VUV Doppler broadening measurement


[Objectives]
To measure ion temperature in the divertor region from the Doppler broadening of carbon and oxygen line emission in the vacuum ultraviolet (VUV) wavelength range.

[Detectors, Diagnostic Method]
VUV line emission from carbon and oxygen ions in the inner divertor region is reflected at an angle of 68degree using a tungsten mirror and is led to a 1.2 m normal incidence VUV spectrometer, which is installed at the ground floor. The Doppler broadening of line emission is measured with the higher order (ex. the 4th order for
C IV 155.08 nm at 620.3 nm) to obtain a high wavelength resolution.

[Specification]
¥Time resolusion :20 ms/spectrum (1024ch)
¥wavelength range:100 - 235 nm
¥dispersion:4.54 nm/mm at 610 nm
¥Spatial resolution:about 10 mm (one chord)
¥Position:P-5 section, U1-2a port
¥Detector:Photodiode array (1024ch) + tandem MCP

[Reference]
(1) A. Sakasai et al., "Spectroscopic System for Measurements of Ion temperatures from Doppler broadening on JT-60", Kakuyugo Kenkyu Vol 59 supplement, 169 (1988), in Japanese.