Bulletin of the American Physical Society
49th Annual Meeting of the Division of Plasma Physics
Volume 52, Number 11
Monday–Friday, November 12–16, 2007; Orlando, Florida
Session JP8: Poster Session IV: Education and Outreach; Undergraduate Research; Electron and Ion Beam/Space Charge; DIII-D I; Reversed Field Pinches; Energetic Ions and Electrons in Helicons
Tuesday, November 13, 2007
Rosen Centre Hotel Room: Grand Ballroom, 2:00pm - 5:00pm
Abstract ID: BAPS.2007.DPP.JP8.75
Abstract: JP8.00075 : Understanding Magnetic Field Error Correction in DIII-D*
Preview Abstract Abstract
R.J. La Haye
A comparison was made between the measured DIII-D magnetic field error and an ideal MHD plasma response model. New measurements of TF coil errors reduced the bounds of unknown errors. Empirical error corrections for DIII--D standard left-handed-pitch plasmas were refined, and a new empirical correction was developed for right-handed-pitch plasmas. Empirical corrections were analyzed by the new Ideal Perturbed Equilibrium Code, which computes the linear free-boundary plasma response to prescribed external error and/or correction fields in real geometry. This analysis explained the paradox of why the DIII-D C-coil empirical correction is $\sim $3 times the error field on a vacuum field basis: the plasma strongly modifies the error and correction fields differently, and the total fields actually come to partial cancellation. The theory provides guidance for error correction with imperfectly matched fields. Separately, a short proof of principle experiment showed that further improvement (locked mode avoidance) is possible if the remaining TF coil current feed error were reduced.
*Work supported by U.S. DOE under DE-FC02-04ER54698.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.DPP.JP8.75
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