A5082385986- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Laser-induced spectroscopy and plasma
- Particle accelerators and beam dynamics
- Dust and Plasma Wave Phenomena
- Fusion materials and technologies
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Electrohydrodynamics and Fluid Dynamics
- Metal and Thin Film Mechanics
- Magnetic Field Sensors Techniques
- Atomic and Molecular Physics
- Laser-Plasma Interactions and Diagnostics
- Diamond and Carbon-based Materials Research
- Lightning and Electromagnetic Phenomena
- Ion-surface interactions and analysis
- Electromagnetic Launch and Propulsion Technology
- Nonlinear Dynamics and Pattern Formation
- Chaos control and synchronization
- Electrostatic Discharge in Electronics
- High voltage insulation and dielectric phenomena
- Vacuum and Plasma Arcs
- Non-Destructive Testing Techniques
- Theoretical and Computational Physics
Universität Innsbruck
2014-2023
University of Ljubljana
2016
Czech Academy of Sciences, Institute of Plasma Physics
2008-2013
University of Stuttgart
2013
University of California, Los Angeles
2011-2013
Technical University of Denmark
2008-2012
Federal Institute of Agricultural Economics
2010
National Agency for New Technologies, Energy and Sustainable Economic Development
2010
Charles University
2009
Birla Institute of Technology, Mesra
2005
Abstract A collaborative study was conducted to evaluate the repeatability and reproducibility of FOSS FoodScan near-infrared spectrophotometer with artificial neural network calibration model database for determination fat, moisture, protein in meat products. Representative samples were homogenized by grinding according AOAC Official Method 983.18. Approximately 180 g ground sample placed a 140 mm round dish, dish FoodScan. The operator ID entered, product profile within software selected,...
Experiments in the tokamaks TEXTOR, CASTOR, T-10 and ISTTOK, as well reversed field pinch RFX have provided new complementary evidence on physics of universal mechanism E×B velocity shear stabilization turbulence, concomitant transport barrier formation radial conductivity by using various edge biasing techniques.
A detailed cross-device investigation on the role of filamentary dynamics in high-density regimes has been performed within EUROfusion framework, comparing ASDEX Upgrade (AUG) and TCV tokamaks. Both devices run density ramp experiments at different levels plasma current, keeping toroidal field or q95 constant order to disentangle parallel connection length current. During scan a field, both scrape-off layer (SOL) profiles tend develop clear SOL shoulder lower edge whenever current is...
An emissive probe has been used in the edge region of CASTOR tokamak order to test possibility direct measurements plasma potential. The difference between floating potential a cold and that an found be approximately 1.3 times electron temperature, which is less than predicted by theory. Several possible reasons explain this discrepancy are offered, such as secondary emission, uncertainties ion different collecting areas for electrons ions, etc. impact space charge formed emitted also discussed.
This paper presents turbulence investigations in the scrape-off layer (SOL) of ASDEX Upgrade ohmic, L-mode and H-mode discharges using electrostatic electromagnetic probes. Detailed studies are performed on small scale ELM filaments. Simultaneous measurements floating plasma potential fluctuations revealed significant differences between these quantities. Large errors can occur when electric field is extracted from measurements, even ohmic discharges. Turbulence plasmas show existence...
Fireballs are discharge phenomena on positively biased small electrodes in plasmas. The arises from electron energization at a double layer. can collect relatively large currents the ambient plasma. become unstable to relaxation oscillations. This paper addresses space–time evolution of pulsed fireballs. Growth and collapse fireballs produce density potential variations near electrode which couple into background plasma production. Unstable emit bursts fast ions ion acoustic waves....
A set of Ohmic density ramp experiments addressing the role parallel connection length in modifying scrape off layer (SOL) properties has been performed on TCV tokamak. The modified by varying poloidal flux expansion fx. It will be shown that this modification does not influence neither detachment threshold, nor development a flat SOL profile which instead depends strongly increase core line average density. upstream profile, with appearance what is generally called shoulder, related to...
This paper focuses on interpretation of fast (1 µs) and local (2–4 mm) measurements plasma density, potential electron temperature in the edge tokamak ASDEX Upgrade. Steady-state radial profiles demonstrate credibility ball-pen probe. We that floating fluctuations measured by a Langmuir probe are dominated rather than potential. Spatial temporal scales found consistent with expectations based interchange-driven turbulence. Conditionally averaged signals for both density also consistent;...
A new fireball configuration has been developed which produces vircator-like instabilities. Electrons are injected through a transparent anode into spherical plasma volume. Strong high-frequency oscillations with period corresponding to the electron transit time sphere observed. The frequency is below frequency, hence does not involve eigenmodes. support electromagnetic eigenmodes at instability frequency. However, rf on gridded create bunches reinforce grid oscillation after one or period,...
The medium size divertor tokamak ASDEX Upgrade (major and minor radii 1.65 m 0.5 m, respectively, magnetic-field strength 2.5 T) possesses flexible shaping versatile heating current drive systems. Recently the technical capabilities were extended by increasing electron cyclotron resonance (ECRH) power, installing 2 × 8 internal magnetic perturbation coils, improving ion range of frequency compatibility with tungsten wall. With reliable suppression large type-I edge localized modes (ELMs)...
Experimental results are presented on the generation and dynamics of concentric as well non-concentric multiple double layers in hot filament type discharge plasma. These emphasize striking similarities between both types layers, i.e. similar potential steps corresponding to ionization energy used gas, hysteresis cycles current–voltage characteristic exciting electrode, dynamic behaviour, etc. The show that a common physical mechanism is at origin phenomena, which electron-neutral impact...
Abstract We report a study of electron saturation current variations at varying probe heating that were found to be closely related wire contamination. The was performed in three types low temperature argon plasma – the weakly magnetized cylindrical magnetron, non‐magnetized double machine and hollow cathode jet, showing different trends. In present work effect overestimation potential by strongly emitting is discussed experimental data are compared with theoretical model. (© 2008 WILEY‐VCH...
See also companion Transit time instabilities in an inverted fireball. I. Basic properties
Magnetically confined plasmas in the high confinement regime are regularly subjected to relaxation oscillations, termed edge localized modes (ELMs), leading large transport events. Present ELM theories rely on a combined effect of current and pressure gradients which result intermediate mode number (n≅10-15) structures (filaments) perpendicular plane extended along field lines. By detailed measurements magnetic perturbation associated type-I filaments, it is shown that these filaments carry...
Emissive probes are standard tools in laboratory plasmas for the direct determination of plasma potential. Usually they consist a loop refractory wire heated by an electric current until sufficient electron emission. Recently emissive were used also measuring radial fluctuation-induced particle flux and other essential parameters edge turbulence magnetized toroidal hot [R. Schrittwieser et al., Plasma Phys. Controlled Fusion 50, 055004 (2008)]. We have developed investigated various types...
Fireballs are luminous regions produced by double layers in front of positively biased electrodes plasmas. Although fireballs have been investigated previously there a great variety unexplained nonlinear phenomena, some which addressed this work. First, it is shown that fireball not an isolated local phenomenon but integral part the entire discharge plasma. Current closure and limits discussed. with currents from milliamperes to tens amperes created depending on whether electron source...
Abstract Emissive probes offer the possibility for a direct determination of plasma potential since sufficient electron emission its floating is ideally equal to Φ pl . By means two such true electric field can be derived. also deliver reliable results if there are drifts and beams in plasma. A conventional emissive probe consists an electrically heated loop refractory wire. We have developed pin graphite or LaB6, by focused infrared laser beam. In this contribution we first discuss question...
The ball-pen probe (BPP) technique is used successfully to make profile measurements of the electron temperature on ASDEX Upgrade (Axially Symmetric Divertor Experiment), COMPASS (COMPact ASSembly), and ISTTOK (Instituto Superior Tecnico TOKamak) tokamak. provided by a combination BPP potential (ΦBPP) floating (Vfl) Langmuir (LP), which compared with Thomson scattering diagnostic COMPASS. Excellent agreement between two diagnostics obtained for circular diverted plasmas different heating...
A probe array consisting of three emissive probes and one cold cylindrical was developed for edge plasma measurements in ISTTOK. Emissive are particularly suitable turbulence studies as they able to deliver a more accurate measure the potential by reducing effect temperature fluctuations. The has advantage recording density, electric field their fluctuations simultaneously. Radial profiles were recorded with without negative biasing an electrode. statistical properties poloidal turbulent...
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...
We report experimental results and theoretical modeling showing the interaction between two fireballs excited on positively biased electrodes immersed in a low-temperature plasma. This leads to synchronized dynamics of fireballs, its frequency depending plasma density, voltages applied electrodes, distance electrodes. By considering that particles (electrons, ions, neutrals) move fractal curves, model describing is developed. The were found be good agreement with results.
The plasma potential Φpl and its fluctuations Φ̃pl were measured by electron emissive probes in the edge regions of two fusion experiments: Instituto Superior Técnico Tokamak (ISTTOK) (Lisbon, Portugal), Czech Academy Sciences Torus (CASTOR) tokamak (Prague, Republic). Into ISTTOK, three inserted outside last closed flux surface (LCFS) on different minor radii. In CASTOR, probes, poloidally separated, cold cylindrical mounted same shaft, used, which could be radially shifted inside LCFS....