A5074011860- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Laser-induced spectroscopy and plasma
- Superconducting Materials and Applications
- Mathematical Biology Tumor Growth
- Nuclear Materials and Properties
- Non-Destructive Testing Techniques
- Gene Regulatory Network Analysis
- Gamma-ray bursts and supernovae
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear reactor physics and engineering
- Atomic and Molecular Physics
- Nonlinear Dynamics and Pattern Formation
- Electrostatic Discharge in Electronics
University of Alberta
2013-2024
University of Saskatchewan
2016-2021
Princeton Plasma Physics Laboratory
2013
Dutch Institute for Fundamental Energy Research
2013
Institute for Atomic and Molecular Physics
2010
Rensselaer Polytechnic Institute
1990-2005
Oak Ridge National Laboratory
1989-1995
Fusion Academy
1987-1994
Massachusetts Institute of Technology
1988-1989
The University of Texas at Austin
1989
JOREK is a massively parallel fully implicit non-linear extended MHD code for realistic tokamak X-point plasmas. It has become widely used versatile studying large-scale plasma instabilities and their control developed in an international community. This article gives comprehensive overview of the physics models implemented, numerical methods applied solving equations studies performed with code. A dedicated section highlights some verification work done hierarchy different available...
Plasma production and heating in the central cell of Tara tandem mirror [Nucl. Fusion 22, 549 (1982); Physics Controlled Nuclear Research, 1986, Proceedings 11th International Conference, Kyoto, Japan (IAEA, Vienna, 1987), Vol. 2, p. 251] have been studied. Using radio-frequency excitation by a slot antenna ion cyclotron frequency range (ICRF), plasmas with peak β⊥ 3%, density 4×1012 cm−3, temperature 800 eV, electron 75–100 eV were routinely produced. The plasma radius decreased increasing...
Accidental melting of metallic plasma-facing materials in future fusion devices poses serious issues regarding the material lifetime and power-handling capabilities as well core plasma performances. The behaviour aluminium (as a proxy for beryllium) tungsten was investigated Pilot-PSI linear device to study melt-layer motion droplet ejection under ITER-relevant conditions. Heat fluxes up 50 MW m−2 raised surface temperature values 5000 K. rotation found depend on magnetic field (up 1.6 T)...
A two-frequency correlation reflectometer has been operated on the Advanced Toroidal Facility (ATF) to measure plasma electron density fluctuations. This uses quadrature phase detection permit true measurement of reflected microwave signal (probing beam). By measuring fluctuations in probing beam, amplitude can be estimated. Simultaneous operation makes it possible coherence between at two radially separated cut-off layers, from which radial lengths and wavenumbers used study edge gradient...
We report on the generation of high transient heat and particle fluxes in a linear plasma device by pulsed operation source. A capacitor bank is discharged into source to transiently increase discharge current up 1.7 kA, allowing peak densities temperature 70×1020 m−3 6 eV corresponding surface power density about 400 MW m−2.
A divertor coil set has been installed on the Tara tandem mirror [Nucl. Fusion 22, 549 (1982); Plasma Physics and Controlled Nuclear Research 1984 (IAEA, Vienna, 1985), Vol. 2, p. 285] for stabilization of m=1 flutelike modes. The effectiveness is discussed in experiments where modes are driven to instability by plug electron cyclotron heating (ECH) an ion heated (ICH) plasma. onset characterized thresholds ECH power, fueling rate, ICH mapping radius null. In general, stability enhanced null...
Heavy ion beam probes (HIBPs) have proven to be a unique tool for measuring fluctuations and particle transport in tokamaks. They been used measure density, electric potential, magnetic vector potential. The density potential fluctuation measurements determined the flux due electrostatic turbulence TEXT ISX-B In these measurements, frequency spectra (0–500 kHz) of phase between wave numbers fluctuations, level are obtained. Three topics discussed this paper. We present during MHD activity...
The fluid theory of a new type electron temperature gradient instability is proposed. This mode closely related to the short wavelength Alfvén in regime k⊥2ρi2>1. Contrary standard modes, which are mostly electrostatic, considered fundamentally electromagnetic and does not exist electrostatic limit. mechanism relies on gradients both magnetic field. It suggested that this may be destabilizing for collisionless microtearing observed number gyrokinetic simulations.
Measurements were made of the return current instability growth rate, demonstrating its concurrence with nonlocal transport. Thomson scattering was used to measure a maximum rate 5.1×10^{9} Hz, which 3 times less than classical Spitzer-Härm theory predicts. The measured plasma conditions indicate heat flux nonlocal, and Vlasov-Fokker-Planck simulations that account for nonlocality reproduce rates. Furthermore, threshold (δ_{T}=0.017±0.002) be in good agreement previous theoretical models.
Recent experiments in the Advanced Toroidal Facility (ATF) torsatron [Plasma Physics and Controlled Nuclear Fusion Research 1990 (IAEA, Vienna, press)] have emphasized role of magnetic configuration control transport studies. Long-pulse plasma operation up to 20 sec has been achieved with electron cyclotron heating (ECH). With neutral beam injection (NBI) power ≥1 MW, global energy confinement times 30 msec obtained line-average densities 1.3×1020 m−3. The operational space ATF are roughly...
Installation of the HIBP on ATF began in summer 1988. All major hardware components have now been installed. The initial operation diagnostic has begun amid final stages testing and control system integration. existence significant magnetic fields gradients outside main plasma volume fully three-dimensional particle trajectories raised several interesting issues during design, assembly, alignment, beamline analyzer. must function a challenging environment. It perform satisfactorily despite...
In a recent study (K.J. Painter and T. Hillen, Spatio-temporal chaos in chemotaxismodel, Physica D, 240 (4), 363-375, 2011) model for chemotaxis incorporatinglogistic growth was investigated its pattern formation properties. particular,a variety of complex spatio-temporal patterning found, including stationary,periodic chaotic. Complicated dynamics appear to arise through asequence ``merging emerging'' events: the merging two neighbouringaggregates or emergence new aggregate an open space....
An absolute calibration of an installed heavy ion beam probe (HIBP) energy analyzer is possible by detecting secondary ions that come from a source at known location maintained potential. It also necessary the magnetic field exists during be same when plasma present. These conditions can met on stellarators, heliotrons, and torsatrons, which produce their configurations with external coil sets. Since no internal current required, suitable sources for producing interaction primary placed...
Density fluctuations in low-collisionality, low-beta (β∼0.1%), currentless plasmas produced with electron cyclotron heating (ECH) the Advanced Toroidal Facility (ATF) torsatron [Fusion Technol. 10, 179 (1986)] have been studied using a 2 mm microwave scattering diagnostic. Pulsed gas puffing is used to produce transient steepening of density profile from its typically flat shape; this leads growth when temperature and gradients both point same direction confinement region. The wave number...
The Advanced Toroidal Facility (ATF) torsatron [Fusion Technol. 10, 179 (1986)] has completed experiments focusing on microwave scattering measurements of density fluctuations and transport studies utilizing the modulation dimensionless parameters. Microwave electron in core low-collisionality cyclotron heated (ECH) plasmas show features that might be evidence trapped instabilities. Starting from gyro-Bohm scaling, additional dependence confinement parameters ν* β (collisionality beta) been...
A heavy ion beam probe (HIBP) has been implemented on the ATF torsatron at Oak Ridge National Laboratory with primary goal of providing direct measurements plasma potential radial profile and thus electric field. The complex geometry magnetic field structure presented a diagnostic environment more challenging than that found previous systems. Particular attention therefore given to in situ system alignment control capabilities. Measurements profiles, electron density fluctuations,...
Recent experiments in the Advanced Toroidal Facility (ATF) [Fusion Technol. 10, 179 (1986)] have been directed toward investigations of basic physics mechanisms that control confinement this device. Measurements density fluctuations throughout plasma volume provided indications for existence theoretically predicted dissipative trapped electron and resistive interchange instabilities. These identifications are supported by results dynamic configuration scans magnetic fields during which well...
Experiments involving plasma improvement, confinement scaling, bootstrap currents, and edge fluctuations have been carried out in the Advanced Toroidal Facility (ATF) torsatron [Fusion Technol. 10, 179 (1986)]. Average densities n̄e≤9×1019 m−3 obtained, with global energy times τ*E≤20 msec. Confinement generally follow stellarator/torsatron empirical scaling law, τSL =0.17×P−0.58n0.69eB0.84a2R0.75 (with seconds, power P megawatts, density ne 1020 m−3, radius a major R meters). Gas injection...
Effects of deliberately introduced magnetic field perturbations on plasma conditions have been studied in the Advanced Toroidal Facility (ATF) torsatron. Magnetic dipole coils, located above at two positions 180 degrees apart, created a perturbation Bz0/Bϕ0 ⩽ 1.4%, which produced large l=1/2 island. Two modes operation were employed: (1) constant gas feed allowing electron density to vary and (2) with feedback controlled. Without control, stored energy approximately halved. With decreased...
The energy analyzer for the ATF heavy ion beam probe has been built and tested. Because will be required to operate in fields as high 550 G on since calibration of absence a field not possible once it is installed, special emphasis made characterize its performance test stand. In order ensure accurate knowledge geometric parameters, was assembled with aid coordinate axis measuring machine. results these tests are presented comparison ideal made.
We present global linear and nonlinear simulations of ion temperature gradient instabilities based on a fluid formulation, with an adapted version the JOREK code. These are performed in realistic tokamak equilibria solution Grad–Shafranov equation. Benchmarking growth rates was successfully completed respect to previously published data. find two distinct types eigenstructures, depending magnetic shear. For high shear, when coupling poloidal harmonics is strong, ballooning-type eigenmodes...