A5025752420- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Magnetic Field Sensors Techniques
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Physics of Superconductivity and Magnetism
- Meteorological Phenomena and Simulations
- Plasma Diagnostics and Applications
- Optical Coatings and Gratings
- Seismic Imaging and Inversion Techniques
- Astronomical Observations and Instrumentation
- Non-Destructive Testing Techniques
- Advanced Optical Sensing Technologies
- High-pressure geophysics and materials
- Time Series Analysis and Forecasting
- Robotics and Automated Systems
- GNSS positioning and interference
- Infrared Target Detection Methodologies
- Copper Interconnects and Reliability
- Environmental Monitoring and Data Management
Max Planck Institute for Plasma Physics
2022-2025
Czech Academy of Sciences, Institute of Plasma Physics
2017-2025
Czech Technical University in Prague
2012-2021
Instruments Research & Development Establishment
1979
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 Understanding the transport processes that determine plasma profile widths in scrape-off layer (SOL) and divertor region of tokamaks is crucial for successful power particle exhaust management future devices. Plasma from SOL into Private Flux Region (PFR) broadens profiles could mitigate challenge. Analysis ion current profiles, measured by Langmuir probes ASDEX Upgrade (AUG) tokamak, shows width PFR, normalized flux expansion between outer target midplane, about \SI{1.5}{mm} L-mode...
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...
Abstract In future fusion reactors disruptions must be avoided at all costs. Disruptions due to the density limit (DL) are typically described by power-independent Greenwald scaling. Recently, a power dependence of disruptive DL was predicted several authors (Zanca et al 2019 Nucl. Fusion 59 126011; Giacomin 2022 Phys. Rev. Lett. 128 185003; Singh and Diamond Plasma Control. 64 084004; Stroth 62 076008; Brown Goldston 2021 Mater. Energy 27 101002). It is investigated whether this increases...
A new system of probes was recently installed in the divertor tokamak COMPASS order to investigate ELM energy density with high spatial and temporal resolution. The consists two arrays rooftop-shaped Langmuir (LPs) used measure floating potential or ion saturation current one array Ball-pen (BPPs) plasma a resolution ~3.5 mm. combination BPPs LPs yields electron temperature microsecond We report on design probe first results profile measurements ELMy H-mode L-mode. also present comparative...
Abstract This paper presents an overview of results from L–H transition experiments that were performed at ASDEX Upgrade (AUG) with the aim identifying underlying mechanisms leading to H-mode confinement. With a broad variety and new diagnostic techniques, as well modeling efforts, AUG has contributed substantially improving our understanding over past years. In this review, important roles ion heat channel edge radial electric field ( E r ) in physics are brought into context known...
Abstract A recently developed reduced model of H-mode sustainment based on interchange-drift-Alfvén turbulence description in the vicinity separatrix matching experimental observations ASDEX Upgrade has been extended to experiments with unfavorable <?CDATA $\nabla B$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">∇</mml:mi> <mml:mi>B</mml:mi> </mml:mrow> </mml:math> drift. The combination theory magnetic-shear-induced...
Abstract To achieve their goals, future thermonuclear reactors such as ITER and DEMO are expected to operate plasmas with a high magnetic field, triangularity confinement. address the corresponding challenges, concept of high-field ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mtext>T</mml:mtext> </mml:mrow> </mml:msub> <mml:mtext>⩽</mml:mtext> </mml:math> 5 T), high-current <mml:mi>I</mml:mi>...
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...
Abstract An analytical formula systematically predicts the observed frequency of pressure relaxation limit cycle oscillations in vicinity transition to high confinement four tokamaks (JET, ASDEX Upgrade, COMPASS, Globus-M). The experimental dataset spans widest available range frequencies, machine sizes and plasma ion species. size dependence is explained by connection length scale flows parallel magnetic field. model also explains up-down poloidal current asymmetry impact species mass charge.
Abstract WEST database analysis shows a correlation of the recycled neutral source around separatrix with core performances. This observation questions causality chain between particle and turbulent transport up to in L-mode, high recycling plasmas, an unavoidable phase all scenarios. The best performances correlate lowest values density at separatrix, <?CDATA ${n_{{\text{sep}}}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub>...
This contribution presents the experimentally observed edge plasma evolution during limit cycle oscillations (LCO) measured with a new Langmuir and ball-pen multi-pin probe head at COMPASS tokamak. The LCO regime modulates intensity of density fluctuations , radial electric field Er emission frequency 3–5 kHz. grow after decreases in strength which appears to be strongly correlated pressure gradient . magnetic signature shows left–right asymmetry propagation from low high side....
Abstract This work presents the first analysis of disruptive locked mode (LM) triggered by dynamics a confinement change. It shows that, under certain conditions, LM threshold during transient is significantly lower than expected from steady states. We investigate sensitivity to controlled n = 1 error field (EF) activated prior L-H transition in COMPASS tokamak, at q 95 ∼ 3, β N 1, and using EF coils on high-field side vessel. A for penetration subsequent identified, which no significant...
The COMPASS tokamak at IPP Prague is a small-size device with an ITER-relevant plasma geometry and operating in both the Ohmic as well neutral beam assisted H-modes since 2012. A basic set of diagnostics installed beginning operation has been gradually broadened type diagnostics, extended number detectors collected channels improved by increased data acquisition speed. In recent years, significant progress diagnostic development motivated performance broadening its scientific programme (L-H...
Abstract Experiments on nitrogen assisted divertor detachment in the improved energy confinement mode (I-mode) are reported from ASDEX Upgrade tokamak. When is introduced into and radiation losses cool plasma down, a loss of core observed, concomitant with an increase low frequency edge fluctuation levels. The can be compensated I-mode maintained by additional heating power input. Detachment inner leg has been observed for first time discharge. outer remains attached these experiments. Good...
The ITER outer vessel steady-state magnetic field sensor diagnostics consist of sixty units. Each unit features a pair ceramic-metal Hall sensors with sensing layer made bismuth. were tested simultaneously in the ranging from -12 T to +12 at temperature range 27 127 °C. coefficient and magnetoresistance bismuth related identified. In operating conditions, dependence on was fitted an exponential function relative error less than 0.08%, Gaussian-like 0.11%. An alternative expression based...
Abstract COMPASS addressed several physical processes that may explain the behaviour of important phenomena. This paper presents results related to main fields research obtained in recent two years, including studies turbulence, L–H transition, plasma material interaction, runaway electron, and disruption physics: Tomographic reconstruction edge/SOL turbulence observed by a fast visible camera allowed visualize turbulent structures without perturbing plasma. Dependence power threshold on...