A5030494589- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Nuclear Physics and Applications
- Physics of Superconductivity and Magnetism
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Radioactive contamination and transfer
- Gyrotron and Vacuum Electronics Research
- Fish Ecology and Management Studies
- GaN-based semiconductor devices and materials
- Quantum chaos and dynamical systems
- Semiconductor materials and devices
- Magnetic Field Sensors Techniques
- Coastal and Marine Management
- Radiation Detection and Scintillator Technologies
- Spacecraft and Cryogenic Technologies
- Electron and X-Ray Spectroscopy Techniques
- Electromagnetic Launch and Propulsion Technology
Culham Centre for Fusion Energy
1996-2021
Culham Science Centre
2000-2021
Czech Academy of Sciences, Institute of Plasma Physics
2021
Czech Academy of Sciences
2021
Indiana University Bloomington
2012
Energy Institute
2002
General Atomics (United States)
1982-1999
United Kingdom Atomic Energy Authority
1981-1997
Fusion UK
1992-1995
Ricardo AEA (United Kingdom)
1991
Experimental results from the COMPASS-C tokamak reveal a sharp threshold in amplitude above which externally applied static resonant magnetic perturbations (RMPs) induce stationary islands. Such islands (in particular, m=2, n=1 islands) give rise to significant degradation energy and particle confinement, suppression of sawtooth oscillation large change impurity ion toroidal velocity. The observed for inducing (2,1) is consistent with phenomenological resistive MHD model takes into account...
Otherwise stable discharges can become nonlinearly unstable to disruptive locked modes when subjected a resonant m=2, n=1 error field from irregular poloidal coils, as in DIII-D [Nucl. Fusion 31, 875 (1991)], or magnetic perturbation coils COMPASS-C [Proceedings of the 18th European Conference on Controlled and Plasma Physics, Berlin (EPS, Petit-Lancy, Switzerland, 1991), Vol. 15C, Part II, p. 61]. Experiments Ohmically heated deuterium with q≊3.5, n̄ ≊ 2 × 1019 m−3 BT 1.2 T show that much...
COMPASS Upgrade is a new medium size, high magnetic field tokamak (R = 0.9 m, Bt 5 T, Ip 2 MA) currently under design in the Czech Republic. It will provide unique capabilities for addressing some of key challenges plasma exhaust physics, advanced confinement modes and configurations as well testing facing materials liquid metal divertor concepts. This paper contains an overview preliminary engineering main systems (vacuum vessel, central solenoid poloidal coils, toroidal support structure,...
This article describes the DEMO cryostat, vacuum vessel, and tokamak building as well system configurations to integrate main in-vessel components auxiliary systems developed during Pre-Conceptual Design Phase. The vessel is primary component for radiation shielding containment of tritium other radioactive material. Various required operate plasma are integrated in its ports. together with external magnetic coils located inside even larger cryostat that has function provide a enable...
Simple scaling laws for the ideal-MHD β-limit (βc) as a function of plasma shape parameters (inverse aspect ratio ε, elongation κ, and triangularity δ) in range covered by recent high-β (≤ 4.5%) experiments Doublet III are derived. β-limits obtained optimizing current profile. A large class profiles is considered. presented single Gaussian profile they do not significantly improve with more elaborate profiles. Excluding region dominated sawtooth activity, experimental values exceed n = ∞...
The poloidal distribution of the halo current density on top dump plate in JET can now be measured thanks to a new set Rogowskii coils. These are first measurements able offer an insight width interaction with wall. Therefore they both validation assumption made for disruption design criteria and one additional point extrapolation expected width, hence (and related local electro-mechanical loads in-vessel components) ITER. During upward events, is consistent total current. footprint extends...
The question of the influence nonaxisymmetric field perturbations on tokamaks is investigated. Recent experiments in COMPASS-C tokamak [in Proceedings 15th Symposium Fusion Technology, Utrecht (North-Holland, Amsterdam, 1989), Vol. 1, p. 361] with externally applied helical fields reveal that magnetic islands do not appear until exceeds a certain value, when plasma rotation and confinement are affected. A new resistive magnetohydrodynamic model including now provides an explanation this...
Using a neutral-beam injection power of 3.4 M W, volume-averaged toroidal betas up to ⟨βT⟩ = 4.5% have been obtained in low-toroidal-field, low-qψ, vertically elongated discharges the Doublet III tokamak. This level is above minimum required for tokamak reactor, thus demonstrating that reactor values are possible device. The observed enhancement with vertical elongation lends confidence design future devices which rely on elongation.
The Indiana University Low Energy Neutron Source (LENS) production target was recently upgraded to handle the high power 13 MeV proton pulsed beam. target, a 2 inch diameter beryllium disk, is 1.2 millimeters thick allowing protons pass completely through and stop in cooling water eliminating buildup of inside beryllium. This change along with upgrading system has produced most reliable date for LENS operations. Details about failure modes will be presented.
Optimization of the higher order moments—specifically squareness—of a tokamak cross-section can significantly enhance stability to ideal magnetohydrodynamic ballooning and kink modes. At conventional aspect ratios, it is shown that access second regime facilitated by moderate squareness. In low ratio, fully bootstrap current driven spherical torus, optimization squareness results in an increase β 10%, leading configuration stable ballooning, axisymmetric, n⩽5 modes at β≃67%.
The observation of a plasma current generated by the absorption rf waves at electron cyclotron resonance is reported. flows in opposite directions on sides electron-cyclotron-resonance position, confirming that driven asymmetric heating distribution function. (\ensuremath{\sim}30 mA/W) varies linearly with microwave power and temperature inversely density.
Non-inductive current drive using second harmonic ECRH at both 28 GHz and 60 has been studied in the CLEO tokamak. At GHz, RF driven currents of up to 5 kA have observed e = 4 × 1018m−3 for 185 kW injected power, indicating an efficiency η ≡ eIRFR0/PRF 0.001 (1020 m−3, A, m, W−1). The scaled linearly with total plasma range 5-15 was maximized when cyclotron resonance located near centre plasma. Sawtooth activity normally strongly affected transient sawtooth stabilization often observed. With...
Indiana University is operating a Low Energy Neutron Source which provides cold neutrons for material research and neutron physics MeV energy the radiation effects studies. Neutrons are being produced by 13 proton beam incident on Beryllium target. The LENS Proton Delivery System (PDS) routinely at 25 mA 1.8% duty factor. RF system, consisting of three Litton 5773 klystron tubes 425 MHz 1 MW each, power AccSys Technology PL-13 LINAC. delivers up to 6 kilowatts Details spreading target...
For a two week period during the Joint European Torus (JET) 2012 experimental campaign, same high confinement plasma was repeated 151 times.The dataset analysed to produce probability density function (pdf) for waiting times between edge-localised instabilities ("ELMs").The result entirely unexpected.Instead of smooth single peaked pdf, succession 4-5 sharp maxima and minima uniformly separated by 7-8 millisecond intervals found.Here we explore causes this newly observed phenomenon, conclude...
The COMPASS-D tokamak has recently obtained H-mode plasmas in a single-null X-point configuration with no additional heating. Clear signatures have been observed including reduction Dalpha light and the unmistakable appearance of ELMs ELM-free periods. Recycling gas puff can play crucial roles achieving terminating H-modes. emergence distinct ELMs, from apparently-random fluctuations, background light, is usually one progression, taking some 10s ms rather than sudden discontinuity....
A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured full flux azimuthal loops divertor region. We focus on Joint European Torus where steady sustained over several seconds, during which ELMs are observed Be II emission at divertor. The analysed arise from intrinsic ELMing, that there no deliberate intent control ELMing process by external means. use ELM timings derived signal perform...
The CLEO device has been used to compare the confinement properties of a variety Ohmically heated toroidal configurations at same magnetic field. These include RFP and OHTE configurations, conventional tokamaks, novel helically assisted low-$q$ tokamak, an $l=3$ stellarator. plasma current density vary over 2 orders magnitude for different configurations. stellarator exhibits best energy time, ${\ensuremath{\tau}}_{E}$, but tokamak achieves $\ensuremath{\beta}{\ensuremath{\tau}}_{E}$ product.
A unique sequence of 120 almost identical plasmas in the Joint European Torus (JET) recently provided two orders magnitude more statistically equivalent data than ever previously available. The purpose was to study movement eroded plasma-facing material from JET's new Beryllium wall, but it has allowed statistical detection otherwise unobservable phenomenon. This includes a resonant-like waiting times between edge-localised plasma instabilities (ELMs), that must be mitigated or avoided large...
We focus on JET plasmas in which ELMs are triggered by pellets the presence of occur naturally. perform direct time domain analysis signals from fast radial field coils and toroidal full flux azimuthal loops. These toroidally integrating provide simultaneous high resolution measurements global plasma dynamics its coupling to control system. examine these where pellet injection is used trigger naturally occurring ELMs. Pellets whose size speed intended maximum local perturbation for ELM...