The Influence of Divertor Plasma Parameter on Tungsten Screening in High Recycling Regime for CFETR

Xu, Guoliang; Zhou, Yifu; Mao, Shaohua; Kong, Defeng; Li, Liu; Chan, V. S.; Ye, Minyou

doi:10.1109/tps.2017.2776227

Cited by 5 publications

(7 citation statements)

References 19 publications

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“…This experimental observation is consistent with the simulation results in Refs. [20,21]. Due to the increase of particle flux onto the target with Ne seeding as shown in Fig.…”

Section: Effect Of Ne Seeding On Divertor W Sputteringmentioning

confidence: 99%

Experimental investigation on divertor tungsten sputtering with neon seeding in ELMy H-mode plasma in EAST tokamak

Ye¹,

Ding²,

Li³

et al. 2022

Chinese Phys. B

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Neon (Ne) seeding is used to cool the edge plasma by radiation to protect the divertor tungsten (W) target in the Experimental Advanced Superconducting Tokamak (EAST). The W sputtering in the outer divertor target with Ne seeding is assessed by the divertor visible spectroscopy system. It is observed that the W sputtering flux initially increases with Ne concentration in the divertor despite the decreasing plasma temperature. After reaching a maximum around 25 eV, the W sputtering rate starts to decrease, presenting a suppression effect. The effect on the divertor W sputtering flux and yield due to the competition between the increase of the Ne concentration and the decrease of the plasma temperature is discussed. The results show that enough Ne seeding is essential to effectively reduce the electron temperature and thus to suppress W sputtering. Moreover, ELM suppression is observed when Ne and W impurities enter the core plasma, which could be correlated to the enhanced turbulence transport in the pedestal.

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“…This experimental observation is consistent with the simulation results in Refs. [20,21]. Due to the increase of particle flux onto the target with Ne seeding as shown in Fig.…”

Section: Effect Of Ne Seeding On Divertor W Sputteringmentioning

confidence: 99%

Experimental investigation on divertor tungsten sputtering with neon seeding in ELMy H-mode plasma in EAST tokamak

Ye¹,

Ding²,

Li³

et al. 2022

Chinese Phys. B

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“…Research on controlled impurity injection and pumping for CFETR are ongoing. Consistent core-edge integrated modeling is under development to ensure the impurity does not affect core performance [41,73]. As a test reactor, CFETR prefers grassy-ELM or ELM-free operation to reduce transient heat flux to the divertor.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

The time-dependent simulation of CFETR baseline steady-state scenarios

et al. 2018

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One of the key issues to achieve the phase I mission of China fusion engineering test reactor (CFETR) is steady-state operation with a modest fusion power up to 200 MW. To study this feasibility, time-dependent modeling of CFETR baseline scenario is performed. The time-dependent scenario design examines actual discharge features, including auxiliary heating and current drive scheme, equilibrium, transport, PF coil systems and plasma control system during the plasma evolution. During plasma current ramp-up, 10 MW of EC or LH heating is used to effectively save volt–second consumption to a reasonable level within magnet coil capability and to reduce li for better plasma control. Three reference scenarios are designed to target full non-inductive operation with different external heating and current drive (H&CD), which are NB + EC, NB + LH, and LH + EC, respectively. Two scenarios with neutral beams reach the required fusion power of CFETR phase I target, while for LH + EC scenario the fusion power and confinement is somewhat lower. A reversed magnetic shear with is sustained with off-axis current drive and bootstrap current for all cases examined. Ideal MHD analysis shows that both large toroidal mode number n ballooning mode and low n kink mode are stable in the three reference cases independent of whether the current is totally relaxed or not. The L mode and H–L back transition ramp-down are designed to successfully reduce the plasma current to 2 MA and keep li below 2 with ramp-down rate of 80 kA s−1. The H–L back transition ramp-down yields improvements in the power transfer and coil current evolution as well as the li evolution. The heating and current drive characteristics of three auxiliary heating sources are indicated by scanning studies. A 2D scan of NB energy and tangency radius indicates the features of NB power deposition, current drive, torque and shine through issue. Both ramp-up and flattop are considered in the scanning of radio frequency parameters. For EC waves, the ramp-up phase constrains the parameter space more. The 2D scan of EC launch angle shows that EC waves launched above the midplane yield a better CD efficiency than using a midplane launcher. Specifically, 10 MW of EC waves launched from LFS above the midplane yield a maximum on axis driven current of about 0.55 MA, while waves launched from top yield a maximum near edge driven current of about 0.45 MA in the region of . Scanning of in LH spectrum shows that should be set around 1.7 to get enough penetration (inside ) for current drive and avoid strong accessibility problem. It is found that LH waves launched from HFS drives more current than that launched from LFS when is small. The maximum LH driven current reaches 1.1 MA with 10 MW of LH power launched from HFS.

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“…The background boundary plasma is generated using the OSM according to our previous work [24]. Generally, the plasma parameters along the target are used for the existing machines [25].…”

Section: Generate the Background Plasmamentioning

confidence: 99%

“…In this work, the simulation study of tungsten transport in the SOL is performed in the background plasma using the OSM-EIRENE-DIVIMP edge (OEDGE) code package [23]. The background plasma is generated based on the design parameters and specified divertor plasma profile by the method developed in our previous work [24]. Because the crossfield transport is not well understood, the influence on the tungsten concentration is studied in a manner of parameter scan for the diffusive and hypothetical convective transport coefficients.…”

Section: Introductionmentioning

confidence: 99%

Simulation study of the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer

Xu¹,

Xu²,

Mao³

et al. 2021

Plasma Phys. Control. Fusion

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It is critical to keep a low level of tungsten impurity concentration in the core plasma of the fusion reactor. Using the OEDGE code, the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer is studied. Based on the design parameters of the China Fusion Engineering Test Reactor, the background plasma with the peak target electron temperature of 15 eV is generated using the onion-skin model. The neon impurity with the assumed concentration of 0.2% inside the separatrix is included for estimating the tungsten sputtering source. In a series of simulations of tungsten transport, the diffusion coefficient D ⊥ is varied from 0.1 to 10 m 2 s −1 , and the hypothetical inward pinch velocity V IMP is in the range of 0-5 m s −1 . The tungsten concentration inside the separatrix increases with decreasing diffusion coefficient and exceeds 10 −5 for the diffusion coefficient lower than about 0.2 m 2 s −1 . When the hypothetical inward pinch is included, the tungsten concentration increases. The relation between the relative increase in tungsten concentration and V IMP /D ⊥ is fitted.

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The Influence of Divertor Plasma Parameter on Tungsten Screening in High Recycling Regime for CFETR

Cited by 5 publications

References 19 publications

Experimental investigation on divertor tungsten sputtering with neon seeding in ELMy H-mode plasma in EAST tokamak

Experimental investigation on divertor tungsten sputtering with neon seeding in ELMy H-mode plasma in EAST tokamak

The time-dependent simulation of CFETR baseline steady-state scenarios

Simulation study of the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer

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