title: Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D.
abstract: Thomson scattering produces neprofiles from measurement of scattered laser beam intensity. Rayleigh scattering provides a first calibration of the relation ne∝ ITS, which depends on many factors (e.g., laser alignment and power, optics, and measurement systems). On DIII-D, the necalibration is adjusted against an absolute nefrom the density-driven cutoff of the 48 channel 2nd harmonic X-mode electron cyclotron emission system. This method has been used to calibrate Thomson nefrom the edge to near the core (r/a > 0.15). Application of core electron cyclotron heating improves the quality of cutoff and depth of its penetration into the core, and also changes underlying MHD activity, minimizing crashes which confound calibration. Less fueling is needed as "ECH pump-out" generates a plasma ready to take up gas. On removal of gyrotron power, cutoff penetrates into the core as channels fall successively and smoothly into cutoff.
authors.affiliation: Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: M W
authors.initials: MW
authors.lastname: Brookman
authors.affiliation: Lawrence Livermore National Lab, Livermore, California 94500, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Austin
authors.affiliation: Lawrence Livermore National Lab, Livermore, California 94500, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: McLean
authors.affiliation: General Atomics, San Diego, California 92122, USA.
authors.forename: T N
authors.initials: TN
authors.lastname: Carlstrom
authors.affiliation: General Atomics, San Diego, California 92122, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Hyatt
authors.affiliation: General Atomics, San Diego, California 92122, USA.
authors.forename: J
authors.initials: J
authors.lastname: Lohr