A5000387915- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Atomic and Molecular Physics
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Superconducting Materials and Applications
- Atomic and Subatomic Physics Research
- Atmospheric Ozone and Climate
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Pulsed Power Technology Applications
- Ion-surface interactions and analysis
- Nuclear physics research studies
- High-pressure geophysics and materials
- Spectroscopy and Laser Applications
- Laser Design and Applications
- Parallel Computing and Optimization Techniques
- Radiation Detection and Scintillator Technologies
- Diamond and Carbon-based Materials Research
Forschungszentrum Jülich
2004-2018
Royal Military Academy
1993
Culham Centre for Fusion Energy
1993
Oak Ridge National Laboratory
1992
École Normale Supérieure - PSL
1986-1989
Edge radial electric fields were induced in the edge of TEXTOR tokamak by means a polarization electrode order to study their influence on plasma profiles and its confinement. The studies include generation H-mode behaviour with either positive or negative polarity. Particle confinement (τp) deuterium impurity ions as well energy (τE) are investigated. For which remain below threshold for L-H transition, an interesting regime reduced particle without noticeable loss is found. A strong...
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.
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...
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...
An overview of the results obtained so far for radiative I-mode regime on upgraded Torus Experiment Technology Oriented Research (TEXTOR-94) [Proceedings 16th IEEE Symposium Fusion Engineering (Institute Electrical and Electronics Engineers, Piscataway, NJ, 1995), Vol. 1, p. 470] is given. This under quasistationary conditions with edge neon seeding in a pumped limiter tokamak circular cross section. It combines high confinement β (up to normalized beta, βn=2) low q values (down qa=2.8)...
The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment the plasma environment. successful merging two worlds has led to routine diagnostic procedures which have contributed enormously understanding underlying processes and also wide acceptance spectroscopy reliable method. In this paper three...
High-Z materials as tungsten are intended to be used in future fusion reactors due their low sputtering rates and high melting points. In this context the important question is whether use of high-Z compatible with concept a cold radiative boundary. To investigate local release transport behaviour impurities, Mo W test limiters were auxiliary heated discharges under different radiation scenarios neon seeding. addition, laser blow-off well xenon gas puffing performed. some particular...
The paper summarizes the main results obtained during first six months of experimental work on TEXTOR with ohmically heated plasmas. machine(R = 175 cm; a 45-50 cm) was operated at wall temperatures up to 303 oC hydrogen gas, toroidal field 2 T and maximum plasma current 500 kA, yielding central electron 1.2 keV, line-averaged densities 4 x 1013 cm-3 discharge durations 2.7 sec (for Ip⩽340 kA). Besides providing long-lasting reproducible plasmas for forthcoming interaction research,...
A new x-ray imaging crystal spectrometer (XICS) has been installed, aligned, and used during experimental campaigns on the WEST tokamak. It three interchangeable crystals for measuring Ar XVII, XVIII, Fe XXV spectra, respectively. patented rotating table holding is to monitor facing plasma remotely without changing position of camera. Here, focus made XVII spectrum, between 3.93 4.00 Å. The design diagnostic presented, a synthetic diagnostic, implemented with Python library ToFu, show...
The recent experiments on accumulative behaviour of heavy impurities in TEXTOR with test limiters molybdenum and tungsten puffing xenon are briefly reviewed. results the reconstruction transport coefficients high-Z ions accumulation stage presented. They confirm neoclassical nature convective particle transport, leading to peaking impurity density. A mechanism triggering accumulation, invoking temperature dependence flows impurities, is discussed threshold obtained compared experimental...
Dielectronic satellite spectra of heliumlike argon, recorded with a high-resolution x-ray crystal spectrometer at the National Spherical Torus Experiment, were found to be inconsistent existing predictions resulting in unacceptable values for power balance and suggesting unlikely existence non-Maxwellian electron energy distributions. These problems resolved calculations from new atomic code. It is now possible perform reliable electron-temperature measurements eliminate uncertainties...
Four new low field side antennae grouped in pairs have been installed on TEXTOR. It is found that the interaction with wall (density rise, impurity generation) significantly reduced when operating each pair out of phase ( pi ) as opposed to (0). The beneficial effect configuration obtained without drop plasma loading. This experimental property shown, from theory, be explained by judicious choice geometrical configuration. A further improvement made possible an appropriate conditioning (wall...
Fuelling efficiency is an important parameter in designing a massive gas injection system for suppression of runaway electrons ITER.In this work Z-dependence the fuelling measured TEXTOR.The dependence covers following gases: He, Ne, Ar, Kr, Xe and 10% Ar-D 2 mixture.It shown that significantly decreases with mass, from above 0.5 He to below 0.03 Xe.To explain variation mass pressure simple model flow valve plasma edge developed.The validated by using available laboratory measurements...
Time-resolved high-resolution soft x-ray spectra from gas-puff injected Ar impurity ions have been investigated for neutral beam heated and ohmically discharges in the TEXTOR tokamak. The experimental show systematic deviations corona model calculations line intensities of forbidden He-like lines x, y, z Li- Be-like dielectronic satellite spectra: theoretical predict significantly too low. High-intensity Li-like inner-shell excited satellites correlate with injection. discrepancies could...
The design for a set of four high-efficiency vacuum ultraviolet/extreme ultraviolet (VUV/XUV) spectrometers has been developed, which shall be used plasma impurity monitoring and transport studies on the stellarator experiment Wendelstein 7-X (W7-X). new XUV overview spectrometer (HEXOS) system covers wavelength range from 2.5 to 160 nm, divided into subsections with some overlapping, thus achieving complete coverage prominent spectral lines relevant elements. Taking account geometries...
Recently, the dynamic ergodic divertor (DED) of TEXTOR has been studied in an m/n = 3/1 set-up which is characterized by a relatively deep penetration perturbation field. The field creates (a) helical divertor, (b) pattern and/or (c) excitation tearing modes, depending on whether DED current static, rotating co-current direction or counter-current direction. Characteristic properties such as high recycling regime enhanced shielding have studied. A strong effect ergodization spin up plasma...
Ion cyclotron heating on TEXTOR has now reached the Megajoule level. The scenario is normally mode conversion but occasionally minority in a D-(H) plasma. With appropriate wall conditioning by carbonization more than 1 MW of RF power been injected for long pulse durations ( approximately s). ICRF heated plasma characterized quasi-stationarity all parameters, little if no impurity increase and loop voltage reduction resulting total coupled to reaching six times remaining ohmic input. Evidence...
Spectra of the 1s-2p resonance line helium-like argon, Ar XVII, and associated satellites in narrow wavelength range from 3.9494 Å to 3.9944 have been observed at TEXTOR-94 with two high-resolution x-ray crystal spectrometers Bragg angles near 54 degrees. Together, these instruments can be used as an polarimeter. The are very sensitive small amounts argon; thus, a count rate 4 × 105 photons/s, which corresponds maximum capability presently detectors, obtained for argon densities less than...
Collapse events at the q = 2 surface occurring during mode locking process of an m / n 2/1 tearing have been observed on TEXTOR. The plasma confinement within collapses without much influence width island (O-point). With external rotating resonant magnetic perturbation (RMP) field induced by dynamic ergodic divertor, secondary structures moving near separatrix primary large with same frequency as RMP after collapse events. recovers when vanish.
A fast camera system is being prepared for the TEXTOR tokamak investigation of magnetohydrodynamics (MHD) instabilities. The will consist a scintillator screen conversion x rays into visible light, fiberoptic cable transport images out Textor magnetic field, an electrostatic image converter amplification and demagnification images, charge-coupled device (CCD) capturing storing data. purpose our two-dimensional imaging islands structure MHD In order to increase signal intensity simultaneously...
The radiative improved mode obtained on the limiter tokamak TEXTOR-94 combines possibility of power exhaust by a radiating plasma boundary (with fraction radiated with respect to total input up 90% neon or argon cooling) energy confinement (as good as in ELM-free H-mode divertor tokamaks) at high densities (line-averaged central-electron density equal even above Greenwald limit ) quasi-stationary discharges. An overview is given substantial changes plasma-edge properties occurring levels ....
A significant influence of the dynamic ergodic divertor (DED) on density limit in TEXTOR has been found. In Ohmic discharges, where without DED detachment normally arises at limit, a MARFE (multifaceted asymmetric radiation from edge) develops when is operated static regime. The threshold onset neutral beam heated plasmas increased by applying 1 kHz ac high-field side. theoretical predictions based parallel energy balance taking poloidal asymmetries into account agree well with experimental...
The TEXTOR research programme focuses on the systematic analysis of plasma wall interaction, development a suitable system and production quasi-stationary long-pulse high-temperature plasmas with tolerable impurity concentrations, well-defined boundary layer relevant particle power fluxes through boundary. authors describe method carbonization developed in Julich some characteristic features obtained this for both metal limiters graphite limiters. Moreover, effect ICRH heating (2 MW, 1 sec)...