title: Measurement of deuterium density profiles in the H-mode steep gradient region using charge exchange recombination spectroscopy on DIII-D.
abstract: Recent completion of a thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. In a H-mode DIII-D discharge, these new measurement capabilities are used to provide the deuterium density profile, demonstrate the importance of profile alignment between Thomson scattering and CER diagnostics, and aid in determining the electron temperature at the separatrix. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the plasma edge, providing high resolution measurements across the pedestal and steep gradient region in H-mode plasmas. Extracting useful physical quantities such as deuterium density is challenging due to multiple photoemission processes. These challenges are overcome using a detailed fitting model and by forward modeling the photoemission using the FIDASIM code, which implements a comprehensive collisional radiative model.
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Haskey
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Grierson
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186, USA.
authors.forename: K H
authors.initials: KH
authors.lastname: Burrell
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186, USA.
authors.forename: C
authors.initials: C
authors.lastname: Chrystal
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Groebner
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Kaplan
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, USA.
authors.forename: N A
authors.initials: NA
authors.lastname: Pablant
authors.affiliation: University of California, Irvine, California 92697, USA.
authors.forename: L
authors.initials: L
authors.lastname: Stagner