title: Radial resolution enhancement of the NSTX Thomson scattering diagnostic.
abstract: Current magnetic confinement plasma physics research has increased the demand for radial resolution in profile diagnostics, in particular in the edge and pedestal regions. On NSTX, an upgrade of the existing multi-point Thomson scattering diagnostic has been implemented in order to respond to the research program needs. Twelve new radial channels have been added bringing the total number of positions to 42. Four previously un-instrumented fiber bundles were put in service. Eight existing "active" fiber bundles were divided in two sub-bundles each in order to increase spatial resolution. Twelve radial channels now cover the pedestal region with a resolution near one centimeter. Fifteen radial channels cover the core and internal transport barrier regions. Two additional channels were added, one near the inner edge and one in the outer scrape-off layer. The intersection of the focused viewing optics field of view with a finite-width laser beam results in major-radius cross talk between adjacent fiber sub-bundles. A discussion and calculation of the cross talk will be presented.
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA. leblanc@pppl.gov
authors.forename: B P
authors.initials: BP
authors.lastname: LeBlanc
authors.forename: A
authors.initials: A
authors.lastname: Diallo
authors.forename: G
authors.initials: G
authors.lastname: Labik
authors.forename: D R
authors.initials: DR
authors.lastname: Stevens