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

Wan, Baonian; Liang, Yun-Feng; Gong, Xianzu; Xiang, Nong; Xu, G. S.; Sun, Yuan; Wang, Liang; Qian, J.; Liu, H.Q.; Zeng, Long; Zhang, L.; Zhang, X.J.; Ding, Bojiang; Zang, Qing; Lyu, Bo; Garofalo, A. M.; Ekedahl, A.; Li, M.H.; Ding, Fang; Ding, Siye; Du, Haifeng; Kong, Defeng; Yu, Yaowei; Yang, Yilin; Luo, Z.P.; Huang, J.; Zhang, T.; Zhang, Y.; Li, G.Q.; Xia, Tie

doi:10.1088/1741-4326/ab0396

Cited by 117 publications

(102 citation statements)

References 41 publications

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“…The experiments were performed in the EAST device [27], with the setups of the key diagnostics shown in figure 1. EAST is a fully superconducting tokamak with major and minor radii: R 0 = 1.88 m and a = 0.45 m, respectively.…”

Section: Methodsmentioning

confidence: 99%

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

Niu

Chen

et al. 2021

Nucl. Fusion

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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 the EAST tokamak.

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Section: Methodsmentioning

confidence: 99%

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

Niu

Chen

et al. 2021

Nucl. Fusion

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“…The brazing process consists of five steps: (1) a nickel plate of a thickness of 5 µm was plated on tungsten prior to the brazing process for the improvement of wettability and bonding strength of the brazing filler, and a heat treatment at a temperature of 600 °C for an hour was followed, which enhanced the quality of the nickel plating; (2) W was brazed onto CuCrZr at 980 °C for 30 min in vacuum; (3) fast cooling from 980 to 400 °C was followed; (4) the aging treatment for CuCrZr was carried out for ~ 180 min at 470 °C; (5) cool down to the room temperature [14]. Figure 1 shows the waveform of the W/Cu/CuCrZr brazing process.…”

Section: Development Of Flat-type Tungsten Bonding Technologymentioning

confidence: 99%

“…The axially symmetric divertor experiment (ASDEX) upgrade (AUG) has changed the inner wall to tungsten coated graphite tiles [2,3]. The experimental advanced superconducting tokamak (EAST) has a full tungsten divertor since 2018 and tungsten environment in steady-state tokamak (WEST) started with several tungsten monoblock fingers and tungsten coated graphite blocks [4,5].…”

Section: Introductionmentioning

confidence: 99%

A brief summary of tungsten technology development in Korea

Hong

2020

Tungsten

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A review of tungsten technology development in Korea is briefly given. According to the upgrade plan of Korea superconducting tokamak advanced research (KSTAR) tokamak associated with Korean fusion energy R&D program, graphite plasma-facing components will be replaced with tungsten-based ones to handle the high-peak heat load caused by an increase of heating power up to 26 MW. Brazing technique to bond tungsten was developed and tungsten blocks were manufactured. Blocks were installed at the central divertor in KSTAR and exposed to high heat flux. Under high heat flux and long-pulse discharge, tungsten blocks were severely damaged. Molten tungsten materials show movements towards the high field side, which is j×B direction. The COMSOL ® modeling described the melting event quantitatively well. The failure of a water cooling system with a metal wall environment during a long-pulse plasma operation is very critical.

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“…ASIPP developed a batch manufacturing technology for ITER-like water-cooled full W-PFC which employs copper alloy (CuCrZr) as a heat sink material and the hot isostatic pressing (HIP) method to join the W-PFM and the CuCrZr heat sink together [6]. Therewith ASIPP upgraded the EAST upper divertor from the bolted graphite tile PFC [7] into the ITER-like watercooled full W-PFC in 2014, and the W divertor came into service successfully [8][9][10][11]. Fully non-inductive steadystate H-mode plasmas (H 98, y2 ~ 1.1) were achieved with a duration of more than 60 s in 2016 experimental campaign [10] and further extended to ~ 100 s in 2017 campaign with a good control of impurity and heat exhaust benefiting from the upper W divertor [11].…”

Section: Application Of Tungsten As Plasma-facing Materials In Eastmentioning

confidence: 99%

“…Therewith ASIPP upgraded the EAST upper divertor from the bolted graphite tile PFC [7] into the ITER-like watercooled full W-PFC in 2014, and the W divertor came into service successfully [8][9][10][11]. Fully non-inductive steadystate H-mode plasmas (H 98, y2 ~ 1.1) were achieved with a duration of more than 60 s in 2016 experimental campaign [10] and further extended to ~ 100 s in 2017 campaign with a good control of impurity and heat exhaust benefiting from the upper W divertor [11]. A new lower W divertor is designed [12] and will replace the existing graphite divertor in 2020.…”

Section: Application Of Tungsten As Plasma-facing Materials In Eastmentioning

confidence: 99%

Plasma–tungsten interactions in experimental advanced superconducting tokamak (EAST)

et al. 2019

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Tungsten (W) is used as the armor material of the International Thermonuclear Experimental Reactor (ITER) divertor and is regarded as the potential first wall material of future fusion reactors. One of the key challenges for the successful application of W in fusion devices is effective control of W at an extremely low concentration in plasma. Understanding and control of W erosion are not only a prerequisite for W impurity control, but also vital concerns to plasma-facing component (PFC) lifetime. Since the application of ITER-like water-cooled full W divertor in EAST in 2014, great efforts were made to investigate W erosion by experiment and simulation. A spectroscopic system was developed to provide a real-time measurement of W sputtering source. Both experiment and simulation results indicate that carbon (C) is the dominant impurity causing W sputtering in L-mode plasmas, which comes from the erosion of C plasma-facing material (PFM) in the lower divertor and the main chamber limiters. The mixture layer on the surface of W PFCs formed through redeposition or the wall coating can effectively suppress W erosion. Increasing the plasma density and radiation can reduce incident ion energy, thus alleviating W sputtering. In H-mode plasmas, control of edge localized mode (ELM) via resonant magnetic perturbation (RMP) proves to be capable of suppressing intra-ELM W erosion. The experiences and lessons from the EAST W divertor are beneficial to the design, manufacturing and operation of ITER and beyond.

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

Cited by 117 publications

References 41 publications

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

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

A brief summary of tungsten technology development in Korea

Plasma–tungsten interactions in experimental advanced superconducting tokamak (EAST)

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