A5038415304- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Nuclear Materials and Properties
- Solar and Space Plasma Dynamics
- Laser-induced spectroscopy and plasma
- Atomic and Molecular Physics
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Spacecraft and Cryogenic Technologies
- High-Energy Particle Collisions Research
- Metallurgical Processes and Thermodynamics
- Mass Spectrometry Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- High-pressure geophysics and materials
- Spectroscopy and Laser Applications
- Gas Dynamics and Kinetic Theory
- Laser Design and Applications
- Electron and X-Ray Spectroscopy Techniques
- Astronomical Observations and Instrumentation
Max Planck Institute for Plasma Physics
2016-2025
Institut de Recherche sur la Fusion par Confinement Magnétique
2024
CEA Cadarache
2024
Fusion Academy
2023
Fusion (United States)
2023
Max Planck Society
2012-2021
Royal Military Academy
2020
Max Planck Institute for Plasma Physics - Greifswald
2007
Max Planck Innovation
1995-2007
Forschungszentrum Jülich
2007
A future fusion reactor is expected to have all-metal plasma facing materials (PFMs) ensure low erosion rates, tritium retention and stability against high neutron fluences. As a consequence, intrinsic radiation losses in the edge divertor are comparison devices with carbon PFMs. To avoid localized overheating divertor, low-Z medium-Z impurities be inserted into convert major part of power flux facilitate partial detachment. For burning conditions ITER, which operates not far above L–H...
Tungsten (W) has moved into the focus of fusion research being a main candidate for plasma facing components (PFCs) ITER and future reactor. A ingredient understanding influence W as impurity its impact on is spatially resolved spectroscopic diagnosis W. The experimental investigations at ASDEX Upgrade most intense emissions ions (about I-like W21+ to Mn-like W49+) in VUV soft x-ray region covering electron temperature range from about 0.5–5.0 keV. relative shape fractional abundances...
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...
The tungsten programme in ASDEX Upgrade is pursued towards a full high-Z device. spectroscopic diagnostic of W has been extended and refined the cooling factor re-evaluated. coated surfaces now represent fraction 65% all plasma facing components (24.8 m2). only two major that are not yet strikepoint region lower divertor as well limiters at low field side. While extending surfaces, concentration discharge behaviour have changed gradually pointing to critical issues when operating with wall:...
The cooling factor of W is evaluated using state the art data for line radiation and an ionization balance which has been benchmarked with experiment. For calculation radiation, level-resolved calculations were performed Cowan code to obtain electronic structure excitation cross sections (plane-wave Born approximation). processed by a collisional radiative model electron density dependent emissions. These then combined power derived from recombination rates bremsstrahlung total factor....
Feedback control of the divertor power load by means nitrogen seeding has been developed into a routine operational tool in all-tungsten clad ASDEX Upgrade tokamak. For heating powers above about 12 MW, its use become inevitable to protect tungsten coating under boronized conditions. The is accompanied improved energy confinement due higher core plasma temperatures, which more than compensates negative effect dilution on neutron rate. This paper describes technical details feedback...
Recent research in scrape-off layer (SOL) and divertor physics is reviewed; new existing data from a variety of experiments have been used to make cross-experiment comparisons with implications for further ITER. Studies the region near separatrix addressed relationship profiles turbulence as well scaling parallel power flow. Enhanced low-field side radial transport implicated driving flows inboard side. The medium-n nature edge localized modes (ELMs) has elucidated measurements determined...
In this paper, a new experimental classification of divertor detachment in ASDEX Upgrade is presented. For purpose, series ohmic and L-mode density ramp discharges at different heating powers, magnetic field directions plasma species were carried out. the first time electron volume occurrence recombination measured by means spectroscopy. It shown that not continuously evolving process but rather undergoes three distinct states while characteristics inner outer are strongly coupled. Before...
The installation of a new poloidal charge exchange recombination spectroscopy (CXRS) diagnostic at ASDEX Upgrade (AUG) has enabled the determination radial electric field, Er, using force balance impurity ions. Er been derived from (CX) spectra measured on different species, such as He2+, B5+, C6+ and Ne10+. resulting profiles are found to be identical within uncertainties regardless species used, thus, demonstrating validity technique. profile compared main ion pressure gradient term, which...
The charge exchange recombination spectroscopy (CXRS) diagnostics at ASDEX Upgrade (AUG) have been upgraded and extended to provide high-resolution measurements of impurity ion temperature, density, rotation profiles. existing core toroidal CXRS diagnostic has refurbished increase the level signal, thus enabling shorter exposure times down 3.5 ms. Additional lines sight more detailed profiles enable simultaneous multiple impurities. In addition, a new system installed, which allows for...
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 plasma diagnostic and control (D&C) system for a future tokamak demonstration fusion reactor (DEMO) will have to provide reliable operation near technical physics limits, while its front-end components be subject strong adverse effects within the nuclear high temperature environment. ongoing developments ITER D&C represent an important starting point progressing towards DEMO. Requirements detailed exploration of are however pushing design using sophisticated methods aiming large spatial...
In the present work, tolerable impurity level and composition for a reactor plasma using several sets of model assumptions are evaluated. Special care was taken to evaluate comprehensive consistent set atomic data 35 different elements, such that various elements may be studied as function their nuclear charge. The not only useful presented work or system codes which design fusion reactors, but also interpretation bolometric measurements. Additionally, predictions spectral distribution...
Abstract Based on particle and energy balances, a reduced model is derived for the physical mechanisms leading to occurrence of stable unstable X-point radiators (XPRs), latter also known as marfes. The roles neutral deuterium density in divertor region initiating XPRs highlighted. An access condition formulated whose parameter dependencies are consistent with experimental observations which could apply process detachment. With an exponential increase recombination rate at low temperature,...
Several experiments were conducted in ASDEX Upgrade to prove the suitability of tungsten as a divertor target material under conditions high density and low temperature divertor. The observed fluxes from tile into plasma are low, keeping with extremely sputtering yields. In addition, very favourable effect `prompt redeposition' (redeposition during first gyration) could be confirmed by experiments. Cooling edge region neon injection seems permissible, i.e. impurity did not increase eroded...
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.
The transport of silicon has been investigated for various heating scenarios in ASDEX Upgrade H-mode discharges. Inside r≈a/4, the diffusion coefficient D is either mainly neoclassical or anomalous depending on method. For all with NBI-heating and off-axis ECRH ICRH, approximately neoclassical, effective heat χeff below ion χi,neo plasma core. When central added, above χi,neo, strongly increases by a factor 3–10, i.e. becomes predominantly anomalous. level 2.
In the ASDEX Upgrade tokamak, power deposition structures on divertor target plates during type-I edge localized modes (ELMs) have been investigated by infrared thermography. addition to axisymmetric strike line, several poloidally displaced stripes are resolved, identifying an ELM as a composite of subevents. This pattern is interpreted being signature helical perturbations in low field side non-linear evolution. Based this observation, related magnetic perturbation midplane can be derived...
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...
After completion of the tungsten coating all plasma facing components, ASDEX Upgrade has been operated without boronization for 1 1/2 experimental campaigns. This allowed study fuel retention under conditions relatively low D co-deposition with low- Z impurities as well operational space a full-tungsten device unfavourable condition high intrinsic impurity level. Restrictions in operation were caused by central accumulation combination density peaking, resulting H–L backtransitions induced...
Observations in the ASDEX Upgrade tokamak show a correlation between gradient of intrinsic toroidal rotation profile and logarithmic electron density profile. The center plasma reverses from co- to countercurrent when gradients are large, turbulence is either dominated by trapped modes or at transition ion temperature modes. A study based on local gyrokinetic calculations suggests that dominant trend observations can be explained combination residual stresses produced E × B shearing mechanisms.