A5064943963- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Gyrotron and Vacuum Electronics Research
- Fusion materials and technologies
- Particle Detector Development and Performance
- Plasma Diagnostics and Applications
- Physics of Superconductivity and Magnetism
- Laser-Plasma Interactions and Diagnostics
- Computational Fluid Dynamics and Aerodynamics
- History and Developments in Astronomy
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Fluid Dynamics and Turbulent Flows
- Quantum and electron transport phenomena
- Nuclear physics research studies
- Radiation Detection and Scintillator Technologies
- Silicon Carbide Semiconductor Technologies
- Quantum chaos and dynamical systems
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Molecular Physics
Oak Ridge National Laboratory
2006-2021
Japan Atomic Energy Agency
2018
Japan Proton Accelerator Research Complex
2018
University College of Bahrain
2013
Spallation Neutron Source
2005-2006
Indiana University Bloomington
2002-2003
SUNY Plattsburgh
2002
Brookhaven National Laboratory
2001
University of Maryland, College Park
2001
Computational Physics (United States)
1998
The transport effects induced by resistive ballooning modes are estimated from a theory, and found to be mainly thermal electron conduction losses. An expression for diffusivity ${\ensuremath{\chi}}_{e}$ is derived. theoretical predictions agree well with experimental values of obtained power balance the ISX-$B$ plasmas at high poloidal beta.
A mechanism for the major disruption in tokamaks is proposed involving nonlinear destabilization of tearing modes by m=2, n=1 mode. three-dimensional cylindrical code based on a set equations valid limit low β and large ratio toroidal poloidal magnetic fields has been constructed. The essential result that safety factor profiles flat plasma core 2/1 mode significantly destabilizes other modes, particularly odd such as 3/2 mode, before island single-pitch expanded to its maximum width. Many...
The nonlinear interaction of tearing modes different helicity in tokamaks is studied for realistic values resistivity and parallel heat conduction. self-consistent evolution the taken into account through electron conduction equation. For equilibrium q profiles inferred from temperature measured before a tokamak disruption, essential result that (m=2;n=1) mode nonlinearly destabilizes other on rapid time scale. Because development magnetic islands helicity, toroidal current density severely...
The stability of the ideal and resistive m=1 internal modes is investigated for tokamak equilibria having a variety different q(r) profiles, including nonmonotonic with multiple q=1 surfaces. Detailed comparisons between analytic theory numerical results from linear toroidal magnetohydrodynamic code are presented. Particular attention paid to study that near marginal stability.
We propose a mechanism for the major disruption in tokamaks that involves nonlinear destabilization of tearing modes by $\frac{(m=2)}{(n=1)}$ mode, where $m$ and $n$ denote poloidal toroidal mode numbers, respectively. The magnetic islands generated can extend across plasma cross section. For resistivities order magnitude these TOSCA LT-3, time scale their appearance is consistent with disruption.
Non-Newtonian viscosity and the primary normal stress difference in steady simple shear flow dynamic storage modulus oscillatory were measured for three viscoelastic fluids. Most of data obtained with a Weissenberg Rheogoniometer. The used to evaluate differential model two integral models, all models predicting same relations material functions. satisfactorily describe non-Newtonian viscosity, each solution, but fail by incorrect slopes “power-law” regions.
The particle accelerator simulation code PyORBIT is presented. structure, implementation, history, parallel and capabilities, future development of the are discussed. a new implementation extension algorithms original ORBIT that was developed for Spallation Neutron Source at Oak Ridge National Laboratory. has two level structure. upper uses Python programming language to control flow intensive calculations performed by lower implemented in C + language. capabilities based on MPI...
Equilibrium and stability properties of high-beta torsatrons are investigated using numerical semianalytical techniques based on the method toroidal averaging. The averaged equilibria compared with those obtained full three-dimensional codes. Good agreement is obtained, thus validating approach. plasmas for configurations different aspect ratios numbers field periods studied. role vertical also studied in detail. main conclusion that moderate-aspect-ratio (Ap≲8), self-stabilizing effect...
The results of investigations nonlinear tearing-mode dynamics in reversed field pinch plasmas are described. linear instabilities have poloidal mode number m=1 and toroidal numbers 10≲n≲20, the resonant surfaces therefore plasma core. result dual cascade processes. first process is a rapid spectral broadening toward high n, with simultaneous spreading magnetic turbulence radially outward field-reversal surface. Global m=0 perturbations, which driven to large amplitudes by instabilities, turn...
The linear stability of the resistive ballooning mode, as described by magnetohydrodynamic (MHD) model, is investigated both analytically and numerically. When pressure evolution approximated fluid convection (reduced MHD model), an instability driven geodesic curvature, with a growth rate γ∼η1/3 β2/3p, found. For conditions relevant to Impurity Study Experiment (ISX-B), it shown that for modest poloidal bets (βp≂1), high current, relatively temperatures, compressibility has significant...
Experimental results on the Texas Tokamak (TEXT) [Nucl. Technol./Fusion 1, 479 (1982)] and Advanced Toroidal Facility (ATF) torsatron [Fusion Technol. 10, 179 (1986)] indicate that electrostatic fluctuations can explain edge transport of particles perhaps energy. Certain mechanisms for drive (radiation ionization, as well density temperature gradients) stabilization (velocity shear) are suggested by these results. The experimental fluctuation levels turbulence characteristics be reproduced...
This paper describes observations of magnetohydrodynamic instability with neutralbeam heating in the ISX-$B$ tokamak and theory specifically developed to support these experiments. The observed activity is explained by resistive model presented but not responsible for degradation confinement. Increasingly important $n>1$ pressure-driven modes are predicted higher experimental ${\ensuremath{\beta}}_{p}$ values, there no verification their presence.
Thin carbon foils are used as strippers for charge exchange injection into high intensity proton rings. However, the stripping become radioactive and produce uncontrolled beam loss, which is one of main factors limiting power in Recently, we presented a scheme laser an ${\mathrm{H}}^{\ensuremath{-}}$ Spallation Neutron Source (SNS) ring. First, atoms converted to ${\mathrm{H}}^{0}$ by magnetic field, then excited from ground state upper levels laser, states protons field. In this paper...
It is shown, for q-profiles which lead to a disruption, that the control of amplitude 2/1 tearing mode avoids measured in T–4 and PLT before major disruption have been studied. Two methods controlling considered: 1) Feedback stabilization with feedback signal locked phase mode. The suppressed if parameters (time delay gain) are properly chosen. Otherwise, only observed. 2) Heating slightly outside q = 2 surface. Modifying current density profile can decrease, even eliminate, –3/2...
ORBIT (Objective Ring Beam Injection and Tracking) is a new particle tracking code for rings. Modelling capabilities include H/sup -/ foil injection mechanisms, longitudinal transverse space charge effects, second order matrix transport. Additional features programmable interactive driver shell, plotting.
Zero-current high-beta equilibria for a stellarator device are calculated using the averaging method. It is found that, by shaping vertical field, rotational transform can be controlled in an approximate way as beta increased. At same time, Pfirsch-Schlüter currents reduced – with no modification of magnetic well. This permits access to regime more favourable profiles. Results presented Advanced Toroidal Facility (ATF) device.
In today's world, demand of cloud computing is increasing day by because its many advantages, like sharing hardware, software and absence fear losing data. As number users for computing, threat protecting confidential data in also increasing. This has led the computer scientists researchers to think finding robust security system computing. Detection, correction prevention provide complete solution Cryptography one solutions which can prevent intruders enter into clouds hacking information....