Statistical analysis of turbulent front propagation in the scrape-off-layer

Ghendrih, Ph.; Sarazin, Y.; Attuel, Guillaume; Benkadda, S.; Beyer, Peter; Darmet, G.; Falchetto, G.; Figarella, C.; Garbet, X.; Grandgirard, V.; Ottaviani, M.

doi:10.1016/j.jnucmat.2004.10.068

Cited by 22 publications

(8 citation statements)

References 11 publications

(21 reference statements)

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“…The model of blob dynamics has been constructed on the assumption that density blobs are isolated events with an ideal shape transverse to B, parameterized by a single wave number. This has to be contrasted by the complex shape of blobs reported in simulations, [4] also shown in Figure 2. It could arise from auto-organization within an isolated blob [5] or from the mutual interaction between separate structures.…”

Section: Model a Blob Dynamicsmentioning

confidence: 86%

“…In diverted configurations, blobs are considered to play an important role in the first wall fluxes, and their importance in setting the divertor SOL width is still subject to debate. In general, an important aspect of a tokamak operation depends on the properties of these transport events: the SOL width itself, the direct environment of radio‐frequency heating systems, particle and heat load to the first wall, and the opacity of the SOL to recycling neutrals. In this work, we propose discussing a theoretical methodology to characterize blobs from experimental data and compare them to theoretical models.…”

Section: Introductionmentioning

confidence: 99%

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On the dynamics of blobs in scrape‐off layer plasma: Model validation from two‐dimensional simulations and experiments in Tore Supra

Fedorczak

Gallo

Tamain

et al. 2018

Contributions to Plasma Physics

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An investigation is proposed on the dynamics of blobs in scrape‐off layer (SOL) plasmas. Starting from a common reduced model predicting the dynamics of isolated blobs, we emphasize the necessity of verifying the meaningfulness of the notion of generic or average blob. A definition and methodology is proposed and tested on turbulent data built from two‐dimensional (2D) flux‐driven simulations. Average blobs are shown to possess physical properties in relatively good agreement with predictions made using the isolated blob model. An application to experimental data from Tore Supra is then demonstrated. A striking agreement is found between average blob velocities measured in experiments and isolated blob model predictions. It suggests that the turbulent transport in the SOL of limited plasmas is correctly described by 2D interchange models. A discussion is finally proposed that blob models have to focus on intermittency in order to find a field of application.

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Section: Model a Blob Dynamicsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

On the dynamics of blobs in scrape‐off layer plasma: Model validation from two‐dimensional simulations and experiments in Tore Supra

Fedorczak

Gallo

Tamain

et al. 2018

Contributions to Plasma Physics

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“…This scaling is calculated analytically and one finds that the ballistic scaling (power 1), that actually governs density transport [603], is in fact partly cancelled by the reduced frequency of the intermittent events as the connection length increases so that the scaling is rather close to the diffusive scaling [602].…”

Section: Present Modelling Effort Of Cross-field Turbulencementioning

confidence: 99%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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“…One then finds that the events first experience an acceleration before propagating with a nearly constant velocity, hence behaving like fronts or avalanches. Since these large events dominate the average flux, it then appears that the microscopic transport is essentially ballistic [8]. A third approach proposed here is based on self similarity of transport such that the appropriate variable is x/t for ballistic transport and x 2 /t for diffusive transport.…”

Section: The Microscopic Turbulent Transportmentioning

confidence: 99%

Thermodynamical and microscopic properties of turbulent transport in the edge plasma

Ghendrih

Norscini

Hasenbeck

et al. 2012

J. Phys.: Conf. Ser.

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Edge plasma turbulence modelled with 2D interchange is shown to exhibit convective transport at the microscale level. This transport property is related to avalanche like transport in such a flux-driven system. Correlation functions and source modulation are used to analyse the transport properties but do not allow one to recover the Fick law that must characterise the system at large scales. Coarse graining is then introduced to average out the small scales in order to recover the Fick law. One finds that the required space averaging is comparable to the system size while the time averaging is comparable to the confinement time. The system is then reduced to a single reservoir such that transport is characterised by a single scalar, either the diffusion coefficient of the Fick law or a characteristic evolution time constant.

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Statistical analysis of turbulent front propagation in the scrape-off-layer

Cited by 22 publications

References 11 publications

On the dynamics of blobs in scrape‐off layer plasma: Model validation from two‐dimensional simulations and experiments in Tore Supra

On the dynamics of blobs in scrape‐off layer plasma: Model validation from two‐dimensional simulations and experiments in Tore Supra

Chapter 4: Power and particle control

Thermodynamical and microscopic properties of turbulent transport in the edge plasma

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