J. Cavalier
A5052559430- Magnetic confinement fusion research
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear Physics and Applications
- Electrohydrodynamics and Fluid Dynamics
- Dust and Plasma Wave Phenomena
- Nuclear Materials and Properties
- Laser-induced spectroscopy and plasma
- Advanced Data Storage Technologies
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
- Seismic Imaging and Inversion Techniques
- Blood donation and transfusion practices
- Electromagnetic Launch and Propulsion Technology
- Atomic and Molecular Physics
- Anatomy and Medical Technology
- Anomaly Detection Techniques and Applications
- Surgical Simulation and Training
- Augmented Reality Applications
- Viral Infections and Vectors
Czech Academy of Sciences, Institute of Plasma Physics
2014-2024
CEA Cadarache
2024
Institute of Nuclear Physics, Polish Academy of Sciences
2021
Czech Academy of Sciences
2021
Institut Jean Lamour
2013-2019
Université de Lorraine
2012-2017
Centre National de la Recherche Scientifique
2012-2017
LFB (France)
1987
Microturbulence has been implicated in anomalous transport at the exit of Hall thruster, and recent simulations have shown presence an azimuthal wave which is believed to contribute electron axial mobility. In this paper, 3D dispersion relation E×B drift instability numerically solved. The mode found resemble ion acoustic for low values magnetic field, as long a non-vanishing component vector along field considered, velocity small compared thermal velocity. these conditions, analytical model...
Abstract The tokamak à configuration variable (TCV) continues to leverage its unique shaping capabilities, flexible heating systems and modern control system address critical issues in preparation for ITER a fusion power plant. For the 2019–20 campaign configurational flexibility has been enhanced with installation of removable divertor gas baffles, diagnostic capabilities an extensive set upgrades new dual frequency gyrotrons. baffles reduce coupling between main chamber allow detailed...
This paper summarizes the status of COMPASS tokamak, its comprehensive diagnostic equipment and plasma scenarios as a baseline for future studies. The former COMPASS-D tokamak was in operation at UKAEA Culham, UK 1992–2002. Later, device transferred to Institute Plasma Physics Academy Sciences Czech Republic (IPP AS CR), where it installed during 2006–2011. Since 2012 has been full with Type-I Type-III ELMy H-modes base scenario. enables together ITER-like shape flexible NBI heating system...
COMPASS Upgrade is a new medium size, high magnetic field tokamak (R = 0.9 m, Bt 5 T, Ip 2 MA) currently under design in the Czech Republic. It will provide unique capabilities for addressing some of key challenges plasma exhaust physics, advanced confinement modes and configurations as well testing facing materials liquid metal divertor concepts. This paper contains an overview preliminary engineering main systems (vacuum vessel, central solenoid poloidal coils, toroidal support structure,...
The first results of particle-in-cell simulations the electrostatic sheath and magnetic pre-sheath thermionically emitting planar tungsten surfaces in fusion plasmas are presented. Plasma conditions during edge localized modes (ELMs) inter-ELM periods have been considered for various inclinations field selected surface temperatures. All runs performed under two assumptions potential drop; fixed or floating. primary focus lies on evaluation escaping thermionic current quantification...
Partial detachment is the desired regime for baseline burning plasma scenario in ITER and next-step devices, as it allows to dissipate majority of energy carried by charged particles through scrape-off-layer (SOL) thus avoids localised heat flux deposition divertor region.The COMPASS tokamak equipped with an open has a relatively short connection length, both factors being unfavourable access detachment.As such, only approach naturally detached operation at very high lineaveraged densities...
A new system of probes was recently installed in the divertor tokamak COMPASS order to investigate ELM energy density with high spatial and temporal resolution. The consists two arrays rooftop-shaped Langmuir (LPs) used measure floating potential or ion saturation current one array Ball-pen (BPPs) plasma a resolution ~3.5 mm. combination BPPs LPs yields electron temperature microsecond We report on design probe first results profile measurements ELMy H-mode L-mode. also present comparative...
Power handling experiments with a special liquid metal divertor module based on the capillary porous system technology were performed in tokamak COMPASS. The performance of two metals (Li and LiSn alloy) tested for first time under ELMy H-mode conditions. No damage mesh good exhaust capability observed both separate up to 12 MW/m2 deposited perpendicular, inter-ELM steady-state heat flux ELMs relative energy ~3% local peak fluence at ~15 kJ.m−2. droplets directly ejected from top surface...
Collective Thomson scattering experiments reveal the presence of high-frequency, axial electron density fluctuations at millimetric wavelengths in Hall thruster plasma. The properties these are investigated experimentally and via linear kinetic theory. relative drift electrons ions direction is found to be insufficient cause excitation observed mode. Instead, mode determined a two-stream instability arising due velocity difference between singly doubly charged ion populations plume.
Abstract Analysis of the divertor edge localized mode (ELM) electron temperature at a uniquely high temporal resolution (10 −5 s) was reported JET tokamak (Guillemaut et al 2018 Nucl. Fusion 58 066006). By collecting probe data obtained during many dozens ELMs, conditional-average (CAV) technique yields surprisingly low peak temperatures, far below pedestal ones (70%–99% reduction!) which we, however, question. This result interpreted through collisional free-streaming kinetic model by...
Two small liquid metal targets based on the capillary porous structure were exposed to divertor plasma of tokamak COMPASS. The first target was wetted by pure lithium and second one a lithium-tin alloy, both releasing mainly atoms (sputtering evaporation) when plasma. Due poorly conductive material steep surface inclination (implying surface-perpendicular heat flux 12–17 MW/m2) for 0.1–0.2 s, LiSn has reached 900 °C under ELMy H-mode. A model conduction is developed serves evaluate...
The significant role of magnetic perturbations in mitigation and losses runaway electrons (REs) was documented dedicated experimental studies RE at the COMPASS tokamak. REs are produced both low density quiescent discharges disruptions triggered by massive gas injection (MGI). seed beginning discharge on subsequent population proved significant. Modulation MHD instabilities observed several characteristic frequencies, as well field oscillations related to power supplies. Magnetic islands...
Abstract Microsecond probe measurements of the electron temperature during tokamak edge localised mode (ELM) instability show that peak values significantly exceed those obtained by conventional techniques. The temperatures measured at plasma facing component (divertor) are around 80% initial value (at pedestal). This challenges current understanding, where only several percent pedestal divertor. Our results imply a negligible energy transfer from electrons to ions ELM instability, and...
Following ELMy H-mode experiments with liquid metal divertor target on the COMPASS tokamak, we predict behavior of a similar Upgrade, where it will be exposed to surface heat fluxes even higher than those expected in future EU DEMO attached divertor.We simulate conduction, sputtering, evaporation, excitation and radiation lithium tin area.Measured high-resolution data from tokamak were rescaled towards Upgrade based many established scalings.Our simulation then yields amount released which...
Abstract The understanding of the halo current properties during disruptions is key to design and operate large scale tokamaks in view thermal electromagnetic loads that they entail. For first time, we present a fully self-consistent model for simulations including neutral particles sheath boundary conditions. used simulate vertical displacement events (VDEs) occurring COMPASS tokamak. Recent experiments have shown parallel density at plasma-wall interface limited by ion saturation...
Magnetically confined fusion plasmas are subject to various instabilities that cause turbulent transport of particles and heat across the magnetic field. In edge plasma region, this takes form long filaments stretched along field lines. Understanding dynamics these filaments, referred as blobs, is crucial for predicting controlling their impact on reactor performance. To achieve this, highly resolved passive fast camera measurements have been conducted COMPASS tokamak. These analyzed using...
For ITER-relevant runaway electron studies, such as suppression, mitigation, termination and/or control of a beam, it is important to obtain the electrons after disruption. In this paper we report on first discharges achieved with post-disruptive termed ‘runaway plateau’, in COMPASS tokamak. The plateau produced by massive gas injection argon. Almost all disruptions plateaus occurred during plasma current ramp-up phase. Ar and without were compared for various parameters. Parametrisation...
Abstract The reduction of the incident heat flux onto divertor will be a necessity for future thermonuclear reactors. Impurity seeding is recognized as an efficient way to achieve partial detachment regime, which allows dissipate large fraction power by radiation. This paper presents real-time feedback system (RTFS) based on impurity controlled combined ball-pen and Langmuir probe array in COMPASS tokamak. A number features have been studied, such type impurity, location, constants used...
Abstract Electron cyclotron wall condition (ECWC) discharges are characterised in ASDEX Upgrade with full tungsten plasma facing components and X2 polarised waves launched from the equatorial ports, relevant to ECWC conditions ITER Pre-Fusion Power Operation phase 1. The characterisation of deuterium plasmas is based on experimental inputs such as electron density measurements, in-vessel pressure poloidal field maps obtained measured coil currents, well advanced tomographic methods camera...
Abstract The presented experimental study realized in the COMPASS tokamak demonstrates, for first time, that current density flows from plasma into vacuum vessel during disruptions is limited by ion particle flux. Such a limitation shows that, at least COMPASS, sheath forms between and wall dominates halo flow. This observation achieved measuring simultaneously saturation with negatively biased Langmuir probes grounded to vessel. These comparative measurements, which were never performed...