A5063462403- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Solar and Space Plasma Dynamics
- Soil Moisture and Remote Sensing
- Laser-induced spectroscopy and plasma
- Atomic and Subatomic Physics Research
- Advanced Fiber Optic Sensors
- Particle Accelerators and Free-Electron Lasers
- Meteorological Phenomena and Simulations
- Wind and Air Flow Studies
- Geophysical Methods and Applications
- Physics of Superconductivity and Magnetism
- Microwave and Dielectric Measurement Techniques
- Particle Detector Development and Performance
- Atmospheric and Environmental Gas Dynamics
- Laser-Matter Interactions and Applications
- Advanced Measurement and Metrology Techniques
- Dust and Plasma Wave Phenomena
- Advanced MEMS and NEMS Technologies
CEA Cadarache
2014-2025
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2014-2025
Culham Science Centre
2006-2024
Institut de Recherche sur la Fusion par Confinement Magnétique
2017-2024
Culham Centre for Fusion Energy
2024
Royal Military Academy
2020
Ghent University
2018-2019
Institute for Plasma Research
2017
Instituto de Engenharia de Sistemas e Computadores Investigação e Desenvolvimento
2004-2007
University of Lisbon
2004-2006
Abstract The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with ITER-like Be/W wall. development started pure Deuterium refinement of current, and toroidal magnetic field choices succeeded solving heat load challenges arising 37 MW injected power ITER like environment, keeping radiation edge core controlled, avoiding MHD instabilities reaching high neutron rates. have re-run Tritium...
Remarkable progress has been made in diagnosing energetic particle instabilities on presentday machines and establishing a theoretical framework for describing them.This overview describes the much improved diagnostics of Alfvén modelling tools developed world-wide, discusses interpreting observed phenomena.A multi-machine comparison is presented giving information performance both different plasma conditions outlining expectations ITER based our present knowledge.
Results from the first measurements of a core plasma poloidal rotation velocity (upsilontheta) across internal transport barriers (ITB) on JET are presented. The spatial and temporal evolution ITB can be followed along with upsilontheta radial profiles, providing very clear link between location steepest region ion temperature gradient localized spin-up upsilontheta. an order magnitude higher than neoclassical predictions for thermal particles in region, contrary to close agreement found...
The stationary edge localized mode (ELM)-free 'Quiescent H-mode' (QH-mode) regime, obtained with counter neutral beam injection, is studied in ASDEX Upgrade and Joint European Torus. QH-mode plasmas have high pedestal core ion temperatures together good High-confinement (H-mode). ELMs are replaced by continuous MHD oscillations, the 'edge harmonic oscillation' (EHO) 'high frequency oscillation'. Stationarity of particle impurity densities linked to occurrence these modes. EHO location...
In order to explain the results of non-inductive current produced in lower hybrid drive (LHCD) experiments, a broadening radiofrequency (RF) power spectrum coupled tokamak plasma needs occur. The presented modelling, supported by diagnostic measurements, shows that parametric instability (PI) driven ion sound quasimodes, which occur scrape-off layer located near antenna mouth, produces significant launched LH spectrum. Considering parameters LHCD experiments JET (Joint European Torus), and...
This letter reports on quasi-coherent (QC) modes observed in fluctuation spectra from Tore Supra and TEXTOR reflectometers. QC have characteristics between coherent broad-band fluctuations as they oscillate around a given frequency but wide spectrum. They are ballooned at the LFS midplane appear usually ranging 30 to 120 kHz. In ohmic plasmas both tokamaks, detected only linear confinement (LOC) regime disappear saturated (SOC) regime. Linear simulations predict that LOC SOC regimes...
Abstract Poloidal flows and avalanches play a key role in tokamak plasma selforganization by suppressing turbulence sheared flow regions, contributing to the formation of weak transport barriers. These structures, predicted GYSELA simulations indirectly observed Tore Supra tokamak, are challenging detect due their millimeter-scale size. This study uses Ultra-Fast-Swept Reflectometer (UFSR), capable high spatial resolution signal-to-noise ratio, analyze characteristics, including flow-induced...
A microwave interferometry technique is applied for the first time detecting a discrete spectrum of Alfvén cascade (AC) eigenmodes excited with fast ions in reversed magnetic shear plasmas Joint European Torus. The measurements plasma density perturbations associated ACs show an unprecedented frequency and resolution superior to that obtained external coils. are used monitoring evolution safety factor rational surfaces region maximum current.
Ion temperature gradient (ITG) and trapped electron modes (TEM) are two important micro-instabilities in the plasma core region of fusion devices (). They usually coexist same range spatial scale (around ), which makes their discrimination difficult. To investigate them, one can perform gyrokinetic simulations, transport analysis phase velocity estimations. In Tore Supra, identification is made possible due to measured frequency fluctuation spectra. Indeed, turbulent spectra generally...
Quasi-coherent (QC) modes have been reported for more than 10 years in reflectometry fluctuations spectra the core region of fusion plasmas. They characteristics in-between coherent and broadband as they oscillate at a marked frequency but wide spectrum. This work presents further evidences link recently established between QC trapped electron (TEM) instabilities (Arnichand et al 2014 Nucl. Fusion 54 123017). In cyclotron resonance heated discharges Tore Supra, an enhancement amplitude is...
JET’s frequency-modulated continuous wave (FMCW) reflectometers have been operating well with the current design since 2005, and density profiles automatically calculated intershot then. However, had long suffered from several shortcomings: poor agreement other diagnostics, sometimes inappropriately moving radially by centimeters, elevated levels of radial jitter, persistent wriggles (strong unphysical oscillations). In this research, techniques are applied to reflectometry data analysis,...
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...
The poloidal distribution of the halo current density on top dump plate in JET can now be measured thanks to a new set Rogowskii coils. These are first measurements able offer an insight width interaction with wall. Therefore they both validation assumption made for disruption design criteria and one additional point extrapolation expected width, hence (and related local electro-mechanical loads in-vessel components) ITER. During upward events, is consistent total current. footprint extends...
Abstract A sequence of fuel recovery methods was tested in JET, equipped with the ITER-like beryllium main chamber wall and tungsten divertor, to reduce plasma deuterium concentration less than 1% preparation for operation tritium. This also a key activity regard refining clean-up strategy be implemented at end 2nd DT campaign JET (DTE2) assess tools that are envisaged mitigate tritium inventory build-up ITER. The began 4 days baking 320 °C, followed by further which Ion Cyclotron Wall...
1 H-mode access studies under conditions of very low plasma density provide valuable information on the physics edge transport barrier formation and are an important part operational scenario development for next step fusion device, ITER. JET operation with a electron density, , MkII gas box septum divertor was found to have significant effect power threshold L–H transition, Pth. A sharp 'turning point' below which Pth increases decreasing is Ip/Bt values 2.5 MA/2.7 T, MA/2.6 MA/2.4 T 2.2 T....
Alfvén cascade (AC) eigenmodes excited by energetic ions accelerated with ion-cyclotron resonance heating in JET reversed-shear discharges are studied experimentally high-density plasmas fuelled neutral beam injection (NBI) and deuterium pellets. The recently developed O-mode interferometry technique Mirnov coils employed for detecting ACs. spontaneous improvements plasma confinement (internal transport barrier (ITB) triggering events) grand ACs found to correlate within 0.2 s densities up...
The main results of the Tore Supra experimental programme in years 2007–2008 are reported. They document significant progress achieved domain steady-state tokamak research, as well more general issues relevant for ITER and fusion physics research. Three areas covered: technology developments tests a real machine environment, operational high power long pulses, plasma physics. Results presented this paper include test validation new, load-resilient concept ion cycotron resonance heating...
A method to extract the radial wave-number spectrum of density fluctuations from reflectometry phase signal is proposed and main points interpret it are described. The buildup based on studies devoted or amplitude variations induced by coherent perturbations. These previous analyses show that all wave numbers up Bragg detection limit kf (fluctuation number) <2ko (incident number in vacuum) contribute fluctuations. Although part comes vicinity cutoff layer entire probing zone...
The paper reports on the first measurements of long-range correlations along field lines in center ohmic plasmas at TEXTOR. are performed with correlation reflectometry. For time poloidal, toroidal and radial extension quasi-coherent modes simultaneously investigated using reflectometry two poloidally toroidally separated positions. experiments also allow local determination velocity from a combination delay estimation safety factor same instrument. investigates whether turbulence which kind...
A new broadband reflectometer operating in the frequency range 50–75 GHz extraordinary mode polarization has been developed and tested on Tore Supra to measure edge density profiles. Using solid state source active multipliers, it performs routine measurements 20 μs. Modulation of is clue heterodyne detection order ensure a high dynamic sensitivity without any phase locking system. The can achieve repetition rate 5 μs between sweeps, so behavior fast plasma events be followed. profile...
The observation of distinct peaks in tokamak core reflectometry measurements - named quasi-coherent-modes (QCMs) are identified as a signature Trapped-Electron-Mode (TEM) turbulence [H. Arnichand et al. 2016 Plasma Phys. Control. Fusion 58 014037]. This phenomenon is investigated with detailed linear and nonlinear gyrokinetic simulations using the \gene code. A Tore-Supra density scan studied, which traverses through Linear (LOC) to Saturated (SOC) Ohmic Confinement transition. LOC SOC...
Three methods to study the effect of density fluctuations on reflected signal, based a 2D full-wave analysis and Born approximation numerical analytical calculations, are developed. The explicit expression for signal produced by an island-like perturbation running in poloidal direction is obtained shown be nice agreement with results techniques small level perturbations. It shown, both numerically analytically, that due small-angle scattering effects, far from cut-off layer may produce...