A5060266641- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Physics of Superconductivity and Magnetism
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Electromagnetic Launch and Propulsion Technology
- Nuclear Physics and Applications
- Laser-induced spectroscopy and plasma
- Electric Motor Design and Analysis
- Electrostatic Discharge in Electronics
- Atomic and Molecular Physics
- Magnetic Field Sensors Techniques
- Induction Heating and Inverter Technology
- Particle Accelerators and Free-Electron Lasers
- Radioactive Decay and Measurement Techniques
- Geomagnetism and Paleomagnetism Studies
- Computational Fluid Dynamics and Aerodynamics
- Advanced Measurement and Detection Methods
- Advanced Sensor Technologies Research
- Laser Design and Applications
- Material Properties and Processing
- Particle Detector Development and Performance
Los Alamos National Laboratory
2002-2023
University of Wisconsin–Madison
1992-1999
CEA Cadarache
1999
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
1999
Culham Centre for Fusion Energy
1997
Advanced Science Research Center
1997
Torrey Pines Institute For Molecular Studies
1997
General Atomics (United States)
1997
The University of Texas at Austin
1997
Princeton Plasma Physics Laboratory
1997
The maximum normalized beta achieved in long-pulse tokamak discharges at low collisionality falls significantly below both that observed short pulse and predicted by the ideal MHD theory. Recent experiments, particular those simulating International Thermonuclear Experimental Reactor (ITER) [M. Rosenbluth et al., Plasma Physics Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1995), Vol. 2, p. 517] scenarios with νe*, are often limited low-m/n nonideal...
The theory of tearing mode stabilization in toroidal plasmas by RF driven currents that are modulated phase with the island rotation is investigated. A time-scale analysis phenomena involved indicates transient effects, such as finite time response currents, during power pulses and inductive plasma, intrinsically important. dynamical model effects developed, based on a 3-D Fokker-Planck code coupled to both electric field diffusion equation evolution equation. Extensive applications ECCD...
NIMROD is a code development project designed to study long-wavelength, low-frequency, nonlinear phenomena in toroidal plasmas with realistic geometry and dynamics. The numerical challenges of solving the fluid equations for fusion plasma are discussed our discretization scheme presented. Simulations resistive tearing mode show that time steps much greater than Alfven possible without loss accuracy. Validation tests interchange shaped equilibrium, ballooning activity reversed-field pinches described.
Nonlinear numerical studies of macroscopic modes in a variety magnetic fusion experiments are made possible by the flexible high-order accurate spatial representation and semi-implicit time advance NIMROD simulation code [A. H. Glasser et al., Plasma Phys. Controlled Fusion 41, A747 (1999)]. Simulation resistive magnetohydrodynamics mode shaped toroidal tokamak equilibrium demonstrates computation with disparate scales, simulations discharge 87009 DIII-D [J. L. Luxon Physics Nuclear Research...
Profiles of noninductive current driven by neutral beam injection into a tokamak have been measured and compared with theory. The can be less than the theoretical prediction (by up to 80%) in presence islands tearing modes.
The application of fluid models in studies transport and macroscopic stability magnetized, nearly collisionless plasmas requires closure relations that are inherently nonlocal. Such closures address the fact particles capable carrying information over parallel scale lengths. In this work, generalized embody Landau, collisional particle-trapping physics derived discussed. A gyro/bounce-averaged drift kinetic equation is solved via an expansion eigenfunctions pitch-angle scattering operator...
A method is developed for determining directly from experimental data the classical tearing mode stability parameter Δ′. Specifically, an analytical fit function derived electron temperature fluctuations (T̃e) in vicinity of a magnetic island. Values Δ′ determined parameters m/n=2/1, 3/2 and 4/3 modes (m n are poloidal toroidal numbers) obtained using high resolution T̃e profile major radius shift (“jog”) experiments on Tokamak Fusion Test Reactor (TFTR) [D. Meade et al., Proceedings...
Numerical studies of the nonlinear evolution magnetohydrodynamic-type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion physics introduces an additional free-energy source for formation magnetic islands through a bootstrap current Ohm’s law. mode is demonstrated to be destabilized plasmas which otherwise Δ′ stable, albeit once island width threshold exceeded. plasma pressure dynamics and growth shown sensitive choice ratio parallel...
The recently developed technique of beam emission spectroscopy (BES) provides a tool to study long-wavelength density turbulence (coherence length ≫ ion gyroradius) in hot tokamak plasmas. To provide an accurate conversion the measured light intensity fluctuations local ñ/n fluctuation and assess influence neutral induced by large edge turbulence, multistate excitation/transport code for realistic experimental geometries has been written. Results from this show that attenuation can give...
Heuristic closures are presented for use in simulations of neoclassical modifications to magnetohydrodynamic phenomenon tokamaks. The capture the dominant physics expected from linear and quasilinear instability theory computationally easy implement. Numerical results NIMROD [A. H. Glasser, C. R. Sovinec, A. Nebel et al., Plasma Phys. Controlled Fusion 41, A747 (1999)] code shown which demonstrate poloidal flow damping, growth rate reduction due enhancement polarization current, generation...
A theoretical categorization of the onset tearing modes in tokamaks is presented using DIII-D equilibrium reconstructions as initial conditions NIMROD nonlinear three-dimensional resistive magnetohydrodynamic code (Sovinec C.R. et al 2004 J. Comput. Phys. 195 355). The mechanism are categorized into three types: spontaneous, mixed and forced depending on importance linear instability versus reconnection. physics early evolution growing simulations with time varying drive, coupling between...
A confinement model for tokamak plasmas based on the idea that a number of low mode magnetic islands appear, grow and interact is described. It suggested fundamental topology given as time-varying mix islands, stochasticity regions with good surfaces. The presence in plasma 'equilibrium' can alter structure stability boundaries ideal ballooning modes tokamaks. envisioned topologies have an important effect understanding interpretation observed fluctuations, properties transport...
In previous work it was shown that progress in attaining and maintaining stable mean reversed-field pinch (RFP) profiles can be made by abandoning the steady-state assumption instead seeking solutions of pressureless (force-free), one-dimensional transport equations are separable time space [E. J. Caramana R. A. Nebel, Phys. Fluids 31, 3322 (1988)]. Here these have been extended to two dimensions therefore formalism is also applicable toroidal helical states as well axisymmetric cylindrical...
A study of the passive stabilization resistive magnetohydrodynamic (MHD) tearing modes is presented in context zero β full-MHD equations with NIMROD [A. H. Glasser et al., Plasma Phys. Controlled Fusion 41, A747 (1999)] code. The effect current modeled by a source term Ohm’s law. This evaluated based on diffusive model anisotropic diffusivities parallel and perpendicular to perturbed magnetic field lines driven spatially localized source. effects spatial localization are explored that...
This paper explores the equilibrium and transient transport properties of a mixed magnetic topology model for tokamak equilibria. The is composed discrete set mostly nonoverlapping islands centered on low-order rational surfaces. Transport across island regions fast due to parallel along stochastic magnetic-field lines about separatrix each island. between assumed be slow low residual cross-field transport. In equilibrium, such leads nonlinear dependence heat flux pressure gradient; power...
Los Alamos "Ranchero" Magnetic Flux Compression Generators (FCGs) have been used to power imploding liner loads. The fundamental FCG design is based on a cylindrical detonation system that expands the armature simultaneously into coaxial generator volume and has shown generate currents as high 76 MA. Analysis of MA test results revealed weakness in at output glide plane. To prevent premature shorting current slot generator, armature/glide plane interface was originally designed lag leading...
Calculations and measurements have been performed to assess radiation doses delivered by the PTB Secondary Standard that employs 147Pm, 204Tl, 90Sr:90Y sources in prescribed geometries, features “beam-flattening” filters assure uniformity of within a 5-cm radius axis from source detector plane. Three-dimensional, coupled, electron-photon Monte Carlo calculations, accounting for transmission through encapsulation backscattering mounting, led energy spectra angular distributions electrons...