J.M. Fontdecaba
A5009096448- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- High-Energy Particle Collisions Research
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Atomic and Molecular Physics
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Laser Design and Applications
- Physics of Superconductivity and Magnetism
- Nuclear Physics and Applications
- Nuclear Materials and Properties
- Aerospace Engineering and Control Systems
- Fault Detection and Control Systems
- Hydraulic Fracturing and Reservoir Analysis
- Fluid Dynamics and Turbulent Flows
- Geotechnical and Geomechanical Engineering
- Adaptive Control of Nonlinear Systems
- Dust and Plasma Wave Phenomena
Universidad Complutense de Madrid
2008-2024
Culham Centre for Fusion Energy
2024
United Kingdom Atomic Energy Authority
2024
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2009-2022
Royal Military Academy
2020
Fusion for Energy
2010
Universitat Politècnica de Catalunya
2002-2005
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...
Sheared flows have been experimentally studied in TJ-II plasmas. In low-density ECH plasmas, sheared can be easily controlled by changing the plasma density, thereby allowing radial origin and evolution of edge velocity shear layer to studied. high density NBI heated plasmas a negative electric field is observed that dominated diamagnetic component. The increases at L–H transition an amount depends on magnetic configuration heating power. Magnetic configurations with without low order...
Abstract The work describes the pedestal structure, transport and stability in an effective mass ( A eff ) scan from pure deuterium to tritium plasmas using a type I ELMy H-mode dataset which key parameters that affect behaviour (normalized pressure, ratio of separatrix density density, ion Larmor radius, collisionality rotation) are kept as constant possible. Experimental results show significant increase at top with increasing , modest reduction temperature pressure. variations heights...
Abstract As part the DTE2 campaign in JET tokamak, we conducted a parameter scan T and D-T complementing existing pulses H D. For different main ion masses, type-I ELMy H-modes at fixed plasma current magnetic field can have pedestal pressure varying by factor of 4 total changing from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>β</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">N</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo>...
Abstract In the paper we present an overview of interpretive modelling a database JET-ILW 2021 D-T discharges using TRANSP code. The main aim is to assess our capability computationally reproducing fusion performance various plasma scenarios different external heating and mixtures, understand driving mechanisms. We find that simulations confirm general power-law relationship between increasing power output, which supported by absolutely calibrated neutron yield measurements. A comparison...
This paper presents the latest results on confinement studies in TJ-II stellarator. The inherently strong plasma–wall interaction of has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z , Li was chosen because there exists a reactor-oriented interest this element, thus giving special relevance to investigation its properties. Li-coating led important changes plasma performance. Particularly, effective density limit NBI plasmas extended...
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...
Abstract The recent deuterium–tritium campaign in JET-ILW (DTE2) has provided a unique opportunity to study the isotope dependence of L-H power threshold an ITER-like wall environment (Be and W divertor). Here we present results from dedicated transition experiments at JET-ILW, documenting tritium plasmas, comparing them with matching deuterium hydrogen datasets. From earlier it is known that as plasma isotopic composition changes deuterium, through varying deuterium/hydrogen concentrations,...
Abstract This paper reports the first experiment carried out in deuterium–tritium addressing integration of a radiative divertor for heat-load control with good confinement. Neon seeding was time D–T plasma as part second campaign JET its Be/W wall environment. The technical difficulties linked to re-ionisation heat load are reported T and D–T. compares impact neon on plasmas their D counterpart detachment, localisation radiation, scrape-off profiles, pedestal structure, edge localised modes global
Abstract The pre-thermal quench (pre-TQ) dynamics of a pure deuterium ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">D</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> ) shattered pellet injection (SPI) into <mml:mn>3</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mi>MA</mml:mi> / <mml:mn>7</mml:mn> <mml:mi>MJ</mml:mi> JET H-mode plasma is studied via 3D non-linear MHD modelling with the JOREK code....
This paper describes a series of experiments performed in TJ-II stellarator with the aim studying influence magnetic configuration on stability and transport properties plasmas. Plasma potential profiles have been measured several configurations up to plasma core heavy ion beam probe diagnostic. Low-order rational surfaces positioned at different radii observing effect features. edge turbulent has studied that are marginally stable due decreased well. Results show dynamical coupling between...
Abstract A reduction of the pedestal pressure with increasing separatrix density over ( n e sep / ped ) has been observed in JET. The physics behind this correlation is investigated. due to two distinct mechanisms. increase till ≈0.4 shifts radially outwards, decreasing peeling-balloning stability and reducing height. effect position saturates above ≈ 0.4. For higher values, ascribed increased turbulent transport and, likely, resistive MHD effects. reduces ∇ /n , η transport. This gradient...
The heavy ion beam probe diagnostic is used in the TJ-II stellarator to study directly plasma electric potential with good spatial (up 1 cm) and temporal 2 μs) resolution. Singly charged ions, Cs+, energies of up 125 keV are column from edge core. Both electron cyclotron resonance heating (ECRH) neutral injection (NBI)-heated plasmas (PECRH = 200 400 kW, PNBI ENBI 28 keV) have been studied.Low-density ECRH [[over bar]n (0.5 1.1) × 1019 m-3] characterized by positive on order 1000 V. A...
This paper presents an overview of experimental results and progress made in investigating density control using Li-coating, transport L–H transitions TJ-II. The Li-coating changes drastically the plasma–wall interaction, decreasing recycling, enlarges substantially operational range device delaying appearance radiative collapse that happens for higher densities, which permits confinement properties much denser plasmas to be studied. Moreover, mode transition has only been achieved after...
The goal of this work is to study the empirical behaviour suprathermal ions in electron cyclotron resonance heating (ECRH) and neutral-beam injection (NBI) phases TJ-II stellarator. Our approach combines passive emission spectroscopy, which detects confined with energies up hundreds electronvolts, a luminescent probe operated as multichannel fast-ion energy spectrometer using pulse height analysis, ⩾1 keV that escape from plasma. We will present data taken density power scans ECRH plasmas...
Abstract Achieving impurity and helium ash control is a crucial issue in the path towards fusion-grade magnetic confinement devices, this particularly case of helical reactors, whose low-collisionality ion-root operation scenarios usually display negative radial electric field which expected to cause inwards pinch. In work we discuss, based on experimental measurements standard predictions neoclassical theory, how plasmas very low ion collisionality, similar those observed hole large device...
Abstract The effect of electron cyclotron heating (ECH) and current drive (ECCD) on energetic-particle (EP)-driven magnetohydrodynamic (MHD) modes is studied in the helical devices LHD, TJ-II Heliotron J. We demonstrate that EP-driven MHD modes, including Alfvén eigenmodes (AEs) energetic particle (EPMs), can be controlled by ECH/ECCD. In LHD device, which has a moderate rotational transform high magnetic shear, co-ECCD enhances toroidal AEs (TAEs) global (GAEs), while counter-ECCD...
Abstract In this paper, we analyze the impact of electron cyclotron resonance heating and current drive on Alfvénic instabilities driven by neutral beam injection observed in TJ-II stellarator. An MHD stability analysis Alfvén eigenmodes compatible with experimental plasma parameters is carried out order to compare data provided magnetic coils, radiation monitors, heavy ion probes. To end, vacuum configuration modified different levels current, thermal fast pressure profiles generated...
This paper presents an overview of experimental results and progress made in investigating the role magnetic configuration on stability transport TJ-II stellarator. Global confinement studies have revealed a positive dependence energy rotational transform plasma density, together with different parametric dependences for metallic boronized wall conditions. Spontaneous biasing-induced improved transitions, some characteristics that resemble those previously reported H-mode regimes other...
Abstract Since the installation of ITER-like wall on JET tokamak, visible emission from a broad range tungsten charge states has complicated plasma ion temperature and toroidal rotation measurements. A plethora exchange transitions, ions up to W 56+ , 21 suspected magnetic dipole transitions have been observed. In particular 39+ 46+ contaminates long-established carbon measurement at 529 nm. Fortunately wavelength relative intensity lines is predictable their influence can be mitigated when...
Abstract TJ-II stellarator results on modelling and validation of plasma flow asymmetries due to on-surface potential variations, fuelling physics, Alfvén eigenmodes (AEs) control stability, the interplay between turbulence neoclassical (NC) mechanisms liquid metals are reported. Regarding neoclassically predicted asymmetries, its impact radial electric field along flux surface has been successfully validated against Doppler reflectometry measurements. Research physics core with pellets...
A mobile luminescent probe has been developed to detect fast ion losses and suprathermal ions escaping from the plasma of TJ-II stellarator device. The priorities for its design have flexibility positioning, ease maintenance, detector sensitivity. It employs a coherent fiber bundle relay, outside vacuum chamber, ionoluminescence images produced by that impinge, after entering head through pinhole aperture, onto screen material. Ionoluminescence light detection is accomplished charge-coupled...
Cryogenic pellet injection is a widely used technique for delivering fuel to the core of magnetically confined plasmas. Indeed, such systems are currently functioning on many tokamak, reversed field pinch and stellarator devices. A pipe-gun-type injector now operated TJ-II, low-magnetic shear heliac type. hydrogen pellets, containing between 3 × 1018 4 1019 atoms, injected at velocities 800 1200 m s−1 from its low-field side into plasmas created and/or maintained in this device by electron...
We present a study of the power threshold for L–H transitions (PLH) in almost pure helium plasmas, obtained recent experiments at JET with an ITER-like wall (Be and W divertor). The most notable new result is that density which PLH minimum, , considerably higher than deuterium hydrogen plasmas. discuss possible implications ITER its pre-fusion operating phase.
Abstract Experiments in ASDEX Upgrade (AUG) and JET with the ITER-like wall (JET-ILW) are performed to separate pedestal core contributions confinement H-modes different main ion masses. A strong isotope mass dependence is found which enhanced at high gas puffing. This because ELM type changes when going from D H for matched engineering parameters, likely due differences inter transport mass. The can be plasmas by varying only triangularity keeping parameters relevant same. With pedestals...