A5009485537- Magnetic confinement fusion research
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Ionosphere and magnetosphere dynamics
- Nuclear Materials and Properties
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Metal and Thin Film Mechanics
- Laser-induced spectroscopy and plasma
- Atomic and Molecular Physics
- Ion-surface interactions and analysis
- Solar and Space Plasma Dynamics
- Nuclear reactor physics and engineering
- Diamond and Carbon-based Materials Research
- Nuclear Physics and Applications
- Advanced materials and composites
- Cold Fusion and Nuclear Reactions
- Atomic and Subatomic Physics Research
- Metal Alloys Wear and Properties
- Advanced Materials Characterization Techniques
- Quantum chaos and dynamical systems
- Meteorological Phenomena and Simulations
- Welding Techniques and Residual Stresses
- Nuclear materials and radiation effects
Forschungszentrum Jülich
2013-2023
Universitätsmedizin Greifswald
2019
Atlas Copco (Germany)
2018
Max Planck Institute for Plasma Physics - Greifswald
2017
Japan External Trade Organization
2015
KTH Royal Institute of Technology
2008-2009
University of California, San Diego
2008
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
2008
Max Planck Institute for Plasma Physics
1998-2003
General Atomics (United States)
1993-2000
Large Type-I edge localized modes (ELMs) are completely eliminated with small n = 3 resonant magnetic perturbations (RMP) in low average triangularity, , plasmas and ITER similar shaped (ISS) plasmas, relevant collisionalities . Significant differences the RMP requirements properties of ELM suppressed found when comparing two triangularities. In ISS current required to suppress ELMs is approximately 25% higher than triangularity plasmas. It also that width q95 window for suppression smaller...
In this paper the manipulation of power deposition on divertor targets at DIII-D by application resonant magnetic perturbations (RMPs) for suppression large type-I edge localized modes (ELMs) is analysed. We discuss modification ELM characteristics RMP applied. It shown that width pattern in ELMy H-mode depends linearly deposited energy, whereas phase discharge those patterns are controlled externally induced perturbation. was also found heat transport due to small, plasma pedestal electron...
The linear plasma device PSI-2 serves as a pilot experiment for the development of components, operational regimes and control systems JULE-PSI, which will be located in nuclear environment allowing studies radioactive toxic samples. is also used fusion reactor relevant plasma-material interaction studies. This contribution describes layout parameters summarizes recent scientific technical progress project, including installation target station sample manipulation analyses.
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...
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...
Experimental results from TEXTOR are presented to provide strong evidence for the feasibility of 'cold radiative plasma mantle', a concept which might be possible solution energy exhaust problem in fusion reactor. The is compared with high density divertor. compatibility other constraints, limitations and open problems discussed, particular issues stationarity (feed-back control, thermal instabilities, q=2), confinement, He-exhaust fuel dilution.
A study of three-dimensional (3D) perturbed magnetic field structures and transport for edge localized mode control experiments with resonant perturbations at DIII-D is presented. We focus on ITER-Similar Shape plasmas ITER relevant electron pedestal collisionalities . This performed in comparison results from TEXTOR-Dynamic Ergodic Divertor circular limiter plasmas. For both the structure analyzed vacuum paradigm—superimposing external RMP unperturbed equilibrium. TEXTOR L-mode this...
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...
Stationary high energy confinement is observed on TEXTOR-94 for times limited only by the flux swing of transformer using strong edge radiation cooling. Necessary tools are feedback control radiated power and plasma content. At highest densities obtained (up to 1.2 Greenwald limit), exceeds edge-localized-mode-free H-mode scaling ITERH93-P more than 20%. β limits reached with fH89/qa≈0.6. No detrimental effect seeded impurity seen. These discharges meet many conditions necessary a fusion...
Impurity injection in the JET ELMy H-mode regime has produced high-confinement, quasi-steady-state plasmas with densities close to Greenwald density. However, at large Ar densities, a sudden loss of confinement is observed. A possible correlation between and observed MHD phenomena, both core edge plasma, was considered. The degradation coincided impurity profile peaking following disappearance sawtooth activity. In addition, density analysis confirmed that central modes prevented peaking....
The magnetic-field perturbation produced by the dynamic ergodic divertor in TEXTOR changes topology of magnetic field plasma edge, creating an open chaotic system. spectrum contains only a few dominant harmonics and therefore it can be described analytical model. modeling is performed vacuum approximation without assuming backreaction does not rely on any experimentally obtained parameters. It shown that this predicts many details observed structure. Several experiments have been to prove...
The main objective of this paper is investigation methods for reduction divertor heat loads in order to increase the lifetime tiles future fusion reactors.Special emphasis given studies transient due edge localized modes (ELMs).Two are compared: argon seeded type-I ELMy H-modes and nitrogen type-III H-modes.In both scenarios, impurity seeding leads a pedestal energy hence released by ELM.This consequentially reduces power load targets.At high radiative fractions H-modes, part that ELM (small...
Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature Te(r, t) and density ne(r, t). In this paper experimental realization status atomic physics employed well major factors for measurement's accuracy are evaluated. On side, hardware specifications described impact beam atoms local plasma parameters shown be negligible. modeling side collisional–radiative model (CRM) applied infer ne Te from measured...
At the TEXTOR tokamak an external resonant magnetic perturbation is applied with dynamic ergodic divertor to control edge transport properties. The approaches analyse impact of such a kind stochastization on apply mostly shell-like picture which includes dependence from field topology in radial direction only. In this paper multiple experimental evidence presented contrast these forms poloidally heterogenous layer characteristics are determined by alternating line behaviour. A thorough...
Tungsten is currently deemed as a promising plasma-facing material (PFM) for the future power plant DEMO. In case of an accident, air can get into contact with PFMs during ingress. The temperature rise up to 1200 °C due nuclear decay heat in damaged coolant supply. Heated neutron-activated tungsten forms volatile radioactive oxide which be mobilized atmosphere.
A model for the transition to radiatively improved (RI) mode triggered in tokamaks by seeding of impurities is proposed. This takes into account that with increasing plasma effective charge growth rate toroidal ion temperature gradient (ITG) instability, considered nowadays as dominant source anomalous energy losses low-confinement (L) mode, decreases. As a result density profile peaks due an inward convection generated trapped electron turbulence. completely quenches ITG induced transport...
Coating of the walls TEXTOR with silicon has led to improved tokamak plasma performance. Very low concentrations C, B, and O are measured. Radiation from is located at periphery r/a\ensuremath{\ge}0.75 decreases increasing density. Density limits enhanced by 30% as compared boronized conditions; large density gradients electron temperatures edge (10 eV) obtained. The confinement regimes observed earlier densities...
Systematic measurements on the edge turbulence and turbulent transport have been made by Langmuir probe arrays TEXTOR under various static Dynamic Ergodic Divertor (DED) configurations. Common features are observed. With DED, in ergodic zone local flux reverses sign from radially outwards to inwards. The properties profoundly modified energy redistribution frequency spectra suppression of large scale eddies. fluctuation poloidal phase velocity changes direction electron ion diamagnetic...
The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating m/n=3/1 mode configuration, are presented. deeply penetrating external magnetic field perturbation this configuration increases toroidal plasma rotation. Staying below excitation threshold for m/n=2/1 tearing mode, rotation is always direction current, even if projection rotating opposite direction. observed consistent with a radial electric field, generated by an enhanced electron transport ergodic layers near...
Good alignment of the magnetic field line pitch angle with mode structure an external resonant perturbation (RMP) is shown to induce modulation pedestal electron pressure p(e) in high confinement rotation plasmas at DIII-D tokamak a shape similar ITER, next step experiment. This caused by edge safety factor q95 enhancement thermal transport, while contrast, RMP induced particle pump out does not show significant resonance. The measured reduction correlates increase modeled stochastic layer...
Experiments were performed in three different facilities order to investigate the impact of combined steady state deuterium plasma exposure and ELM-like thermal shock events on performance ultra high purity tungsten. The electron beam facility JUDITH 1 was used simulate pure loads. In addition linear devices PSI-2 Pilot-PSI have been for successive as well simultaneous where transient heat loads applied by a energy laser pulsed operation, respectively. results show that damage behaviour...