale can also be excluded. In addition, these plasmas are heated by RF-dominated heating methods and their core line-averaged densities are at or above the density minimum of P L-H .…”

Section: Effect Of N H /(N H + N D ) On P L-hmentioning

confidence: 99%

On the role of the hydrogen concentration in the L-H transition power threshold in EAST

Shao

et al. 2020

Nucl. Fusion

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A decrease in the L-H transition power threshold P L-H under the lithium wall conditioning has been observed since 2010 in EAST. The physical mechanism responsible for the reduced P L-H is found to be related to three phases of wall recycling as determined by the accumulation of lithium in the vessel. In phase I (a few rounds of wall conditioning) the wall recycling is low, while no clear variation of L-H transition power threshold is observed. In phase II (after another few rounds of wall conditioning) a clear increase in the wall recycling is observed, leading to decreased L-H transition power threshold. In phase III the wall recycling is higher and the hydrogen concentration n H / ( n H + n D ) is lower compared to phases I and II. In this third phase the L-H transition power threshold is mainly reduced by the decreased n H / ( n H + n D ) . During phase III of the wall recycling, the quantitative relationship between the hydrogen content and normalized L-H transition power threshold P L-H / P s c a l e is studied for campaigns in 2010, 2012, 2015 and 2016. Data scaling reveals that P L − H / P s c a l e = ( − 1.513 ± 0.135 ) × e ( − 6.989 ± 0.362 ) × n H / ( n H + n D ) + ( 1.698 ± 0.050 ) in the hydrogen concentration range of 3–45%, i.e. P L-H / P s c a l e increases significantly for 3 % < n H / ( n H + n D ) < 20 % , while it increases mildly for 20 % < n H / ( n H + n D ) < 45 % .

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“…In addition, there are more magnetic field parameters that affect the power threshold to the H-mode that are not involved in Eq. ( 1) for the electric field, like the ∇B drift direction with respect to the X-point, the X-point height or triangularity [14,15,16,17]. Some theoretical analyses have proposed an effect of the Pfirsch-Schlüter current on the radial electric field in the edge that could qualitatively explain the dependency of the power threshold of the L-H transition on some of the magnetic field parameters previously mentioned [18].…”

Section: Introductionmentioning

confidence: 99%

Conservation of currents in reduced full-F electromagnetic kinetic and fluid models

Gerrú¹,

Wiesenberger²,

Held³

et al. 2022

Plasma Phys. Control. Fusion

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In this paper we present an analysis of the conservation of currents in a full-F electromagnetic gyro-kinetic model in the long-wavelength limit. This equation corresponds to what is usually named ”vorticity equation”, which is not strictly correct as it cannot be formulated as the curl of a velocity equation. In the paper we will therefore use the term ”current conservation equation” instead. Our results are relevant to reduced plasma descriptions like gyro-kinetic, drift-kinetic, gyro-ﬂuid and drift-ﬂuid models for tokamaks and stellarators. The equation describes the change of the polarization charge density (often called ”vorticity”) in terms of the polarization stress due to the E × B ﬂow, external sources and three currents: the parallel current, the curvature current and a current related to the magnetic ﬁeld ﬂuctuations. We compare this equation with previous driftand gyro-ﬂuid equations and ﬁnd general agreement except in the vorticity source terms where previous drift-ﬂuid models fail to capture the heating and density sources. We discuss the role of the currents in the dynamics of diamagnetic and E × B ﬂow shear. The possible connection between these currents with phenomena observed in experiments that inﬂuence the radial electric ﬁeld in the edge of tokamak plasmas, like resonant magnetic perturbations, diﬀerent magnetic ﬁeld conﬁgurations and shapes, is presented.

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

Abstract: Team, EAST. (2018). Effect of del B drift on the H-mode power threshold in upper single null plasmas with ITER-like tungsten divertor on EAST. Physics of Plasmas, 25 (7), [072504]. https://doi.

Cited by 16 publications

References 48 publications

Recent advances in EAST physics experiments in support of steady-state operation for ITER and CFETR

Recent advances in EAST physics experiments in support of steady-state operation for ITER and CFETR

On the role of the hydrogen concentration in the L-H transition power threshold in EAST

Conservation of currents in reduced full-F electromagnetic kinetic and fluid models

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