A5012059670- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Nuclear reactor physics and engineering
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Image Retrieval and Classification Techniques
- Time Series Analysis and Forecasting
- Remote-Sensing Image Classification
- Particle accelerators and beam dynamics
- Advanced Statistical Methods and Models
- Blind Source Separation Techniques
- Plasma Diagnostics and Applications
- Medical Imaging Techniques and Applications
- Face and Expression Recognition
- Statistical Mechanics and Entropy
- Neural Networks and Applications
- Atomic and Subatomic Physics Research
- Cold Fusion and Nuclear Reactions
- Nuclear Engineering Thermal-Hydraulics
- Target Tracking and Data Fusion in Sensor Networks
- Advanced Image and Video Retrieval Techniques
- Morphological variations and asymmetry
- Anomaly Detection Techniques and Applications
Ghent University
2015-2024
Culham Centre for Fusion Energy
2024
Culham Science Centre
2016-2024
Royal Military Academy
2014-2023
Ghent University Hospital
2011-2021
CEA Cadarache
2018-2019
Max Planck Institute for Plasma Physics
2016
University of Antwerp
2008
Institute for Atomic and Molecular Physics
2006
Supélec
2006
Abstract Progress in physics understanding and theoretical model development of plasma transport confinement (TC) the ITPA TC Topical Group since publication ITER Physics Basis (IPB) document (Doyle et al 2007 Nucl. Fusion 47 S18) was summarized focusing on contributions to burning prediction control. This paper provides a general streamlined overview advances that were mainly led by joint experiments activities for last 15 years (see JEX/JA table appendix). starts with scientific strategy...
Studies that validate statistical methods for functional magnetic resonance imaging (fMRI) data often use simulated to ensure the ground truth is known. However, fMRI are almost always generated using in-house procedures because a well-accepted simulation method lacking. In this article we describe R package neuRosim, which collection of generation functions neuroimaging data. We will demonstrate possibilities generate from simple time series complete 4D images and user create her own method.
Abstract The multi-machine International Tokamak Physics Activity (ITPA) Global H-mode Confinement Database has been upgraded with new data from JET the ITER-like wall and ASDEX Upgrade full tungsten wall. This paper describes database presents results of regression analysis to estimate global energy confinement scaling in plasmas using a standard power law. Various subsets are considered, focusing on type divertor materials, regime (all H-modes, ELMy H or ELM-free) constraints. Apart...
Abstract The EUROfusion JET-ILW pedestal database is described, with emphasis on three main issues. First, the technical aspects are introduced, including a description of data selection, datasets, diagnostics used, experimental and theoretical methods implemented definitions. Second, structure stability described. In particular, work describes links between engineering parameters (power, gas divertor configuration) disagreement peeling-ballooning (PB) model ideal magnetohydrodynamics...
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,...
Over the last few years progress has been made on front of disruption prediction in tokamaks. The less forgiving character new metallic walls at JET emphasized importance and mitigation. Being able not only to predict but also classify type will enable one better choose appropriate mitigation strategy. From this perspective, a clustering method, based geodesic distance probabilistic manifold, applied database. This approach allows error bars measurements be taken into account proved clearly...
This contribution concerns the retrieval of colour texture. The interband correlation structure is considered by modeling heavy-tailed image wavelet histograms with a multivariate generalized Gaussian. As similarity measure we propose to use Rao geodesic distance, which, in contrast Kullback-Leibler divergence, exists closed form for any fixed value shape pa rameter distribution. We apply this several experiments. significantly increases rates, while distance shown outperform Kullback-...
Abstract In-depth experimental characterisation of spontaneous shear flow patterning into a so-called <?CDATA $\mathbf{E}\times \mathbf{B}$ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mrow> <mml:mi mathvariant="bold">E</mml:mi> </mml:mrow> <mml:mo>×</mml:mo> mathvariant="bold">B</mml:mi> </mml:mstyle> </mml:math> staircase—named after its planetary analogue—is shown in magnetised plasma turbulence, using...
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)...
Nuclear fusion is a promising alternative to address the problem of sustainable energy production. The tokamak an approach based on magnetic plasma confinement, constituting complex physical system with many control challenges. We study characteristics and optimization reservoir computing (RC) for real-time adaptive prediction profiles in DIII-D tokamak. Our experiments demonstrate that RC achieves comparable results state-of-the-art (deep) convolutional neural networks (CNNs) long...
Abstract The required heating power, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>P</mml:mi> <mml:mi>LH</mml:mi> </mml:mrow> </mml:msub> </mml:math> , to access the high confinement regime (H-mode) in tritium containing plasmas is investigated JET with ITER-like wall at a toroidal magnetic field of <mml:mi>B</mml:mi> <mml:mi>t</mml:mi> <mml:mo>=</mml:mo> <mml:mn>1.8</mml:mn> T and plasma current <mml:mi>I</mml:mi>...
A reproducible stationary improved confinement mode (I-mode) has been achieved recently in the Experimental Advanced Superconducting Tokamak (EAST), featuring good without particle transport barrier.The microscopic mechanism of sustaining I-mode, based on coupling between turbulence transitions and edge temperature oscillation, discovered for first time.A radially localized ring oscillation (ETRO) with azimuthally symmetric structure (n = 0, m 0) identified it is accompanied by alternating...
Abstract Modern tokamaks have achieved significant fusion production, but further progress towards steady-state operation has been stymied by a host of kinetic and MHD instabilities. Control identification these instabilities is often complicated, warranting the application data-driven methods to complement improve physical understanding. In particular, Alfvén eigenmodes are class ubiquitous mixed that important identify control because they can lead loss confinement potential damage walls...
We study the retrieval of coloured textures from a database. In statistical framework we model heavy-tailed wavelet histograms through generalized Gaussian distribution (GGD). choose Kullback-Leibler divergence (KLD) as similarity measure and obtain closed-form expression for KLD between two zero-mean bivariate GGDs. This allows us to take into account rich correlation structure colour bands by two. show that this results in considerably improved rate and, addition, demonstrate superior...
This paper presents a new texture retrieval algorithm based on elliptical distributions for the modeling of wavelet sub- bands. For measuring similarity between two images, geodesic distance (GD) is considered. A closed form fixed shape parameters and an approximation when assuming coordinate functions as straight lines are given. Taken into various choices, multivariate Laplace G <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup>...
Light reflections are one of the main and often underestimated issues plasma emissivity reconstruction in visible light spectral range. Metallic other specular components tokamak generate systematic errors optical measurements that could lead to wrong interpretation data. Our analysis is performed at data from COMPASS. It a D-shaped with metallic vessel possibility H-mode plasma. Data fast camera were used for tomographic background subtraction study boundary. In this article, we show...
Gaussian process tomography (GPT) [J. Svensson, JET Internal Report EFDA-JET-PR(11)24, 2011 and D. Li, J. H. Thomsen, F. Medina, A. Werner, R. Wolf, Rev. Sci. Instrum. 84, 083506 (2013)] is a recently developed method applied earlier to soft X-ray (SXR) spectroscopy on WEST—Tungsten (W) Environment in Steady-state Tokamak. The short execution time of the algorithm makes GPT an important candidate for providing real-time information impurity transport fast MHD control. In work, has shown its...
Reliable and accurate estimates of the ion effective charge <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Z_{\rm eff}$ </tex></formula> in tokamak plasmas are key importance with respect to impurity transport studies establishment thermonuclear burn criteria. These issues fundamental interest ITER reactor operational scenarios general. However, eff}$</tex></formula> derived from bremsstrahlung...
Gaussian process tomography (GPT) is a recently developed method based on the Bayesian probability theory [J. Svensson, JET Internal Report EFDA-JET-PR(11)24, 2011 and Li et al., Rev. Sci. Instrum. 84, 083506 (2013)]. By modeling soft X-ray (SXR) emissivity field in poloidal cross section as process, SXR can be carried out robust extremely fast way. Owing to short execution time of algorithm, GPT an important candidate for providing real-time reconstructions with view impurity transport...
Abstract Alfvén eigenmodes (AEs) are an important and complex class of plasma dynamics commonly observed in tokamaks other devices. In this work, we manually labeled a small database 26 discharges from the DIII-D tokamak order to train simple neural-network-based models for classifying AEs. The provide spatiotemporally local identification four types AEs by using array 40 electron cyclotron emission (ECE) signals as inputs. Despite minimal dataset, strategy performs well at localized...
This paper presents a new wavelet based retrieval approach on Spherically Invariant Random Vector (SIRV) modeling of subbands. Under this multivariate model, coefficients are considered as realization random vector which is product the square root scalar variable (called multiplier) with an independent Gaussian vector. We propose to work joint distribution multiplier and process. For measuring similarity between two texture images, geodesic distance provided for various priors. A comparative...
Abstract In fusion research, the diagnostic data are obtained from different systems, which relatively independent (in terms of response function, noise, calibration, etc…). The consequence is that many measurements providing same physical quantity could provide results. this work, Bayesian probability inference has been applied to frequency modulated continuous wave reflectometry and Far-infrared laser interferometer systems on HL-2A tokamak, offering integrated analysis (IDA) for electron...