GITR: An accelerated global scale particle tracking code for wall material erosion and redistribution in fusion relevant plasma–material interactions

Younkin, Timothy; Green, David L.; Simpson, Adam B.; Wirth, Brian D.

doi:10.1016/j.cpc.2021.107885

Cited by 22 publications

(16 citation statements)

References 4 publications

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“…Since the incoming plasma He ions are normal incidence, the He sputtered W polar angle distribution is uniform. Additional documentation of these results can be found in reference [5]. In addition to this surface model for the He-W interaction, the flux profile for the low and high flux cases sets the spatial distribution for eroded W. This is done using a degree 4 constrained polynomial fit function of radius and assumed axially symmetric as shown in figure 3.…”

Section: Modeling Methodsmentioning

confidence: 99%

“…The W-W self-interaction model used during GITR execution includes tables of sputtering and reflection yields. Energy and angle distributions for each of those combinations are also included in reference [5].…”

Section: Modeling Methodsmentioning

confidence: 99%

“…In this work, GITR [5], a computational model for material erosion, impurity ionization, migration, and deposition, is used to simulate dedicated linear plasma exposure experiments in PISCES-A, and formal uncertainty quantification (UQ) methods are used to estimate the impact of model input uncertainties on the resulting model predictions.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Modeling Methodsmentioning

confidence: 99%

Section: Modeling Methodsmentioning

confidence: 99%

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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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“…We modeled PISCES experiments of W exposure to a range in plasma fluxes (0.5-5.4 × 10 22 m −2 s −1 ), biasing voltages (V bias = 75 V, V bias = 250 V) and plasma compositions (100% He, 10% He-90% D, 100% D). Further details on these PISCES experiments, their analysis, and comparison to the model, which served as initial benchmark of our integrated model, are provided in existing and upcoming publications [26,27].…”

Section: Building the Integrated Modelmentioning

confidence: 99%

“…The model was first applied to simulating dedicated PISCES linear plasma device experiments. Comparison to these experiments also served as benchmark of the model capability to address W impurity transport and sub-surface gas dynamics [26,27]. The integrated model was then applied to predicting the evolution of the ITER divertor under early He plasma operations (see details in reference [28]) and full power burning plasma operations (BPO) [29,30].…”

Section: Introductionmentioning

confidence: 99%

Integrated model predictions on the impact of substrate damage on gas dynamics during ITER burning-plasma operations

Lasa¹,

Blondel²,

Bernholdt³

et al. 2021

Nucl. Fusion

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Divertor design and choice of plasma-facing materials (PFM) will be essential to the success of next-generation fusion reactors as they operate under more powerful scenarios. Understanding and controlling interactions between the plasma and PFM is essential to making these choices. Within these plasma–material interactions and especially in tungsten (W), the interplay between the most abundant plasma species (hydrogen isotopes and helium, He) with the wall material alters fuel retention. However, this interplay is yet to be sufficiently understood to confidently project fuel retention levels to future fusion devices. The paper presents a series of integrated simulations of fusion plasmas and their interaction with tungsten. Specifically, this study assesses the impact of He plasma pre-exposure on hydrogenic species retention during 100 s of burning plasma operations (BPO) in ITER. Multiple pre-exposure scenarios are considered, including sub-surface damage resulting from exposures in the linear device PISCES and from early ITER He-operation. The predictions from these consecutive He-BPO exposures show that fuel content and spatial distribution in the material are largely determined by the He-induced damage, as manifest in: (i) changes in surface temperature expected during BPO have little effect on fuel retention in the presence of He-induced damage; (ii) gas content stabilizes quickly in substrates pre-exposed in PISCES, at levels set by the concentration of pre-existing vacancies, while it continues to increase in substrates initially pristine or pre-exposed to ITER He plasmas; (iii) the presence of He and He–V clusters in the near-surface region locally increases hydrogenic retention, but decreases its permeation; this results in hydrogenic species that remain closer to the surface in pre-damaged substrates, while the bulk content is higher for initially pristine cases. In summary, the interaction and binding of D and T with the pre-existing He–V clusters modifies retention and permeation of hydrogen species during ITER BPO.

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Unstructured mesh tools for magnetically confined fusion system simulations

Shephard,

Merson,

Sahni

et al. 2024

Engineering with Computers

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GITR: An accelerated global scale particle tracking code for wall material erosion and redistribution in fusion relevant plasma–material interactions

Cited by 22 publications

References 4 publications

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

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

Integrated model predictions on the impact of substrate damage on gas dynamics during ITER burning-plasma operations

Unstructured mesh tools for magnetically confined fusion system simulations

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