J.W. Coenen
A5011309220- Fusion materials and technologies
- Magnetic confinement fusion research
- Advanced materials and composites
- Nuclear Materials and Properties
- Metal and Thin Film Mechanics
- Advanced ceramic materials synthesis
- Laser-Plasma Interactions and Diagnostics
- Intermetallics and Advanced Alloy Properties
- Superconducting Materials and Applications
- Nuclear reactor physics and engineering
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Titanium Alloys Microstructure and Properties
- Plasma Diagnostics and Applications
- Metal Alloys Wear and Properties
- Nuclear Physics and Applications
- Aluminum Alloys Composites Properties
- High-Temperature Coating Behaviors
- Microstructure and mechanical properties
- Nuclear materials and radiation effects
- High-Energy Particle Collisions Research
- Metallurgical and Alloy Processes
- Atomic and Molecular Physics
- Semiconductor materials and devices
- Laser-induced spectroscopy and plasma
Forschungszentrum Jülich
2016-2025
University of Wisconsin–Madison
2020-2024
Royal Military Academy
2020
Atlas Copco (Germany)
2018
Osaka University
2017
KTH Royal Institute of Technology
2017
Kyushu University
2017
Max Planck Institute for Plasma Physics
2016
Technical University of Munich
2016
Erich Schmid Institute of Materials Science
2016
JET underwent a transformation from full carbon-dominated tokamak to fully metallic device with beryllium in the main chamber and tungsten divertor. This material combination is foreseen for activated phase of ITER. The ITER-Like Wall (ILW) experiment at shall demonstrate plasma compatibility walls reduction fuel retention. We report on set experiments (Ip = 2.0 MA, Bt 2.0–2.4 T, δ 0.2–0.4) different confinement conditions global gas balance analysis demonstrating strong long-term retention...
Abstract The optimized superconducting stellarator device Wendelstein 7-X (with major radius , minor and plasma volume) restarted operation after the assembly of a graphite heat shield 10 inertially cooled island divertor modules. This paper reports on results from first high-performance operation. Glow discharge conditioning ECRH discharges in helium turned out to be important for density edge radiation control. Plasma densities with central electron temperatures were routinely achieved...
Abstract Research on magnetic confinement of high-temperature plasmas has the ultimate goal harnessing nuclear fusion for production electricity. Although tokamak 1 is leading toroidal magnetic-confinement concept, it not without shortcomings and community therefore also pursued alternative concepts such as stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) field geometry. The availability this additional dimension opens up an extensive configuration...
Abstract The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is high-confinement mode. In this regime, however, periodic relaxations of plasma edge can occur. These edge-localized modes pose a threat to integrity fusion device. Here we reveal strong impact energetic ions on spatio-temporal structure in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between fast at electromagnetic...
In fusion reactors, surfaces of plasma facing components (PFCs) are exposed to high heat and particle flux. Tungsten Copper alloys primary candidates for materials (PFMs) coolant tube materials, respectively, mainly due thermal conductivity and, in the case tungsten, its melting point. this paper, recent understandings future issues on responses tungsten Cu environments (high flux (including T He), flux, neutron doses) reviewed. This review paper includes; Tritium retention (K. Schmid M....
The key remaining physics design issue for the ITER tungsten (W) divertor is question of monoblock (MB) front surface shaping in high heat flux target areas actively cooled targets. Engineering tolerance specifications impose a challenging maximum radial step between toroidally adjacent MBs 0.3 mm. Assuming optical projection parallel loads, magnetic shadowing these edges required if quasi-steady state melting to be avoided under certain conditions during burning plasma operation and...
This paper reports the impact on confinement and power load of high-shape 2.5 MA ELMy H-mode scenario at JET a change from all carbon plasma-facing components to an metal wall. In preparation this change, systematic studies reduction as result fuelling in combination with nitrogen seeding were carried out JET-C are compared their counterpart metallic An unexpected significant is reported decrease pedestal but partially recovered injection nitrogen.
DEMO is the name for first stage prototype fusion reactor considered to be next step after ITER towards realizing fusion.For realization of energy especially materials questions pose a significant challenge already today.Heat, particle and neutron loads are problem material lifetime when extrapolating DEMO.For many issues faced advanced solution under discussion or development.In particular components such as wall divertor can benefit from introducing new approaches composites alloys into...
The impact of carbon and beryllium/tungsten as plasma-facing components on plasma radiation, divertor power particle fluxes, neutral conditions in the divertors has been assessed JET both experimentally by edge fluid code simulations for plasmas low-confinement mode. In high-recycling studies show a 30% reduction total radiation scrape-off (SOL) layer when replacing (JET-C) with beryllium main chamber tungsten (JET-ILW). Correspondingly, at low-field side (LFS) plate two-fold increase...
For the next step fusion reactor use of tungsten is inevitable to suppress erosion and allow operation at elevated temperature high heat loads.Tungsten fibre-reinforced composites overcome intrinsic brittleness its susceptibility embrittlement thus as a structural well an armour material.That this concept works in principle has been shown recent years.In contribution we present development approach towards their future reactor.A multilayer needed addressing all composite constituents...
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...
The original goals of the JET ITER-like wall included study impact an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek 083023). ITER has recently decided to install a full-tungsten (W) from start operations. One key inputs required in support this decision was possibility melting melt splashing during transients. Damage type can lead modifications surface topology which could higher disruption frequency or compromise subsequent...
JET is used as a test bed for ITER, to investigate beryllium migration which connects the lifetime of first-wall components under erosion with tokamak safety, in relation long-term fuel retention. The (i) limiter and (ii) divertor configurations have been studied JET-ILW (JET Be first wall W divertor), compared those former JET-C carbon-based plasma-facing (PFCs)). For configuration, gross at contact point was determined situ by spectroscopy between 4% (Ein = 35 eV) more than 100%, caused...
Component development for operation in a large-scale fusion device requires thorough testing and qualification the intended operational conditions. In particular environments are necessary which comparable to real conditions, allowing at same time situ/in vacuo diagnostics flexible operation, even beyond design limits during testing. Various electron neutral particle devices provide capabilities high heat load tests, suited material samples components from lab-scale dimensions up full-size...
The erosion of tungsten (W), induced by the bombardment plasma and impurity particles, determines lifetime plasma-facing components as well impacting on performance influx W into confined region. screening divertor transport in largely content core, but source strength itself has a vital impact this process. JET tokamak experiment provides access to large set erosion-determining parameters permits detailed description closest ITER one: (i) effective sputtering yields fluxes function energy...
Abstract WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up 1000 s. In support of ITER operation and DEMO conceptual activities, key missions are: (i) qualification high heat flux plasma-facing components integrating both technological physics aspects relevant particle exhaust conditions, particularly for the monoblocks foreseen divertor; (ii) integrated steady-state at confinement, with a focus on power issues. During phase...
Abstract Since the publication of review Progress in ITER Physics Basis (PIPB) 2007, significant progress has been made understanding processes at plasma-material interface. This review, part ITPA Nuclear Fusion Special Issue On Path to Burning Plasma Operation , presents these developments, focusing on key areas such as physics plasma exhaust, interactions, and properties plasma-facing materials their evolution under exposure. The coordinated efforts Topical Group Scrape-Off Layer Divertor...
The W-transport in the core plasma of JET is investigated experimentally by deriving W-concentration profiles from modelling signals soft x-ray cameras. For case pure neutral beam heating W accumulates (r/a < 0.3) approaching W-concentrations 10−3 between sawtooth crashes, which flatten W-profile to a concentration about 3 × 10−5. When central Ion cyclotron resonant additionally applied decays phases that exhibit changed mode activity, while also electron temperature increases and density...
Applying liquid metals as plasma facing components for fusion power-exhaust can potentially ameliorate lifetime issues well limitations to the maximum allowed surface heat loads by allowing a more direct contact with coolant. The material choice has so far been focused on lithium (Li), it showed beneficial impact operation. Here materials such tin (Sn), gallium (Ga) and aluminum (Al) are discussed alternatives higher operating temperatures without strong evaporation. Power of up 25 MW m−2...
Cracking thresholds and crack patterns in tungsten targets after repetitive ITER-like edge localized mode (ELM) pulses have been studied recent simulation experiments by laser irradiation. The specimens were tested under selected conditions to quantify the thermal shock response. A Nd:YAG capable of delivering up 32 J energy per pulse with a duration 1 ms at fundamental wavelength λ = 1064 nm has used irradiate ITER-grade samples heat loads. exposures performed for room temperature (RT) as...
In October 2014, JET completed a scoping study involving high power scenario development in preparation for DT along with other experiments critical ITER.These have involved intentional and unintentional melt damage both to bulk beryllium main chamber tiles divertor tiles.This paper provides an overview of the findings concern machine protection ITER, illustrating each case resolution images taken by remote handling or after removal from machine.The upper dump plate some been repeatedly...