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Kajita, Shin; Hatae, Takaki; Kusama, Yoshinori
Review of Scientific Instruments, 79(10), p.10E726_1 - 10E726_4, 2008/10
Times Cited Count：3 Percentile：19.4(Instruments & Instrumentation)In ITER edge Thomson scattering measurement system, it is planned that polychromator by use of optical filters and avalanche photodiodes is used for the detection system. In this paper, the optimization of the filter transmission wavelength ranges is performed by minimizing the numerically calculated electron temperature error. The Thomson spectrum extends to considerably low wavelength ranges because high electron temperature measurement is required; therefore, it is important to eliminate the line emission from the plasma. It has been found that a filter below 656 nm, which corresponds to the strong line emission of 
, is important for evaluating the electron density and temperature because the required maximum temperature is 10 keV, in which the tail of the spectrum is broadened around 400 nm. Moreover, the calculation indicates that a filter, transmission wavelength of which is higher than 1064 nm, is also useful to reduce the measurement error.
Ishikawa, Masao; Kondoh, Takashi; Nishitani, Takeo; Kusama, Yoshinori
Review of Scientific Instruments, 79(10), p.10E507_1 - 10E507_4, 2008/10
Times Cited Count：14 Percentile：53.6(Instruments & Instrumentation)Micro-fission chambers (MFCs) are one of the most important diagnostics to measure the fusion power in ITER. The MFCs for high power operation (measurement range: fusion power of 100 kW - 1 GW) and MFCs for low power operation (fusion power of 
100 kW) will be used in combination in order to cover the target measurement requirements of ITER. The MFCs for high power operation will be installed in the vacuum vessel. However, since size of the MFCs for low power operation is large, those will be installed in the equatorial (EQ) port. Several kinds of neutron shield exist between the plasma and MFCs. Then, we estimate the effect of these shields by a neutron Monte Carlo calculation using MCNP code. Effect of the changes in the plasma positions is also investigated. It is found that correction based on the position of the plasma center for output of the MFCs is needed for the horizontal changes in the plasma position for the MFC for low power operation.
Shinohara, Koji; Okuji, Toshio*; Ishikawa, Masao; Baba, Mamoru*; Itoga, Toshiro*
Review of Scientific Instruments, 79(10), p.10E509_1 - 10E509_4, 2008/10
Times Cited Count：3 Percentile：19.4(Instruments & Instrumentation)Suzuki, Takahiro; Isayama, Akihiko; Matsunaga, Go; Oyama, Naoyuki; Fujita, Takaaki; Oikawa, Toshihiro
Review of Scientific Instruments, 79(10), p.10F533_1 - 10F533_5, 2008/10
Times Cited Count：8 Percentile：39.24(Instruments & Instrumentation)Motional Stark effect (MSE) diagnostics in JT-60U works as polarimeter to measure the pitch angle of magnetic field as well as beam-emission-spectroscopy (BES) monochromator simultaneously at 30 spatial channels. Fluctuation in the BES signal using MSE optics (MSE/BES) contains fluctuations in not only the density but also the pitch angle (or the magnetic field). Correlation analysis of the magnetic fluctuation between two spatial channels have been applied to a high beta plasma with m/n=2/1 MHD activity at frequency of about 0.9 kHz. It has been found that the magnetic fluctuation measured by the MSE/BES is spatially localized near q=2 surface measured by the MSE diagnostic and that the phase of the fluctuation is inverted at about the q=2 surface, suggesting magnetic island-structure by neo-classical tearing mode (NTM). The magnetic fluctuation measured by the MSE/BES at outside of the q=2 surface is consistent with that by the pick-up coil placed outside the plasma.
Hayashi, Takao; Nishitani, Takeo; Sukegawa, Atsuhiko; Ishikawa, Masao; Shinohara, Koji
Review of Scientific Instruments, 79(10), p.10E506_1 - 10E506_3, 2008/10
Times Cited Count：6 Percentile：32.32(Instruments & Instrumentation)In D-D or D-T operation fusion devices, the fusion neutron yield is the most important parameter to estimate the fusion power. We have conducted calibrations of a microfission chamber, 14 mm in diameter and 200 mm in length, by both Cf-252 neutron source and real plasmas in JT-60U. The detector employs both pulse counting and Campbelling modes in the electronics to cover 10
dynamic range of the neutron source strength. The efficiencies were influenced by the various components. The point efficiencies can be integrated and averaged with angle to provide toroidal line efficiencies. The line efficiencies of microfission chamber and the nearest neutron monitor of U-235 fission chamber was 5.38 
10
and 1.77 10
, respectively. Then the calibration using real plasma was also performed. The detection efficiency in Campbelling mode was about three-tenth of the nearest neutron monitor, which is consistent with the calibration result using Cf-252 neutron source.
Howard, J.*; Hatae, Takaki
Review of Scientific Instruments, 79(10), p.10E704_1 - 10E704_3, 2008/10
Times Cited Count：3 Percentile：19.4(Instruments & Instrumentation)