title: Upgraded divertor Thomson scattering system on DIII-D.
abstract: A design to extend the unique divertor Thomson scattering system on DIII-D to allow measurements of electron temperature and density in high triangularity plasmas is presented. Access to this region is selectable on a shot-by-shot basis by redirecting the laser beam of the existing divertor Thomson system inboard - beneath the lower floor using a moveable, high-damage threshold, in-vacuum mirror - and then redirecting again vertically. The currently measured divertor region remains available with this mirror retracted. Scattered light is collected from viewchords near the divertor floor using in-vacuum, high temperature optical elements and relayed through the port window, before being coupled into optical fiber bundles. At higher elevations from the floor, measurements are made by dynamically re-focusing the existing divertor system collection optics. Nd:YAG laser timing, analysis of the scattered light spectrum via polychromators, data acquisition, and calibration are all handled by existing systems or methods of the current multi-pulse Thomson scattering system. Existing filtered polychromators with 7 spectral channels are employed to provide maximum measurement breadth (Tein the range of 0.5 eV-2 keV, nein the range of 5 × 1018-1 × 1021m3) for both low Tein detachment and high Temeasurement up beyond the separatrix.
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: F
authors.initials: F
authors.lastname: Glass
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: T N
authors.initials: TN
authors.lastname: Carlstrom
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: D
authors.initials: D
authors.lastname: Du
authors.affiliation: Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: McLean
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Taussig
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Boivin