B2.5-Eunomia simulations of Magnum-PSI detachment experiments: I. Quantitative comparisons with experimental measurements

Chandra, R.; Blank, H. J. de; Diomede, P.; Eck, H.J.N. van; Meiden, H.J. van der; Morgan, T.W.; Vernimmen, J.W.M.; Westerhof, E.

doi:10.1088/1361-6587/ac11b6

Cited by 13 publications

(47 citation statements)

References 31 publications

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“…Φ t is reduced due to increasing Φ vol with increasing neutral background pressure, p n is satisfied with the slight visible differences due to the numerical tolerance in B2.5's solution of the plasma equations. It is also shown here that Φ t reduces with increasing p n , as discussed in [18]. However, it is shown now that Φ vol ∝ p n which reflects the expectation that increasing the neutral background pressure will increase the rate of plasma-neutral interaction.…”

Section: Global Particle Momentum and Power Balancesupporting

confidence: 60%

“…The ionization potential flux is simply the particle flux times the potential, Φ t E α , where E α = −13.6 eV. This flux can be included in (18), such that Q t reflects the energy deposited to the target, and can be modified into:…”

Section: Global Particle Momentum and Power Balancementioning

confidence: 99%

“…As the neutral pressure increases, more of the plasma volume is emitting light, and eventually the volume is visibly moving away from the target. The plasma parameters observed using Thomson scattering (TS) during this transition have been simulated using the coupled plasma and neutral particle code B2.5 [16]-Eunomia [17] and reported in [18]. B2.5-Eunomia includes molecular hydrogen processes in vibrationally excited states and treats vibrationally excited H 2 molecules as test particles.…”

Section: Introductionmentioning

confidence: 99%

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B2.5-Eunomia simulations of Magnum-PSI detachment experiments: II. Collisional processes and their relevance

Chandra

Blank

Diomede

et al. 2021

Plasma Phys. Control. Fusion

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Detachment is achieved in Magnum-PSI by increasing the neutral background pressure in the target chamber using gas puﬃng. The plasma is studied using the B2.5 multi ﬂuid plasma code B2.5 coupled with Eunomia, a Monte Carlo solver for neutral species. This study focuses on the eﬀect of increasing neutral background pressure to the plasma volumetric loss of particle, momentum and energy. The plasma particle and energy loss almost linearly scale with the increase of neutral background pressure, while the momentum loss does not scale as strongly. Plasma recombination processes include molecular activated recombination (MAR), dissociative attachment, and atomic recombination. Atomic recombination, which includes radiative and three-body recombination, is the most relevant plasma process in reducing the particle ﬂux and, consequently, the heat ﬂux to the target. The low temperature where atomic recombination becomes dominant is achieved by plasma cooling via elastic H+-H2 collisions. The transport of vibrationally excited H2 molecules out of the plasma serves as an additional electron cooling channel with relatively small contribution. Additionally, the transport of highly vibrational H2 has a signiﬁcant impact in reducing the eﬀective MAR and dissociative attachment collision rates and should be considered properly. The relevancy of MAR and atomic recombination occupy separate electron temperature regimes, respectively, at Te = 1.5 eV and Te = 0.3 eV, with dissociative attachment being relevant in the intermediary. Plasma cooling via elastic H+-H2 collisions is eﬀective at Te ≤ 1 eV.

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Section: Global Particle Momentum and Power Balancesupporting

confidence: 60%

Section: Global Particle Momentum and Power Balancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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B2.5-Eunomia simulations of Magnum-PSI detachment experiments: II. Collisional processes and their relevance

Chandra

Blank

Diomede

et al. 2021

Plasma Phys. Control. Fusion

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“…For Eunomia, these collisions are the ones used in Ref. [7]. For Eirene, the reactions obtained while generating a generic case for a tokamak in SOLPS-ITER for H and H 2 are employed.…”

Section: Introductionmentioning

confidence: 99%

“…4 using a frozen plasma background extracted from the High Density scenario from Ref. [7]. Differences in elastic proton-atom and proton-molecule collisions, as well as electron impact ionization and molecular assisted recombination, are studied in detail.…”

Section: Introductionmentioning

confidence: 99%

Comparison between SOLPS-ITER and B2.5-Eunomia for simulating Magnum-PSI

González¹,

Chandra²,

Blank³

et al. 2022

Plasma Phys. Control. Fusion

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The interaction among plasma, neutrals and surfaces in fusion reactors is of immense importance for heat and particle control, specially for the next generation of devices. Heat loads of 10 MW m-2 are expected for steady state operation at ITER and up to 20 MW m-2 in slow transient situations. To study the complex physics appearing between the plasma and the divertor material, as well as techniques for heat flux mitigation, plasma linear devices are employed. Magnum-PSI, located at DIFFER, can reproduce heat and particle loads expected at ITER. However, due to the complexity of the plasma-wall interaction, numerical models are required to better understand the experiments and to extrapolate the results to a tokamak divertor configuration. For tokamak geometries, SOLPS-ITER (formerly known as B2.5-Eirene) is employed to solve the plasma and neutral distribution in a coupled way. However, the utilization of this code for linear devices is not straight forward. Thus, a neutral module was developed with linear devices in mind, named Eunomia. Nevertheless, there is still a relevant interest in using SOLPS-ITER with linear devices, as it allows to easily transfer knowledge about relevant atomic and molecular processes close to the surface and the effect of different mitigation techniques. This work presents a systematic comparison between the two neutral modules, Eirene and Eunomia, in stand-alone and coupled runs. Special attention is paid to the implementation of plasma-neutral interactions, in which both codes diverge significantly. The sources of particles and energy that are used by B2.5 in a coupled run are analysed. Significant differences in the implementation of electron impact ionization, molecular assisted recombination and proton-molecule elastic collisions lead to disparate sources of particles and energy and, in some cases, differences in the distribution of neutrals achieved by each code. Moreover, a double counting in proton-atom collisions was identified in Eunomia as a result of this analysis, artificially increasing the plasma-neutral sink of energy. These would lead to different plasma evolutions in coupled runs. Nevertheless, additional free parameters in both coupled code suites leave sufficient freedom to match experimental data. Additional data would be required to further constrain these parameters and the coupled solution.

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