Modelling of Impurity Transport and Plasma–Wall Interaction in Fusion Devices with the ERO Code: Basics of the Code and Examples of Application

Kirschner, A.; Tskhakaya, D.; Kawamura, G.; Borodin, D.; Brezinsek, S.; Ding, Rui; Linsmeier, Ch.; Romazanov, J.

doi:10.1002/ctpp.201610014

Cited by 24 publications

(13 citation statements)

References 15 publications

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“…Two tungsten rings were inserted in the lower divertor of DIII-D, and 25 repeated attached L-mode plasma shots in the reverse-B t configuration were performed with the outer strike point located on the outboard tungsten ring. The modeling and analysis of these experiments were conducted using the ERO model [20,31], and numerical simulations were performed with ERO-D3D. Plasma conditions and E × B drifts used in ERO-D3D were reconstructed with a standard onionskin model using experimental measurements of plasma conditions from LP and DTS [25].…”

Section: Discussionmentioning

confidence: 99%

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ERO modeling and analysis of tungsten erosion and migration from a toroidally symmetric source in the DIII-D divertor

Guterl¹,

Abrams²,

Johnson³

et al. 2019

Nucl. Fusion

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A toroidally symmetric tungsten ring inserted in the lower outer divertor of DIII-D was exposed to 25 repeated, attached L-mode shots in reverse- configuration. Radial profiles of the W gross erosion flux inferred in situ from spectroscopic measurements of the WI line (400.9 nm) during these experiments are well reproduced by ERO-D3D simulations of carbon and tungsten impurity erosion, transport and redeposition in the outer divertor region. Tungsten gross erosion is mainly induced by physical sputtering of tungsten by carbon impurities. The outward radial transport of carbon impurities in the outer divertor is shown to be mainly governed by drifts in the sheath region. In addition, the erosion and redeposition of carbon on tungsten, induced by the implantation of carbon into tungsten modeled with the homogeneous mixed material model, increases the effective flux of carbon impurities onto the tungsten ring (carbon recycling on tungsten). The dynamics of carbon implantation in tungsten is shown to be consistent with the plasma shot duration in DIII-D. Moreover, it is shown that the localized deposition of tungsten measured experimentally in the outboard region away from the tungsten ring is caused by the long-range radial transport of tungsten impurities in the outer divertor region induced by the interplay between poloidal and radial drifts. Such experimental measurements might provide direct quantitative estimations of tungsten net erosion. The modeling and analysis of carbon and tungsten erosion and redeposition presented in this paper demonstrates that various physical mechanisms and their synergistic effects need to be taken into account to accurately describe erosion, transport and redeposition of impurities in tokamak divertors.

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Section: Discussionmentioning

confidence: 99%

“…Impurity erosion, transport and redeposition in the outer divertor are modeled with the ERO model [20,31]. Numerical simulations are performed with ERO-D3D, which is an enhanced high performance computing version of the original ERO code.…”

Section: Reconstruction Of Plasma Conditionsmentioning

confidence: 99%

ERO modeling and analysis of tungsten erosion and migration from a toroidally symmetric source in the DIII-D divertor

Guterl¹,

Abrams²,

Johnson³

et al. 2019

Nucl. Fusion

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“…The analysis of the prompt re-deposition of tungsten was conducted with the Monte-Carlo code ERO [22], which simulates the three-dimensional trajectories of tungsten impurities physically sputtered from a flat divertor target during gyro-orbits assuming uniform plasma conditions across and along the divertor material surface. Only the sheath electric field and collisions of tungsten impurities with plasma electrons inducing the ionization of tungsten impurities are considered [23].…”

Section: Scaling Law For W Prompt Re-depositionmentioning

confidence: 99%

“…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]. The overall agreement reported between interpretative modeling and experimental data for various plasma configurations suggests that current numerical models effectively include fundamental physics mechanisms governing tungsten prompt re-deposition and net erosion in tokamak divertors.…”

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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“…We note that sensitivity studies varying background plasma parameters have been performed with WALLDYN [9] to investigate impurity transport and material evolution in mixed carbon-lithium-oxygen-deuterium conditions [10], and in an ERO [11] simulation of beryllium erosion [12]. However, the use of formal methods for uncertainty quantification on impurity transport have yet to be explored extensively in the field of impurity migration and transport.…”

Section: Introductionmentioning

confidence: 99%

Quantification of the effect of uncertainty on impurity migration in PISCES-A simulated with GITR

Younkin¹,

Sargsyan²,

Casey³

et al. 2022

Nucl. Fusion

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A Bayesian inference strategy has been used to estimate uncertain inputs to global impurity transport code (GITR) modeling predictions of tungsten erosion and migration in the linear plasma device, PISCES-A. This allows quantification of GITR output uncertainty based on the uncertainties in measured PISCES-A plasma electron density and temperature profiles (n e, T e) used as inputs to GITR. The technique has been applied for comparison to dedicated experiments performed for high (4 × 1022 m−2 s−1) and low (5 × 1021 m−2 s−1) flux 250 eV He–plasma exposed tungsten (W) targets designed to assess the net and gross erosion of tungsten, and corresponding W impurity transport. The W target design and orientation, impurity collector, and diagnostics, have been designed to eliminate complexities associated with tokamak divertor plasma exposures (inclined target, mixed plasma species, re-erosion, etc) to benchmark results against the trace impurity transport model simulated by GITR. The simulated results of the erosion, migration, and re-deposition of W during the experiment from the GITR code coupled to materials response models are presented. Specifically, the modeled and experimental W I emission spectroscopy data for a 429.4 nm line and net erosion through the target and collector mass difference measurements are compared. The methodology provides predictions of observable quantities of interest with quantified uncertainty, allowing estimation of moments, together with the sensitivities to plasma temperature and density.

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Modelling of Impurity Transport and Plasma–Wall Interaction in Fusion Devices with the ERO Code: Basics of the Code and Examples of Application

Cited by 24 publications

References 15 publications

ERO modeling and analysis of tungsten erosion and migration from a toroidally symmetric source in the DIII-D divertor

ERO modeling and analysis of tungsten erosion and migration from a toroidally symmetric source in the DIII-D divertor

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

Quantification of the effect of uncertainty on impurity migration in PISCES-A simulated with GITR

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