title: Asymmetries in the motional Stark effect emission on the DIII-D tokamak.
abstract: Spectrometer measurements and filter upgrades to a motional Stark effect polarimeter measuring the outer half-radius of the DIII-D tokamak helped to identify asymmetries in the polarization angle of Stark-split emission. The measured polarization angle of the π components differs and is not orthogonal to the σ component. These differences persist over a range of densities and with low levels of background light. It is suggested that the difference in the polarization angle between components is from a change in the ellipticity of the emitted light across the Stark components coupled with imperfect polarization preservation from an in-vessel mirror.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Victor
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: C T
authors.initials: CT
authors.lastname: Holcomb
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Allen
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: W H
authors.initials: WH
authors.lastname: Meyer
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Makowski
authors.affiliation: Plasma Research Laboratory, Australia National University, Canberra ACT 0200, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Thorman