A5074405525- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Advanced Data Storage Technologies
- Dust and Plasma Wave Phenomena
- Metal and Thin Film Mechanics
- Semiconductor materials and devices
- Solar and Space Plasma Dynamics
- Atomic and Subatomic Physics Research
- Precipitation Measurement and Analysis
- Tropical and Extratropical Cyclones Research
- Refrigeration and Air Conditioning Technologies
- High-Energy Particle Collisions Research
- Power Line Communications and Noise
- Pulmonary Hypertension Research and Treatments
- Radio Wave Propagation Studies
- Nuclear materials and radiation effects
- Image and Signal Denoising Methods
- Nuclear Engineering Thermal-Hydraulics
École Polytechnique Fédérale de Lausanne
2016-2025
University of California, San Diego
2015-2024
Sandia National Laboratories
2024
Sandia National Laboratories California
2024
National Agency for New Technologies, Energy and Sustainable Economic Development
2021
University of Toronto
2007-2018
Plasma Technology (United States)
1990
Fusion Academy
1990
DIII-D experiments on rapid shutdown runaway electron (RE) beams have improved the understanding of processes involved in RE beam control and dissipation. Improvements feedback enabled stable confinement out to volt-second limit ohmic coil, as well enabling a ramp down zero current. Spectroscopic studies shown that neutrals tend be excluded from centre. Measurements energy distribution function indicate broad with mean order several MeV peak energies 30–40 MeV. The appears more skewed...
Divertor detachment is explored on the TCV tokamak in alternative magnetic geometries. Starting from typical single-null shapes, poloidal flux expansion at outer strikepoint varied by a factor of 10 to investigate X-divertor characteristics, and total 70 study properties super-X divertor. The effect an additional X-point near target investigated divertors. Detachment studied these plasmas during Ohmic density ramps with ion B drift away primary X-point. threshold, depth detachment, stability...
Self-consistent full-size turbulent-transport simulations of the divertor and SOL existing tokamaks have recently become feasible. This enables direct comparison turbulence against experimental measurements. In this work, we perform a series diverted Ohmic L-mode discharges on TCV tokamak, building first-of-a-kind dataset for validation edge models. dataset, referred to as TCV-X21, contains measurements from 5 diagnostic systems -- giving total 45 1- 2-D observables in two toroidal magnetic...
A detailed cross-device investigation on the role of filamentary dynamics in high-density regimes has been performed within EUROfusion framework, comparing ASDEX Upgrade (AUG) and TCV tokamaks. Both devices run density ramp experiments at different levels plasma current, keeping toroidal field or q95 constant order to disentangle parallel connection length current. During scan a field, both scrape-off layer (SOL) profiles tend develop clear SOL shoulder lower edge whenever current is...
Abstract The favorable confinement properties of negative-triangularity (NT) tokamak configurations were discovered in the TCV late 1990s and documented over two following decades, through investigations predominantly electron-heated plasmas limited topologies. most recent experimental campaign has marked a leap forward, characterized by development variety diverted NT shapes that are robustly stable with basic Ohmic heating. application auxiliary heating, directed now at both electrons ions...
Abstract The impact of plasma shaping on the properties high density H-mode scrape-off layer (SOL) profiles and transport at outer midplane has been investigated Tokamakà configuration variable. experimental dataset acquired by evolving upper triangularity while keeping other parameters constant. scan comprises <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>δ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">u</mml:mi>...
The inboard limiters for ITER were initially designed on the assumption that parallel heat flux density in scrape-off layer (SOL) could be approximated by a single exponential with decay length λq. This was found not to adequate 2012, when infra-red (IR) thermography measurements inner column during JET limiter discharges clearly revealed presence of narrow channel adjacent last closed surface. near-SOL occurs λq ∼ few mm, much shorter than main SOL λq, and can raise at apex factor up ∼4...
Most of the detachment experiments done to date on tokamak à configuration variable (TCV), both in standard and alternative divertor geometries, focused L-mode integrated core density ramps. In view extending these studies high-power, high-confinement regimes, where impurity seeding will be necessary for detachment, properties nitrogen seeded TCV are assessed here with extensive set edge diagnostics similarities differences () ramp elucidated. It is found that high current, reversed field...
Abstract The Tokamak à Configuration Variable (TCV) tokamak is in the midst of an upgrade to further its capability investigate conventional and alternative divertor configurations. To that end, modular removable gas baffles have been installed decrease coupling between plasma core. primarily seek suppress transit recycling neutrals closed flux surfaces. A first experimental campaign with has shown baffled remains compatible a wide range configurations including snowflake super- X divertors....
Abstract In recent years, negative triangularity (NT) has emerged as a potential high-confinement L-mode reactor solution. this work, detachment is investigated using core density ramps in lower single null Ohmic plasmas across wide range of upper, lower, and average (the mean upper triangularity: δ ) the TCV tokamak. It universally found that more difficult to access for NT shaping. The outer divertor leg discharges with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Abstract An accurate battery model is crucial for a Battery Management System (BMS). However, considering that complex chemical reactions inside the battery, multi-timescale effect of creates difficulties in designing parameter identification algorithms. This paper proposes novel two-time-scale method to parameters which described transfer and diffusion process lithium-ions battery. In this model, second-order equivalent circuit (ECM) by short timescale long built Variable Recursive Least...
A particle balance analysis was conducted during a deuterium (D2) shattered pellet injection-induced plasma shutdown on the DIII-D tokamak to determine why less than 20% of material is assimilated into core by mid-current quench (CQ). Initially, most D2 injected as frozen shards and ionized upon entering vessel. During thermal quench, particles move divertors subsequently center post (CP) walls, where they rapidly recycle partially accumulate neutrals without assimilating plasma. In...
This paper investigates the power loads at inner and outer divertor targets of attached, Ohmic L-mode, deuterium plasmas in TCV tokamak, various experimental situations using an Infrared thermography system. The study comprises variations leg length target flux expansion, plasma current a reversal magnetic field direction. direct impact geometry on scrape-off layer (SOL) transport—parameterised by SOL fall-off , spreading factor Su in-out asymmetry—is reported for constant core properties....
Research towards a plasma exhaust solution for fusion power plant aims at validating edge physics models, strengthening predictive capabilities and improving the divertor configuration. The TCV tokamak is extensively used to investigate extent that geometric configuration modifications can affect performance. Recent experiments continue previous detachment studies of Ohmically heated L-mode plasmas in standard single-null configurations, benefitting from range improved diagnostic...
A set of Ohmic density ramp experiments addressing the role parallel connection length in modifying scrape off layer (SOL) properties has been performed on TCV tokamak. The modified by varying poloidal flux expansion fx. It will be shown that this modification does not influence neither detachment threshold, nor development a flat SOL profile which instead depends strongly increase core line average density. upstream profile, with appearance what is generally called shoulder, related to...
A large database of reciprocating probe data from the edge plasma TCV (Tokamak à Configuration Variable) is used to test radial velocity scalings filaments analytical theory [Myra et al., Phys. Plasmas 13, 112502 (2006)]. The measured velocities are mainly scattered between zero and a maximum which varies as function size collisionality in agreement with scalings. scatter consistent mechanisms that tend slow individual filaments. While were clustered 0.5 2 km/s, minority reached outward high...
Divertor detachment in the TCV tokamak has been investigated through experiments and modelling. Density ramp were carried out ohmic heated L-mode pulses with ion ∇B drift directed away from primary X-point, similar to previous studies [1]. Before roll-over current outer strike point, C III Dα emission leg recede slowly point toward at a rate of ∼2.0 × 10−19 m/m−3 along magnetic field as electron temperature reduces increasing density. Around onset detachment, upstream density profile target...
The Tokamak à Configuration Variable (TCV) has recently been equipped with gas baffles to increase its divertor closure for a broad range of magnetic geometries. First experimental results reported in Reimerdes et al. (2021) demonstrated compatibility geometries and confirmed the main design constraints baffles, particular an increased neutral pressure. present article presents more in-depths analysis extended experiments this first baffle assessment on TCV boundary plasma. It is shown that...
A new Gas Puff Imaging (GPI) diagnostic has been installed on the TCV tokamak, providing two-dimensional insights into Scrape-Off-Layer (SOL) turbulence dynamics above, at and below magnetic X-point. detailed study in L-mode, attached, lower single-null discharges shows that statistical properties have little poloidal variations, while vast differences are present 2D behaviour of intermittent filaments. Strongly elongated filaments, just above X-point divertor far-SOL, show a good...
Abstract Multi-spectral imaging of helium atomic emission (HeMSI) has been used to create 2D poloidal maps <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> </mml:msub> </mml:math> and <mml:mi>n</mml:mi> in TCV’s divertor. To achieve these measurements, MANTIS multispectral cameras (Perek et al 2019 Rev. Sci. Instrum. 90 123514) simultaneously imaged four He I lines (two...
Large relativistic runaway electron currents (0.1–0.5 MA) persisting for ∼100 ms are created in the DIII-D tokamak during rapid discharge shut down caused by argon pellet injection. Slow upward and downward ramps were found response to externally applied loop voltages. Comparison between observed current growth/decay rate expected from knock-on avalanche mechanism suggests that classical collisional dissipation of runaways alone cannot account measured growth/damping rates. It appears a...
A deep understanding of plasma transport at the edge magnetically confined fusion plasmas is needed for handling and control heat loads on machine first wall. Experimental observations collected a number tokamaks over last three decades taught us that flux profiles divertor targets X-point configurations can be parametrized by using two scale lengths scrape-off layer (SOL) transport, separately characterizing main SOL () (Sq). In this work we challenge current interpretation these as well...
Theory-based scaling laws of the near and far scrape-off layer (SOL) widths are analytically derived for L-mode diverted tokamak discharges by using a two-fluid model. The SOL pressure density decay lengths obtained leveraging balance among power source, perpendicular turbulent transport across separatrix, parallel losses at vessel wall, while model intermittent mediated filaments. analytical estimates length in is then compared to results three-dimensional, flux-driven, global, turbulence...
Abstract Using recently installed scrape-off layer diagnostics on the tokamak à configuration variable, we characterise poloidal and parallel properties of turbulent filaments. We access both attached detached divertor conditions across a wide range core densities ( f G ∈ [0.09, 0.66]) in diverted L-mode plasma configurations. With gas puff imaging (GPI) diagnostic at outer midplane observed filaments with monotonic increase radial velocity (from 390 m s −1 to 800 ) cross-field radii 8.5 mm...