A5059797234- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Atomic and Subatomic Physics Research
- Dust and Plasma Wave Phenomena
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Physics of Superconductivity and Magnetism
- High-Energy Particle Collisions Research
- X-ray Spectroscopy and Fluorescence Analysis
- Electrostatic Discharge in Electronics
- Radiation Detection and Scintillator Technologies
- Nuclear Engineering Thermal-Hydraulics
- Silicon Carbide Semiconductor Technologies
- Advanced Frequency and Time Standards
- Nuclear Materials and Properties
- Advancements in Semiconductor Devices and Circuit Design
- Astro and Planetary Science
École Polytechnique Fédérale de Lausanne
2014-2024
V. N. Karazin Kharkiv National University
2024
Tokamak Energy (United Kingdom)
2023
Ghent University
2022
Culham Science Centre
2016-2021
Barcelona Supercomputing Center
2020
Universitat Politècnica de Catalunya
2020
Royal Military Academy
2020
University of Lisbon
2017
Culham Centre for Fusion Energy
2017
The TCV tokamak offers outstanding variability of the plasma shape. Using x-ray tomography, shape inner flux surfaces a poloidal cross section can be reconstructed, including fast variations due to MHD activity. Both hardware and software 200 channel system developed for are described.
This paper is an overview of recent results relating to turbulent particle and heat transport, the triggering internal transport barriers (ITBs). The dependence pinch velocity on plasma parameters has been clarified compared with experiment. Magnetic shear collisionality are found play a central role. Analysis made progress along two directions: dimensionless scaling laws, which agree prediction for electrostatic turbulence, analysis modulation experiments, provide stringent test models....
The physical processes producing electron particle transport in the core of tokamak plasmas are described. Starting from gyrokinetic equation, a simple analytical derivation is used as guidance to illustrate main mechanisms driving turbulent convection. A review experimental observations on tokamaks presented and consistency with theoretical predictions discussed. An overall qualitative agreement, some cases even specific quantitative emerges between complex equally observations, exhibiting...
The dependence of plasma transport and confinement on the main hydrogenic ion isotope mass is fundamental importance for understanding turbulent and, therefore, accurate extrapolations from present tokamak experiments, which typically use a single hydrogen isotope, to burning plasmas such as ITER, will operate in deuterium–tritium mixtures. Knowledge properties edge barrier formation species critical view initial, low-activation phase ITER operations or helium its implications subsequent...
Particle transport in magnetized plasmas is investigated with a fluid model of drift wave turbulence. An analytical calculation shows that magnetic field curvature and thermodiffusion drive an anomalous pinch. The driven pinch velocity consistent the prediction turbulence equipartition theory. flux found to be directed inward for small ratio electron ion pressure gradient, it reverses its sign when increasing this ratio. Numerical simulations confirm turbulent particle exists. It mainly by...
During the first year of operation, TCV tokamak has produced a large variety plasma shapes and magnetic configurations, with 1.0<or=Btor<or=1.46 T, Ip<or=800 kA, kappa <or=2.05, -0.7<or= delta <or=0.7. A new shape control algorithm, based on finite element reconstruction current in real time, been implemented. Vertical growth rates 800 sec-1 corresponding to stability margin f=1.15, have stabilized. Ohmic H-modes, energy confinement times reaching 80 ms, normalized beta ( toraB/Ip) 1.9 tau...
For the first time, scalings for density peaking in tokamaks are obtained from a database consisting of observations two devices, ASDEX Upgrade and JET. The investigation relies on an inversion method interferometer signals which grants consistent reconstructions despite differences geometries. By combining these correlations between physics parameters investigated their role determining reduced. Multiple regression analyses show that combined collisionality is most relevant parameter....
This paper summarizes the physical principles behind novel three-ion scenarios using radio frequency waves in ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for and fast-ion generation multi-ion species plasmas. The theoretical section provides practical recipes selecting plasma composition realize scenarios, including two equivalent possibilities choice resonant absorbers that have been identified....
Abstract After the second Deuterium–Tritium Campaign (DTE2) in JET tokamak with ITER-Like Wall (ILW) and full tritium campaigns that preceded followed after DTE2, a sequence of fuel recovery methods was applied to promote removal from wall components. The started several days baking main chamber walls at 240 °C 320 °C. Subsequently, superimposed Ion-Cyclotron Conditioning (ICWC) Glow Discharge (GDC) cleaning cycles deuterium. Diverted plasma operation deuterium different strike point...
A steady-state, fully noninductive plasma current has been sustained for the first time in a tokamak using electron cyclotron drive only. In this discharge, 123 kA of have entire gyrotron pulse duration 2 s. Careful distribution across minor radius power deposited from three 0. 5-MW gyrotrons was essential reaching steady-state conditions. With central drive, up to 153 replaced transiently 100 ms. The scenario is confirmed by ability recharge Ohmic transformer. dependence efficiency on also...
Results from an extensive database analysis of JET density profiles in stationary conditions show that the peaking factor ne0/⟨ne⟩ H modes increases near 1.2 at high collisionality to around 1.5 as plasma decreases towards values expected for ITER. This result confirms earlier observation on AUG. The behaviour L is remarkably different modes, scaling with overall shear (ne0/⟨ne⟩ ∼ 1.5li), independently collisionality. H-mode no dependence, except lowest collisionalities. No evidence LTe,...
This paper outlines an approach towards improved rigour in tokamak turbulence transport model validation within integrated modelling. Gaussian process regression (GPR) techniques were applied for profile fitting during the preparation of modelling simulations allowing rigourous sensitivity tests prescribed initial and boundary conditions as both fit derivative uncertainties are provided. was demonstrated by a JETTO simulation JET ITER-like-wall H-mode baseline discharge #92436 with QuaLiKiz...
Dedicated experiments to generate energetic D ions and fusion-born alpha particles were performed at the Joint European Torus (JET) with ITER-like wall (ILW). Using 3-ion radio frequency (RF) heating scenario, deuterium from neutral beam injection (NBI) accelerated in core of mixed plasmas higher energies ion cyclotron resonance (ICRF) waves, turn leading a core-localized source particles. The fast-ion distribution RF-accelerated D-NBI was controlled by varying ICRF NBI power ( 4–6 MW, 3–20...
Abstract We present an overview of results from a series L–H transition experiments undertaken at JET since the installation ITER-like-wall (JET-ILW), with beryllium wall tiles and tungsten divertor. Tritium, helium deuterium plasmas have been investigated. Initial in tritium show ohmic transitions low density power threshold for ( P LH ) is lower than ones densities, while we still lack contrasted data to provide scaling high densities. In there notable shift which minimum <?CDATA...
Observations are reported of resolved components deuterium Balmer emission in neutral beam heated JET plasmas. The features interpreted as Doppler-shifted from the beams spectrally into by nu *B motional Stark electric field. mechanisms excitation elucidated and modelled. Attention is drawn to diagnostic potential observations for measurement local magnetic fields, deuteron density effective plasma ion charge.
Substantial losses of plasma stored energy and toroidal ion momentum are observed in JET during large amplitude oscillating or quasi-stationary MHD activity when mode coupling effects become important. The degradation the diamagnetic due to low m,n modes increases with amplitude, reaching ΔW/W > 30% at a r/Bθ 0.4%. Favourable comparisons made incremental confinement time such as predicted by Chang Callen. reduction momentum, from charge exchange measurements on C 6+ ions, depends extent...
An overview is given of the experimental method, analysis technique and results for trace tritium experiments conducted on JET tokamak in 2003. Observations associated with events such as sawtooth collapses, neo-classical tearing modes edge localized are described. Tritium transport seen to approach levels plasma core at high density low q(95), barrier region internal (ITB) discharges. remains well above all other cases. The correlation measured diffusion coefficient convection velocity...
The generic problem of how, in a turbulent plasma, the experimentally relevant conditions particle flux very close to null are achieved, despite presence strong heat fluxes, is addressed. Nonlinear gyrokinetic simulations plasma turbulence tokamaks reveal complex dependence as function spatial scale and velocity space collisionality increased. At experimental values collisionality, found null, agreement with experiment, due balance between inward outward contributions at small large scales,...
In DT plasmas, toroidal Alfvén eigenmodes (TAEs) can be made unstable by the alpha particles resulting from fusion reactions, and may induce a significant redistribution of fast ions. Recent experiments have been conducted in JET deuterium plasmas order to prepare scenarios aimed at observing alpha-driven TAEs future campaign. Discharges low density, large core temperatures associated with presence internal transport barriers characterised good energetic ion confinement performed. ICRH has...
Dedicated experiments were conducted in mixed H-D plasmas JET to demonstrate the efficiency of 3-ion ICRF scheme for plasma heating, relying on injected fast NBI ions as resonant ion species.Strong core localization RF power deposition close vicinity ion-ion hybrid layer was achieved, resulting an efficient generation energetic D ions, strong enhancement neutron rate and observation Alfvénic modes.A consistent physical picture that emerged from a range fast-ion measurements at JET, including...
Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. elongation, 1.1 < κ< 2.15, and triangularity, -0.65 ⩽ δ 0.55. The energy confinement time found to increase with owing part the current elongation. beneficial effect negative triangularities most effective at low power tended decrease higher powers used. large variety sawtooth types observed for different deposition locations, from on-axis q = 1 region, simulated model that included local...
The JET tokamak relies on an active charge exchange spectroscopy diagnostic for measurements of ion temperature, toroidal rotation velocity and impurity density profiles. It uses the neutral heating beams as provides at eight to twelve radial positions simultaneously with a time resolution about 100 ms. A description instrument is given, together analysis experimental data account recent results. Profiles temperature frequency, based carbon C VI n = 8 7 transition 5290.5 A, are presented...
Observations on Alcator C-Mod confirm and extend previous measurements from ASDEX Upgrade (AUG) JET, where density peaking in H-mode was seen to increase as collisionality lowered. In the earlier work, also strongly correlated with ne/nG, ratio of plasma limit, it not possible eliminate latter parameter principal scaling variable. This led divergent predictions for profile ITER. The addition data allows correlation be broken, strengthening case controlling parameter. At lowest...
Experimental observations on core particle and impurity transport from the Axial Symmetric Divertor Experiment Upgrade [O. Gruber, H.-S. Bosch, S. Günter et al., Nucl Fusion 39, 1321 (1999)] Joint European Torus [J. Pamela, E. R. Solano, JET EFDA Contributors, Nucl. 43, 1540 (2003)] tokamaks are reviewed compared. Robust general experimental behaviors observed in both devices related parametric dependences identified. The compared with most recent theoretical results field of transport.
The isotope dependence of plasma transport will have a significant impact on the performance future D-T experiments in JET and ITER eventually fusion gain economics reactors. In preparation for operation JET, dedicated comprehensive analyses were performed H, D H-D mixed plasmas. analysis data has demonstrated an unexpectedly strong favourable global confinement energy, momentum particles ELMy H-mode plasmas atomic mass main ion species, energy time scaling as ${\tau _E}\sim {A^{0.5}}$...