Verification of the 2D Tokamak Edge Modelling Codes for Conditions of Detached Divertor Plasma

Kotov, V.; Reiter, D.; Coster, D.; Kukushkin, A.S.

doi:10.1002/ctpp.201010048

Cited by 9 publications

(10 citation statements)

References 12 publications

(25 reference statements)

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“…At the rollover and beyond in the ramp, the simulated particle flux densities are much closer no matter which neutral model is invoked. The reason for the difference in J sat at lower n u is still unclear, but similar behavior was reported from a comparison between SOLPS4.3 and SOLPS5.0 in [41].…”

Section: Edge2d-eirene/solps43 Comparisonsupporting

confidence: 70%

Influence of atomic physics on EDGE2D-EIRENE simulations of JET divertor detachment with carbon and beryllium/tungsten plasma-facing components

et al. 2014

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The EDGE2D-EIRENE code is applied for simulation of divertor detachment during matched density ramp experiments in high triangularity, L-mode plasmas in both JET-Carbon (JET-C) and JET-ITER-Like Wall (JET-ILW). The code runs without drifts and includes either C or Be as impurity, but not W, assuming that the W targets have been coated with Be via main chamber migration. The simulations reproduce reasonably well the observed particle flux detachment as density is raised in both JET-C and JET-ILW experiments and can better match the experimental in-out divertor target power asymmetry if the heat flux entering the outer divertor is artificially set at around 2–3 times that entering the inner divertor. A careful comparison between different sets of atomic physics processes used in EIRENE shows that the detachment modelled by EDGE2D-EIRENE relies only on an increase of the particle sinks and not on a decrease of the ionization source. For the rollover and the beginning of the partially detached phase, the particle losses by perpendicular transport and the molecular activated recombination processes are mainly involved. For a deeper detachment with significant target ion flux reduction, volume recombination appears to be the main contributor. The elastic molecule-ion collisions are also important to provide good neutral confinement in the divertor and thus stabilize the simulations at low electron temperature (Te), when the sink terms are strong. Comparison between EDGE2D-EIRENE and SOLPS4.3 simulations of the density ramp in C shows similar detachment trends, but the importance of the elastic ion-molecule collisions is reduced in SOLPS4.3. Both codes suggest that any process capable of increasing the neutral confinement in the divertor should help to improve the modelling of the detachment. A further outcome of this work has been to demonstrate that key JET divertor diagnostic signals—Langmuir probe Te and bolometric tomographic reconstructions—are running beyond the limit of validity in high recycling and detached conditions and cannot be reliably used for code validation. The simulations do, however, reproduce the trend of the evolution of the line integrated bolometer chord measurements. The comparison between the code results and high-n Balmer line radiation intensity profiles confirms that a strong volume recombination is present during the experimental detachment and may play a role in this process, as suggested by the code.

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Section: Edge2d-eirene/solps43 Comparisonsupporting

confidence: 70%

Influence of atomic physics on EDGE2D-EIRENE simulations of JET divertor detachment with carbon and beryllium/tungsten plasma-facing components

et al. 2014

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“…It is chosen to take the molecular dissociation energy as volumetric losses, although this is an overestimation of the real target power reduction. drift effects) [45,50] the momentum flux due to the anomalous particle transport. S mom denotes the sources of momentum (see [45] for details), found to be dominated by momentum transfer to neutrals.…”

Section: Discussionmentioning

confidence: 99%

“…Using the current conservation, the electric field contribution can be eliminated by introducing, amongst others, the static electron pressure. With x the poloidal direction and y the radial one, the following equation is derived (in steady state and in the absence of drift effects) [45,50]: and h x , h y and h z = 2πR the metric coefficients, √ g = h x h y h z the elementary cell volume, Γ visc m the viscous momentum flux and Γ anom m the momentum flux due to the anomalous particle transport. S mom denotes the sources of momentum (see [45] for details), found to be dominated by momentum transfer to neutrals.…”

Section: Appendix B Derivation Of the Equation For The Ion Currentmentioning

confidence: 99%

Comparison of high density and nitrogen seeded detachment using SOLPS-ITER simulations of the tokamak á configuration variable

Smolders¹,

Wensing²,

Carli³

et al. 2020

Plasma Phys. Control. Fusion

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First of a kind SOLPS-ITER simulations on TCV that include nitrogen have been performed to model recent nitrogen seeded detachment experiments.Based on spectroscopic measurements, a nitrogen recycling coefficient R N p ≈ 0.3 − 0.5 on the graphite walls of TCV is estimated. The experimentally observed decrease of core nitrogen density with increasing plasma density is reproduced and linked to a reduction of the ionisation mean free path in the SOL. Although the influence of sputtered carbon impurities from TCV's graphite wall cannot be fully eliminated, seeding nitrogen increases control over the total impurity density. This facilitates disentangling the effect of impurities from that of high upstream density on the main characteristics of detachment, namely target power and ion current reductions and the development of a parallel pressure drop. Increasing the density and the seeding rate reduce the power on the divertor targets in a different way: with density, the ion current increases and the target temperature strongly decreases, whereas seeding impurities decreases the ion current and affects less strongly the temperature. The reduction in ion current when seeding nitrogen is due to a lower ionisation source, which is not related to power limitation nor an increased momentum loss, but to a decrease of the ionisation reaction rate. Impurity seeding leads to less volumetric momentum losses (and hence pressure drop) than density ramps, for the same level of energy flux reduction. Additionally, main chamber sputtering of carbon is identified as a possible explanation for the missing target ion current roll-over during density ramps in the simulations.

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“…In the initial phase of our ITER JINTRAC simulation studies, we conducted a considerable benchmark between EDGE2D and SOLPS 4.3 [33], which showed that the SOL/divertor physics description was in agreement between the two codes [34] (see appendix B). Moreover, we have also significantly modified EDGE2D to model plasmas with He as the majority species.…”

Section: Introductionmentioning

confidence: 99%

JINTRAC integrated simulations of ITER scenarios including fuelling and divertor power flux control for H, He and DT plasmas

et al. 2022

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We have modelled self-consistently how to most efficiently fuel ITER hydrogen (H), helium (He) and deuterium–tritium (DT) plasmas with gas and/or pellets with the integrated core and 2D SOL/divertor suite of codes JINTRAC. This paper presents the first overview of full integrated simulations from core to divertor of ITER scenarios following their evolution from X-point formation, through L-mode, L–H transition, steady-state H-mode, H–L transition and current ramp-down. Our simulations respect all ITER operational limits, maintaining the target power loads below 10 MW m−2 by timely gas fuelling or Ne seeding. For the pre-fusion plasma operation (PFPO) phase our aim was to develop robust scenarios and our simulations show that commissioning and operation of the ITER neutral beam (NB) to full power should be possible in 15 MA/5.3 T L-mode H plasmas with pellet fuelling and 20 MW of ECRH. For He plasmas gas fuelling alone allows access to H-mode at 7.5 MA/2.65 T with 53–73 MW of additional heating, since after application of NB and during the L–H transition, the modelled density build-up quickly reduces the NB shine-through losses to acceptable levels. This should allow the characterisation of ITER H-mode plasmas and the demonstration of ELM control schemes in PFPO-2. In ITER DT plasmas we varied the fuelling and heating schemes to achieve a target fusion gain of Q = 10 and to exit the plasma from such conditions with acceptable divertor loads. The use of pellets in DT can provide a faster increase of the density in L-modes, but it is not essential for unrestricted NB operation due to the lower shine-through losses compared to H. During the H–L transition and current ramp-down, gas fuelling and Ne seeding are required to keep the divertor power loads under the engineering limits but accurate control over radiation is crucial to prevent the plasma becoming thermally unstable.

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Verification of the 2D Tokamak Edge Modelling Codes for Conditions of Detached Divertor Plasma

Cited by 9 publications

References 12 publications

Influence of atomic physics on EDGE2D-EIRENE simulations of JET divertor detachment with carbon and beryllium/tungsten plasma-facing components

Influence of atomic physics on EDGE2D-EIRENE simulations of JET divertor detachment with carbon and beryllium/tungsten plasma-facing components

Comparison of high density and nitrogen seeded detachment using SOLPS-ITER simulations of the tokamak á configuration variable

JINTRAC integrated simulations of ITER scenarios including fuelling and divertor power flux control for H, He and DT plasmas

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