A5019708277- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Computational Fluid Dynamics and Aerodynamics
- Geomagnetism and Paleomagnetism Studies
- Particle Detector Development and Performance
- Axial and Atropisomeric Chirality Synthesis
- Electrostatic Discharge in Electronics
- Physics of Superconductivity and Magnetism
- Fluid Dynamics Simulations and Interactions
- Silicon Carbide Semiconductor Technologies
- Engineering Applied Research
- earthquake and tectonic studies
- Advanced Wireless Communication Techniques
- Advancements in Semiconductor Devices and Circuit Design
- Structural Health Monitoring Techniques
- Quantum chaos and dynamical systems
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
Princeton Plasma Physics Laboratory
2009-2022
Boston Fusion (United States)
2017-2020
CEA Cadarache
2017-2020
Zhejiang University
2020
Institute of Ionized Gas
2017-2020
Princeton University
2003-2015
Oak Ridge National Laboratory
1998
The University of Texas Southwestern Medical Center
1996
Torrey Pines Institute For Molecular Studies
1996
ift Rosenheim
1903-1908
This article describes the recent findings on two-fluid effects magnetic reconnection in plasmas with variable collisionality experiment (MRX) [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)]. The MRX device has been upgraded to accommodate a variety of operation modes and high energy density experiments by increasing its capacitor bank extending discharge duration. As our experimental regime moved from collisional collision-free, have become more evident. It is observed that two-dimensional...
Global hybrid simulations of energetic particle effects on the n=1 internal kink mode have been carried out for tokamaks. For International Thermonuclear Experimental Reactor (ITER) [ITER Physics Basis Editors et al., Nucl. Fusion 39, 2137 (1999)], it is shown that alpha are stabilizing mode. However, elongation ITER reduces stabilization significantly. Nonlinear precessional drift fishbone instability circular tokamak plasmas show saturates due to flattening distribution function near...
The M3D-C1 (Breslau et al 2009 Phys. Plasmas 16 092503) code is designed for performing three-dimensional nonlinear magnetohydrodynamics (MHD) calculations of a tokamak plasma that span the timescales associated with ideal and resistive stability as well parallel perpendicular transport. This requires scalable fully implicit time advance where step not limited by Courant condition based on MHD wave velocities or flow but chosen instead to accurately efficiently resolve physics. In order...
Nonlinear simulations with the M3D code [W. Park et al., Phys. Plasmas 6, 1796 (1999)] are performed of disruptions produced by large scale magnetohydrodynamic instabilities. The toroidally asymmetric wall forces during a disruption calculated in an ITER [T. Hender Nucl. Fusion 47, S128 (2007)] model. is vertical displacement event and kink mode. Expressions derived for force, including sideways using thin conducting scaling force γτw obtained, where γ growth rate τw penetration time....
Research on the National Spherical Torus Experiment, NSTX, targets physics understanding needed for extrapolation to a steady-state ST Fusion Nuclear Science Facility, pilot plant, or DEMO. The unique operational space is leveraged test theories next-step tokamak operation, including ITER. Present research also examines implications coming device upgrade, NSTX-U. An energy confinement time, τE, scaling unified varied wall conditions exhibits strong improvement of BTτE with decreased electron...
Extensive linear and nonlinear simulations have been carried out to investigate the energetic particle-driven fishbone instability in spherical tokamak plasmas with weakly reversed q profile qmin slightly above unity. The global kinetic-MHD hybrid code M3D-K is used. Numerical results show that a excited by beam ions preferentially at higher values, consistent observed appearance of before “long-lived mode” MAST NSTX experiments. In contrast, lower tends be stable. this case, ion effects are...
Steady state solutions for anisotropic heat transport in a chaotic magnetic field are determined numerically and compared to set of ``ghost surfaces''---surfaces constructed via an action-gradient flow between the minimax minimizing periodic orbits. The ghost surfaces remarkable agreement with temperature contours.
A set of scalar variables and projection operators for the vector momentum magnetic field evolution equations is presented that has several unique desirable properties, making it a preferred system solving magnetohydrodynamic in torus with strong toroidal field. “weak form” these derived explicitly conserves energy suitable Galerkin finite element formulation provided basis elements have C1 continuity. Systems reduced are discussed, along their conservation properties. An implicit time...
The mission of the National Spherical Torus Experiment (NSTX) is demonstration physics basis required to extrapolate next steps for spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based (ST-CTF), and support ITER. Key issues are transport, steady state high β operation. To better understand electron new high- k scattering diagnostic was used extensively investigate gyro-scale fluctuations with varying temperature gradient scale length. Results from n = 3...
Computational optimization has revolutionized the field of stellarator design. To date, optimizations have focused primarily on neoclassical confinement and ideal MHD stability, although limited other parameters also been performed. The purpose this paper is to outline a select set new concepts for that, when taken as group, present significant step forward in concept. One criticisms that leveled at existing methods design complexity resultant coils. Recently, coil code—COILOPT++, which uses...
A critical issue for ITER is to evaluate the forces produced on surrounding conducting structures during plasma disruptions. We calculate non-axisymmetric ‘sideways’ wall force Fx, in Simulations were carried out of disruptions by destabilization n = 1 modes a vertical displacement event (VDE). The depends strongly γτwall, where γ mode growth rate and τwall penetration time, largest γτwall = constant, which initial conditions. caused model massive gas injection also performed. It was found...
Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile minimum above but close to unity, are susceptible an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate persist induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The also lead large energetic particle transport significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear...
In the development of magnetic confinement fusion which will potentially be a future source for low cost power, physicists must able to analyze field that confines burning plasma. While can described as vector field, traditional techniques analyzing field's topology cannot used because its Hamiltonian nature. this paper we describe technique developed collaboration between and computer scientists determines toroidal using fieldlines with near minimal lengths. More specifically, Poincaré map...
Motivated by experimental observations of apparently triggerless tearing modes, we have performed linear and nonlinear MHD analysis showing that a non-resonant mode with toroidal number n = 1 can develop in the National Spherical Torus eXperiment (NSTX) at moderate normalized β N when shear is low central safety factor q 0 close to but greater than one. This mode, which related previously identified ‘infernal’ will saturate persist, poloidal m 2 magnetic islands agreement experiments. We...
Nonlinear simulations of sawteeth and related energetic particle transport are carried out using the kinetic/magnetohydrodynamic (MHD) hybrid code M3D-K. MHD show repeated sawtooth cycles for a model tokamak equilibrium. Furthermore, test to study due crash. The results that particles redistributed radially in plasma core, depending on pitch angle energy. For trapped particles, redistribution occurs energy below critical value agreement with existing theories. co-passing is strong little...
The National Spherical Torus Experiment (NSTX) is currently being upgraded to operate at twice the toroidal field and plasma current (up 1 T 2 MA), with a second, more tangentially aimed neutral beam (NB) for rotation control, allowing pulse lengths up 5 s. Recent NSTX physics analyses have addressed topics that will allow NSTX-Upgrade achieve research goals critical Fusion Nuclear Science Facility. These include producing stable, 100% non-inductive operation in high-performance plasmas,...
A new approach for solving the 3D MHD equations in a strongly magnetized toroidal plasma is presented which uses high-order 2D finite elements with C1 continuity. The vector fields use physics-based decomposition. An efficient implicit time advance separates velocity and field advance. ITAPS (SCOREC) adaptivity software TOPS solvers are used.
Tokamaks vertical displacement events (VDEs) and disruptions simulations in toroidal geometry by means of a single fluid visco-resistive magneto-hydro-dynamic (MHD) model are presented this paper. The plasma is completed with the presence 2D wall finite resistivity which allows study relatively slowly growing magnetic perturbation, resistive mode (RWM), is, paper, main drive disruption evolution. Amplitudes asymmetries halo currents pattern at also calculated comparisons tokamak experimental...
As part of an early PPPL pilot plant study engineering exercise was undertaken to straighten the stellarator modular coil (MC) back legs provide greater access plasma components. Saddle coils were located within separate enclosures and configured reconstitute changes in magnetic fields caused by straightening MC legs. A follow on lab directed research looked further improve maintenance considering higher aspect ratio plasmas along with improving defining metrics adding requirements physics...
The multilevel physics, massively parallel plasma simulation code, M3D has been used to study spherical toris (STs) and tokamaks. magnitude of outboard shift density profiles relative electron temperature seen in NSTX under strong toroidal flow is explained. Internal reconnection events ST discharges can be classified depending on the crash mechanism, just as tokamak discharges; a sawtooth crash, disruption due stochasticity, or high-β disruption. Toroidal shear reduce linear growth internal...
The sawtooth instability is one of the most fundamental dynamics an inductive tokamak discharge such as will occur in ITER [R. Aymar et al., Plasma Phys. Controlled Fusion 44, 519 (2002)]. Sawtooth behavior complex and remains incompletely explained. Center for Extended MHD Modeling (CEMM) SciDAC project has undertaken ambitious campaign to model this periodic motion a small accurately possible using extended model. Both M3D [W. Park Plasmas 6, 1796 (1999)] NIMROD [C. R. Sovinec 10, 1727...
Toroidal rotation can be produced by disruptions, as observed in several experiments. There is a concern that rotating asymmetric forces during an ITER disruption might resonate with the blanket and other structures surrounding plasma. Here it shown, both computationally using M3D code, analytically, toroidal magnetohydrodynamic turbulence. In particular, vertical displacement event (AVDE) disruption. poloidal are also edge localized modes (ELMs), may consistent scaling law found for...
Energetic particle modes and Alfvén eigenmodes driven by super-Alfvénic fast ions are routinely observed in neutral beam heated plasmas on the National Spherical Torus eXperiment (NSTX). These can significantly impact ion transport thus cause redistribution or loss. Self-consistent linear simulations of Toroidal Eigenmodes (TAEs) NSTX have been carried out with kinetic/magnetohydrodynamic hybrid code M3D-K using experimental plasma parameters profiles including toroidal rotation. The show...