Effects of resistivity and rotation on the linear plasma response to non-axisymmetric magnetic perturbations on DIII-D
Date
2015
Authors
Haskey, S R
Lanctot, M J
Liu, Y Q
Paz-Soldan, C
King, J D
Blackwell, B D
Schmitz, O
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing
Abstract
Parameter scans show the strong dependence of the plasma response on the poloidal structure
of the applied field highlighting the importance of being able to control this parameter using
non-axisymmetric coil sets. An extensive examination of the linear single fluid plasma
response to n = 3 magnetic perturbations in L-mode DIII-D lower single null plasmas is
presented. The effects of plasma resistivity, toroidal rotation and applied field structure
are calculated using the linear single fluid MHD code, MARS-F (Liu et al 2000 Phys.
Plasmas 7 3681). Measures which separate the response into a pitch-resonant and resonant
field amplification (RFA) component are used to demonstrate the extent to which resonant
screening and RFA occurs. The ability to control the ratio of pitch-resonant fields to RFA
by varying the phasing between upper and lower resonant magnetic perturbations coils sets
is shown. The predicted magnetic probe outputs and displacement at the x-point are also
calculated for comparison with experiments. Additionally, modelling of the linear plasma
response using experimental toroidal rotation profiles and Spitzer like resistivity profiles are
compared with results which provide experimental evidence of a direct link between the decay
of the resonant screening response and the formation of a 3D boundary (Schmitz et al 2014
Nucl. Fusion 54 012001). Good agreement is found during the initial application of the MP,
however, later in the shot a sudden drop in the poloidal magnetic probe output occurs which is
not captured in the linear single fluid modelling.
Description
Keywords
non-axisymmetric coil, plasma response, magnetic perturbation, toroidal rotation, plasma resistivity
Citation
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Source
Plasma Physics and Controlled Fusion
Type
Journal article