skip to main content

Title: Method for correction of measured polarization angles from motional Stark effect spectroscopy for the effects of electric fields

An approximate method to correct the motional Stark effect (MSE) spectroscopy for the effects of intrinsic plasma electric fields has been developed. The motivation for using an approximate method is to incorporate electric field effects for between-pulse or real-time analysis of the current density or safety factor profile. The toroidal velocity term in the momentum balance equation is normally the dominant contribution to the electric field orthogonal to the flux surface over most of the plasma. When this approximation is valid, the correction to the MSE data can be included in a form like that used when electric field effects are neglected. This allows measurements of the toroidal velocity to be integrated into the interpretation of the MSE polarization angles without changing how the data is treated in existing codes. In some cases, such as the DIII-D system, the correction is especially simple, due to the details of the neutral beam and MSE viewing geometry. The correction method is compared using DIII-D data in a variety of plasma conditions to analysis that assumes no radial electric field is present and to analysis that uses the standard correction method, which involves significant human intervention for profile fitting. The comparison shows thatmore » the new correction method is close to the standard one, and in all cases appears to offer a better result than use of the uncorrected data. Lastly, the method has been integrated into the standard DIII-D equilibrium reconstruction code in use for analysis between plasma pulses and is sufficiently fast that it will be implemented in real-time equilibrium analysis for control applications.« less
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [3]
  1. General Atomics, San Diego, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Dartmouth College, Hanover, NH (United States)
Publication Date:
OSTI Identifier:
1372084
Grant/Contract Number:
FC02-04ER54698; AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 12; Related Information: T.C. Luce, C.C. Petty, W.H. Meyer, C.T. Holcomb, K.H. Burrell, and L.J. Bergsten, "Method for correction of measured polarization angles from motional Stark effect spectroscopy for the effects of electric fields", Plasma Phys. Control. Fusion 58, 125010 (2016); Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE Office of Nuclear Energy (NE)
Contributing Orgs:
Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550 USA Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 USA
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; motional Stark effect; tokamak equilibrium reconstruction; radial electric field; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY