A comparison between a refined two-point model for the limited tokamak SOL and self-consistent plasma turbulence simulations

Wersal, Christoph; Ricci, Paolo; Loizu, Joaquim

doi:10.1088/1361-6587/aa5cf9

Cited by 9 publications

(9 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the SOL, the electron temperature drop towards the limiter is due to the balance between radial turbulent transport, parallel heat conduction and convection, the ionization energy loss close to the limiter, and the parallel outflow of plasma to the limiter (see, e.g. our recent work on a refined two-point model [24]). …”

Section: Self-consistent Turbulence Simulationmentioning

confidence: 99%

Impact of neutral density fluctuations on gas puff imaging diagnostics

Wersal

Ricci

2017

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

A three-dimensional turbulence simulation of the SOL and edge regions of a toroidally limited tokamak is carried out. The simulation couples self-consistently the drift-reduced two-fluid Braginskii equations to a kinetic equation for neutral atoms. A diagnostic neutral gas puff on the low-field side midplane is included and the impact of neutral density fluctuations on light emission investigated. We find that neutral density fluctuations affect the emission. In particular, at a radial distance from the gas puff smaller than the neutral mean free path, neutral density fluctuations are anti-correlated with plasma density, electron temperature, and fluctuations. It follows that the neutral fluctuations reduce the emission in most of the observed region and, therefore, have to be taken into account when interpreting the amplitude of the emission. On the other hand, higher order statistical moments (skewness, kurtosis) and turbulence characteristics (such as correlation length, or the autocorrelation time) are not significantly affected by the neutral fluctuations. At distances from the gas puff larger than the neutral mean free path, a non-local shadowing effect influences the neutral density fluctuations. There, the fluctuations are correlated with the neutral density fluctuations, and the high-order statistical moments and measurements of other turbulence properties are strongly affected by the neutral density fluctuations.

show abstract

Section: Self-consistent Turbulence Simulationmentioning

confidence: 99%

Impact of neutral density fluctuations on gas puff imaging diagnostics

Wersal

Ricci

2017

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…Increased resistivity can directly affect the plasma potential (affecting the scale of potential fluctuations and the magnitude of the E × B transport) [13], extend the inertial regime of SOL blobs [69] and change the position where blobs are generated [70]. Reduced heat conductivity leads to a higher fraction of the heat flux being convected by parallel flows [71], broader profiles [72] and allows larger parallel temperature gradients to develop.…”

Section: Impact Of Relaxed Parametersmentioning

confidence: 99%

Validation of edge turbulence codes against the TCV-X21 diverted L-mode reference case

Oliveira,

Body,

Galassi

et al. 2021

Preprint

View full text Add to dashboard Cite

Full-size turbulence simulations of the divertor and scrape-off-layer of existing tokamaks have recently become feasible, allowing direct comparisons of turbulence simulations to experimental measurements. We present a validation of three flux-driven turbulence codes -GBS, GRILLIX and TOKAM3X -against an experimental dataset from diverted Ohmic L-mode discharges on the TCV tokamak. This "TCV-X21" dataset covers the divertor targets, volume, entrance and the outboard midplane via 5 diagnostic systems, giving a total of 45 comparison observables over two toroidal field directions. The simulations show good agreement at the outboard midplane for most observables. At the divertor targets and in the divertor volume, several individual observables show good agreement, but the overall match is lower than at the outboard midplane. The simulations typically find the correct order-of-magnitude and the approximate shape for the divertor mean profiles, with the match varying for different observables and codes. The experimental profiles of the divertor density, potential, current and velocity vary strongly with field direction, while a weaker effect is found in the simulations. The simulated divertor profiles are found to be sensitive to the choice of sheath boundary conditions and the use of artificially increased collisionality. Additionally, the observed divertor flows suggest that divertor neutral ionisation is nonnegligible. This indicates that the match could be improved by using improved boundary conditions, more realistic parameters and including self-consistent neutral physics. Future validation and benchmarking against the TCV-X21 reference dataset will assess the impact of improvements to the codes and will guide their targeted development -a process which can be extended to other turbulence codes via the freely available TCV-X21 reference dataset. As such, this work assesses the current capabilities of edge/divertor turbulence simulations and provides a systematic path towards their improved interpretive and predictive capability.

show abstract

“…This work generalizes the implementation of the neutral-plasma interaction in GBS described in reference [37] for single-component plasmas. Single-component GBS simulations were used to study the electron temperature drop along the magnetic field [38] and to determine the influence of neutrals on gas puff imaging (GPI) diagnostics [39]. The model has been improved recently through the implementation of mass-conservation by taking toroidal geometry consistently into account and by making use of particle-conserving boundary conditions to properly describe the recycling processes [40].…”

Section: Introductionmentioning

confidence: 99%

A self-consistent multi-component model of plasma turbulence and kinetic neutral dynamics for the simulation of the tokamak boundary

Coroado

Ricci

2022

Nucl. Fusion

View full text Add to dashboard Cite

A self-consistent model is presented for the simulation of a multi-component plasma in the tokamak boundary. A deuterium plasma is considered, with the plasma species that include electrons, deuterium atomic ions and deuterium molecular ions, while the deuterium atoms and molecules constitute the neutral species. The plasma and neutral models are coupled via a number of collisional interactions, which include dissociation, ionization, charge-exchange and recombination processes. The derivation of the three-fluid drift-reduced Braginskii equations used to describe the turbulent plasma dynamics is presented, including its boundary conditions. The kinetic advection equations for the neutral species are also derived, and their numerical implementation discussed. The first results of multi-component plasma simulations carried out by using the GBS code are then presented and analyzed, being compared with results obtained with the single-component plasma model.

show abstract

A comparison between a refined two-point model for the limited tokamak SOL and self-consistent plasma turbulence simulations

Cited by 9 publications

References 24 publications

Impact of neutral density fluctuations on gas puff imaging diagnostics

Impact of neutral density fluctuations on gas puff imaging diagnostics

Validation of edge turbulence codes against the TCV-X21 diverted L-mode reference case

A self-consistent multi-component model of plasma turbulence and kinetic neutral dynamics for the simulation of the tokamak boundary

Contact Info

Product

Resources

About