IMPGYRO: The full-orbit impurity transport code for SOL/divertor and its successful application to tungsten impurities

Yamoto, S.; Homma, Y.; Hoshino, Kazuo; Toma, M.; Hatayama, A.

doi:10.1016/j.cpc.2019.106979

Cited by 10 publications

(7 citation statements)

References 38 publications

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“…During external impurity seeding, the edge plasma influences the impurity transport, while the power radiation by impurities in turn changes the background plasma. These two interactions consequently determine the distribution of impurity [18][19][20]. In our previous work, the W erosion on EAST with neon seeding in different divertor operation regimes has been evaluated [10], which found that the seed neon impurity has significant impact on the W erosion.…”

Section: Introductionmentioning

confidence: 99%

Simulation of tungsten target erosion and tungsten impurity transport during argon seeding on EAST

Wang¹,

Sang²,

Zhang³

et al. 2021

Plasma Phys. Control. Fusion

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The upgrade of experimental advanced superconducting tokamak lower divertor to use tungsten (W) target is undertaken, however the target erosion and W impurity accumulation in the core pose a great challenge during high power discharge with external impurity seeding. This paper aims to study the influence of argon (Ar) seeding on the target erosion and the W impurity transport on steady-state operation. The scrape-off layer/divertor plasma as well as W impurity are self-consistently simulated by using SOLPS-ITER code package. With the constant input power, the Ar seeding rate is varied to study the changes on divertor plasma, incident Ar flux, the target erosion and W impurity transport. The simulation results indicate that the external Ar impurity influences W target erosion through both reducing the plasma temperature and introducing heavier incident particles, which significantly complicates the erosion process. The eroded W flux has great impact on the W core accumulation, and the divertor plasma condition influences W impurity transport remarkably. A correlation between peak electron temperature (T e ) at the outer target and the W concentration (C W ) at the core-edge-interface is found. Moreover, the influence of the W impurity on the background boundary plasma is also evaluated.

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Section: Introductionmentioning

confidence: 99%

Simulation of tungsten target erosion and tungsten impurity transport during argon seeding on EAST

Wang¹,

Sang²,

Zhang³

et al. 2021

Plasma Phys. Control. Fusion

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“…To further understand the general influence of the tungsten impurity cross-field transport inside the SOL, the simulation study will be systematically performed for different divertor plasma parameters, the diffusion coefficient, and the pinch velocity. Furthermore, the simulation scheme used in this work also needs to be improved for studying the effect of the parallel flow [35,51] and drifts [29,30] in the SOL, and the influence of ELM [52].…”

Section: Discussionmentioning

confidence: 99%

“…Along the field line, the motion of the ions is described by the classical transport, while the cross-field diffusive and convective coefficients are input for computing the ions' movement across the field line. Unlike the full-orbit codes such as IMPGYRO [29] and ERO [30], drift effects are not included in DIVIMP, and the prompt redeposition is described by a simple model.…”

Section: Simulation Schemementioning

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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“…As a result of the large width of the sheath near divertor targets, a vast majority of tungsten impurities sputtered from divertor PFMs are ionized multiple times within the sheath and accelerated back toward the divertor surfaces by the sheath electric field over a distance comparable to the Larmor radius, a process known as prompt re-deposition [6][7][8]. The complexity of predictive models for tungsten prompt re-deposition and net erosion in divertors has been noted [9][10][11][12][13][14][15]. Experimental measurements of tungsten net erosion in divertors of various devices, such as JET [16], DIII-D [17][18][19], ASDEX-Upgrade [20] or WEST [21], are generally well-reproduced by numerical models, e.g., ERO [22].…”

Section: Introductionmentioning

confidence: 99%

Recent DIII-D progress toward validating models of tungsten erosion, re-deposition, and migration for application to next-step fusion devices

Abrams,

Guterl,

Abe

et al. 2023

Mater. Res. Express

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Fundamental mechanisms governing the erosion and prompt re-deposition of tungsten impurities in tokamak divertors are identified and analyzed to inform the lifetime of tungsten plasma-facing components in ITER and other future devices. Various experiments conducted at DIII-D to benchmark predictive models are presented, leveraging the DiMES removable sample exposure probe capability and the Metal Rings Campaign, in which toroidally symmetric rows of tungsten-coated tiles were installed in the DIII-D divertor. In tokamak divertors, the width of the electric sheath is of the order of the main ion Larmor radius, and a vast majority of sputtered tungsten impurities are typically ionized within the sheath. Therefore, W prompt redeposition is mainly governed by the ratio of the characteristic ionization mean-free path of neutral tungsten to the width of the sheath. In-situ monitoring of the prompt redeposition of tungsten impurities in divertors is demonstrated via the use of WII/WI line ratios and the ionizations/photon (S/XB) method in L-mode discharges. Even with this relatively limited set of emission measurements, net erosion measurements were found to be a consistent upper bound to an analytic scaling based on the ratio of the W ionization length, λ iz , and the width of the magnetic sheath rather than the ratio of λ iz and the W+ gyro-radius. In the far-scrape-off layer (SOL) of the ITER divertor, however, it is calculated that the measurement of photon emissions associated with the ionization of tungsten impurities up to W 5 + may be required. Finally, W deposition patterns on DiMES collector probes, interpreted via DIVIMP-WallDYN modelling, reveal the key roles of progressive W erosion/re-deposition staps and E × B drifts in regulating long-range high-Z material migration.

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IMPGYRO: The full-orbit impurity transport code for SOL/divertor and its successful application to tungsten impurities

Cited by 10 publications

References 38 publications

Simulation of tungsten target erosion and tungsten impurity transport during argon seeding on EAST

Simulation of tungsten target erosion and tungsten impurity transport during argon seeding on EAST

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

Recent DIII-D progress toward validating models of tungsten erosion, re-deposition, and migration for application to next-step fusion devices

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