A5029011234- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Vacuum and Plasma Arcs
- Laser-Plasma Interactions and Diagnostics
- Diamond and Carbon-based Materials Research
- Nuclear reactor physics and engineering
- Boron and Carbon Nanomaterials Research
- Solar and Space Plasma Dynamics
- Spacecraft and Cryogenic Technologies
- Metal and Thin Film Mechanics
- Nuclear Physics and Applications
- Electrical Fault Detection and Protection
- Advanced Sensor Technologies Research
- Nuclear Materials and Properties
- Laser-induced spectroscopy and plasma
- Magnetic Field Sensors Techniques
- Ion-surface interactions and analysis
- Characterization and Applications of Magnetic Nanoparticles
- Advanced materials and composites
- Adhesion, Friction, and Surface Interactions
- Rare-earth and actinide compounds
FH Kärnten
2021
Sensors (United States)
2021
Max Planck Institute for Plasma Physics
2009-2020
Max Planck Society
2009-2020
Max Planck Institute for Plasma Physics - Greifswald
2006-2020
Max Planck Innovation
1995-2017
Australian National University
2016
Oak Ridge National Laboratory
2016
Physikalisch-Technische Bundesanstalt
2016
University of Opole
2016
Abstract The ASDEX Upgrade (AUG) programme is directed towards physics input to critical elements of the ITER design and preparation operation, as well addressing issues for a future DEMO design. Since 2015, AUG equipped with new pair 3-strap ICRF antennas, which were designed reduction tungsten release during operation. As predicted, factor two on ICRF-induced W plasma content could be achieved by sheath voltage at antenna limiters via compensation image currents central side straps in...
Recent experiments on the Type I ELMy H-mode regime performed at JET with improved diagnostics have expanded range of parameters for study ELM energy and particle losses. Deviations from standard behaviour such losses in some areas operating space revealed that are correlated (density temperature) pedestal plasma before crash, while other global characteristics (such as frequency) a consequence ELM-driven flux in-between confinement. The relative loss (to energy) is found to correlate well...
Feedback-controlled puffing of neon and deuterium has been applied to control the edge-localized-mode behavior target plate power deposition during high-power $H$-mode discharges in ASDEX Upgrade. A regime found which more than 90% heating is lost through radiation divertor detachment occurs, without deterioration energy confinement. The plasma remains $H$ mode, exhibiting small-amplitude, high-frequency ELM's, do not penetrate plates strike zone region.
Abstract β‐rhombohedral boron doped with carbon up to about 1 at% is investigated by X‐ray diffraction, optical transmission spectroscopy in the spectral range of absorption edge and its low energy tail, I R reflection lattice vibration range, Raman scattering. The atoms substitute for sites icosahedra shrinking as a consequence increased intraicosahedral bonding force. Hence constants decrease increasing content. Within accuracy measurement interband transition energies are not influenced...
ASDEX Upgrade has recently finished its transition towards an all-W divertor tokamak, by the exchange of last remaining graphite tiles to W-coated ones. The plasma start-up was performed without prior boronization. It found that large He content in plasma, resulting from DC glow discharges for conditioning, leads a confinement reduction. After change D inter-shot quickly dropped and, parallel, usual H-Mode with H factors close one achieved. initial conditioning phase, oxygen concentrations...
At the central column of ASDEX Upgrade, an area 5.5 m2 graphite tiles was replaced by tungsten-coated representing about two-thirds total column. No negative influence on plasma performance found, except for internal transport barrier limiter discharges. The tungsten influx ΓW stayed below detection limit only during direct wall contact or reduced clearance in divertor discharges spectroscopic evidence could be found. From these observations a penetration factor order 1% and effective...
Recent experiments at ASDEX Upgrade have achieved advanced scenarios with high βN (>3) and confinement enhancement over ITER98(y, 2) scaling, HH98y2 = 1.1–1.5, in steady state. These discharges been obtained a modified divertor configuration for Upgrade, allowing operation higher triangularity, changed neutral beam injection (NBI) system, more tangential, off-axis deposition. The figure of merit, βNHITER89-P, reaches up to 7.5 several seconds plasmas approaching stationary conditions....
The elements of transport into and across the scrape-off layer in poloidal divertor tokamak ASDEX Upgrade are analysed for different operational regimes with emphasis on enhanced confinement an edge barrier. Utilizing existing set diagnostics, especially high-resolution multi-pulse Thomson scattering system, combination long discharge plateaus, radial sweeps advanced averaging techniques, detailed mid-plane profiles diverted plasmas obtained. Profiles smooth separatrix, indicating strong...
Abstract The anisotropy of the electronic interband transitions β‐rhombohedral boron is determined by optical absorption measurements. band gaps (indirect allowed transitions) are 1.32(1) and 1.50(1) eV for E ∥ c , respectively, 1.29(1) 1.46(1) ⟂ (extrapolated to T = 0 K). At low temperatures these decrease, while thermal equilibrium develops. temperature dependence gap attributed disorder caused phonons 121.9 ( ) 94.1 meV ü i . representing most prominent intraicosahedral vibrations. Six...
Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters December 2015. At end of 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were operation, allowing detailed studies many interesting plasma phenomena. For example, fast neutral gas manometers supported video cameras (including one fast-frame camera frame rates...
Tungsten-coated tiles, manufactured by plasma spray on graphite, were mounted in the divertor of ASDEX Upgrade tokamak and cover almost 90% surface facing strike zone. Over 600 discharges have been performed to date, around 300 which auxiliary heated with heating powers up 10 MW. The production tungsten was monitored a W I line at 400.8 nm. In centre an array spectral lines 5 nm emitted ionization states XXX measured. From intensity these content derived. Under normal discharge conditions...
The completely detached high confinement (CDH) regime established recently in power ASDEX-Upgrade single null divertor discharges is described. standard CDH mode scenario with feedback controlled external deuterium and neon puffing analysed detail respect to its detachment properties. Impurity transport pumping effects the density operation windows of are outlined. First results other impurity radiators (N,Ar) given. Finally space discussed terms main chamber scrape-off layer plus radiation...
Wendelstein 7-X (W7-X) is a large optimized stellarator (B=2.5T, V=30m3) aiming at demonstrating the reactor relevance of stellarators. In 2015 W7-X will begin its first operation phase (OP1.1) with five inertially cooled inboard limiters made graphite. Assuming heat loads can be spread out evenly between limiters, 1 second discharges 2 MW ECRH heating power could run in OP1.1. The expected plasma parameters sufficient to demonstrate readiness installed diagnostics and even physics program....
The net erosion and deposition pattern of carbon from the Test Divertor Unit (TDU) stellarator W7-X was determined. Special target elements with marker layers consisting about 300 nm molybdenum 5–10 μm on top were used during operational phase OP 1.2a. thicknesses determined by elastic backscattering spectrometry (EBS) using 2.5 MeV protons before after plasma exposure laser-induced breakdown spectroscopy selected exposure. Scanning electron microscopy for investigating surface morphology...
The closed ASDEX Upgrade Divertor II, `LYRA', is capable of handling heating powers up to 20 MW or P/R 12 MW/m, owing a reduction the maximum heat flux target plates by more than factor 2 compared with open I. This caused high radiative losses from carbon and hydrogen inside divertor region in agreement B2-EIRENE modelling predictions. At medium densities H mode, type I ELM behaviour shows no dependence on method (NBI, ICRH). Upgrade-JET dimensionless identity experiments showed...
In the ASDEX Upgrade, X-point marfe formation and its behaviour up to density limit is investigated in gas-fuelled ohmically-heated single-null discharges over a wide range of parameters: Ip=0.6-1.2 MA, BTF=1.35-2.4 T, plasma elongation 1.6 Zeff<2. The standard-ion Del B drift directed towards X-point. At medium electron densities inevitably develops vicinity active consistent with model thermal instabilities radiating edge plasma. Moreover, stable steady-state operation demonstrated marfes...
The ASDEX Upgrade programme is directed towards physics input to critical elements of the ITER design and preparation operation, as well addressing issues for a future DEMO design. After finalization tungsten coating plasma facing components, re-availability all flywheel-generators allowed high-power operation with up 20 MW heating power at I p 1.2 MA. Implementation alternative ECRH schemes (140 GHz O2- X3-mode) facilitated central above n e = × 10 m −3 low q 95 B t 1.8 T. Central O2-mode...
Ion and electron temperature profiles in conventional L H mode on ASDEX Upgrade are generally stiff limited by a critical gradient length ∇T/T as given ion (ITG) driven turbulence. ECRH experiments indicate that (Te) also stiff, predicted turbulence with streamers. Accordingly, the core edge temperatures proportional to each other plasma energy is pedestal pressure for fixed density profiles. Density not confinement improves peaking. Medium triangularity shapes (δ<0.45) show strongly...