A5021328492- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Laser-induced spectroscopy and plasma
- Superconducting Materials and Applications
- Meteorological Phenomena and Simulations
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- X-ray Spectroscopy and Fluorescence Analysis
- Radiation Detection and Scintillator Technologies
- Fluid Dynamics and Turbulent Flows
- Cold Fusion and Nuclear Reactions
- Laser Design and Applications
- Metallurgical Processes and Thermodynamics
- Climate variability and models
- Microbial infections and disease research
- Ion-surface interactions and analysis
- Dust and Plasma Wave Phenomena
- Financial Risk and Volatility Modeling
- Solid State Laser Technologies
HUN-REN Centre for Energy Research
2020-2025
HUN-REN Wigner Research Centre for Physics
2012-2023
Plasma Technology (United States)
2023
Fusion Academy
2023
University of Pecs
2020
General Atomics (United States)
2019
Max Planck Society
2019
Max Planck Institute for Plasma Physics
2019
Korea Institute of Fusion Energy
2018
Institute of Plasma Physics
2018
Abstract We present novel experimental evidence of parametric decay instability microwave beams in the plasma edge Wendelstein 7-X stellarator. propose that is sustained by trapping only one daughter wave non-monotonic density profile measured with high spatial resolution within a stationary magnetic island. The power levels and spectral shapes detected signal are reproduced numerical modelling theoretical threshold predicted around 300 kW, comparable observations. predict fraction drained...
The Alfvén instability nonlinearly excited the energetic-particle-driven geodesic acoustic mode on ASDEX-Upgrade tokamak, as demonstrated experimentally. mechanism of excitation and nonlinear evolution is not yet fully understood. In present work, a first-principles simulation using MEGA code investigated properties in both linear growth saturated phases. Here we show that successfully reproduced coexistence these two modes, agreed with experimental results well. Conclusive evidence showed...
Abstract Neoclassical Tearing Modes (NTMs) have been identified as the most deleterious perturbations in high-performance plasmas at Mega-Amp Spherical Tokamak Upgrade (MAST-U). They produce magnetic islands that flatten electron temperature profile and enhance fast-ion transport. Understanding NTM-induced losses can reveal paths to mitigate them, thus increasing energy available heat up plasma. The MAST-U loss detector (FILD) is equipped with a high-resolution camera high-speed...
The high-k () wavenumber spectrum of density fluctuations has been measured for the first time in MAST (Lloyd et al 2003 Nucl. Fusion 43 1665). This was accomplished with implementation Doppler backscattering (DBS) core measurements a spherical tokamak. DBS become well-established and versatile diagnostic technique measurement intermediate- k (, higher) flows magnetically confined fusion experiments. Previous implementations have standard, large aspect ratio tokamaks. A novel two-dimensional...
An avalanche photodiode based (APD) detector for the visible wavelength range was developed low light level, high frequency beam emission spectroscopy (BES) experiments in fusion plasmas. This solid state has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it internal gain. paper describes as well noise model of electronic circuit. By understanding sources amplification process, optimal amplifier APD reverse voltage setting can be determined, where...
Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that turbulence correlation time, drift time associated with ion temperature or gradients, particle (ion) streaming along magnetic field, and consistently comparable, suggesting a "critically balanced" determined by local equilibrium. The resulting scalings poloidal radial lengths derived tested. nonlinear inferred from is longer than other times; its ratio scales as...
Observations of ion-scale (kyρi ⩽ 1) density turbulence relative amplitude ≳0.2% are available on the Mega Amp Spherical Tokamak (MAST) using a 2D (8 radial × 4 poloidal channel) imaging beam emission spectroscopy diagnostic. Spatial and temporal characteristics this turbulence, i.e., amplitudes, correlation times, perpendicular lengths apparent phase velocities contours, determined by means analysis. For low-density, L-mode discharge with strong equilibrium flow shear exhibiting an internal...
A new beam emission spectroscopy turbulence imaging system has recently been installed onto the MAST spherical tokamak. The utilises a high-throughput, direct coupled optics, and single large interference filter for collection of Doppler shifted Dα from ∼2 MW heating ∼70 keV injection energy. collected light is imaged 2D array detector with 8 × 4 avalanche photodiode sensors which incorporated into custom camera unit to perform simultaneous 14-bit digitization at 2 MHz all 32 channels....
A diagnostic instrument is described for the Experimental Advanced Superconducting Tokamak (EAST) measurement of edge plasma electron density profile and turbulence properties. An accelerated neutral lithium beam injected into tokamak Doppler shifted 670.8 nm light emission Li2p-2s transition detected. novel compact setup used, where injection observation take place from same equatorial port radial-poloidal resolution achieved with microsecond time resolution. The direction optimized in...
Diagnosing the density profile at edge of high temperature fusion plasmas by an accelerated lithium beam is a known technique since decades. By knowledge relevant atomic physics rate coefficients, plasma electron can be calculated from relatively calibrated light along beam. Several additional possibilities have already been demonstrated: Charge Exchange Resonance Spectroscopy (CXRS) for ion temperature/flow and Zeeman polarimetry current; therefore Li-beam diagnostic offers wealth...
Abstract Experimental evidence of parametric decay instability (PDI) is observed in the Wendelstein 7-X stellarator, when high-power microwave beams cross a stationary magnetic island at plasma edge. Here, trapping and build-up upper hybrid waves within density bump (measured by alkali beam emission spectroscopy) responsible for reduction power threshold below maximum gyrotron power. In this paper, we provide first experimental connection between mechanism excitation PDI-related signals. We...
The mean motion of turbulent patterns detected by a two-dimensional beam emission spectroscopy (BES) diagnostic on the mega amp spherical tokamak (MAST) is determined using cross-correlation time delay method. Statistical reliability method studied means synthetic data analysis. experimental measurements MAST indicate that apparent poloidal density in lab frame arises because longest correlation direction (parallel to local background magnetic fields) not parallel fastest plasma flows...
A 60 keV neutral lithium beam system was designed and built up for emission spectroscopy measurement of edge plasma on the KSTAR EAST tokamaks. The electron density profile its fluctuation can be measured using accelerated beam-based system. thermionic ion source developed with a SiC heater to emit around 4-5 mA current from 14 mm diameter surface. optic is following 2 step design used other devices small modifications reach about 2-3 cm in at 4 m source. newly recirculating sodium vapour...
Abstract Filaments or blobs are well known structures in turbulence magnetic fusion devices, they considered to be the major cross-transport channel scrape off layer. They originate at last closed flux surface and propagate out on low field side of toroidal devices due polarization curved field. The Wendelstein 7-X stellarator has a complex three-dimensional structure additionally plasma is bounded by chain islands, forming an island divertor. After first observation filaments with video...
Beam emission spectroscopy (BES) of the energetic deuterium (D(0)) heating beams can provide a means characterizing density turbulence in tokamak plasmas. First such measurements have been performed on MAST spherical using trial BES system, which shares collection optics charge-exchange recombination system. This with eight spatial channels covering outer part plasma cross section, uses avalanche photodiode detectors custom preamplifiers to at 1 MHz bandwidth resolution 4 cm. Simulations...
A 60 kV neutral Li beam is injected into the edge plasma of JET to measure electron density. The observation system has been improved by replacing a Czerny-Turner spectrometer with high-resolution transmission-grating and fast back-illuminated frame-transfer camera. larger throughput spectrometer, increased sensitivity, faster readout new camera allow inter-ELM (edge localized mode) measurements (frame rate 100 Hz). calibration setup, as well an spectral fitting technique in presence carbon...
Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, measure the plasma electron density profile in edge and scrape off layer region. A light splitting optics system was installed into observation of lithium beam emission spectroscopy diagnostic at Joint European Torus (JET) tokamak, which allows simultaneous measurement with a spectrometer fast avalanche photodiode (APD) camera. The reconstruction ∼10 ms time resolution, absolute...
The fuelling of plasmas by shallow frozen pellets with simultaneous mitigation edge localised modes (ELM) external magnetic perturbation is demonstrated on the MAST tokamak. Post-pellet particle loss dominated ELMs and inter-ELM gas fuelling. It shown that size post-pellet can be controlled perturbations. remove particles from large part pellet deposition zone including area positive density gradient. mechanism explaining this peculiarity suggested.
Abstract A baseline scenario of deuterium–tritium (D–T) plasma with peripheral high-field-side fuelling pellets has been produced in JET order to mimic the situation ITER. The isotope mix ratio is controlled target value 50%–50% by a combination tritium gas puffing and deuterium pellet injection. Multiple factors controlling efficiency individual are analysed, following findings: (1) prompt particle losses due pellet-triggered edge-localised modes (ELMs) detected, (2) plasmoid drift velocity...
The beam emission spectroscopy (BES) turbulence diagnostic on MAST is to be upgraded in June 2010 from a one-dimensional trial system two-dimensional imaging (8 radial×4 poloidal channels) based newly developed avalanche photodiode array camera. spatial resolution of the new calculated terms point spread function account for effects field-line curvature, observation geometry, finite lifetime excited state atoms, and attenuation divergence. It found that radial ∼2-3 cm ∼1-5 depending viewing...
The sensitivity of two numerical methods for the detection zonal flows, especially geodesic acoustic modes (GAMs), through movement turbulence eddies is studied. One them widely used time delay estimation method which determines a propagation between measurement points. second technique based on analyzing movements minimum in autocorrelation function single signal (ACFM method). applicability both analyzed detail terms resolution, signal-to-noise ratio (SNR) and velocity modulation...