Premium
Magnetic Perturbation Spectrum Produced by Non‐Axisymmetric Scrape‐Off Layer Current and the X‐Point Shadow
Author(s) -
Joseph I.
Publication year - 2010
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201010054
Subject(s) - physics , separatrix , harmonics , rotational symmetry , magnetic field , perturbation (astronomy) , dissipative system , plasma , kinetic energy , current (fluid) , atomic physics , computational physics , mechanics , classical mechanics , voltage , quantum mechanics , thermodynamics
The applied magnetic perturbation spectrum produced by non‐axisymmetric scrape‐off layer current is calculated for the symmetric two‐wire model of a diverted plasma at large aspect‐ratio. The spectral peak lies close to the magnetic field line pitch‐resonance condition near the separatrix, but moves toward larger poloidal harmonics on flux surfaces in the core. Dissipative and kinetic effects limit the ability of the asymmetric parallel current to reach the midplane when the biasing region is sufficiently close to the strike point. Thus, the X‐point casts a thin “shadow” across the separatrix where it is not possible to drive current. The size of the region of reduced current drive efficiency is estimated based on fluid and kinetic limits (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)