Radial Resolution Enhancement of the NSTX Thomson Scattering Diatnostic
Authors: B.P. LeBlanc, A. Diallo, G. Labik, and D.R. Stevens
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 multipoint
Thomson scattering (MPTS) 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 in order to increase spatial resolution. Twelve radial channels now cover the
pedestal region with a resolution near one centimeter, which is comparable to the thermal-ion Larmor radius
of high power plasmas. 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, which now has
five radial channels. The intersection of the focused viewing optics field of view with a finite-width laser
beam results in major-radius crosstalk between adjacent fiber sub-bundles. A discussion and calculation of
the crosstalk will be presented.
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Submitted to: Review of Scientific Instruments (May 2012) and 19th Topic al Conference High-Temperature Plasma Diagnostics, Monterey, CA May 6-10, 2012
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Download PPPL-4759 (pdf 589 KB 3 pp)
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