The first implementation of active detachment feedback control in EAST PCS

Yuan, Q.P.; Wu, Kai; Wang, L.; Xu, Jichan; Li, K.D.; Liu, J.B.; Meng, Lingyi; Zhan, Rui; Luo, Zhi; Xiao, Bingjia; Eldon, D.; Barr, J.L.; Hyatt, A.W.

doi:10.1016/j.fusengdes.2020.111557

Cited by 21 publications

(21 citation statements)

References 8 publications

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“…The technique for active control of plasma detachment has been successfully developed using divertor particle flux measured by divertor Langmuir probes as the feedback controller [43]. The control algorithm based on the divertor particle flux worked effectively during the experiments with divertor impurity seeding.…”

Section: Impact Of Plasma Detachment On the Density Shouldermentioning

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: Impact Of Plasma Detachment On the Density Shouldermentioning

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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“…In recent years, the real-time active feedback control of a detached divertor is focused [39] in magnetic fusion research, and various methods have been developed successfully. For example, feedback controls of divertor detachment relying on the tile current [40], target ion saturation current [41,42], target temperature from proximity thermocouples [43] or infrared thermography [44], radiated power from bolometry [45][46][47] or absolute extreme ultraviolet (AXUV) [48,49] and impurity emission front locations [50] have been investigated experimentally.…”

Section: Introductionmentioning

confidence: 99%

Study on pedestal fluctuations in H-modes without large ELMs during the transition to a detached tungsten divertor in EAST

Yang

Chen

et al. 2021

Nucl. Fusion

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Simultaneous control of the damaging erosion induced by the transient and steady-state heat/particle fluxes on the divertor target material is one of the critical issues for next-step magnetic fusion devices. H-mode operation without large edge-localized modes has been achieved in EAST with an ITER-like tungsten divertor, while being compatible with the partial and pronounced detachment in divertor, via either ramping-up of bulk density or injection of low/high-Z impurities. The pedestal characteristics during the transition from the attached to the detached divertor and the reversed transition (detached to attached) under different detachment methods are studied in detail, where the evolution of multi fluctuating structures commonly residing in the H-mode pedestal of EAST (edge coherent mode (ECM), magnetic coherent mode (MCM) and high frequency mode (HFM)) is highlighted. In addition, the possible mechanisms that affect the behavior of these modes, such as the pedestal pressure gradient and the collisionality, have also been discussed. The radial structures of ECM, MCM and HFM are detected, for the first time, in one discharge. Relevant research may provide contribution to obtaining an integrated small/no ELM and radiative divertor scenario in the next step.

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“…The ELM mitigation has also been successfully achieved with the Fig. 51 Active feedback control achieved by SMBI D 2 fueling at divertor region in EAST H-mode experiment (Yuan et al 2020) fueling gas, impurity gases, and impurity mixture gas injected by the SMBI system. Several approaches to achieve ELM mitigation exist, such as the change in the instability boundary and the nonlinear interaction between the ELMs and pedestal turbulence.…”

Section: Discussionmentioning

confidence: 95%

“…Recently, the mid-plane SMBI was also valid in EAST radiative feedback control experiments, which improved the control accuracy and response speed (Yuan et al 2020). This control system consists of a diagnostic (Langmuir probes), controller, and SMBI system, and can be applied to modify the radiative level under various conditions.…”

Section: Active Control Of Divertor Heat With Smbimentioning

confidence: 99%

A review of supersonic molecular beam injection for plasma fueling and physical studies in magnetic fusion devices

Xiao

Zhong

Duan

et al. 2022

Rev. Mod. Plasma Phys.

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In magnetic confinement fusion devices, supersonic molecular beam injection (SMBI) is commonly used as a fueling method, which has also performed well in physical studies since it was first proposed on the HL-1 tokamak by Southwestern Institute of Physics. This study presents the development of the SMBI technique since its first use in fusion experimental devices and reviews the progress on the investigation of plasma physics using the SMBI. In addition, this study further discusses the potential applications of the SMBI technique on future fusion devices.

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The first implementation of active detachment feedback control in EAST PCS

Cited by 21 publications

References 8 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

Study on pedestal fluctuations in H-modes without large ELMs during the transition to a detached tungsten divertor in EAST

A review of supersonic molecular beam injection for plasma fueling and physical studies in magnetic fusion devices

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