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Title: Decoupled recovery of energy and momentum with correction of n = 2 error fields

Experiments applying known n = 2 “proxy” error fields (EFs) find that the rotation braking introduced by the proxy EF cannot be completely alleviated through optimal n = 2 correction with poorly matched poloidal spectra. This imperfect performance recovery demonstrates the importance of correcting multiple components of the n = 2 field spectrum and is in contrast to previous results with n = 1 EFs despite similar execution. Measured optimal n = 2 proxy EF correction currents are consistent with those required to null dominant mode coupling to the resonant surfaces and minimize the neoclassical toroidal viscosity (NTV) torque, calculated using ideal MHD plasma response computation. Unlike rotation braking, density pumpout can be fully corrected despite poorly matched spectra, indicating density pumpout is driven only by a single component proportional to the resonant coupling. Through precise n = 2 spectral control density pumpout and rotation braking can thus be decoupled. Rotation braking with n = 2 fields is also found to be proportional to the level of concurrent toroidal rotation, consistent with NTV theory. Lastly, plasmas with modest countercurrent rotation are insensitive to the n = 2 field with neither rotation braking nor density pumpout observed.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [1] ;  [2] ;  [2] ;  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Columbia Univ., New York, NY (United States)
Publication Date:
Grant/Contract Number:
AC02-09CH11466; AC05-00OR22725; AC05-06OR23100; FC02-04ER54698; FG02-04ER54761; SC0001961
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 8; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); U.S. Dept. of Energy, Washington, D.C. (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; error fields; plasma response; resonant magnetic perturbations; neoclassical toroidal viscosity; density pumpout; resonant; magnetic perturbations
OSTI Identifier:
1350065
Alternate Identifier(s):
OSTI ID: 1238921; OSTI ID: 1260743; OSTI ID: 1345402