N. Fedorczak
A5071726061- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Nuclear Materials and Properties
- Fluid Dynamics and Turbulent Flows
- Dust and Plasma Wave Phenomena
- Gyrotron and Vacuum Electronics Research
- Nuclear Physics and Applications
- Image and Signal Denoising Methods
- Atomic and Subatomic Physics Research
- Fluid Dynamics and Thin Films
- Physics of Superconductivity and Magnetism
- Welding Techniques and Residual Stresses
- Diamond and Carbon-based Materials Research
- Metal and Thin Film Mechanics
- Pulsed Power Technology Applications
- Metallurgical Processes and Thermodynamics
- Electromagnetic Compatibility and Measurements
- Earthquake Detection and Analysis
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016-2025
CEA Cadarache
2016-2025
Institut de Recherche sur la Fusion par Confinement Magnétique
2015-2024
Max Planck Institute for Plasma Physics
2012-2023
Atomic Energy (Canada)
2020
Royal Military Academy
2020
CEA Grenoble
2017
Culham Centre for Fusion Energy
2016
Culham Science Centre
2016
University of California, San Diego
2011-2013
An overview of the physics intrinsic torque is presented, with special emphasis on phenomenology toroidal rotation in tokamaks, its theoretical understanding, and variety momentum transport bifurcation dynamics.Ohmic reversals ECH-driven counter are discussed some detail.Symmetry breaking by LSN vs. USN asymmetry related to origin at separatrix.
Experiments on HL-2A, DIII-D and EAST show that turbulence just inside the last closed flux surface (LCFS) acts to reinforce existing sheared ExB flows in this region.This flow drive gets stronger as heating power is increased L-mode, leads development of a strong oscillating shear which can transition into H-mode regime when rate energy transfer from exceeds threshold.These effects become compressed time during an L-H transition, but key role turbulent still observed.The results compare...
The provision of a particle and power exhaust solution which is compatible with first-wall components edge-plasma conditions key area present-day fusion research mandatory for successful operation ITER DEMO. work package plasma-facing (WP PFC) within the European programme complements laboratory experiments, i.e. in linear plasma devices, electron ion beam loading facilities, studies performed toroidally confined magnetic such as JET, ASDEX Upgrade, WEST etc. connection both groups done via...
With WEST (Tungsten Environment in Steady State Tokamak) (Bucalossi et al 2014 Fusion Eng. Des. 89 907–12), the Tore Supra facility and team expertise (Dumont Plasma Phys. Control. 56 075020) is used to pave way towards ITER divertor procurement operation. It consists implementing a configuration installing ITER-like actively cooled tungsten monoblocks tokamak, taking full benefit of its unique long-pulse capability. user platform, open all partners. This paper describes physics basis WEST:...
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...
Velocity fields and density fluctuations of edge turbulence are studied in I-mode [F. Ryter et al., Plasma Phys. Controlled Fusion 40, 725 (1998)] plasmas the Alcator C-Mod [I. H. Hutchinson Plasmas 1, 1511 (1994)] tokamak, which characterized by a strong thermal transport barrier while providing little or no to both bulk impurity particles. Although previous work showed clear geodesic-acoustic modes (GAM) on C-Mod, using newly implemented, gas-puff-imaging based time-delay-estimate velocity...
The kinetic energy transfer between shear flows and the ambient turbulence is investigated in Experimental Advanced Superconducting Tokamak during L-H transition. As rate of from into flow becomes comparable to input turbulence, transition H-mode occurs. observed behavior exhibits several predicted features zonal flows, results show key role that play mediating H-mode.
The absolute rate of nonlinear energy transfer among broadband turbulence, low-frequency zonal flows (ZFs) and geodesic acoustic modes (GAMs) was measured for the first time in fusion-grade plasmas using two independent methods across a range heating powers. results show that turbulent kinetic from intermediate frequencies (20--80 kHz) transferred into ZFs GAMs, as well fluctuations at higher ($>80\text{ }\text{ }\mathrm{kHz}$). As power increased, turbulence GAMs GAM amplitudes peaked then...
Abstract Ion cyclotron resonance frequency (ICRF) heating has been an essential component in the development of high power H-mode scenarios Jet European Torus ITER-like wall (JET-ILW). The ICRF performance was improved by enhancing antenna-plasma coupling with dedicated main chamber gas injection, including preliminary minimization RF-induced plasma-wall interactions, while RF where optimized for core impurity screening terms ion position and minority hydrogen concentration. impact on...
Abstract Tungsten erosion in H-mode plasmas is quantified the outer divertor of JET ITER-Like Wall environment with optical emission spectroscopy on 400.9 nm atomic neutral tungsten line. A novel cross-calibration procedure developed to link slow, high spectral resolution and fast photomultiplier tube measurements order obtain ELM-resolved photon fluxes. Inter-ELM W exclusively impurity sputtering by beryllium because sputter threshold for deuterons. Low concentrations resulted low inter-ELM...
This paper presents the current wall-embedded Langmuir probe system installed on Tokamak à Configuration Variable (TCV), as well analysis tool chain used to interpret current-voltage characteristic obtained when probes are operated in swept-bias conditions. The is based a four-parameter fit combined with minimum temperature approach. In order reduce effect of plasma fluctuations and measurement noise, several characteristics usually averaged before proceeding fitting. impact this procedure...
Plasma exhaust has been identified as a major challenge towards the realisation of magnetic confinement fusion. To mitigate risk that single null divertor (SND) with high radiation fraction in scrape-of-layer (SOL) adopted for ITER will not extrapolate to DEMO reactor, EUROfusion consortium is assessing potential benefits and engineering challenges alternative configurations. Alternative configurations could be readily design include X (XD), Super-X (SXD), Snowflake (SFD) double (DND). The...
The TCV tokamak is augmenting its unique historical capabilities (strong shaping, strong electron heating) with ion heating, additional heating compatible high densities, and variable divertor geometry, in a multifaceted upgrade program designed to broaden operational range without sacrificing fundamental flexibility. rooted three-pronged approach aimed at ITER support, explorations towards DEMO, research. A 1 MW, tangential neutral beam injector (NBI) was recently installed promptly...
Abstract The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, exploratory plasmas driven by theoretical insight, exploiting device’s unique shaping capabilities. Disruption avoidance real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic radiation triggers. Runaway generation high- Z noble-gas injection runaway dissipation...
Abstract ITER will operate with a tungsten divertor, material featuring surface morphology changes when exposed to helium plasmas, in particular the formation of so called fuzz under specific conditions. Investigating interactions between plasma facing components and plasmas tokamak environment is therefore key point consolidate predictions for divertor performance lifetime. To this end, dedicated campaign was performed full WEST tokamak, cumulating ∼2000 s repetitive L mode discharges. It...
Abstract The choice of first wall material is paramount importance for the plasma start-up conditions in ITER and future fusion power plants. In this context, present work focuses on correlations between impurity sources total radiated during tungsten (W) Environment Steady-state Tokamak (WEST). objective to highlight experimental indications a preferable combination scenario materials. Until 2019, WEST featured full high Z with all limiters exposing only W surfaces plasma. To study impact...
Abstract The full W environment that is now foreseen for ITER puts strong emphasis on experimental results obtained in present devices similar conditions. In this context, the WEST tokamak well equipped to bring key contributions preparation of operation, thanks its capability perform long pulses dominant electron heating, torque-free scheme based RF systems, and ITERgrade actively cooled divertor. Recent interest cover understanding tungsten contamination evaluation conditioning methods,...
Abstract The turbulent flux of momentum—or Reynolds stress—is a mechanism responsible for the generation sheared flow by turbulence. structure flux-surface-averaged stress <?CDATA $\langle \tilde{v}_r \tilde{v}_{\bot} \rangle$ ?> is investigated in edge region an L-mode tokamak plasma. induced perpendicular tilting ballooning modes considered. In addition to E × B shear, which negative viscosity effect, magnetic-shear-induced stress—called $\hat{s}$ -residual stress—arises as consequence...
In this paper, the nature of primary instability present in pedestal forming region prior to transition into H mode is analysed using a gyrokinetic code on JET-ILW profiles. The linear analysis shows that resistive nature, and can therefore be stabilized by increased temperature, hence power. unstable modes are identified as being ballooning modes. Their growth rates decrease for temperatures increasing towards experimentally measured temperature at L–H transition. larger lower effective...
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....
A physics and engineering analysis of alternative divertor configurations is carried out by examining benefits problems comparing the baseline single null solution with a Snowflake, an X- Super-X divertor. It observed that can provide margin resilience against large power fluctuations, but their has intrinsic difficulties, especially in balance between structural solidity accessibility components when specific poloidal field coil positioning poses further constraints. hybrid proposed as...
After three years of operation (2017–2019) and four experimental campaigns (C1 to C4), the first phase WEST tokamak has now come an end. During that period, operated with tungsten coated copper-based carbon-based plasma facing components in order comply a full metallic environment. A set components, called units, using ITER monoblock technology was also installed onto one sector lower divertor test their behaviour real This paper gives overview ageing these during situ visual inspections. It...
Abstract As part of ITPA-Integrated Operational Scenario activities, this contribution reviews recent experimental characterizations radio-frequency (RF)-induced scrape-off layer (SOL) modifications various tokamaks worldwide and the LArge Plasma Device at UCLA. The phenomenology, as observed using a large variety measurement techniques, is consistent with expectations from RF sheath rectification. Emphasis then put on complex three-dimensional (3D) spatial patterns RF–SOL interaction, in...