title: Upgrade of the neutral particle analyzers for the TJ-II stellarator.
abstract: The TJ-II stellarator, a magnetically confined plasma device, is equipped with a broad range of diagnostics for plasma characterization. These include 4 neutral particle analyzers (NPAs), consisting of two Acord-12's, to perform poloidal measurements, plus a compact NPA, and an Acord-24, these in tangential viewing positions. The Acord-12's were originally equipped with two rows of 6 channels each, one for hydrogen neutrals and the other for deuterium neutrals but were changed to a single row of 12 detectors for hydrogen, the principal working gas in TJ-II. With this upgrade the resultant improved energy resolution spectrum has allowed more reliable ion temperature estimates to be obtained. Here we present the upgrades undertaken and present results to demonstrate the improved performance of this diagnostic.
authors.affiliation: Laboratorio Nacional de Fusión, CIEMAT, Madrid 28040, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Fontdecaba
authors.affiliation: Ioffe Physical-Technical Institute, Saint Petersburg 194024, Russian Federation.
authors.forename: S Ya
authors.initials: SY
authors.lastname: Petrov
authors.affiliation: Ioffe Physical-Technical Institute, Saint Petersburg 194024, Russian Federation.
authors.forename: V G
authors.initials: VG
authors.lastname: Nesenevich
authors.affiliation: Laboratorio Nacional de Fusión, CIEMAT, Madrid 28040, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Ros
authors.affiliation: Ioffe Physical-Technical Institute, Saint Petersburg 194024, Russian Federation.
authors.forename: F V
authors.initials: FV
authors.lastname: Chernyshev
authors.affiliation: Laboratorio Nacional de Fusión, CIEMAT, Madrid 28040, Spain.
authors.forename: K J
authors.initials: KJ
authors.lastname: McCarthy
authors.affiliation: Departamento de Electrónica, CIEMAT, Madrid 28040, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Barcala