A5015806001- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear Physics and Applications
- Ionosphere and magnetosphere dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Particle accelerators and beam dynamics
- Radiation Detection and Scintillator Technologies
- Atomic and Molecular Physics
- Plasma Diagnostics and Applications
- Particle Detector Development and Performance
- Nuclear reactor physics and engineering
- GNSS positioning and interference
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
- Laser-induced spectroscopy and plasma
- Gyrotron and Vacuum Electronics Research
- Nuclear Materials and Properties
- Chemical and Physical Properties of Materials
- Pulsed Power Technology Applications
- CCD and CMOS Imaging Sensors
- Advanced Materials Characterization Techniques
- Atomic and Subatomic Physics Research
- Advanced Data Storage Technologies
Fusion Academy
2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2012-2024
CEA Cadarache
2012-2024
Max Planck Institute for Plasma Physics
2013-2023
Institut de Recherche sur la Fusion par Confinement Magnétique
2021-2022
École Polytechnique Fédérale de Lausanne
2022
Max Planck Society
2013-2016
National Agency for New Technologies, Energy and Sustainable Economic Development
2012
Czech Academy of Sciences, Institute of Plasma Physics
2012
The SPARC tokamak will be equipped with a hard X-ray (HXR) monitor system capable of measuring the bremsstrahlung emission from runaway electrons photon energies in excess about 100 keV. This diagnostic detect formation electron beams during plasma start-up and inform control to terminate discharge early protect machine. In this work, we present 0D estimate HXR start-up. Then discuss characterization prototype monitor. detector mounts 1 × 1-in.2 LaBr3 inorganic scintillator coupled...
An overview is given of SPARC’s three main x-ray diagnostics, with a focus on the functions they fulfill respect to tokamak operation. The first an in-vessel soft tomography diagnostic, aimed at providing early campaign information plasma position, MHD activity, and impurity content. second ex-vessel set hard scintillators detecting presence runaway electrons, in particular during startup phases. third Bragg spectrometers, located outside hall, informing ion temperature as indirect...
This paper is focused on the soft x-ray (SXR) tomography system setup at Tore Supra (DTOMOX) and recent developments made to automatically get precise information about plasma features from inverted data. The first part describes main aspects of tomographic inversion optimization process. Several observations are using this new tool a set shape factors defined help characterizing emissivity field in real-time perspective. second presents detailed off-line analysis comparing positions...
This article debates about data fast acquisition and histogramming method for the X-ray GEM detector. The whole process of is performed by FPGA chips (Spartan-6 series from Xilinx). results are stored in an internal memory then sent to PC. In PC merged processed MATLAB. structure firmware functionality implemented FPGAs described. Examples test measurements presented.
Absolute flux of fast ion losses induced by tearing modes have been measured means loss detectors (FILD) for the first time in RF heated plasmas ASDEX Upgrade tokamak. Up to 30 MW m−2 are FILD at 5 cm from separatrix, consistent with infra-red camera measurements, energies range 250–500 keV and pitch angles corresponding large trapped orbits. A resonant interaction between ions high energy tail ICRF distribution a m/n = 5/4 mode leads enhanced losses. Around % found be coherent scale...
Tungsten transport is investigated in WEST long pulse L-mode plasmas operated with the strike point on actively cooled upper tungsten divertor. The pulses are mostly heated by lower hybrid waves. It experimentally found that does not centrally accumulate throughout these ∼ 30 s reproducible discharges despite large normalised electron density gradients . To explain observations, turbulent and neoclassical of electrons ions computed GKW Peeters A.G. et al (2009 Computer Phys. Commnun. 180...
Abstract Achieving a successful plasma current ramp-up in full tungsten tokamak can be challenging due to the large core radiation (and resulting low temperature) that faced with this heavy metallic impurity if its relative concentration is too high. Nitrogen injection during of WEST discharges greatly improves temperature and magnetohydrodynamic (MHD) stability. Experimental measurements integrated simulations RAPTOR code, complemented QuaLiKiz neural network for computing turbulent...
Abstract This paper describes a new method to derive, from soft x-ray (SXR) tomography, robust estimates of the core displacement, growth rate and frequency 1/1 sawtooth crash precursor. The is valid for very peaked SXR profiles against both inversion algorithm presence tungsten in rotating plasma. Three typical ASDEX Upgrade crashes are then analysed. In all cases postcursor observed, suggesting incomplete reconnection. Despite different dynamics, three displacement shows similar features....
A new x-ray imaging crystal spectrometer (XICS) has been installed, aligned, and used during experimental campaigns on the WEST tokamak. It three interchangeable crystals for measuring Ar XVII, XVIII, Fe XXV spectra, respectively. patented rotating table holding is to monitor facing plasma remotely without changing position of camera. Here, focus made XVII spectrum, between 3.93 4.00 Å. The design diagnostic presented, a synthetic diagnostic, implemented with Python library ToFu, show...
The SPARC tokamak is a high-field, Bt0 ∼12 T, medium-sized, R0 = 1.85 m, that presently under construction in Devens, MA, led by Commonwealth Fusion Systems. It will be used to de-risk the high-field path fusion power plant and demonstrate commercial viability of energy. SPARC’s first campaign plan achieve Qfus > 1 using an ICRF-heated, <10 MW, high current, Ip ∼ 8.5 L-mode fueled D–T gas injection, its second investigate H-mode operations D–D. To facilitate plasma control...
Recent experiments on the ASDEX Upgrade tokamak aim at improving physics base for ITER and DEMO to aid machine design prepare efficient operation. Type I edge localized mode (ELM) mitigation using resonant magnetic perturbations (RMPs) has been shown low pedestal collisionality . In contrast previous high ν* regime, suppression only occurs in a narrow RMP spectral window, indicating process, concomitant confinement drop is observed due reduction of top density electron temperature. Strong...
A Gaseous Electron Multiplier (GEM)-based detector is being developed for soft X-ray diagnostics on tokamaks. Its main goal to facilitate transport studies of impurities like tungsten. Such are very relevant ITER, where the excessive accumulation in plasma core should be avoided. This contribution provides details preliminary tests at ASDEX Upgrade (AUG) with a focus most important aspects operation harsh radiation environment. It was shown that both spatially and spectrally resolved data...
Tearing mode formation after internal crash events like sawteeth or fishbones is one of the most important MHD processes that results in a big island structure and associated confinement degradation.The process implies magnetic reconnection at rational surface, which has been investigated great detail ASDEX Upgrade tokamak.Using direct local measurements it found leads to an ideal kink with large saturated amplitude resonant surface immediately sawtooth crash.This transforms into tearing on...
Abstract High power experiments, up to 9.2 MW with LHCD and ICRH, have been carried out in the full tungsten tokamak WEST. Quasi non inductive discharges achieved allowing extend plasma duration 53 s stationary conditions particular respect contamination. Transitions H mode are observed, H-modes lasting 4 obtained. The increase stored energy is weak since crossing separatrix close L–H threshold. Hot L plasmas (central temperature exceeding 3 keV) a confinement time following ITER L96 scaling...
Abstract WEST database analysis shows a correlation of the recycled neutral source around separatrix with core performances. This observation questions causality chain between particle and turbulent transport up to in L-mode, high recycling plasmas, an unavoidable phase all scenarios. The best performances correlate lowest values density at separatrix, <?CDATA ${n_{{\text{sep}}}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub>...
Abstract The observation of radiative collapses during ion cyclotron resonance heating (ICRH) operation on the full tungsten WEST tokamak constitutes a unique opportunity to get quantitative balance sources and sinks in core region plasma. Experimental analysis numerical modelling evidence significant reduction effective electron heat source delivered by ICRH compared with expectations one hand, complex interplay mechanisms acting collisional peaking other hand. Besides providing an...
SPARC will be outfitted with three systems of x-ray crystal spectrometer arrays. Two these are designed using cylindrically bent crystals to achieve high spectral-resolution for ion temperature and toroidal velocity measurements via imaging He-like Kr Ne-like Xe. The last acts as a spectral survey system monitor W nearby H- emission from Cr, Fe, Co, Ni, Cu. Line radiation intensities calculated the Flexible Atomic Code atomic data ColRadPy collisional-radiative modeling, then convoluted...
To obtain a fast estimation of the total impurity density distribution in poloidal cross section from soft X-ray (SXR) measurements during quasi-stationary phases, possibility that ionization equilibrium may have little influence on emissivity profile Ni and Fe core region tokamak plasmas is investigated. Preliminary encouraging results support this assumption under certain conditions are found. A simplified approach aimed at computing satisfactory unique identified directly an absolutely...
Plasma heating in the full tungsten (W) environment a steady-state tokamak (WEST) relies on electromagnetic waves both lower hybrid (LH) and ion cyclotron range of frequencies (ICRF). The present study focuses mostly optimization discharges heated with ICRF, by reporting different methods to first optimize wave coupling, their absorption reduce impurity production. It is shown that ICRF coupling can be optimized moving plasma closer antennas, increasing density, frequency LH power. We show...
Deriving impurity density from local soft x-ray (SXR) emissivity (reconstructed by background-subtracted tomography during trace injections) line-emission modelling leads to uncertainties due the unknown ionization balance, especially for medium-Z impurities. This paper proposes a paradigm shift in way SXR is used, one that maximizes signal at expense of uncertain relies on sharper spectral resolution used better understand what exactly being measured. It indeed shown measured an may be...
This contribution reviews an important example of current developments in diagnostic systems and data analysis tools aimed at improved understanding control transport processes magnetically confined high temperature plasmas. The choice tungsten for the plasma facing components ITER probably also DEMO means that impurity fusion plasmas is now a crucial challenge. Soft X-ray (SXR) serve as key sensor experimental studies with clear prospective its via actuators based mainly on heating systems....
The in-vessel silicon diode arrays that are used for soft x-ray detection in many tokamaks sensitive to neutron damage, making them unsuitable burning plasma devices such as SPARC. In a device, the diodes would need be placed far from plasma—limiting their field of view—or an alternative detector could used. Here, we present design camera containing array chemical vapor deposition single-crystal diamonds, which will upper and lower port plugs SPARC tokamak with large enough view poloidal...