J.L. de Pablos
A5068128775- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Electron and X-Ray Spectroscopy Techniques
- Radiation Detection and Scintillator Technologies
- Nuclear reactor physics and engineering
- X-ray Spectroscopy and Fluorescence Analysis
- Astro and Planetary Science
- Advanced X-ray and CT Imaging
- Rheumatoid Arthritis Research and Therapies
- Oil Spill Detection and Mitigation
- Image and Signal Denoising Methods
- Infrared Target Detection Methodologies
- Tryptophan and brain disorders
- Particle Detector Development and Performance
- Oil and Gas Production Techniques
- Marine and coastal ecosystems
- Spondyloarthritis Studies and Treatments
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2014-2024
Research Institute Hospital 12 de Octubre
2009-2023
Universidad Complutense de Madrid
2008-2021
Royal Military Academy
2020
Unidades Centrales Científico-Técnicas
1991-2017
Instituto Superior Técnico
2006
Princeton Plasma Physics Laboratory
2005-2006
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...
Heavy ion beam probing (HIBP) is a unique diagnostics to study the core plasma potential and turbulence. Advanced HIBPs operate in T-10 tokamak TJ-II flexible heliac with fine focused (<1 cm) intense (100 µA) beams. They provide measurements wide density interval = (0.3–5) × 1019 m−3, range of Ohmic electron cyclotron resonance heated (ECRH) discharges various currents at T-10, magnetic configurations ECR neutral injection (NBI) heating TJ-II. Time evolution radial profiles and/or local...
Energetic ion driven Alfvén eigenmodes (AEs) are believed to be an important element disturbing the transport in a future fusion reactor. The studies of AE properties modern toroidal devices have made crucial contributions reactor relevant physics. AEs conventionally studied by magnetic probes (MPs), which provide poloidal m and n mode numbers their spectral characteristics. Heavy beam probing (HIBP) has become new tool study with high spatial frequency resolution. HIBP TJ-II heliac observes...
A direct comparison of the electric potential and its fluctuations in T-10 tokamak TJ-II stellarator is presented for similar plasma conditions two machines, using heavy ion beam probe diagnostic. We observed following similarities: (i) potentials several hundred volts, resulting a radial field E r tens V cm −1 ; (ii) negative sign at central line-averaged electron densities larger than , with comparable values both even when different heating methods; (iii) increasing density n e or energy...
The new JET ITER-like wall (made of beryllium and tungsten) is more fragile than the former carbon fiber composite requires active protection to prevent excessive heat loads on plasma facing components (PFC). Analog CCD cameras operating in near infrared wavelength are used measure surface temperature PFCs. Region interest (ROI) analysis performed real time maximum measured each ROI sent vessel thermal map. system started October 2011 has already successfully led a safe landing when hot...
Abstract Alfvén eigenmodes (AEs) were studied in neutral beam injection (NBI) heated plasmas the TJ-II stellarator using a heavy ion probe (HIBP) core, and by Langmuir (LP) Mirnov probes (MP) at edge. AEs detected over whole plasma radius HIBP with spatial resolution of about 1 cm. AE-induced oscillations density n e , electric potential φ poloidal magnetic field B pol frequencies 50 kHz < f AE 300 kHz. The LP, MP data showed high level coherency for specific branches AEs. Poloidal mode...
Excitation of modes in the Alfvénic frequency range, 30 kHz < fAE 300 kHz, was observed hydrogen plasma heated by neutral beam injection (NBI) TJ-II heliac. Co-field and counter-field NBI were injected, components poloidal magnetic field varied one combinations, order to investigate beam-driven over an extended range rotational transform values, . Taking advantage unique capabilities, a dynamic configuration experiment with variation during discharges has shown strong effects on mode via...
The application of adaptive methods to the solution automatic radioisotope identification problem using energy spectrum is described. carried out by means neural networks, which allow use relatively reduced computational structures, while keeping high pattern recognition capability. In this context, it has been found that one these simple once adequately trained, quite suitable identify a given isotope present in mixture elements as well relative proportions each identified substance....
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...
Electric field Ε or electric potential φ plays a key role in the transport and turbulence of toroidal plasmas. It is believed that mean radial Er suppresses eddies via E × B shear, while oscillatory (zonal flows geodesic acoustic modes, GAM) presents mechanism self-regulation. Various aspects electron cyclotron resonance heating (ECRH), e.g. variation power PECRH value deposition effect on static components were studied two machines similar size by heavy ion beam probe (HIBP), operating now...
This paper reports the impact of different confinement regimes on 2D structure edge turbulence. An image analysis method based two-dimensional continuous wavelet transformation is used to localize structures (blobs) in images and extract their geometrical characteristics (position, scale, orientation angle aspect ratio). We study shear-layers these aspects blobs. Results show a reduction angular dispersion blobs as shear layer established boundary, well an increase elongation structures....
Abstract Alfvén eigenmodes (AEs) were studied in low magnetic shear flexible heliac TJ-II ( B 0 = 0.95 T, R 1.5 m, <?CDATA $\langle a\rangle $ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mrow> <mml:mo>〈</mml:mo> <mml:mi>a</mml:mi> <mml:mo>〉</mml:mo> </mml:mrow> </mml:mstyle> </mml:math> 0.22 m) neutral beam injection (NBI) heated plasmas P NBI ⩽ 1.1 MW, E 32 keV) using the heavy ion probe (HIBP). L-mode hydrogen with...
Abstract 2D plasma potential ϕ distribution was measured in the electron cyclotron resonance heating (ECRH) and neutral beam injection (NBI) plasmas of TJ-II stellarator with heavy ion probe for whole radial range wide area poloidal angle, supported by Langmuir data at edge. The operation domain on-axis ECRH explored ( <?CDATA ${\bar n_{\text{e}}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mover> <mml:mi>n</mml:mi>...
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...
Plasma potential and turbulent particle flux ΓE×B in the plasma core were measured for first time during L–H/H–L transitions TJ-II heliac using a heavy ion beam probe. The L–H transition is characterized by simultaneous drop ∼−100 V over whole radius, formation of density pedestal strong radial electric field Er between −100 to −150 cm−1 edge (0.8 < ρ 0.9), suppression broadband oscillations plasma.
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...
The universality of the observed characteristics sheared flows points to a general ingredient explain damping/driving mechanisms responsible for development these in plasma boundary region fusion devices. Experiments TJ-II stellarator showing that generation spontaneous at edge requires minimum density or gradient, open unique possibility characterize dynamics flow plasmas.
A new type of instability mode, related to suprathermal electrons, was found in extremely low-density plasmas, (ne = (0.2-0.5) × 1019 m−3) with electron cyclotron resonance heating and current drive (ECRH/ECCD) the TJ-II heliac. The quasi-monochromatic density plasma potential oscillations frequency range 20-120 kHz tend have several "branches" constant shift between them. typical amplitude mode induced estimated be ΔφEM ∼ 20 V. branches an individual finite radial extent, odd low poloidal...
Abstract Beam-driven Alfvén eigenmodes (AEs) have been studied in the TJ-II low-magnetic-shear flexible heliac ( B 0 = 0.95 T, 〈 R 〉 1.5 m, a 0.22 m), L-mode hydrogen plasmas with NBI and ECR heating P ⩽ 1.0 MW, E 32 keV, ECRH 0.6 MW). In low-density range <?CDATA $\overline{{{n}_{\text{e}}}}$ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mrow> <mml:mover accent="true"> <mml:msub> <mml:mi>n</mml:mi> </mml:mrow>...