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Title: Computation of three-dimensional tokamak and spherical torus equilibria

Abstract

A nominally axisymmetric plasma configuration, such as a tokamak or a spherical torus, is highly sensitive to nonaxisymmetric magnetic perturbations due to currents outside of the plasma. The high sensitivity means that the primary interest is in the response of the plasma to very small perturbations, i.e., vertical bar b-vector/B-vector vertical bar {approx_equal}10{sup -2} to 10{sup -4}, which can be calculated using the theory of perturbed equilibria. The ideal perturbed equilibrium code (IPEC) is described and applied to the study of the plasma response in a spherical torus to such external perturbations.

Authors:
; ;  [1];  [2];  [2]
  1. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20974970
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2732170; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AXIAL SYMMETRY; CALCULATION METHODS; CURRENTS; DISTURBANCES; EQUILIBRIUM; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA CONFINEMENT; PLASMA SIMULATION; SPHERICAL CONFIGURATION; THREE-DIMENSIONAL CALCULATIONS; TOKAMAK DEVICES

Citation Formats

Park, Jong-kyu, Boozer, Allen H., Glasser, Alan H., Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, and Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Computation of three-dimensional tokamak and spherical torus equilibria. United States: N. p., 2007. Web. doi:10.1063/1.2732170.
Park, Jong-kyu, Boozer, Allen H., Glasser, Alan H., Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, & Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Computation of three-dimensional tokamak and spherical torus equilibria. United States. doi:10.1063/1.2732170.
Park, Jong-kyu, Boozer, Allen H., Glasser, Alan H., Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, and Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Tue . "Computation of three-dimensional tokamak and spherical torus equilibria". United States. doi:10.1063/1.2732170.
@article{osti_20974970,
title = {Computation of three-dimensional tokamak and spherical torus equilibria},
author = {Park, Jong-kyu and Boozer, Allen H. and Glasser, Alan H. and Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 and Los Alamos National Laboratory, Los Alamos, New Mexico 87545},
abstractNote = {A nominally axisymmetric plasma configuration, such as a tokamak or a spherical torus, is highly sensitive to nonaxisymmetric magnetic perturbations due to currents outside of the plasma. The high sensitivity means that the primary interest is in the response of the plasma to very small perturbations, i.e., vertical bar b-vector/B-vector vertical bar {approx_equal}10{sup -2} to 10{sup -4}, which can be calculated using the theory of perturbed equilibria. The ideal perturbed equilibrium code (IPEC) is described and applied to the study of the plasma response in a spherical torus to such external perturbations.},
doi = {10.1063/1.2732170},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • A nominally axisymmetric plasma configuration, such as a tokamak or a spherical torus, is highly sensitive to non-axisymmetric magnetic perturbations due to currents outside of the plasma. The high sensitivity means that the primary interest is in the response of the plasma to very small perturbations, | →(over) β/→(over)Β | ≈ 10 -2 to 10 -4, which can be calculated using the theory of perturbed equilibria. The Ideal Perturbed Equilibrium Code (IPEC) is described and applied to the study of the plasma response in a spherical torus to such external perturbations.
  • The orientation of 3D equilibria in the Madison Symmetric Torus (MST) [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field pinch can now be controlled with a resonant magnetic perturbation (RMP). Absent the RMP, the orientation of the stationary 3D equilibrium varies from shot to shot in a semi-random manner, making its diagnosis difficult. Produced with a poloidal array of saddle coils at the vertical insulated cut in MST's thick conducting shell, an m = 1 RMP with an amplitude b{sub r}/B ∼ 10% forces the 3D structure into any desired orientation relative to MST's diagnostics. This control has led to improvedmore » diagnosis, revealing enhancements in both the central electron temperature and density. With sufficient amplitude, the RMP also inhibits the generation of high-energy (>20 keV) electrons, which otherwise emerge due to a reduction in magnetic stochasticity in the core. Field line tracing reveals that the RMP reintroduces stochasticity to the core. A m = 3 RMP of similar amplitude has little effect on the magnetic topology or the high-energy electrons.« less
  • A procedure is described for precision modeling of the views for imaging diagnostics monitoring tokamak internal components, particularly high heat flux divertor components. Such modeling is required to enable predictions of resolution and viewing angle for the available viewing locations. Since oblique views are typically expected for tokamak divertors, fully three-dimensional (3D) perspective imaging is required. A suite of matched 3D CAD, graphics and animation applications are used to provide a fast and flexible technique for reproducing these views. An analytic calculation of the resolution and viewing incidence angle is developed to validate the results of the modeling procedures. Themore » tokamak physics experiment (TPX) diagnostics1 for infrared viewing are used as an example to demonstrate the implementation of the tools. As is generally the case in tokamak experiments, the available diagnostic locations for TPX are severely constrained by access limitations and the resulting images can be marginal in both resolution and viewing incidence angle. The procedures described here provide a complete design tool for in-vessel viewing, both for camera location and for identification of viewed surfaces. Additionally, these same tools can be used for the interpretation of the actual images obtained by the diagnostic cameras. {copyright} {ital 1997 American Institute of Physics.}« less
  • The first quantitative comparison of linear ideal magnetohydrodynamic (MHD) theory with external magnetic measurements of the nonaxisymmetric plasma perturbation driven by external long-wavelength magnetic fields in high-temperature tokamak plasmas is presented. The comparison yields good (within 20%) agreement for plasma pressures up to approx75% of the ideal stability limit calculated without a conducting wall. For higher plasma pressures, the ideal MHD model tends to overestimate the perturbed field indicating the increasing importance of stabilizing nonideal effects.