Investigation of multifaceted asymmetric radiation from the edge (MARFE) with impurity injection from the upper divertor on the Experimental Advanced Superconducting Tokamak

Luo, Yu; Ding, Fang; Wang, Liang; Duan, Yanmin; Ming, Tingfeng; Mao, Shifeng; Wang, Yumin; Chen, Xiaohua; Li, Kedong; Ye, Dawei; Meng, Lingyi; Xu, Jichan; He, Tao; Nian, Feifei; Ma, Qun; Hu, Zhenhua; Yang, Zhongshi; Luo, Guang–Nan; Xu, G. S.; Sun, Youwen; Hu, Jiansheng

doi:10.1088/1361-6587/ab8a62

Cited by 9 publications

(9 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering that chemical sputtering should be significant under the detached condition, the cause of the doublepeaked emission phenomenon, i.e. carbon deposition on the upper divertor, is suspected to have an influence on the X-point MARFE in EAST [55], which is an important issue for achieving a high radiation fraction in ITER and any future fusion reactor. This will be studied in future work.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the double peak in the visible-light range of radiative divertor emission profiles on the EAST tokamak

Guo¹,

Lu²,

Jia³

et al. 2021

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

The double-peaked emission profile has been identified by tomographic reconstruction from the signals of the tangentially viewing visible-light imaging system on EAST. In the upper-single-null discharge with neon seeding, two light emission peaks are located near the X-point and in the high-field-side (HFS) scrape-off layer (SOL) on the poloidal cross-section while the outer divertor target is still attached. The double-peaked emission phenomenon has not been reported for other tokamaks. In particular, the existence of the emission peak near the X-point under the attached condition is unexpected because it is usually an indication of X-point multifaceted asymmetric radiation from the edge under the detached condition. Therefore, it is of fundamental importance for the divertor physics to make clear the mechanism of the double-peaked emission phenomenon. The computational simulations with SOLPS-ITER and DIVIMP are performed in this work. The simulated results show the contribution of W impurity to the double-peaked emission profile is negligible with the upper tungsten divertor. Considering the existence of a lower carbon divertor in EAST, the influence of the possible deposition of the carbon on the upper divertor is further investigated. The simulating CIII (465 nm) and CII (514 nm) emissions, which make a significant contribution to the visible-light emission in channel B (blue) and G (green), respectively, are found to be similar tothe experimental results. The emission peak near the X-point is related to the carbon deposited on the dome, while that in the HFS SOL is contributed by the carbon on the inner baffle. The ionization source of the carbon impurity and the net force pointing to the X-point are analyzed to understand the concentration of the carbon impurity near the X-point, which in turn causes the emission peak.

show abstract

Section: Discussionmentioning

confidence: 99%

Investigation of the double peak in the visible-light range of radiative divertor emission profiles on the EAST tokamak

Guo¹,

Lu²,

Jia³

et al. 2021

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…EAST is a non-circular fully superconducting magnetic confinement facility with ITER-like magnetic field configurations and heating schemes, plasma current up to 1 MA, toroidal magnetic field B t up to 3.5 T, elongation κ = 1.2-2, and triangularity δ = 0.4-0.7 [13,19]. The major radius is R ∼ 1.83 m and minor radius is a ∼ 0.45 m in the cross-section.…”

Section: Methodsmentioning

confidence: 99%

“…Both pellet fueling and MARFE will be involved in future fusion reactors, so it is important to have a good knowledge of their interactions between them. MARFE has been thought to be a result of a specific thermal instability in the edge plasma and it can move up and down along the poloidal cross-section [13,14]. Its final poloidal position involves the toroidal magnetic field B t direction and the conducted power to the edges of the MARFE [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

MARFE movement and density fluctuations after deuterium pellet injections in H-mode plasmas on EAST tokamak

Hou¹,

Chen²,

Zuo³

et al. 2022

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

The MARFE, which is generally considered to be the result of a radiation thermal instability in the edge and usually occurs in high density operation, has been firstly observed to move up and down along the poloidal cross-section due to edge cooling after cryogenic deuterium pellet injections in EAST tokamak with tungsten divertor. A maximum electron density of 0.84×nGW has been obtained using continuous cryogenic pellet fueling. In the meantime, MARFEs, initially located near the divertors of EAST, moves to the inner wall on HFS after each pellet injection. This movement should be attributed to the asymmetry of the power flow to the two sides of the MARFE after pellet injections. Accompanied with MARFE movement, two kinds of strong density fluctuations have been observed. The ones with continuous and regular frequency spectrum, which doesn’t cause a reduction of main plasma density, are confirmed to be induced by MARFE. The others, appearing with magnetic fluctuations, have been determined to be induced by the m/n=2/1 MHD activities after pellet injections. All the investigations in this paper will be meaningful for the steady high density operation of future fusion reactors, such as ITER.

show abstract

“…This reveals that the transient ELM mitigation and the steady divertor detachment could be simultaneously achieved by RMP. On EAST, the RMP phase difference Δϕ UL is found to influence divertor plasma density and promote plasma detachment [55], which could be attributed to the change of density pump-out. Recent observations in KSTAR support that divertor detachment can be achieved at a relatively low level of density with the application of RMP [56].…”

Section: Rmp-induced Elm Mitigationmentioning

confidence: 99%

The impact of ELM mitigation on tungsten source in the EAST divertor

Chen¹,

Ding²,

Wang³

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

Divertor tungsten (W) erosion source during edge localized mode (ELM) bursts in EAST is investigated based on optical emission spectroscopy on atomic neutral tungsten line emission at 400.9 nm. Both temporal evolution and total source strength are analyzed and compared in three different ELM mitigation schemes including natural ELMs, resonant magnetic perturbations (RMP) and 2.45 GHz lower hybrid wave (LHW). The mitigation of W source caused by single ELM impact at the divertor target is mainly attributed to the reduction of the W source production in the ELM decay phase. However, with the increase of ELM frequency, the time-averaged intra-ELM W source during an ELM cycle rises and dominates the evolution of the total W source with increasing fraction, which exhibits strong correlation with the core W level in the RMP scheme. In the natural ELM scheme, the pedestal electron temperature is found not only to control the effective W sputtering yield at target during ELMs, thus influencing the intra-ELM W source, but also to be related to the delay time between the divertor ELM WI emission and the core extreme ultraviolet bolometer (XUV) signal which can scale with the parallel ion transit time. Furthermore, the delay time is found to have more consistent dependence on the pedestal plasma collisionality. The rise time of intra-ELM WI emission increases when RMP or LHW is applied, revealing a different ELM mitigation mechanism in comparison with the natural ELM scheme. The temporal profiles of the intra-ELM WI emission in different ELM mitigation schemes are compared and the potential mechanism is discussed. Besides, the ELM mitigation effects with RMP are found to be asymmetric at the outer and inner divertor targets, which is characterized by the different variations of the intra-ELM W source strength and the rise time of WI emission with the ramp-up of RMP coil current. Divertor partial detachment is achieved simultaneously with strong ELM mitigation under a suitable RMP phase difference without additional gas puff.

show abstract

Investigation of multifaceted asymmetric radiation from the edge (MARFE) with impurity injection from the upper divertor on the Experimental Advanced Superconducting Tokamak

Cited by 9 publications

References 50 publications

Investigation of the double peak in the visible-light range of radiative divertor emission profiles on the EAST tokamak

Investigation of the double peak in the visible-light range of radiative divertor emission profiles on the EAST tokamak

MARFE movement and density fluctuations after deuterium pellet injections in H-mode plasmas on EAST tokamak

The impact of ELM mitigation on tungsten source in the EAST divertor

Contact Info

Product

Resources

About