Stabilizing effect of enhanced resistivity on peeling-ballooning instabilities on EAST

Lin, Xiaohui; Banerjee, Debabrata; Zhu, Ping; Xu, G. S.; Ye, Y; Wang, Y F; Li, H L; Zang, Qing; Zhang, T; Chen, Y J

doi:10.1088/1361-6587/ab6d47

Cited by 2 publications

(2 citation statements)

References 43 publications

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“…For the mechanism of ELM mitigation, the impurity effects including dilution effect, increased effective charge number Z eff and lower separatrix temperature are usually considered, which can provide a stabilizing effect on the pedestal instabilities [21]. Some simulations have indicated that the enhanced resistivity could also have a stabilizing effect on the peeling-ballooning modes (PBMs) [22,23]. Besides, impurity could also influence the ELM behavior through affecting the pedestal turbulence and thus changing the pedestal gradient and bootstrap current [24].…”

Section: Introductionmentioning

confidence: 99%

Compatibility of large ELM control and stable partial detachment with neon/argon seeding in EAST

Lin

Yang

et al. 2023

Nucl. Fusion

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It is necessary to achieve simultaneous exhaust of excessive transient and steady-state heat fluxes on the divertor target for the divertor protection in the future fusion reactors. The sustained large ELM control and stable partial detachment have been achieved concurrently with argon (Ar) or neon (Ne) seeding in EAST. With Ne seeding, the large ELMs with frequency fELM ~ 100 Hz disappear and a stable ELM-free state with H98,y2 > 1 is maintained. Meanwhile, the electron temperature Tet around the lower outer strike point decreases from more than 70 eV during the large ELM burst to less than 5 eV in the stable ELM-free phase. In addition, a slight improvement of plasma confinement is observed in the partially detached state, mainly attributed to the increased electron density ne and ion temperature Ti in the core region. In the pedestal region, the density gradient and the electron temperature show subtle variation. The effective charge number Zeff increases significantly after Ne seeding, leading to a decrease in the edge bootstrap current and the pedestal pressure gradient, and thus the stabilization of ELMs. With Ar seeding, the large ELMs are also suppressed at first, but soon transit to type-III ELMs with a high fELM ~ 1 kHz, highly correlated with the energy confinement degradation. The steady-state and transient heat fluxes on the divertor can be both well reduced with Ar/Ne seeding in EAST.

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Section: Introductionmentioning

confidence: 99%

Compatibility of large ELM control and stable partial detachment with neon/argon seeding in EAST

Lin

Yang

et al. 2023

Nucl. Fusion

Self Cite

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show abstract

“…Higher Z eff reduces the ion density through dilution effect and edge bootstrap current at higher collisionality, facilitating the stabilization of peeling-ballooning modes (PBMs) [19,22]. Some simulations have also suggested that the enhanced resistivity due to increased Z eff could also provide a stabilizing effect on the PBMs [23,24].…”

Section: Introductionmentioning

confidence: 99%

Impacts of recycling impurity on the background ELM behavior during repetitive radiative divertor experiments in EAST

Yang

Lin

et al. 2023

Nucl. Fusion

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A significant change in the background ELM behavior prior to neon (Ne) seeding has been observed in a series of repetitive radiative divertor experiments in EAST. With similar operational parameters, the ELM behavior before Ne seeding changes from large to mixed ELMs, and finally evolves to pure small ELMs. Meanwhile, a significant increase in both Ne and high-Z impurity (W and Mo) emissions has been observed in the bulk plasma, suggesting the retention and recycling of Ne impurity from the wall surface. Experimental results show that the variation in background ELM behavior is highly correlated with the occurrence of high-Z impurity accumulation. The increased accumulation of high-Z impurities leads to a lower electron temperature both in the plasma core and edge, accompanied by a higher and more peaked electron density in the plasma core. Pedestal linear stability analysis reveals that the decreased pedestal electron temperature and thus the lower pressure gradient and lower edge current density are the primary reason for the change of background ELM behavior. The concentration of recycling Ne in the bulk plasma is estimated to be ~1% in the discharges with pure small ELMs.

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Stabilizing effect of enhanced resistivity on peeling-ballooning instabilities on EAST

Cited by 2 publications

References 43 publications

Compatibility of large ELM control and stable partial detachment with neon/argon seeding in EAST

Compatibility of large ELM control and stable partial detachment with neon/argon seeding in EAST

Impacts of recycling impurity on the background ELM behavior during repetitive radiative divertor experiments in EAST

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