A5018779735- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Atomic and Molecular Physics
- Nuclear reactor physics and engineering
- Metal and Thin Film Mechanics
- Stellar, planetary, and galactic studies
- Laser Design and Applications
- Astronomy and Astrophysical Research
- High-Energy Particle Collisions Research
- Nuclear Materials and Properties
- Electromagnetic Launch and Propulsion Technology
- Geomagnetism and Paleomagnetism Studies
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Vacuum and Plasma Arcs
- Anomaly Detection Techniques and Applications
- Fluid Dynamics and Turbulent Flows
- Cosmology and Gravitation Theories
Forschungszentrum Jülich
2016-2024
Max Planck Institute for Plasma Physics
2018-2024
Huazhong University of Science and Technology
2018-2024
Plasma (Russia)
2023
Australian National University
2016-2021
Royal Military Academy
2020
Max Planck Society
2016-2018
Institute of Plasma Physics
2018
Chinese Academy of Sciences
2018
Oak Ridge National Laboratory
2016
Abstract The optimized superconducting stellarator device Wendelstein 7-X (with major radius , minor and plasma volume) restarted operation after the assembly of a graphite heat shield 10 inertially cooled island divertor modules. This paper reports on results from first high-performance operation. Glow discharge conditioning ECRH discharges in helium turned out to be important for density edge radiation control. Plasma densities with central electron temperatures were routinely achieved...
Abstract Fusion energy research has in the past 40 years focused primarily on tokamak concept, but recent advances plasma theory and computational power have led to renewed interest stellarators. The largest most sophisticated stellarator world, Wendelstein 7-X (W7-X), just started operation, with aim show that earlier weaknesses of this concept been addressed successfully, intrinsic advantages persist, also at parameters approaching those a future fusion plant. Here we first physics...
The Wendelstein 7-X (W7-X) optimized stellarator fusion experiment, which went into operation in 2015, has been operating since 2017 with an un-cooled modular graphite divertor. This allowed first divertor physics studies to be performed at pulse energies up 80 MJ, as opposed 4 MJ the phase, where five inboard limiters were installed instead of a This, and number other upgrades device capabilities, extension regimes higher plasma density, heating power, performance overall, e.g. setting new...
The investigation of edge plasmas at the stellarator W7-X requires a flexible tool for integration variety different diagnostics as e.g. electrical probes, probing magnetic coils, material collection, or exposition and gas injection. A multi-purpose manipulator (MPM) system has been developed attached to vessel before operational phase 1.1. was designed user facility many diagnostics, which can be mounted on unique interface without breaking vacuum. system, located in equatorial plane,...
Abstract Classical particle drifts are known to have substantial impacts on fluxes of particles and heat through the edge plasmas in both tokamaks stellarators. Here we present results from first dedicated investigation drift effects W7-X stellarator. By comparing similar plasma discharges conducted with a forward- reverse-directed magnetic field, could be isolated observation up-down asymmetries flux profiles divertor targets. In low-density plasmas, radial locations strike lines (i.e....
Abstract After a long device enhancement phase, scientific operation resumed in 2022. The main new components are the water cooling of all plasma facing and water-cooled high heat flux divertor units. Water allowed for first long-pulse campaign. A maximum discharge length 8 min was achieved with total heating energy 1.3 GJ. Safe demonstrated attached detached mode. Stable detachment is readily some magnetic configurations but requires impurity seeding small pitch angle within edge islands....
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...
The W7-X Scrape-Off Layer (SOL) with its characteristic magnetic island chain has been investigated using electric probes mounted on a reciprocating manipulator close to the outboard mid-plane.A survey of configuration space shows that presence and particular topology islands significantly affects SOL profiles electron temperature, density, field plasma flows.Particularly relevant for divertor operation, very wide heat flux have observed in some configurations, which we link islands.In these...
This paper reports on the design and performance of recently upgraded X-ray imaging spectrometer systems, crystal high resolution spectrometer, installed at optimized stellarator Wendelstein 7-X. High spectra highly ionized, He-like Si, Ar, Ti, Fe as well H-like Ar have been observed. A cross comparison ion electron temperature profiles derived from a spectral fit tomographic inversion shows reasonable match with both spectrometers. The also measured impurity density peaked densities radial...
We present a detailed overview and first results of the new laser blow-off system on stellarator Wendelstein 7-X. The allows impurity transport studies by repetitive controlled injection different tracer ions into plasma edge. A Nd:YAG is used to ablate thin metal film, coated glass plate, with repetition rate up 20 Hz. remote-controlled adjustable optical variation spot diameter enables positioning non-ablated areas target between pulses. During experiments, clear spectral lines from higher...
Abstract On the J-TEXT tokamak, dynamics of edge magnetic topology during opening islands induced by external Resonant Magnetic Perturbation (RMP) are investigated. The island chain is pushed outward increasing plasma toroidal current to intersect poloidally and toroidally localized divertor plate, forming an open in Scrape-Off Layer (SOL). location strike points on plate predicted HINT code agreement with experimental observations. influence profiles has also been investigated using...
Diverted plasmas in the stellarator W7-X are investigated using a hopping poloidal correlation reflectometer and set of Langmuir probes to investigate plasma edge scrape off layer at two different toroidal positions cross sections, respectively. The properties studied as function magnetic configurations parameters. experimentally determined radial position inversion point electric field is compared with calculations. For certain remnant island observed current. Different methods determine...
Abstract W7-X completed its plasma operation in hydrogen with island divertor and inertially cooled test unit (TDU) made of graphite. A substantial set plasma-facing components (PFCs), including particular marker target elements, were extracted from the vessel analysed post-mortem. The analysis provided key information about underlying plasma–surface interactions (PSI) processes, namely erosion, transport, deposition as well fuel retention graphite components. net carbon (C) erosion...
Wendelstein 7-X (W7-X), started operation in December 2015 with a limiter configuration. In conjunction the multi-purpose manipulator, carrier for fast reciprocating probe systems, combined has been installed. This is able to measure local electron temperatures and densities, magnetic field, electric field plasma flow. These parameters are very useful ascertaining edge perfomance. addition, line tracing feature of W7-X webservices was used calculate connection length along path probe, each
This paper proposes a new approach for the Power Spectrum (PS)-based feature extraction applied to probabilistic Laban Movement Analysis (LMA), sake of human behaviour understanding. A Bayesian network is presented understand action and based on 3D spatial data using LMA concept which known movement descriptor. We have two steps classification process. The first step estimating parameters are built describe motion situation by some low level features. Then having these parameters, it...
For the first operation phase of optimized stellarator W7-X, a heterodyne poloidal correlation reflectometry diagnostic is installed and put into operation. The system intended to measure perpendicular (with respect magnetic field) turbulence rotation properties, such as decorrelation time length at plasma edge. Furthermore, it can give information on field line pitch angle. consists an array microwave antennas distributed in toroidal directions. frequency range 22 GHz–40 GHz allows us...
A group of edge diagnostics and modelling has been developed for investigation synergy between 3D physics plasma-wall interactions on Wendelstein 7-X (W7-X). Two endoscopes have designed visible ultraviolet spectroscopy tomography the plasma edge, along with infrared thermography divertor tiles. 2D profiles impurities (e.g. helium, carbon) will be measured by two viewing island region in a spatial resolution <2 mm. multipurpose manipulator, which is used as carrier either probe head...
During its second operational campaign (OP 1.2a) W7-X operated with an edge island divertor. Much higher densities (1020m−3) than in to the previous, limiter were achieved. In order asses this improved performance and nature of transport regard expected other parameters such as electron ion temperature, electric field plasma flow, measurements at conducted reciprocating probe, mounted on a Manipulator. The probe contains set Langmuir pins, Mach probes, compensation coils 3D pick up for...
a versatile gas injection system and an absolute calibrated spectroscopic observation with more than 200 lines-of-sight have been installed in two divertor locations the Wendelstein 7-X stellarator. This powerful setup enables among other measurements to infer T e n region by means of line-ratio spectroscopy on thermal helium. is robust routinely used diagnostic at W7-X this work describes its main characteristics shows some examples profiles. In particular it shown that inclusion high...
Abstract The role of toroidal plasma currents for the island divertor scrape-off layer in stellarator Wendelstein 7-X is investigated using reciprocating electric probes. Experiments show that small amounts (of a few kA) current are sufficient to significantly affect conditions, whereas higher above 10kA result more drastic changes. This behavior linked effect on rotational transform profile, which can significant shifts edge magnetic islands. These interaction islands with and eventually...
Abstract To support the planning of high-performance long-pulse plasma operation for W7-X, role equilibrium effects structure island divertor and its profound impacts on heat flux distribution have been investigated. Finite-beta full-field three-dimensional equilibria four most important configurations W7-X (‘standard’, ‘high-mirror’, ‘high-iota’ ‘low-iota’) were obtained with HINT code. Equilibrium calculations show a strong dependence edge stochastization magnetic configurations....
This paper reports on the effect of on- and off-axis heating power deposition impurity confinement in purely electron cyclotron resonance heated He plasmas stellarator Wendelstein 7-X. Therefore, transport times τI have been determined after Fe injections by laser ablations monitoring temporal emissivities x-ray imaging spectrometer HR-XIS. A significant increase has observed when changing from to with energy τE being mainly unaffected. In addition, scaling properties respect a variation...
Wendelstein 7-X (W7-X) was operated successfully with the first divertor plasma in operation phase 1.2a (OP1.2a). A new combined probe head, developed and installed on multiple-purpose manipulator, is able to measure edge profiles (), variation of magnetic field, poloidal radial turbulence structures. The scrape-off layer (SOL) parameters two configurations (standard high mirror) are good agreement island structure field line connection length calculated by tracer. In both standard mirror...