A5054179864- Magnetic confinement fusion research
- Fusion materials and technologies
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Nuclear reactor physics and engineering
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Atomic and Subatomic Physics Research
- Plasma Diagnostics and Applications
- Medical Imaging Techniques and Applications
- Seismic Imaging and Inversion Techniques
- Radiation Detection and Scintillator Technologies
- Solar and Space Plasma Dynamics
- Physics of Superconductivity and Magnetism
- Particle Detector Development and Performance
- Cold Fusion and Nuclear Reactions
- High-Energy Particle Collisions Research
- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray and CT Imaging
- Atomic and Molecular Physics
- Wireless Sensor Networks for Data Analysis
- Advanced MRI Techniques and Applications
- Radiation Therapy and Dosimetry
- Advanced Optical Sensing Technologies
Czech Academy of Sciences, Institute of Plasma Physics
2014-2024
Czech Technical University in Prague
2011-2024
CEA Cadarache
2012-2024
National Centre for Nuclear Research
2018-2021
Royal Military Academy
2020
Culham Science Centre
2004-2019
Max Planck Society
2014-2016
Max Planck Institute for Plasma Physics
2016
Charles University
2007-2016
University of Southampton
2016
The behaviour of tungsten in the core hybrid scenario plasmas JET with ITER-like wall is analysed and modelled a combination neoclassical gyrokinetic codes. In these discharges, good confinement conditions can be maintained only for first 2?3?s high power phase. Later W accumulation regularly observed, often accompanied by onset magneto-hydrodynamical activity, particular tearing modes (NTMs), both which have detrimental effects on global energy confinement. dynamics process examined, taking...
The W-transport in the core plasma of JET is investigated experimentally by deriving W-concentration profiles from modelling signals soft x-ray cameras. For case pure neutral beam heating W accumulates (r/a < 0.3) approaching W-concentrations 10−3 between sawtooth crashes, which flatten W-profile to a concentration about 3 × 10−5. When central Ion cyclotron resonant additionally applied decays phases that exhibit changed mode activity, while also electron temperature increases and density...
Disruptions are a major operational concern for next generation tokamaks, including ITER.They may generate excessive heat loads on plasma facing components, large electromagnetic forces in the machine structures and several MA of multi-MeV runaway electrons.A more complete understanding processes methods to suppress them is necessary ensure safe reliable operation future tokamaks.Runaway electrons were studied at JET-ILW showing that their dependencies (accelerating electric field, avalanche...
Recent developments in theory-based modelling of core heavy impurity transport are presented, and shown to be necessary for quantitative description present experiments JET ASDEX Upgrade. The treatment impurities is complicated by their large mass charge, which result a strong response plasma rotation or any small background electrostatic field the plasma, such as that generated anisotropic external heating. These forces lead poloidal asymmetries density, have recently been added numerical...
This paper summarizes the status of COMPASS tokamak, its comprehensive diagnostic equipment and plasma scenarios as a baseline for future studies. The former COMPASS-D tokamak was in operation at UKAEA Culham, UK 1992–2002. Later, device transferred to Institute Plasma Physics Academy Sciences Czech Republic (IPP AS CR), where it installed during 2006–2011. Since 2012 has been full with Type-I Type-III ELMy H-modes base scenario. enables together ITER-like shape flexible NBI heating system...
Abstract Ion cyclotron resonance frequency (ICRF) heating has been an essential component in the development of high power H-mode scenarios Jet European Torus ITER-like wall (JET-ILW). The ICRF performance was improved by enhancing antenna-plasma coupling with dedicated main chamber gas injection, including preliminary minimization RF-induced plasma-wall interactions, while RF where optimized for core impurity screening terms ion position and minority hydrogen concentration. impact on...
Abstract A series of experiments have been executed at JET to assess the efficacy newly installed shattered pellet injection (SPI) system in mitigating effects disruptions. Issues, important for ITER disruption mitigation system, such as thermal load mitigation, avoidance runaway electron (RE) formation, radiation asymmetries during quench electromagnetic control and RE energy dissipation addressed over a large parameter range. The efficiency has examined various SPI strategies. paper...
A steady-state, fully noninductive plasma current has been sustained for the first time in a tokamak using electron cyclotron drive only. In this discharge, 123 kA of have entire gyrotron pulse duration 2 s. Careful distribution across minor radius power deposited from three 0. 5-MW gyrotrons was essential reaching steady-state conditions. With central drive, up to 153 replaced transiently 100 ms. The scenario is confirmed by ability recharge Ohmic transformer. dependence efficiency on also...
Extensive analysis of disruptions in JET has helped advance the understanding trends disruption-generated runaway electrons. Tomographic reconstruction soft x-ray emission made possible a detailed observation magnetic flux geometry evolution during disruptions. With aid and hard diagnostics electrons have been detected at very beginning A study electron parameters shown that an approximate upper bound for conversion efficiency pre-disruptive plasma currents into runaways is about 60% over...
Retrieving spatial distribution of plasma emissivity from line integrated measurements on tokamaks presents a challenging task due to ill-posedness the tomography problem and limited number lines sight. Modern methods therefore implement a-priori information as well constraints, in particular some form penalisation complexity. In this contribution, current under development (Tikhonov regularisation, Bayesian neural networks) are briefly explained taking into account their potential for...
The role of the COMPASS tokamak in research generation, confinement and losses runaway electron (RE) population is presented. Recently, two major groups experiments aimed at improved understanding control REs have been pursued. First, effects massive gas injection ( Ar/Ne particles) impurity seeding were studied systematically. observed phenomena include generation post-disruption RE beam current conversion from plasma to RE. Zero loop voltage was implemented order study decay simplified...
Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. elongation, 1.1 < κ< 2.15, and triangularity, -0.65 ⩽ δ 0.55. The energy confinement time found to increase with owing part the current elongation. beneficial effect negative triangularities most effective at low power tended decrease higher powers used. large variety sawtooth types observed for different deposition locations, from on-axis q = 1 region, simulated model that included local...
This paper is focused on the soft x-ray (SXR) tomography system setup at Tore Supra (DTOMOX) and recent developments made to automatically get precise information about plasma features from inverted data. The first part describes main aspects of tomographic inversion optimization process. Several observations are using this new tool a set shape factors defined help characterizing emissivity field in real-time perspective. second presents detailed off-line analysis comparing positions...
Abstract The paper presents an overview of the design status Radial Neutron Camera (RNC), that, together with Vertical Camera, will provide, through reconstruction techniques applied to measured line-integrated neutron fluxes, time resolved measurement ITER and α-source profile (i.e. emissivity, neutrons emitted per unit volume). RNC is composed two subsystems, In-Port Ex-Port located, respectively, inside outside Plug Equatorial Port #01. subsystem in a more advanced stage since it has...
Post-disruption runaway electron (RE) beams in tokamaks with large current can cause deep melting of the vessel and are one major concerns for ITER operations. Consequently, a considerable effort is provided by scientific community order to test RE mitigation strategies. We present an overview results obtained at FTU TCV controlling position improve safety repeatability studies such as massive gas (MGI) shattered pellet injections (SPI). show that proposed beam controller (REB-C) implemented...
Radiation asymmetries during disruption mitigation by massive gas injection (MGI) can result in substantial first wall heat loads ITER and have, therefore, to be minimised. This paper gives a analysis of the relation between magnetohydrodynamic instabilities governing thermal quench (TQ) toroidal distribution radiated power MGI experiments at JET. It is found that radiation asymmetry closely linked phase mode. The mode phase, on other hand, influenced itself, with O-point being displaced...
Experiments with high-power electron cyclotron heating (ECH) and current drive (ECCD) in the TCV tokamak are discussed. Power up to 2.7 MW from six gyrotrons is delivered at second-harmonic frequency (82.7 GHz) X-mode. The power transmitted plasma by independent launchers, each equipped steerable mirrors that allow a wide variety of injection angles both poloidal toroidal directions. Fully non-inductive operation has been achieved steady state, for full 2 s gyrotron pulse duration, co-ECCD...
The significant role of magnetic perturbations in mitigation and losses runaway electrons (REs) was documented dedicated experimental studies RE at the COMPASS tokamak. REs are produced both low density quiescent discharges disruptions triggered by massive gas injection (MGI). seed beginning discharge on subsequent population proved significant. Modulation MHD instabilities observed several characteristic frequencies, as well field oscillations related to power supplies. Magnetic islands...
This paper presents two scenarios used for generation of a runaway electron (RE) beam in the COMPASS tokamak with focus on decay phase and control beam. The first scenario consists massive gas injection argon into current ramp-up phase, leading to disruption accompanied by plateau generation. In second scenario, smaller amount is order isolate RE from high-temperature plasma. performances radial vertical position feedback were experimentally studied analysed. role energy stability seems be...