H-mode operation in helium plasma with tungsten divertor and low input torque in EAST

Zhang, Bin; Gong, Xianzu; Qian, J.; Ding, Rui; Huang, Jun; Sun, Youwen; Gu, Xiaojing; Li, Y. Y.; Gao, Wei; Yu, Yang; Li, M. H.; Sun, Zhuo; Zhong, Guoqiang; Duan, Yanmin; Mao, Shifeng; Wang, L.; Ding, Fang; Zang, Qing; Lyu, Bo; Liu, H. Q.; Wang, Y. M.; Ma, Qun; Wang, Y. F.; Zhu, Xiang; Wang, S. X.; Huang, Yusheng; Liu, J. W.; Chen, Y. J.; Yang, Zhendong

doi:10.1088/1741-4326/ab9be6

Cited by 8 publications

(6 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As is well-known, NB power can direct heat main ions, which is the main difference compared to dominant electron heating via RF power. Besides, the four blue diamond points at n e ∼ 4 × 10 19 m −3 own even higher P loss values compared to the corresponding H-mode threshold power in He plasma, which is mainly attributed to the higher helium concentration (C He > 70%), which should play a critical role in pedestal physics [3].…”

Section: Impact Of Helium Concentration On I-mode Operationmentioning

confidence: 90%

“…The L-H threshold power against plasma density in He plasma has been intensively investigated at various operation parameters of I p = 0.4-0.5 MA and B T = 1.8-2.4 T, see [3]. Figure 4 gives the results of L-I threshold power (diamond symbols) against plasma density at I p = 0.5 MA and B T = 2.4 T, along with the L-H statistic results (circle symbols) for reference.…”

Section: Impact Of Helium Concentration On I-mode Operationmentioning

confidence: 99%

“…The lower C He plasma entered into H-mode (t ∼ 3 s) with total RF power of ∼3.7 MW, while only I-mode achieved for high C He with optimized plasma density at even higher heating power level by adding extra 0.5 MW of LH. Note that running at n e ∼ 3.6 × 10 19 m −3 was expected to facilitate H-mode access, corresponding to the minimum L-H transition power threshold [3]. Due to the helium concentration effect on enhancing heating power needs for accessing H-mode, the higher C He plasma for shot #94369 could only go into the I-mode regime with such an insufficient power source.…”

Section: Impact Of Helium Concentration On I-mode Operationmentioning

confidence: 99%

“…In order to support future ITER non-nuclear operation phase, comprehensive experiments with helium (He) ion (refer to the helium-4 isotope) as the dominant ion species have been carried out in the superconducting tokamak EAST under the condition of pure radio-frequency (RF) wave heating and ITER-like tungsten divertor [1,2]. The helium concentration (C He ), defined as the ratio of helium (He) to deuterium (D) content, was found to play a critical role in determining plasma performance [3]. Both energy confinement time and edge localized modes (ELMs) frequency correlate with the change of C He .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

Zhang¹,

Gong²,

Qian³

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

The characteristics of I-mode operation in helium (He) plasma with radio-frequency (RF) wave heating and ITER-like tungsten divertor have been investigated for the first time on EAST, under the favorable B T configuration. Stationary I-mode in He plasma lasting for ∼5.4 s was achieved at I p = 0.5 MA, B T = 2.4 T with a total injected RF power of 3.5 MW, along with the appearance of the 30–90 kHz weakly coherent mode and the ∼13 kHz edge temperature ring oscillation. The pulse length was only limited by the heating power duration. He concentration was found to play a critical role in I-mode operation, as L–I transition threshold power was increased and the energy confinement was degraded with increasing He concentration. The experimental investigation result on energy confinement and divertor heat flux between I- and H-mode plasma was also given at a similar He concentration.

show abstract

Section: Impact Of Helium Concentration On I-mode Operationmentioning

confidence: 90%

Section: Impact Of Helium Concentration On I-mode Operationmentioning

confidence: 99%

Section: Impact Of Helium Concentration On I-mode Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

Zhang¹,

Gong²,

Qian³

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…In order to provide references for the ITER helium operation phase, helium experiments were carried out on EAST in 2019. During the helium campaign, type-I ELMy H-modes have been achieved [19], which provide a good platform to investigate the tungsten erosion during ELMs.…”

Section: Methodsmentioning

confidence: 99%

An interpretive model for the double peaks of divertor tungsten erosion during type-I ELMs in EAST

Ding

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

Double peaks of divertor tungsten erosion during type-I edge-localized modes (ELMs) were observed in the EAST tokamak. To study this unique phenomenon, an analytical model of plasma expansion into vacuum was used to investigate the ELM parallel transport along the magnetic field line to the divertor target. The modeling results reveal that during ELM bursts, the energetic C6+ transport is slower than the main ions due to a lower initial thermal speed. The time of C6+ arriving at the divertor target from the modeling is consistent with the second tungsten erosion peak. Based on the particle flux from the transport model, a newly developed mixed-material model quantitively reproduced the intra-ELM tungsten erosion profiles for both deuterium and helium discharges. A lithium–carbon coating makes the heavier impurity (C6+) comparatively more effective than the main ions on tungsten sputtering, and thus makes the second tungsten erosion peak more remarkable on EAST experiments.

show abstract

Recent advances in developing natural and impurity-induced small/no-ELM H-mode regimes in EAST

Wang

Yang

et al. 2023

Rev. Mod. Plasma Phys.

View full text Add to dashboard Cite

One critical issue in steady-state and high-performance operation in future tokamak fusion reactors is to develop H-mode operational regimes that mitigate or eliminate the large-amplitude ELMs to decrease the transient heat flux on the divertor and first wall. This paper reviews recent advances in extending and understanding the access and sustainment of natural and impurity-induced small/no-ELM H-mode regimes in EAST. Highly reproducible stationary grassy ELM regime with good energy confinement and excellent tungsten impurity exhaust capability has been obtained in EAST with water-cooled metal wall, compatible with low rotation, high normalized density, high bootstrap current fraction, radiative divertor and fully non-inductive operations, which are the conditions required for future fusion reactor-level plasmas. Grassy-like small-ELM H-mode regime has been achieved in helium (He) plasma experiments, which will be conducted during the pre-fusion power operation phase in ITER. The exploration for type-II ELM regime in EAST is also briefly introduced. Three spontaneous no-ELM H-mode regimes frequently observed in EAST are introduced, including an enhanced-recycling no-ELM regime, a non-inductive low-recycling no-ELM regime and a transient spontaneous no-ELM regime at relatively low pedestal collisionality ($${v}_{e}^{*}<1$$ v e ∗ < 1 ). These no-ELM regimes show different characteristic signatures of pedestal fluctuation and profiles, and the physical mechanisms behind have been studied. In addition, small/no-ELM regimes with impurity seeding have also been achieved in EAST. The ELM behavior changing from mixed small and large ELMs to pure grassy ELMs has been observed with neon (Ne) seeding. A highly reproducible no-ELM H-mode regime with radiative divertor has been demonstrated through CD4 seeding in EAST. These results are believed to be helpful for the application of small/no-ELM H-mode regimes to future tokamak fusion reactors.

show abstract

H-mode operation in helium plasma with tungsten divertor and low input torque in EAST

Cited by 8 publications

References 28 publications

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

An interpretive model for the double peaks of divertor tungsten erosion during type-I ELMs in EAST

Recent advances in developing natural and impurity-induced small/no-ELM H-mode regimes in EAST

Contact Info

Product

Resources

About