Paraxial WKB description of short wavelength eigenmodes in a tokamak

Authors
Citation
Gv. Pereverzev, Paraxial WKB description of short wavelength eigenmodes in a tokamak, PHYS PLASMA, 8(8), 2001, pp. 3664-3672
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICS OF PLASMAS
ISSN journal
1070-664X → ACNP
Volume
8
Issue
8
Year of publication
2001
Pages
3664 - 3672
Database
ISI
SICI code
1070-664X(200108)8:8<3664:PWDOSW>2.0.ZU;2-L
Abstract
A novel asymptotic approach for solving the eigenvalue problem in the short -wavelength limit is developed. This approach, called the paraxial WKB meth od, is presented and applied to the analysis of gradient-driven instabiliti es in a tokamak. In some respects, the paraxial WKB method is more general than the ballooning representations usually used for this problem. For inst ance, the paraxial WKB method can describe drift-ballooning instabilities i n the presence of sheared plasma rotation when the ballooning representatio n fails. Being different from other techniques, the paraxial WKB method not only sheds new light on the physics of drift-ballooning instabilities, but also provides a description for short-wave instabilities of other types. O ther possible extensions of the paraxial WKB technique, such as the applica tion to three-dimensional systems like stellarators, are briefly discussed. Finally, advantages and disadvantages of the paraxial WKB method in compar ison with the ballooning representation are considered. (C) 2001 American I nstitute of Physics.