A5079448549- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Fluid Dynamics and Turbulent Flows
- Particle accelerators and beam dynamics
- Meteorological Phenomena and Simulations
- Underwater Acoustics Research
- Plasma Diagnostics and Applications
- Geomagnetism and Paleomagnetism Studies
- Nuclear reactor physics and engineering
- Electromagnetic Launch and Propulsion Technology
- Laser-induced spectroscopy and plasma
- Inertial Sensor and Navigation
- Ocean Waves and Remote Sensing
- GNSS positioning and interference
- Remote Sensing and Land Use
- Seismic Waves and Analysis
- Dust and Plasma Wave Phenomena
- Gas Dynamics and Kinetic Theory
- Atomic and Subatomic Physics Research
- Tropical and Extratropical Cyclones Research
- earthquake and tectonic studies
Laboratoire de Physique des Plasmas
2015-2025
École Polytechnique
2012-2024
Max Planck Institute for Plasma Physics
2006-2023
Centre National de la Recherche Scientifique
2011-2022
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2004-2021
Sorbonne Université
2018-2021
Université Paris-Saclay
2018-2021
Université Paris-Sud
2018-2021
Japan External Trade Organization
2015
CEA Cadarache
2004-2013
Turbulence in hot magnetized plasmas is shown to generate permeable localized transport barriers that globally organize into the so-called "ExB staircase" [G. Dif-Pradalier et al., Phys. Rev. E, 82, 025401(R) (2010)]. Its domain of existence and dependence with key plasma parameters discussed theoretically. Based on these predictions, staircases are observed experimentally Tore Supra tokamak by means high-resolution fast-sweeping X-mode reflectometry. This observation strongly emphasizes...
With WEST (Tungsten Environment in Steady State Tokamak) (Bucalossi et al 2014 Fusion Eng. Des. 89 907–12), the Tore Supra facility and team expertise (Dumont Plasma Phys. Control. 56 075020) is used to pave way towards ITER divertor procurement operation. It consists implementing a configuration installing ITER-like actively cooled tungsten monoblocks tokamak, taking full benefit of its unique long-pulse capability. user platform, open all partners. This paper describes physics basis WEST:...
In order to gain reliable predictions on turbulent fluxes in tokamak plasmas, physics based transport models are required. Nonlinear gyrokinetic electromagnetic simulations for all species still too costly terms of computing time. On the other hand, interestingly, quasi-linear approximation seems retain relevant fairly reproducing both experimental results and nonlinear simulations. Quasi-linear made two parts: (1) response transported quantities (2) saturated fluctuating electrostatic...
Turbulence measurements in TORE SUPRA tokamak plasmas have been quantitatively compared to predictions by nonlinear gyrokinetic simulations. For the first time, numerical results simultaneously match within experimental uncertainty (a) magnitude of effective heat diffusivity, (b) rms values density fluctuations, and (c) wave-number spectra both directions perpendicular magnetic field. Moreover, simulations help revise as an instrumental effect apparent evidence strong turbulence anisotropy...
The geodesic acoustic mode (GAM) is a coherently oscillating zonal flow that may regulate turbulence in toroidal plasmas. Uniquely, the complete poloidal and structure of magnetic component turbulence-driven GAM has been mapped TCV tokamak. Radially localized measurements fluctuating density, ECE radiative temperature show fully coherent, radially propagating wave. These observations are consistent with electrostatic, gyrokinetic simulations.
Abstract Using a recently installed impurity powder dropper (IPD), boron (<150 μ m) was injected into lower single null (LSN) L-mode discharges in WEST. IPDs possibly enable real-time wall conditioning of the plasma-facing components and may help to facilitate H-mode access full-tungsten environment The this experiment featured I p = 0.5 MA, B T 3.7 T, q 95 4.3, t pulse 12–30 s, n e,0 ∼ 4 × 10 19 m −2 , P LHCD 4.5 MW. Estimates deuterium particle fluxes, derived from combination visible...
Abstract Magnetic confinement fusion offers the promise of sustainable and safe energy production on Earth. Advanced experimental scenarios exploit fascinating yet uncommon ability confined plasmas to bifurcate into states enhanced performance upon application additional free sources. Self-regulation small-scale turbulent eddies is essential accessing these improved regimes. However, after several decades, basic principles for bifurcations are still largely debated clarifications from first...
Turbulence self-organization is studied in the flux-driven regime by means of reduced model Tokam1D. Derived electrostatic and isothermal limit but keeping finite electron ion temperatures, it features two instabilities that are suspected to dominate turbulent transport at edge L-mode tokamak plasmas: interchange (a version resistive ballooning modes) collisional drift waves, governed respectively an effective gravity parameter $g$ adiabaticity $C$ . The usual properties these recovered...
The influence of changing collisionality on density fluctuation characteristics is studied during dedicated ν∗ scaling experiments, using Doppler backscattering system. First, the repartition energy over different spatial scales, as represented by wavenumber spectrum, investigated and a modification shape perpendicular spectrum in low part observed when collisionality. In addition, new procedure to evaluate dispersion relation micro-turbulence presented. From behavior mean velocity...
Over the last years, owing to hardware progress and development of new methods, reflectometry has become a common diagnostic on plasma fusion devices. This paper presents some results obtained with transport, turbulence magnetohydrodynamic (MHD). The emphasis is put from Tore-Supra. Combining density profile fluctuation measurement, it was shown Tore-Supra that particle pinch inside q = 1 surface close neoclassical value in ohmic plasma, while observed small diffusion agreement very low...
This paper presents the first observation of geodesic acoustic modes (GAMs) on Tore Supra plasmas. Using Doppler backscattering system, oscillations plasma flow velocity, localized between r/a = 0.85 and 0.95, with a frequency, typically around 10 kHz, have been observed at edge in numerous discharges. When additional heating power is varied, frequency found to scale Cs/R. The MUltiple SIgnal Classification (MUSIC) algorithm employed access temporal evolution perpendicular velocity density...
A model of E × B staircases is proposed based on a wave kinetic equation coupled to poloidal momentum equation. staircase pattern idealized as periodic radial structure zonal shear layers that bound regions propagating packets, viewed avalanches. Wave packets are trapped in flow due refraction. In this model, an motif emerges the interaction between (avalanches) and waves presence instability drive. Amplitude, shape, spatial period predicted functions background fluctuation spectrum growth...
Abstract Sheared flows are known to reduce turbulent transport by decreasing the correlation length and/or intensity of structures. The barrier that takes place at edge during improved regimes such as H mode, corresponds establishment a large shear radial electric field. In this context, shape field or more exactly perpendicular E × B velocity appears key element in accessing confinement regimes. paper, we present profile measured using Doppler back-scattering system plasma, dominated...
Steady state full noninductive current tore supra plasmas offer a unique opportunity to study the local parametric dependence of particle pinch velocity, in order discriminate among different theories. Magnetic field shear is found generate an inward which dominant gradient region (normalized radius 0.3</=r/a</=0.6). In contrast, direction plasma core (r/a</=0.3) correlated with electron temperature length. The results are agreement both turbulent theoretical and computational predictions.
In a dedicated collisionality scan in Tore Supra, the geodesic acoustic mode (GAM) is detected and identified with Doppler backscattering technique. Observations are compared to results of simulation gyrokinetic code GYSELA. We found that GAM frequency experiments lower than predicted by theory. Moreover, disagreement higher low scenario. Bursts non harmonic oscillations have been characterized filtering techniques, such as Hilbert-Huang transform. When comparing this dynamical behaviour...
Abstract WEST L-mode plasmas with dominant electron heating and no core torque source have observed improvements in confinement during boron (B) powder injection. These results are reminiscent of previous injection experiments on other devices gaseous impurity seeding WEST. During injection, the stored energy increased up to 25% due enhanced ion heat particle confinement. The were not indicative an L-H transition. To identify mechanisms causality chain behind these confinement, we employ...
Abstract For a comprehensive comparison with theoretical models and advanced numerical turbulence simulations, large spectrum of fluctuation parameters was measured on the devices ASDEX Upgrade, TCV, Tore-Supra. Radial profiles scale-resolved levels in H-mode discharges are compared GENE simulations transition range from ion-temperature-gradient to trapped-electron-mode turbulence. Correlation reflectometry is used study microscopic structure GAMs where poloidal flow damping varied by means...
The L to H mode transition occurs at a critical power which depends on various parameters, such as the magnetic field, density, etc. Experimental evidence tokamaks (JET, ASDEX-Upgrade, DIII-D, Alcator C-Mod) points towards existence of temperature characterizing transition. This criterion for L-H is local and therefore easier be compared theoretical approaches. In order shed light mechanisms transition, simple ideas are used derive threshold (Tth). They based stabilization underlying...
The knowledge of the turbulence characteristics is a key point to build models able predict confinement time in fusion reactor. A method extract radial profile density fluctuations from fast swept reflectometry phase signal proposed and tested on Tore Supra (TS). relationship between wavenumber spectrum set perturbations obtained during frequency sweep itself aim method. This can be derived analytically for O-mode. For X-mode it established by full wave simulations. As result, mere...
First β scan experiments have been made in ASDEX Upgrade H-mode plasmas with type-I ELMs. Two sets of discharges, performed different density ranges, between βN = (1.4–2.2) and (1.4–2). Global analysis these dedicated exhibits a strong unfavourable scaling as Bτth ∝ β−0.9. This tendency is confirmed by local which shows an increase the thermal heat diffusivity increasing χeff/B β0.65. These results are discussed compared studies DIII-D, JET JT-60U.
Abstract Reynolds stress is a key facet of turbulence self-organization. In the magnetized plasmas controlled fusion devices, zonal flows that are driven by averaged modify confinement performance. We address this problem with full- f gyrokinetic simulations ion temperature gradient-driven turbulence. From detailed analysis three-dimensional electric potential and transverse pressure fields, we show diamagnetic contribution to stress—stemming from finite Larmor radius effects—exceeds...
Abstract High power experiments, up to 9.2 MW with LHCD and ICRH, have been carried out in the full tungsten tokamak WEST. Quasi non inductive discharges achieved allowing extend plasma duration 53 s stationary conditions particular respect contamination. Transitions H mode are observed, H-modes lasting 4 obtained. The increase stored energy is weak since crossing separatrix close L–H threshold. Hot L plasmas (central temperature exceeding 3 keV) a confinement time following ITER L96 scaling...
Investigations on magnetohydrodynamics (MHD) modes using X-mode frequency modulated continuous wave reflectometry have been realized Tore Supra. Two heterodyne reflectometers operating between 50?75?GHz and 75?110?GHz probe the low field side of plasma, detection magnetic islands is performed through perturbations recorded onto phase amplitude reflected signal. Fast sweep technique associated with a high repetition rate provides radial resolution temporal (up to 20?kHz). The localization...