Turbulent transport and the plasma edge

Naulin, V.

doi:10.1016/j.jnucmat.2006.12.058

Cited by 89 publications

(91 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent advances in theory, numerical simulations and experimental measurements have identified radial propagation of filamentary structures as the dominant contribution to the cross-field transport [5][6][7][8][9][10]. The turbulence-driven particle and heat fluxes result in broad SOL plasma profiles and enhanced levels of plasma-wall interactions that may be an issue for the next generation plasma confinement experiments and future fusion power reactors [11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Scrape-off layer turbulence in TCV: evidence in support of stochastic modelling

Theodorsen

Garcia

Horáček

et al. 2016

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

Abstract. Intermittent fluctuations in the TCV scrape-off layer have been investigated by analysing long Langmuir probe data time series under stationary conditions, allowing calculation of fluctuation statistics with high accuracy. The ion saturation current signal is dominated by the frequent occurrence of large-amplitude bursts attributed to filament structures moving through the scrape-off layer. The average burst shape is well described by a double-exponential wave-form with constant duration, while the waiting times and peak amplitudes of the bursts both have an exponential distribution. Associated with bursts in the ion saturation current is a dipole shaped floating potential structure and radially outwards directed electric drift velocity and particle flux, with average peak values increasing with the saturation current burst amplitude. The floating potential fluctuations have a normal probability density function while the distributions for the ion saturation current and estimated radial velocity have exponential tails for large fluctuations. These findings are discussed in the light of prevailing theories for filament motion and a stochastic model for intermittent scrape-off layer plasma fluctuations.

show abstract

Section: Introductionmentioning

confidence: 99%

Scrape-off layer turbulence in TCV: evidence in support of stochastic modelling

Theodorsen

Garcia

Horáček

et al. 2016

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

show abstract

“…In tokamaks, the intermittent expulsion of magnetic-field-aligned plasma filaments from the last closed flux surface (LCFS) is responsible for a large fraction of the effective radial transport to the wall [1][2][3][4][5][6]. Filament propagation appears to be governed by a ballooning-type instability in the unfavourable magnetic curvature region on the low field side.…”

Section: Introductionmentioning

confidence: 99%

Comparison of scrape-off layer profiles in outboard-versus inboard-limited plasmas in Tore Supra

Kočan¹,

Gunn

2010

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

In the Tore Supra tokamak, the scrape-off layer profiles of discharges limited either on the inboard or on the outboard side are compared. Inboard-limited discharges are characterized by substantially longer SOL e-folding lengths of ion and electron temperatures and electron density measured near the top of the plasma, providing strong evidence that the ion and electron energy transport across the SOL is enhanced on the outboard side, similar to the particle transport. The parallel heat flux density extrapolated to the last closed flux surface is found to be inversely proportional to its e-folding length in the SOL. The outboard limiters thus receive higher and more peaked heat loads than the inboard limiters. These results are important for the optimization of the plasma start-up scenario and design of the first wall in ITER.PACS 52.25.Fi, 52.25.Xz, 52.35.Ra, 52.55.Fa, 52.70.Ds IntroductionIn tokamaks, the intermittent expulsion of magnetic-field-aligned plasma filaments from the last closed flux surface (LCFS) is responsible for a large fraction of the effective radial transport to the wall [1][2][3][4][5][6]. Filament propagation appears to be governed by a ballooning-type instability in the unfavourable magnetic curvature region on the low field side. As the filaments propagate outward, they also expand freely along the magnetic field lines, driving pressure-driven field-direction-independent parallel flows. Mach probe measurements in many divertor tokamaks (e.g. [7] and references therein) show flow patterns consistent with this model (i.e. stagnant flow poloidally approximately halfway between the outer midplane and the X-point), in which the filaments can be seen as an important particle source in the scrape-off layer (SOL). Similar observations in limiter tokamaks [8][9][10][11][12] prove that enhanced radial particle transport on the outboard side of the plasma is a universal phenomenon, independent of the presence of an X-point divertor. The enhancement of the radial particle transport on the outboard side of the limiter plasmas was confirmed by the 3D fluid turbulence code TOKAM-3D [13]. When the plasma contact point is on the inboard limiters, the filaments propagate freely out to the wall, filling all the available volume outside the LCFS and leading to a broad SOL with nearly flat density profiles. On the other hand, it was demonstrated [12] that outboard modular limiters suppress the radial particle transport when they are near the LCFS, leading to a very thin SOL. It is probable [8] that the limiters act as simple mechanical barriers that intercept the parallel particle flux in the region in which the enhanced radial convection.

show abstract

“…8 In general, there is still no clear quantitative understanding of the SOL turbulence or turbulence-induced transport, so relevant theory is still in the process of development. [9][10][11][12] The GEMR code used for this paper is described in Ref. 2.…”

Section: Introductionmentioning

confidence: 99%

Comparison of scrape-off layer turbulence in Alcator C-Mod with three dimensional gyrofluid computations

et al. 2009

View full text Add to dashboard Cite

This paper describes quantitative comparisons between turbulence measured in the scrape-off layer ͑SOL͒ of Alcator C-Mod ͓S. Scott, A. Bader, M. Bakhtiari et al., Nucl. Fusion 47, S598 ͑2007͔͒ and three dimensional computations using electromagnetic gyrofluid equations in a two-dimensional tokamak geometry. These comparisons were made for the outer midplane SOL for a set of inner-wall limited, near-circular Ohmic plasmas. The B field and plasma density were varied to assess gyroradius and collisionality scaling. The poloidal and radial correlation lengths in the experiment and computation agreed to within a factor of 2 and did not vary significantly with either B or density. The radial and poloidal propagation speeds and the frequency spectra and poloidal k-spectra also agreed fairly well. However, the autocorrelation times and relative D a fluctuation levels were higher in the experiment by more than a factor of 2. Possible causes for these disagreements are discussed.

show abstract

Turbulent transport and the plasma edge

Cited by 89 publications

References 56 publications

Scrape-off layer turbulence in TCV: evidence in support of stochastic modelling

Scrape-off layer turbulence in TCV: evidence in support of stochastic modelling

Comparison of scrape-off layer profiles in outboard-versus inboard-limited plasmas in Tore Supra

Comparison of scrape-off layer turbulence in Alcator C-Mod with three dimensional gyrofluid computations

Contact Info

Product

Resources

About