-
Author(s):
M. Yokoyama, N. Nakajima and M. Okamoto
-
Title:
Realization and Classification of Symmetric Stellarator Configurations through Plasma Boundary Modulations
Date of publication:
Dec. 1997
-
Key words:
plasma boundary modulations, magnetic field spectra, Boozer coordinates, symmetric stellarator configurations
-
Abstract:
The basic roles of several principle modulations of plasma boundary shape on magnetohydrodynamic (MHD) equilibria are investigated. The appropriate combination of principle helical modulations for elimination of bumpy field component to realize the quasi-axisymmetric (QAS) and quasi-helically symmetric (QHS) configurations is explained by considering the variation of area of magnetic surface cross sections. The triangular modulation is effectively utilized to form the magnetic well by shifting the magnetic axis outward compared to the center of mass of magnetic surface cross section. The spatialization of the magnetic axis or the bumpy modulations of plasma boundary is rather important to reduce the toroidicity in the magnetic field, which can lead to QHS configurations. . Some stellarator magnetic configurations under design activity or in the existing experimental device are mentioned from the point of views of plasma boundary modulations. Based on these principle understandings of plasma boundary modulations, examples of essential approach to QAS and QHS configurations are demonstrated step by step. The possibility of quasi-bumpy (or poloidally) symmetric (QBS) configuration is also mentioned.
-
|
