A5052843951- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Fluid Dynamics and Turbulent Flows
- Superconducting Materials and Applications
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Dust and Plasma Wave Phenomena
- Physics of Superconductivity and Magnetism
- Astrophysics and Star Formation Studies
- Laser-induced spectroscopy and plasma
- High-pressure geophysics and materials
- Granular flow and fluidized beds
- Frequency Control in Power Systems
- Quantum chaos and dynamical systems
- Computational Physics and Python Applications
- Meteorological Phenomena and Simulations
- Gas Dynamics and Kinetic Theory
- Atomic and Molecular Physics
- Geomagnetism and Paleomagnetism Studies
- Electromagnetic Launch and Propulsion Technology
- Advanced Combustion Engine Technologies
CEA Cadarache
2016-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016-2024
Institut de Recherche sur la Fusion par Confinement Magnétique
2016-2024
Max Planck Institute for Plasma Physics
2024
École Polytechnique Fédérale de Lausanne
2019-2022
Laboratoire de Physique des Plasmas
2018-2022
École Normale Supérieure - PSL
2018
Université Paris Sciences et Lettres
2018
École Polytechnique
2018
Centre National de la Recherche Scientifique
2018
Abstract Magnetic confinement fusion offers the promise of sustainable and safe energy production on Earth. Advanced experimental scenarios exploit fascinating yet uncommon ability confined plasmas to bifurcate into states enhanced performance upon application additional free sources. Self-regulation small-scale turbulent eddies is essential accessing these improved regimes. However, after several decades, basic principles for bifurcations are still largely debated clarifications from first...
Abstract We utilize the global full-F gyrokinetic code GYSELA to analyze nonlocal transport in presence of modulated heat source, period which is range a timescale. In submarginal stable case, it observed that localized and time-modulated source can trigger both diffusive avalanche-like transport. When source-stimulated occurs, propagation turbulence faster than pulse. addition, speed correlated with intensity source. This correlation also identified from analytic expression derived...
Abstract The interaction between a plasma and solid surface is studied in (1D-1V) kinetic approach using immersed boundary conditions penalization to model the wall. Two solutions for penalized wall region are investigated that either allow currents flow within material or not. Essential aspects of sheath physics recovered both cases their parametric dependencies investigated. Importantly, we show how two approaches can be reconciled when accounting relevant effects. Non-Maxwellian features...
Trace impurity transport is studied with the flux-driven gyrokinetic GYSELA code [V.Grandgirard et al., Comp.Phys.Commun.207, 35 (2016)].A reduced and linearized multi-species collision operator has been recently implemented, so that both neoclassical turbulent channels can be treated self-consistently on an equal footing.In Pfirsch-Schlüter regime likely relevant for tungsten, standard expression of flux shown to recovered from gyrokinetics employed operator.Purely simulations deuterium...
Large-scale reactor-relevant fusion plasmas are likely to operate near marginal stability. In this regime, we show clear evidence of interplay between core and edge regions the plasma. This result illustrates aspects controversial 'shortfall problem' in far-core, near-edge so-called 'No Man's Land' region a possible route resolve issue. More generally, it emphasises global-scale organisation turbulence relevance dynamics confinement.
A penalization technique is applied in global and flux driven gyrokinetic simulations to model a limiter configuration. The immersed boundary implemented terms of restoring force cold distribution function. It acts as perfect heat absorber. Parallel kinetic propagation front generated by the tested with 1-D 1-V single species model. An analytical expression derived describe initial transient density, particle energy profiles, induced ballistic phase space(x, v). same recovered code on...
Abstract The interaction between a plasma and solid surface is studied in (1D–1V) kinetic framework using localized particle convective energy source. Matching the quasineutral region sheath horizon addressed fluid with zero heat flux closure. It highlights non-polytropic nature of physics parallel transport. Shortfalls this approach compared to reference simulation highlight importance as measure effects. Non-collisional closure higher moment are used determine sound velocity. Within these...
Abstract A reduced model for trapped electron mode stability has been developed, which incorporates the basic effects of magnetic surface shaping, in particular, elongation and triangularity. This shows that while is stabilising, though weakly, negative triangularity usually leads to a more unstable plasma. marked contrast with experimental evidence better confinement at triangularity, recent gyrokinetic linear simulations. paradox solved when finite orbit and/or extent along field lines...
Radial fluxes of parallel momentum due to and magnetic drifts are shown be correlated in tokamak plasmas. This correlation comes from the onset poloidal convective cells generated by turbulence. The entire process requires a symmetry breaking mechanism, e.g. mean shear flow. An analytical calculation shows that anti-correlation between components turbulent Reynolds stress results curvature drifts.
Two full-F global gyrokinetic codes are benchmarked to compute flux-driven ion temperature gradient (ITG) turbulence in tokamak plasmas. For this purpose, the Semi-Lagrangian code GYrokinetic SEmi-LAgrangian and Eulerian GT5D employed, which solve equation with a realistic fixed flux condition. The equilibrium poloidal flow profile formation processes compared against local neoclassical theory. simulations above carried out without turbulence, agree well each other theoretical estimates....
Poloidal asymmetries of impurities are commonly observed experimentally. Density asymmetry is already known to impact significantly the neoclassical prediction impurity fluxes. In this article, effect pressure and anisotropy on flux derived analytically. This compared with simulations performed gyrokinetic code GYSELA, featuring both turbulent transports. A fair agreement found between analytical result simulation. On special cases which considered, effects shown play a prominent role in...
In absence of external torque, plasma rotation in tokamaks results from a balance between collisional magnetic braking and turbulent drive. The outcome this competition cooperation is essential to determine the flow. A reduced model, supported by gyrokinetic simulations, first used explain quantify only. ripple amplitude above which drag overcomes viscosity obtained. synergetic impact on toroidal Reynolds stress explored. Simulations show that main effect comes an enhancement radial electric...
Abstract In this article an approximated version of the multi-species, non-linear Coulomb collision operator is derived via use a truncated moment expansion distribution function to compute Rosenbluth potentials. The evolution due takes form Fokker–Planck equation that can be efficiently solved by Langevin approach in particle-in-cell (PIC) framework. This kinetic then implemented global gyrokinetic PIC code ORB5 while neglecting finite Larmor effects. ensures exact conservation density,...
Abstract On the road to fusion energy production, many alternative scenarios have been investigated in order address certain well-known problems of tokamak devices; among which, anomalous transport, ELMs and disruptions. The studies on plasma shaping fall into this effort. In particular, it has experimentally observed that when operating L mode, negative triangularity (NT) features better confinement properties than positive (PT). However, even though trend is quite clear, a complete...
The staircase transport regime reported in kinetic simulations of plasma turbulent magnetic confinement is recovered with a simple 2D fluid model allowing for reduced damping the zonal flows. Some complex dynamics zonation are but pattern corrugation appears to be sinusoidal characteristic scale comparable that turbulence modes largest spectral energy, contrast regimes observed global and flux-driven simulations. Enhanced flows govern both an overall reduction SOL width gradual steepening...
We quantify the contribution of kinetic electrons to GAM damping. This is not negligible due a resonance between barely trapped/passing bounce/transit frequency and mode pulsation.
The role of poloidal convective cells—i.e. low frequency axisymmetric modes the electric potential—on transport processes is studied with full-F gyrokinetic code GYSELA. In order to understand impact cells, we apply a numerical filter cells and compare simulation results without filter. energy flux driven by magnetic drifts (due curvature field lines gradient intensity ∇B) turns out be reduced factor about 2 once applied. A careful analysis reveals that spectrum well-correlated turbulent...
Abstract Energy transfer from electron-cyclotron (EC) waves to the plasma is being routinely used in tokamaks heat and drive current through electron channel. Technical applications such as magnetohydrodynamic mode mitigation require power deposition with a high degree of localization. However, observations made show broader distribution suprathermal electrons than predicted by standard drift-kinetic codes. The present paper explores possible wave-induced increase turbulent transport that...
Barely trapped and passing electrons have been recently predicted to strongly enhance the damping rate of Geodesic Acoustic Modes (GAMs) in tokamak plasmas, while keeping their real frequency almost unchanged as compared case with adiabatic electrons. In this paper, dedicated gyrokinetic simulations are successfully these analytical predictions. Specifically, scaling GAM respect ion electron mass ratio, temperature safety factor, aspect ratio is recovered most regions relevant parameter space.
Abstract A quasilinear operator for wave–particle interactions in the electron cyclotron range is derived using cold plasma dispersion relation. The finite width of beam implies a broadening resonance layer velocity space which allows use numerically efficient treatment operator. specific case pure heating injected at outer mid-plane then treated. It to treat propagation and absorption easily, simplifying implementation source term gyrokinetic code. This implemented particle-in-cell code...
Abstract Electromagnetic waves that resonate with the cyclotron motion of electrons in a magnetized plasma can efficiently transfer their momentum and energy to plasma. This is routinely used heat or drive current tokamak plasmas. The impact this localized source on turbulence retro-action resonant interaction between electromagnetic wave has been scarcely studied due difficulty self-consistently simulating two physical mechanisms. In paper, realistic representing electron-cyclotron...
Abstract We complete the 2D 2-fields turbulence model previously used with an interchange-like instability by slightly modifying parallel loss terms to drive drift wave instabilities. show that driven temperature fluctuations of sheath losses is identical turbulence. The linear analysis performed and select control parameters yield maximum growth rates for interchange alone instability. Combining two instabilities doubles rate. non-linear simulations are analyse SOL width. allow one identify...