Investigating the effect of different impurities on plasma detachment in linear plasma machine Magnum-PSI

Perillo, R.; Chandra, R.; Akkermans, Gijs; Classen, I. G. J.; Korving, S. Q.; team, Magnum Psi

doi:10.1063/1.5120180

Cited by 22 publications

(15 citation statements)

References 58 publications

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“…Note that only one-dimensional models were used to analyze the plasma transport behavior in the innermost flux tube of the plasma beam. For a more thorough interpretation of the results, advanced numerical tools such as B2.5-Eunomia [40,41], particle-in-cell [7,42] and Vlasov [43,44] are recommended for future work.…”

Section: Discussionmentioning

confidence: 99%

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Li¹,

Morgan²,

Berg-Stolp³

et al. 2021

Plasma Phys. Control. Fusion

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The lifetime of plasma-facing components (PFCs) will have a strong influence on the efficiency and viability of future fusion power plants. However, the PFCs suffer from thermal stresses and physical sputtering induced by edge-localized modes (ELMs). ELMs in future fusion devices are expected to occur with a high plasma density compared to current day devices such that coupling of recycling neutrals and plasma ions will be strong. Because of the scale hierarchy of future fusion devices compared to the present ones, the influence of this coupling is difficult to predict. Here, we investigate the ELM-like hydrogen plasma induced heat loads on tungsten in the linear device Magnum-PSI, producing ∼1 ms plasma pulses with electron densities up to 3.5 × 10 21 m −3 . A combination of time-resolved Thomson scattering and coherent Thomson scattering was used to acquire plasma parameters in front of the target. Moreover, a fast infrared camera coupled to finite element thermal analyses allowed to determine the deposited heat loads on the target. We found a significant inconsistency between the plasma power calculated with a conventional collisionless sheath model and the absorbed power by the target. Moreover, plasma stagnation upstream and plasma cooling downstream were observed during the pulses. The observations are explained based on ionization and elastic collisions between the recycling neutrals and plasma ions. The results highlight the impact of plasma-neutral interaction on the power deposition behavior of ELM-like hydrogen plasma on tungsten.

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Section: Discussionmentioning

confidence: 99%

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Li¹,

Morgan²,

Berg-Stolp³

et al. 2021

Plasma Phys. Control. Fusion

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“…Such an approach is able to predict spatially averaged (global) plasma parameters such as densities or temperatures, by solving ordinary differential equations (ODEs) and without knowing a priori upstream quantities. Although widely used in the investigation of low temperature plasmas with a complex chemical kinetics [22], global models are only scarcely used in the context of fusion research [23][24][25]. However, the development of a model based on the volume average of multi-dimensional fluid equations could give a direct connection with the results of codes like SOLPS.…”

Section: Introductionmentioning

confidence: 99%

A point plasma model for linear plasma devices based on SOLPS-ITER equations: application to helium plasma

et al. 2021

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Linear plasma devices represent an essential tool for nuclear fusion research, whereby understanding crucial aspects related to plasma-wall interactions or edge plasma behaviour. Simplified models are of great importance to complement and integrate experimental and simulation results of complex systems such as plasmas in linear machines, because they are fast and simple to employ. In this work, we present a global volume-averaged (0D) model for plasma investigation in linear machines. The 0D model equations are based on the space integration of the state of the art edge plasma model implemented in the SOLPS-ITER code. Comparisons between helium plasmas described with 2D simulations performed with SOLPS-ITER and with the 0D model highlight that contributions often neglected in tokamak edge models, e.g. electron-neutral excitation, may be relevant when describing weakly ionized plasmas in linear devices. The model is used to perform sensitivity studies with respect to several parameters and to analyse the time evolution of the system, leading to the identification of two relevant time scales governing the system. Lastly, a comparison of 0D results with experimental data from the linear device GyM is performed, showing satisfactory agreement. Our methods and results provide crucial interpretative keys in the investigation of the physics of edge plasmas.

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“…This coupling process is repeated until equilibrium is reached. For the modeling of Magnum-PSI detachment experiments [20,21], the list of collisions that are implemented for the results of this paper is presented in table 1.…”

Section: Nr Collision Formulamentioning

confidence: 99%

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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Investigating the effect of different impurities on plasma detachment in linear plasma machine Magnum-PSI

Cited by 22 publications

References 58 publications

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

A point plasma model for linear plasma devices based on SOLPS-ITER equations: application to helium plasma

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

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