Transport of neutral particles in turbulent scrape-off layer plasmas

Marandet, Y.; Mekkaoui, A.; Reiter, D.; Börner, P.; Génésio, P.; Catoire, F.; Rosato, J.; Capes, H.; Godbert‐Mouret, L.; Koubiti, M.; Stamm, R.

doi:10.1088/0029-5515/51/8/083035

Cited by 36 publications

(42 citation statements)

References 24 publications

(40 reference statements)

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“…A more detailed discussion of this topic based on statistical methods can be found in Ref. 19. The process discussed here corresponds to the fast recycling case of Ref.…”

Section: -6mentioning

confidence: 99%

“…The process discussed here corresponds to the fast recycling case of Ref. 19 with relatively small changes in the neutral distribution in the region of a few mean free path lengths away from the target.…”

Section: -6mentioning

confidence: 99%

“…(19), this vorticity equation-or similar versions-has been used in previous models. In the following, it is shown that this approximation results in an inconsistency with respect to energy conservation.…”

Section: Appendix C: Traditional Approximations Of the Vorticity Equamentioning

confidence: 99%

“…(C2) instead of Eq. (19) and/or simplified advection terms instead of the full parallel and perpendicular pieces as in Eqs. (11)- (14) fail to conserve energy properly.…”

Section: Appendix C: Traditional Approximations Of the Vorticity Equamentioning

confidence: 99%

“…(21) are obtained by evaluating the extended vorticity Eq. (19) for the case of cylindrical geometry considered here. For the sake of completeness, the detailed expressions are listed in the following:…”

Section: Appendix D: Coefficients Of Eq (21)mentioning

confidence: 99%

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Revisited global drift fluid model for linear devices

Reiser

2012

Physics of Plasmas

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The problem of energy conserving global drift fluid simulations is revisited. It is found that for the case of cylindrical plasmas in a homogenous magnetic field, a straightforward reformulation is possible avoiding simplifications leading to energetic inconsistencies. The particular new feature is the rigorous treatment of the polarisation drift by a generalization of the vorticity equation. The resulting set of model equations contains previous formulations as limiting cases and is suitable for efficient numerical techniques. Examples of applications on studies of plasma blobs and its impact on plasma target interaction are presented. The numerical studies focus on the appearance of plasma blobs and intermittent transport and its consequences on the release of sputtered target materials in the plasma. Intermittent expulsion of particles in radial direction can be observed and it is found that although the neutrals released from the target show strong fluctuations in their propagation into the plasma column, the overall effect on time averaged profiles is negligible for the conditions considered. In addition, the numerical simulations are utilised to perform an a-posteriori assessment of the magnitude of energetic inconsistencies in previously used simplified models. It is found that certain popular approximations, in particular by the use of simplified vorticity equations, do not significantly affect energetics. However, popular model simplifications with respect to parallel advection are found to provide significant deterioration of the model consistency. [http://dx

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“…A more detailed discussion of this topic based on statistical methods can be found in Ref. 19. The process discussed here corresponds to the fast recycling case of Ref.…”

Section: -6mentioning

confidence: 99%

Section: -6mentioning

confidence: 99%

Section: Appendix C: Traditional Approximations Of the Vorticity Equamentioning

confidence: 99%

“…(C2) instead of Eq. (19) and/or simplified advection terms instead of the full parallel and perpendicular pieces as in Eqs. (11)- (14) fail to conserve energy properly.…”

Section: Appendix C: Traditional Approximations Of the Vorticity Equamentioning

confidence: 99%

Section: Appendix D: Coefficients Of Eq (21)mentioning

confidence: 99%

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Revisited global drift fluid model for linear devices

Reiser

2012

Physics of Plasmas

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Transport of Neutrals in Scrape‐Off Layer Plasmas: Autoregressive Beta Process to Describe Plasma Density and Temperature Fluctuations

Mekkaoui¹,

Marandet²,

Rosato³

et al. 2012

Contrib. Plasma Phys.

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Improving the description of the far scrape-off layer (SOL) in current edge code suites such as SOLPS is the subject of current efforts, given the importance of main chamber plasma wall interactions (first wall recycling and sputtering) in the design and operation of tokamaks. One of the specific features of the far SOL is the large amplitude of turbulent fluctuations. Neutral particles (atom and molecules) are affected by these fluctuations through the rates of atomic physics processes. In accordance with experimentally measured PDF (probability density function) for both the plasma density and temperature fluctuations, ne and Te are modeled using a Beta PDF. Space and time correlations are accounted for by using an autogressive process. The effects of fluctuations on the neutral atoms penetration depth, as well as on the beryllium sputtering yield are discussed.

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Effect of Statistical Noise on Simulation Results with a Plasma Fluid Code Coupled to a Monte Carlo Kinetic Neutral Code

Marandet

Bufferand

Ciraolo

et al. 2016

Contrib. Plasma Phys.

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Power exhaust is one of the major challenges that future devices such as ITER and DEMO will face. Because of the lack of identified scaling parameters, predictions for divertor plasma conditions in these devices have to rely on detailed modelling. Most plasma edge simulations carried out so far rely on transport codes, which most of the times consist of a fluid code for the plasma coupled to a kinetic Monte Carlo (MC) code for neutral particles. One of the main difficulties in interpreting code results is the statistical noise from the MC procedure, which makes it difficult to define a convergence criterion for the simulations. In this work, we elaborate on similarities between noisy transport code simulations and turbulence simulations, and argue that the time averaged solution is a well defined stationary solution for the system. We illustrate these ideas with a simple slab test case with fluid neutrals, to which we add synthetic noise. In this case, the effects of noise are found to be significant only at high noise levels and for large enough correlations times.

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Transport of neutral particles in turbulent scrape-off layer plasmas

Cited by 36 publications

References 24 publications

Revisited global drift fluid model for linear devices

Revisited global drift fluid model for linear devices

Transport of Neutrals in Scrape‐Off Layer Plasmas: Autoregressive Beta Process to Describe Plasma Density and Temperature Fluctuations

Effect of Statistical Noise on Simulation Results with a Plasma Fluid Code Coupled to a Monte Carlo Kinetic Neutral Code

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