A5072157255- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Stellar, planetary, and galactic studies
- Laser-induced spectroscopy and plasma
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Metal and Thin Film Mechanics
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Diamond and Carbon-based Materials Research
- Astronomical Observations and Instrumentation
- Ion-surface interactions and analysis
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Frequency and Time Standards
- Spectroscopy and Laser Applications
- Advanced materials and composites
- Astro and Planetary Science
Forschungszentrum Jülich
2016-2025
PricewaterhouseCoopers (United States)
2025
Max Planck Institute for Plasma Physics
2025
University Hospital of Zurich
2017-2024
University of Zurich
2024
University of Applied Sciences Upper Austria
2023
Culham Science Centre
2005-2023
University of Graz
2023
Berliner Hochschule für Technik
2021-2022
Atlas Copco (Germany)
2021
GRAVITY is a new instrument to coherently combine the light of European Southern Observatory Very Large Telescope Interferometer form telescope with an equivalent 130 m diameter angular resolution and collecting area 200 m$^2$. The comprises fiber fed integrated optics beam combination, high spectroscopy, built-in analysis control, near-infrared wavefront sensing, phase-tracking, dual operation laser metrology [...]. This article gives overview reports on performance first astronomical...
We report the detection of continuous positional and polarization changes compact source SgrA* in high states ('flares') its variable near- infrared emission with near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, position centroids exhibit clockwise looped motion on sky, scales typically 150 micro-arcseconds over a few tens minutes, corresponding to about 30% speed light. At same time, flares rotation angle,...
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...
This paper gives an overview of the CARMENES instrument and survey that will be carried out with it during first years operation. (Calar Alto high-Resolution search for M dwarfs Exoearths Near-infrared optical Echelle Spectrographs) is a next-generation radial-velocity under construction 3.5m telescope at Calar Observatory by consortium eleven Spanish German institutions. The scientific goal project conducting 600-night exoplanet targeting ~ 300 completed instrument. consists two separate...
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the sample by publishing one spectrum each dwarf. These spectra cover wavelength range 520--1710nm at a resolution of least $R > 80,000$, and measure its RV, H$\alpha$ emission, projected rotation velocity. We an atlas high-resolution M-dwarf compare atmospheric models. To quantify RV precision that can be achieved in low-mass stars over range, analyze our...
We have measured the absolute frequency of hydrogen $1S\ensuremath{-}2S$ two-photon resonance with an accuracy 3.4 parts in ${10}^{13}$ by comparing it $28\mathrm{th}$ harmonic a methane-stabilized $3.39\ensuremath{\mu}\mathrm{m}$ He-Ne laser. A mismatch 2.1 THz at $7\mathrm{th}$ is bridged phase-locked chain five optical interval dividers. From ${f}_{1S\ensuremath{-}2S}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2466061413187.34(84)\mathrm{kHz}$ and published data other authors we...
We have determined the hydrogen-deuterium isotope shift of $1S\ensuremath{-}2S$ two-photon resonance with a 150-fold increase in accuracy compared to previous measurements. Our experimental result $670994334.64(15)$ kHz has been obtained an optical frequency comb generator and ${\mathrm{CH}}_{4}$-stabilized He-Ne reference laser which provides stability our spectrometer while switching between isotopes. From this measurement we derive values for difference mean square charge radii proton...
Disruption mitigation is mandatory for ITER in order to reduce forces, mitigate heat loads during the thermal quench and avoid runaway electrons (REs). A fast disruption valve has been installed at JET study by massive gas injection. Different species amounts have investigated with respect timescales efficiency. We discuss of halo currents as well sideways forces vertical displacement events, increased energy dissipation through radiation, which could arise asymmetric radiation suppression REs.
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.
Context. Teegarden's Star is the brightest and one of nearest ultra-cool dwarfs in solar neighbourhood. For its late spectral type (M7.0V), star shows relatively little activity a prime target for near-infrared radial velocity surveys such as CARMENES. Aims. As part CARMENES search exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements analysed them planetary signals. Methods. We find periodic variability velocities Star. also studied photometric to rule out...
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.
Context: The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M-dwarfs included in sample had been observed before with HIRES and HARPS either were reported have one short period planetary companion (GJ15A, GJ176, GJ436, GJ536 GJ1148) or are multiple systems (GJ581 GJ876). Aims: We aim report new precise optical radial velocity measurements for these planet hosts test overall capabilities CARMENES. Methods: combined our Doppler those available...
Analysis and understanding of wall erosion, material transport fuel retention are among the most important tasks for ITER future devices, since these questions determine largely lifetime availability fusion reactor. These data also extreme value to improve validate models in vessel build-up T inventory D–T devices. So far, research areas is supported by post-mortem analysis tiles. However, access samples will be very much restricted next-generation devices (such as ITER, JT-60SA, W7-X, etc)...
Future fusion reactors require a safe, steady state divertor operation. A possible solution for the power exhaust challenge is detached operation in scenarios with high radiated fractions. The radiation can be increased by seeding impurities, such as N dominant scrape-off-layer radiation, Ne or Ar SOL and pedestal Kr core radiation. Recent experiments on two of all-metal tokamaks, ASDEX Upgrade (AUG) JET, demonstrate fractions fully-detached N, conventional vertical target geometry. For both...
The CARMENES instrument is a pair of high-resolution (R⪆80,000) spectrographs covering the wavelength range from 0.52 to 1.71 μm, optimized for precise radial velocity measurements. It was installed and commissioned at 3.5m telescope Calar Alto observatory in Southern Spain 2015. first large science program survey ~ 300 M dwarfs, which started on Jan 1, 2016. We present an overview all subsystems (front end, fiber system, visible-light spectrograph, near-infrared calibration units, etalons,...
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...
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...
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...
SOLPS 4.2 is a version of the B2-EIRENE code which currently used for predictive modelling studies ITER divertor design. This paper presents results calculations made series high density shots at JET employing exactly same physics model as that application. A complete possible comparison with experimental data has been performed and relatively good agreement (within factor 2) found outer (with exception temperature profile). At inner worse, particularly highest density.
Recent experiments on JET have shown that type-I edge localized modes (ELMs) can be controlled by the application of static low n = 1 external magnetic perturbation fields produced four error field correction coils (EFCC) mounted far away from plasma between transformer limbs. When an with amplitude a few mT at (the normalized poloidal flux, ?, is larger than 0.95) applied during stationary phase ELMy H-mode plasma, ELM frequency rises ~30?Hz up to ~120?Hz. The energy loss per total stored...
Disruptions are a critical issue for ITER because of the high thermal and magnetic energies that released on short timescales, which results in extreme forces heat loads. The choice material plasma-facing components (PFCs) can have significant impact loads arise during disruption. With ITER-like wall (ILW) JET made beryllium main chamber tungsten divertor, finding is low fraction radiation. This has dropped significantly with ILW from 50–100% total energy being dissipated disruptions CFC...