title: Far-infrared tangential interferometer/polarimeter design and installation for NSTX-U.
abstract: The Far-infrared Tangential Interferometer/Polarimeter (FIReTIP) system has been refurbished and is being reinstalled on the National Spherical Torus Experiment-Upgrade (NSTX-U) to supply real-time line-integrated core electron density measurements for use in the NSTX-U plasma control system (PCS) to facilitate real-time density feedback control of the NSTX-U plasma. Inclusion of a visible light heterodyne interferometer in the FIReTIP system allows for real-time vibration compensation due to movement of an internally mounted retroreflector and the FIReTIP front-end optics. Real-time signal correction is achieved through use of a National Instruments CompactRIO field-programmable gate array.
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Scott
authors.affiliation: Department of Applied Science, University of California, Davis, California 95616, USA.
authors.forename: R
authors.initials: R
authors.lastname: Barchfeld
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA.
authors.forename: P
authors.initials: P
authors.lastname: Riemenschneider
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Domier
authors.affiliation: General Atomics, San Diego, California 92121, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Muscatello
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA.
authors.forename: M
authors.initials: M
authors.lastname: Sohrabi
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA.
authors.forename: R
authors.initials: R
authors.lastname: Kaita
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA.
authors.forename: N C
authors.initials: NC
authors.lastname: Luhmann