Multichordal spectroscopy on JT-60

Abstract

In order to study impurity behavior on the JT-60 plasma, a spectroscopic diagnostic system, which is capable of measuring many spectra of impurity ions and their spatial distributions simultaneously, has been developed. This system consists of interchangeable unit-type spectrographs which have different lines of sight. Four types of grazing incidence spectrographs are prepared as unit-type spectrographs. These spectrographs cover the nominal wavelength regions 0.5-5,0.5-50,2.0-50, and 50-122 nm, respectively, and have holographic gratings with flat focal fields. Image-intensified 1024-or 512-channel photodiode arrays are used as detectors for all spectrographs. Four unit-type spectrographs are used for observing the main plasma, and two unit-type spectrographs are used for observing the plasma near the null point of the diverted discharge. One of these spectrographs has been calibrated absolutely in the wavelength region 27.5-120 nm using synchrotron radiation from the Photon Factory (N ationai Laboratory for High Energy Physics) .

Radiation process of carbon ions in JT-60U detached divertor plasmas

“…The detailed specification and setup of the spectrometer is found in Refs. [5,4], respectively. With this spectrometer, the spectral lines of C III (2p 3 P À 3d 3 D : 45:96 nmÞ, C III (2p 3 P À 3s 3 S : 53:83 nmÞ, C III (2p 1 P À 3d 1 D : 57:43 nmÞ and C III (2s 1 S À 2p 1 P : 97:70 nmÞ were measured simultaneously.…”

“…With this spectrometer, the spectral lines of Fig. 1, the viewing chord for a VUV (Vacuum Ultra Violet) spectrometer [5] is shown, which corresponds to 17-29 ch of the viewing chords of the visible spectrometer. The spectral range of 20-120 nm is covered and the dispersion at a wavelength of 35 nm is 2.4 nm/mm.…”

Balance of ionization and recombination of carbon ions in high density peripheral plasmas of the JT-60 U tokamak

“…In Fig. 1(left), the viewing chord for two VUV ( Vacuum Ultra Violet) spectrometers [5] is shown, which corresponds to 17 -29 ch of the viewing chords of the visible spectrometer. The spectral range of 20 -120 nm is covered by one VUV spectrometer, and the dispersion at a wavelength of 35 nm is 2.4 nm / mm.…”

Development of Electrothermal Actuator with Optimized Motion Characteristics

“…In figure 1, the viewing chord for a VUV (vacuum ultra-violet) spectrometer [6] is shown, which corresponds to 17-29 ch of the viewing chords of the visible spectrometer. The incident light through an entrance slit with a width of 10 µm and a height of 5 mm injects with an angle of 85 • to a holographic grating with 300 grooves mm −1 , and is then detected by a microchannel-plate detector with 1024 channels having a pixel width of 50 µm.…”