Some practical considerations involving spectral representations of 3D plasma equilibria

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · J. Comput. Phys.; (United States)

DOI:https://doi.org/10.1016/0021-9991(87)90092-1· OSTI ID:6135868

Attenberger, S E; Houlberg, W A; Hirshman, S P

For describing magnetically confined toroidal plasmas, it is convenient in some instances to use a cylindrical coordinate system whose origin is on the major axis of the torus and in others to use a ''flux coordinate'' system bound to the magnetic flux which is embedded in the plasma. A good estimate of the flux surface geometry is available in spectral form in many cases, permitting a simple transformation from flux coordinates to cylindrical coordinates. A modified Newton iteration is described for performing the ''inverse'' transformation from cylindrical coordinates coordinates to flux coordinates. An accurate technique for radial spline interpolation of the spectral coefficients is given which is particularly useful for computing magnetic fields near the magnetic axis. Given a spectral representation of the plasma it is possible to track a chord through the plasma, determining in sequence its intersections with a given set of flux surfaces. This technique is the starting point for many calculations including neutral beam heating, pellet fueling, evaluation of absorption or plasma sources along the lines-of-sight of detectors, etc. An efficient algorithm for performing this calculation is given. These algorithms permit the determination of plasma ''profiles'' from chordal data by a straightforward least-squares technique, without any restrictions on the orientation of the chords. The method shown is contrasted to those based on generalized Abel transforms. copyright 1987 Academic Press, Inc.

• Research Organization: Computing and Telecommunications Division, Oak Ridge National Laboratory, Oak ridge, Tennessee 37831
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6135868
• Journal Information: J. Comput. Phys.; (United States), Journal Name: J. Comput. Phys.; (United States) Vol. 72:2; ISSN JCTPA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
ALGORITHMS
ANNULAR SPACE
CONFIGURATION
COORDINATES
HEATING
ITERATIVE METHODS
MAGNETIC FIELDS
MAGNETIC FLUX
MATHEMATICAL LOGIC
PLASMA HEATING
PLASMA SIMULATION
SIMULATION
SPACE
TOROIDAL CONFIGURATION