A5079335141- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Nuclear Physics and Applications
- Plasma Diagnostics and Applications
- Fluid Dynamics and Turbulent Flows
- Nuclear Engineering Thermal-Hydraulics
- Dust and Plasma Wave Phenomena
- Geomagnetism and Paleomagnetism Studies
- Atomic and Molecular Physics
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Physics of Superconductivity and Magnetism
- High-Energy Particle Collisions Research
- Meteorological Phenomena and Simulations
- Tropical and Extratropical Cyclones Research
- Particle Dynamics in Fluid Flows
- Characterization and Applications of Magnetic Nanoparticles
- Nuclear Materials and Properties
Culham Science Centre
2016-2025
Culham Centre for Fusion Energy
2014-2025
United Kingdom Atomic Energy Authority
1995-2024
National Centre for Nuclear Research
2021
Royal Military Academy
2020
Universitat Politècnica de Catalunya
2020
Barcelona Supercomputing Center
2020
The University of Texas at Austin
2004-2017
Oak Ridge National Laboratory
2017
Fusion (United States)
1995-2017
This chapter reviews the progress accomplished since redaction of first ITER Physics Basis (1999 Nucl. Fusion 39 2137–664) in field energetic ion physics and its possible impact on burning plasma regimes. New schemes to create ions simulating fusion-produced alphas are introduced, accessing experimental conditions direct relevance for plasmas, terms Alfvénic Mach number normalised pressure gradient ions, though orbit characteristics size cannot always match those ITER. Based theoretical...
High fusion power experiments using DT mixtures in ELM-free H mode and optimized shear regimes JET are reported. A of 16.1 MW has been produced an at 4.2 MA/3.6 T. The transient value the amplification factor was 0.95±0.17, consistent with high nDT(0)τEdiaTi(0) = 8.7 × 1020±20% m-3 s keV, maintained for about half energy confinement time until excessive edge pressure gradients resulted discharge termination by MHD instabilities. ratio DD to powers (from separate but otherwise similar...
Experiments were carried out in the JET tokamak to determine critical ion temperature inverse gradient length (R/LTi=R|nablaTi|/Ti) for onset of modes and stiffness Ti profiles with respect deviations from value. Threshold have been compared linear nonlinear predictions gyrokinetic code GS2. Plasmas higher values toroidal rotation show a significant increase R/LTi, which is found be mainly due decrease level. This finding has implications on extrapolation future machines present day results...
This paper describes advances made in the field of energetic-particle physics since topical review Alfvén eigenmode observations toroidal plasmas (Wong 1999 Plasma Phys. Control. Fusion 41 R1–R56). The development plasma confinement scenarios with reversed magnetic shear and significant population energetic particles, novel diagnostics were main milestones past decade, these are experimental subjects this review. theory cascade eigenmodes reversed-shear tokamaks its use magnetohydrodynamic...
This paper discusses the behaviour and consequences of expected populations energetic ions in ITER plasmas. It begins with a careful analytic numerical consideration stability Alfvén Eigenmodes 15 MA baseline scenario. The threshold is determined by balancing ion drive against dominant damping mechanisms it found that only outer half plasma (r/a>0.5) can fast overcome thermal Landau damping. spite reduced numbers alpha-particles beam this region but means any Eigenmode-induced...
Abstract The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with ITER-like Be/W wall. development started pure Deuterium refinement of current, and toroidal magnetic field choices succeeded solving heat load challenges arising 37 MW injected power ITER like environment, keeping radiation edge core controlled, avoiding MHD instabilities reaching high neutron rates. have re-run Tritium...
Alfv\'en spectra in a reversed-shear tokamak plasma with population of energetic ions exhibit quasiperiodic pattern primarily upward frequency sweeping (Alfv\'en cascade). Presented here is an explanation for such asymmetric behavior which involves finding new particle mode localized around the point zero magnetic shear.
Physics knowledge (theory and experiment) in energetic particles relevant to design of a reactor scale tokamak is reviewed, projections for ITER are provided this Chapter the Basis. The review includes single particle effects such as classical alpha heating toroidal field ripple loss, well collective instabilities that might be generated plasmas by particles. overall conclusion fusion expected provide an efficient plasma ignition sustained burn next step device. major concern localized heat...
Persistent rapid up and down frequency chirping modes with a toroidal mode number of zero (n = 0) are observed in the JET tokamak when energetic ions, range several hundred keV, created by high field side ion cyclotron resonance heating. Fokker–Planck calculations demonstrate that heating method enables formation an energetically inverted distribution which supplies free energy for ions to excite related geodesic acoustic mode. The large shifts this attributed phase space structures whose...
Experiments designed for generating internal transport barriers in the plasmas of Joint European Torus [JET, P. H. Rebut et al., Proceedings 10th International Conference, Plasma Physics and Controlled Nuclear Fusion, London (International Atomic Energy Agency, Vienna, 1985), Vol. I, p. 11] reveal cascades Alfvén perturbations with predominantly upward frequency sweeping. These experiments are characterized by a hollow plasma current profile, created lower hybrid heating drive before main...
We present the results of experiments in JET to study effect plasma shape on high density ELMy H-modes, with geometry magnetic boundary similar that envisaged for standard Q = 10 operation ITER. The described are single lower null plasmas, q profile, neutral beam heating and gas fuelling, average triangularity δ calculated at separatrix ~0.45-0.5 elongation κ~1.75. In agreement previous obtained other divertor Tokamaks, thermal energy confinement time maximum achievable steady state a given...
The formation of internal transport barriers (ITBs) has been experimentally associated with the presence rational q surfaces in both JET and ASDEX Upgrade. triggering mechanisms are related to occurrence magneto-hydrodynamic (MHD) instabilities such as mode coupling fishbone activity. These events could locally modify poloidal velocity increase transiently shearing rate values comparable linear growth ion temperature gradient modes. For reversed magnetic shear scenarios, ITB emergence occurs...
This paper reports recent progress in the field of γ-ray diagnosis fast ions JET tokamak. The γ-rays, born nuclear reactions between and main plasma impurities and/or fuel ions, are analysed with a new modelling tool (the GAMMOD code) that has been developed for quantitative analysis measured energy spectra. spectra identifies different giving rise to emission assesses effective tail temperatures relative concentrations these ions. assessment is possible, since excitation functions well...
This Letter presents the first direct experimental measurements of damping toroidicity-induced Alfv\'en eigenmodes (TAE), carried out in JET tokamak. These were obtained during experiments to drive these modes with antennas external a tokamak plasma. Different regimes corresponding different dominant TAE absorption mechanisms wide range rates, ${10}^{\ensuremath{-}3}\ensuremath{\le}\ensuremath{\gamma}/\ensuremath{\omega}\ensuremath{\le}{10}^{\ensuremath{-}1}$, have been identified Ohmically...
Tokamak plasmas with reversed magnetic shear are prone to the excitation of Alfvén cascade (AC) eigenmodes by energetic particles. These modes exhibit a quasiperiodic pattern predominantly upward frequency sweeping. Observations also reveal that AC spectral lines sometimes bend at low frequencies, which is significant deviation from wave dispersion relation. This paper shows underlying reasons for such bending finite pressure plasma and geodesic curvature precludes perturbations being...
Neutral beam injection into reversed magnetic shear DIII-D and ASDEX Upgrade plasmas produces a variety of Alfvénic activity including toroidicity-induced Alfvén eigenmodes (RSAEs). These modes are studied during the discharge current ramp phase when incomplete penetration results in high central safety factor increased drive due to multiple higher order resonances. Scans injected 80 keV neutral power on showed transition from classical AE dominated fast ion transport and, as previously...
Remarkable progress has been made in diagnosing energetic particle instabilities on presentday machines and establishing a theoretical framework for describing them.This overview describes the much improved diagnostics of Alfvén modelling tools developed world-wide, discusses interpreting observed phenomena.A multi-machine comparison is presented giving information performance both different plasma conditions outlining expectations ITER based our present knowledge.
The JET exploitation plan foresees D–T operations in 2020 (DTE2). With respect to the first campaign 1997 (DTE1), when was equipped with a carbon wall, experiments will be conducted presence of beryllium–tungsten ITER-like wall and benefit from an extended improved set diagnostics higher additional heating power (32 MW neutral beam injection + 8 ion cyclotron resonance heating). There are several challenges presented by new wall: general deterioration pedestal confinement; risk heavy...
This paper summarizes the physical principles behind novel three-ion scenarios using radio frequency waves in ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for and fast-ion generation multi-ion species plasmas. The theoretical section provides practical recipes selecting plasma composition realize scenarios, including two equivalent possibilities choice resonant absorbers that have been identified....
Abstract In the paper we present an overview of interpretive modelling a database JET-ILW 2021 D-T discharges using TRANSP code. The main aim is to assess our capability computationally reproducing fusion performance various plasma scenarios different external heating and mixtures, understand driving mechanisms. We find that simulations confirm general power-law relationship between increasing power output, which supported by absolutely calibrated neutron yield measurements. A comparison...
Plasma configurations with shear reversal are prone to the excitation of unusual Alfvén eigenmodes by energetic particles. These modes exhibit a quasiperiodic pattern predominantly upward frequency sweeping (Alfvén cascades) as safety factor q changes in time. This work presents theory that employs two complementary mechanisms for establishing cascades: (1) nonstandard adiabatic response particles large orbits and (2) toroidal magnetohydrodynamic effects second-order inverse aspect ratio....