A5051359847- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- High-Energy Particle Collisions Research
- Solar and Space Plasma Dynamics
- Soil Moisture and Remote Sensing
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- Meteorological Phenomena and Simulations
- Gyrotron and Vacuum Electronics Research
- Advanced Fiber Optic Sensors
- RFID technology advancements
- GNSS positioning and interference
- Engineering Applied Research
- Antenna Design and Analysis
- Nuclear Physics and Applications
- Nuclear Engineering Thermal-Hydraulics
- Gallbladder and Bile Duct Disorders
- Plasma and Flow Control in Aerodynamics
- Nutrition and Health in Aging
ITER
2020-2024
Banco de la República Colombia
2024
Pontificia Universidad Católica de Chile
2011-2024
Universidad Cooperativa de Colombia
2024
International Center for Tropical Agriculture
2024
University of Lisbon
2005-2020
Royal Military Academy
2020
Instituto Superior Técnico
2005-2019
Instituto Superior de Tecnologias Avançadas
2019
Culham Science Centre
2006-2018
Abstract Ion cyclotron resonance frequency (ICRF) heating has been an essential component in the development of high power H-mode scenarios Jet European Torus ITER-like wall (JET-ILW). The ICRF performance was improved by enhancing antenna-plasma coupling with dedicated main chamber gas injection, including preliminary minimization RF-induced plasma-wall interactions, while RF where optimized for core impurity screening terms ion position and minority hydrogen concentration. impact on...
High spatial resolution Doppler backscattering measurements in JET have enabled new insights into the development of edge Er. We observe fine-scale structures Er well with a wave number krρi≈0.4-0.8, consistent stationary zonal flows, characteristics which vary density. The flow amplitude and wavelength both decrease local collisionality, such that E×B shear increases. Above minimum L-H transition power threshold dependence on density, flows are present during L mode disappear following...
The JET exploitation plan foresees D–T operations in 2020 (DTE2). With respect to the first campaign 1997 (DTE1), when was equipped with a carbon wall, experiments will be conducted presence of beryllium–tungsten ITER-like wall and benefit from an extended improved set diagnostics higher additional heating power (32 MW neutral beam injection + 8 ion cyclotron resonance heating). There are several challenges presented by new wall: general deterioration pedestal confinement; risk heavy...
A reflectometry system has been developed for ASDEX Upgrade to measure the plasma profile from scrape-off layer until bulk plasma, simultaneously at high and low field sides. Unique features of are ultrafast broadband frequency modulation a continuous wave using solid state stable hyper abrupt tuned oscillators (down 10 μs), side channels fully remote control operation, via optical fiber links. Due special design transmission line, with decoupled in going out lines one-antenna configuration,...
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...
The electron temperature and density pedestals tend to vary in their relative radial positions, as observed DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) ASDEX Upgrade (Dunne 2017 Plasma Control. Fusion 59 14017). This so-called shift has an impact on the pedestal magnetohydrodynamic (MHD) stability hence height (Osborne 2015 Nucl. 55 063018). present work studies effect of JET ITER-like wall (JET-ILW) baseline low triangularity (δ) unseeded plasmas, similar JET-C discharges. As...
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...
A new system has been installed on the JET tokamak consisting of six independent fast-sweeping reflectometers covering four bands between 44 and 150 GHz using orthogonal polarizations. It designed to measure density profiles from plasma edge center, launching microwaves through 40 m oversized corrugated waveguides. routinely produced with a maximum repetition rate one profile every 15 μs up 100,000 per pulse.
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...
Abstract L to H transition studies at JET have revealed an n = 0, m 1 magnetic oscillation starting immediately the (called M-mode for brevity). While is present a weak ELM-less H-mode regime obtained, with clear increase of density and electron temperature pedestal. It intermediate state between H-mode. In ICRH heated plasmas or low NBI mode pedestal can remain steady (with small oscillations) duration heating phase, order 10 s more. The axisymmetric has period ~0.5–2 ms, poloidal number 1:...
Abstract A dimensionless collisionality scan in low-triangularity plasmas the Joint European Torus with ITER-like wall (JET-ILW) has been performed. The increase of normalized energy confinement (defined as ratio between thermal and Bohm time) decreasing is observed. Moreover, at low collisionality, a factor H 98 , comparable to JET-C, achieved. At high related degraded pedestal stability reduction density-profile peaking. due both an core regions. improvement stability. driven by (i)...
Particle transport has been extensively studied by performing several dimensionally matched collisionality scans in various plasma scenarios JET.Gas puff modulation technique developed with high quality time-dependent density profile measurements to determine particle coefficients.Density peaking found increase decreasing * all H-mode while L-mode, no dependency was found.The experimentally determined coefficients suggest that NBI fueling is main contributor the observed H-mode.This...
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...
Three dimensionless scans in the normalized Larmor radius ρ*, collisionality ν* and plasma pressure β have been performed JET with ITER-like wall (JET-ILW).
Clear low frequency (typically 5–25 kHz) coherent type-I ELM precursor modes have been identified in JET. They are detected through various diagnostics, especially the ECE and Mirnov signals, but also on SXR cameras multichannel O-mode edge reflectometer. The propagate direction of ion-diamagnetic drift usually accompanied by a slight rise divertor Dα-emission. precursors show no radial phase inversions localized to few centimetres inside separatrix, pedestal region. time which onset...
Abstract Geodesic acoustic modes (GAMs) have been investigated in JET ohmic discharges using mainly Doppler backscattering. Characteristics and scaling properties of the GAM are studied. Time spatial resolved measurements perpendicular velocity indicate that GAMs located a narrow layer at edge density gradient region with amplitude corresponding to about 50% mean local velocity. on appear be regulated by turbulence drive rather than their damping rate. It is also shown ~20% larger deuterium...
This paper discusses the extension of 'three-ion' species ICRF technique for heating mixture plasmas using fast injected NBI ions as resonant 'third' species. In this scenario power is absorbed by beam in vicinity mode conversion layer where left-hand polarized RF electric field E+ strongly enhanced. The velocity distribution that have a Doppler-shifted resonance close to efficiently absorb and undergo acceleration. We show first experimental observations D-NBI H-D JET with ITER-like wall....
Abstract The isotope effect on intrinsic rotation was studied at the Joint European Torus (JET) tokamak. With unique capability of JET to operate with tritium (T), for first time, experiments in hydrogen (H), deuterium (D) and T Ohmic plasmas were compared. Two reversals per type are observed plasma density scans spanning linear saturated confinement regimes. A clear mass dependence is higher densities. magnitude core found depend mass, stronger co-current H. Change characteristics coexist a...
The broadband microwave reflectometry system on ASDEX Upgrade has been recently upgraded with new channels. It now 12 channels that probe simultaneously the high and low fields plasma, ultrafast sweeping (20–100 μs). X mode (33–75 GHz) is used for scrape off layer, O (16–110 reflected from densities between 0.3×1019 1.5×1019 m−3. A fast heterodyne was developed highest frequency (50–110 to cope higher losses lower incident power. Fixed operation employed fluctuation measurements. dedicated...
At the tokamak Joint European Torus (JET), electron cyclotron emission spectra in O-mode and X-mode polarisations are diagnosed simultaneous absolute terms for several harmonics with two Martin-Puplett interferometers. From second harmonic range polarisation, temperature profile can be deduced outboard side (low magnetic field strength) of JET but only some parts inboard (high strength). This spatial restriction bypassed, if a cutoff is not present inside plasma waves first range. Then, from...
A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of Ion Cyclotron Range Frequencies (ICRF) antenna. The design three-strap ICRF antenna integrates ten pairs (sending receiving) microwave antennas. reflectometer can use three these profiles up 2 × 1019 m−3, at different poloidal locations, allowing direct study local layers...
The design of the ITER low-field side reflectometer (LFSR) has matured to a complete end-to-end preliminary design. LFSR will supply three important plasma measurements: (1) electron density profile, (2) fluctuations, and (3) poloidal rotation. Simultaneous measurements quantities are enabled by an array six monostatic antennas which inject from equatorial port on outboard vessel. Low-loss transmission lines, consisting corrugated, overmoded waveguide miter bends, transmit 30–165 GHz, O-...
The JET scrape-off layer (SOL) has been characterized with a reciprocating probe in inner wall (IW), and outer (OW), limited plasmas. Experiments revealed that SOL profiles are substantially broader (by factor of ~5–7.5 the power e-folding length) for IW than OW Results consistent larger radial turbulent transport found Major differences observed between plasmas on density electron temperature lengths, parallel flow, as well temporal spatial characteristics fluctuations. Experimental...