A5031032963- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Gyrotron and Vacuum Electronics Research
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Dust and Plasma Wave Phenomena
- Pulsed Power Technology Applications
- Atomic and Subatomic Physics Research
- Electromagnetic Launch and Propulsion Technology
- Nuclear reactor physics and engineering
- Energy Harvesting in Wireless Networks
- Solar and Space Plasma Dynamics
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- Diamond and Carbon-based Materials Research
- Mass Spectrometry Techniques and Applications
- Electrostatic Discharge in Electronics
- Nuclear Physics and Applications
- Silicon Carbide Semiconductor Technologies
- Ion-surface interactions and analysis
- Gas Dynamics and Kinetic Theory
École Polytechnique Fédérale de Lausanne
2016-2025
Laboratoire d'étude de l'apprentissage et du développement
2024
Université de Bourgogne
2024
Laboratoire de Physique des Plasmas
2007-2012
Institute of Plasma Physics
2012
United Kingdom Atomic Energy Authority
2006
University of California, Los Angeles
1998-2003
Plasma Technology (United States)
2001-2003
Los Alamos National Laboratory
2002
Fusion Academy
2001
The physics base for the ITER Physics Design Guidelines is reviewed in view of application to DEMO and areas are pointed out which improvement needed arrive at a consistent set Guidelines. Amongst proposed improvements, area power exhaust plays crucial role since predictive capability present-day models low this expected play major limiting designs due much larger value Ptot/R than devices even ITER.
Analysis of MHD activity in pellet enhanced performance (PEP) pulses is used to determine the position rational surfaces associated with safety factor q. This gives evidence for negative shear central region plasma. The plasma equilibrium calculated from measured q values yields a Shafranov shift reasonable agreement experimental value about 0.2 m. corresponding current profile has two large off-axis maxima bootstrap electron temperature and density measurements. A transport simulation shows...
Abstract The achievable efficiency for external current drive through electron-cyclotron waves in a demonstration tokamak reactor is investigated. Two possible designs, one steady state and pulsed operation, are considered. Beam propagation, absorption modelled employing the beam-tracing technique including momentum conservation electron–electron collisions. It found that midplane injection limited by second-harmonic at levels consistent with previous studies. Higher efficiencies can be...
Abstract The favorable confinement properties of negative-triangularity (NT) tokamak configurations were discovered in the TCV late 1990s and documented over two following decades, through investigations predominantly electron-heated plasmas limited topologies. most recent experimental campaign has marked a leap forward, characterized by development variety diverted NT shapes that are robustly stable with basic Ohmic heating. application auxiliary heating, directed now at both electrons ions...
Here we present the first measurements by collective Thomson scattering of evolution fast-ion populations in a magnetically confined fusion plasma. 150 kW and 110 Ghz radiation from gyrotron were scattered TEXTOR tokamak plasma with energetic ions generated neutral beam injection ion cyclotron resonance heating. The temporal behavior spatially resolved velocity distribution is inferred received radiation. dynamics at sawteeth slowdown after switch off auxiliary heating time. latter shown to...
The European Union is working toward providing 2-MW, coaxial-cavity, continuous-wave (cw) 170-GHz gyrotrons for ITER. Their design based on results from an experimental preprototype tube having a pulse length of several milliseconds, in operation at Forschungszentrum Karlsruhe (FZK) years now. first industrial prototype was designed cw but, phase, aimed 1 s the Gyrotron Test Facility Lausanne, Switzerland, as part phased testing/development program (1 s, 60 cw). this gyrotron are reported...
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.
The effects of plasma shaping, in particular triangularity (δ), on temperature fluctuations the tokamak à configuration variable have been studied using correlation electron cyclotron emission system. It has found that, ohmic discharges with comparable density profiles, relative fluctuation level measured at edge is significantly reduced plasmas negative respect to positive ones. Additionally, critical gradients for onset turbulence are observed increase plasmas. An estimation length...
Abstract In recent years, negative triangularity (NT) has emerged as a potential high-confinement L-mode reactor solution. this work, detachment is investigated using core density ramps in lower single null Ohmic plasmas across wide range of upper, lower, and average (the mean upper triangularity: δ ) the TCV tokamak. It universally found that more difficult to access for NT shaping. The outer divertor leg discharges with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Routine reaction to approaching disruptions in tokamaks is currently largely limited machine protection by mitigating an ongoing disruption, which remains a basic requirement for ITER and DEMO [1]. Nevertheless, mitigated disruption still generates stress the device. Additionally, future fusion devices, high-performance discharge time itself will be very valuable. Instead of reacting only on generic features, occurring shortly before ultimate goal actively avoid at early stage, sustain...
Local gyrokinetic simulations with the GENE code are used to investigate turbulent transport for different levels of neutral beam injection heating power in Tokamak à Configuration Variable (TCV) plasmas both positive and negative edge triangularity. The sensitivity heat fluxes respect main plasma parameters, including background gradients, impurity content, electron temperature, is systematically studied. experimentally measured recovered variations profiles compatible experimental error...
The change in thermal transport across the L to H transition is studied detail for those JET high performance H-modes which have a very fast transition. It found that these pulses changes rapidly (<4 msecs) over large radial region 0.5< rho <1, and barrier formed. reasons formation of this are discussed.
Fast ions created in the fusion processes will provide up to 70% of heating ITER. To optimize and current drive magnetically confined plasmas insight into fast-ion dynamics is important. First measurements such by collective Thomson scattering (CTS) were recently reported [Bindslev, Phys. Rev. Lett. 97, 205005 2006]. Here we extend discussion these results which obtained at TEXTOR tokamak. The fast are generated neutral-beam injection ion-cyclotron resonance heating. CTS system uses...
The TCV tokamak facility is used to study the effect of innovative plasma shapes on core and edge confinement properties. In low collisionality L-mode plasmas with electron cyclotron heating (ECH) increases increasing negative triangularity δ. improvement correlates a decrease inner heat transport, even though vanishes core, pointing non-local transport has recently started effects in H-mode plasmas. known improve towards positive triangularity, due increase pedestal height, plagued by...
Results from the first experiments to drive Alfven eigenmodes (AEs) with antennas external a tokamak plasma are presented. In ohmically heated discharges, direct experimental measurements of damping toroidicity induced AEs (TAEs) have allowed an identification different regimes corresponding dominant TAE absorption mechanisms wide range rates, 10-3 ⩽ γ/w 10-1. plasmas by ion cyclotron resonance heating, neutral beam injection lower hybrid heating and high current ohmic new class weakly...
The VH-mode regime of high confinement has been observed in both DIII-D and JET. is characterized by thermal twice that seen H-mode, with the edge transport barrier penetrating deeper into plasma. Two mechanisms have identified as important achieving this level confinement. Expansion E*B velocity shear turbulence suppression zone allowing reductions local transport, while access to second ballooning stability allows avoidance or elimination ELMs which impede improvement. performance phase...
Intense electron cyclotron resonance heating (ECRH) and current drive (ECCD) are employed on the Tokamak à Configuration Variable (TCV) both in second- third-harmonic X-mode (X2 X3). The plasma behaviour under such conditions is driven largely by dynamics, motivating extensive studies of relaxation phenomena governing thermal suprathermal populations. In particular, dynamics electrons intimately tied to physics X2 ECCD. ECRH also a useful tool for manipulating distribution function physical...
The effects of negative triangularity (δ) on confinement and fluctuations in plasmas covering a large range parameters were investigated the tokamak à configuration variable (TCV).The conditions explored this paper include discharges where neutral beam (NB) heating was employed to obtain an electron-ion temperature ratio Te/T i ∼ 1 across fraction plasma profile.This significantly extended δ studied TCV towards more relevant future reactor-like tokamaks.Negative found improve over full...
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...
Electron heat transport experiments are performed in L-mode discharges at various plasma triangularities, using radially localized electron cyclotron heating to vary independently both the temperature Te and normalized gradient over a large range. Local gyro-fluid (GLF23) global collisionless gyro-kinetic (LORB5) linear simulations show that, present experiments, trapped mode (TEM) is most unstable mode. Experimentally, diffusivity χe shown decrease with increasing collisionality, no...
The dynamics of fast ion populations in the TEXTOR tokamak are measured by collective Thomson scattering millimetre wave radiation generated a gyrotron operated at 110 GHz and 100–150 kW. Temporal evolution energetic velocity distribution switch on neutral beam injection (NBI) slowdown after off NBI measured. turn phase has, furthermore, been plasmas with range electron densities temperatures. All these measurements shown to be good agreement simple Fokker–Planck modelling. Bulk rotation is also
A transport analysis of the different kinds heat pulses in JET L and H mode discharges has been made. These include L-H transitions, sawtooth crashes, cold initiated by impurity ablation giant edge localized modes (ELMs). Analysis experiments shows that all near separatrix propagate inward on a time-scale is much shorter than characteristic energy confinement time. On other hand, outward propagation pulse, if it not influenced short lived ballistic effect, can be easily described usual...
The evolution of the energy, momentum and particle transport through L-H transition are determined in JET NBI heated discharges. Both normal periodic transitions studied. It is found that all coefficients drop at over a wide radial region not just edge as was previously thought to be case. Indeed it shown by two different modelling techniques conventional model which changes narrow cannot explain time behaviour electron temperature. Measurements fluctuation level reflectometry also show very fast
In ITER, EC heating and current drive (H&CD) is foreseen not only as a principal auxiliary system for plasma assist start-up, but considered essential in meeting the key requirement of neoclassical tearing mode (NTM) stabilisation, by localized drive. reference ECH design, ITER requires total 20 MW/CW power at 170 GHz using gyrotrons with unit 1 MW. A higher per (2 MW/gyrotron) would result strong reduction cost whole ECRH system, also relax room constraints on launcher antenna design. view...