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Hayashi, Takao; Nishitani, Takeo; Ishikawa, Masao
Review of Scientific Instruments, 75(10), p.3575 - 3577, 2004/10
Times Cited Count：12 Percentile：53.63(Instruments & Instrumentation)Micro fission chambers, which are pencil sized ionization chamber with fissile material inside, to be installed in the vacuum vessel as neutron monitor for the International Thermonuclear Experimental Reactor (ITER). The micro fission chamber has been installed inside toroidal field coils in JT-60U, in order to investigate the technical validity as neutron monitor in a magnetic field of about 2 T. Compared with the neutron yield measured by three 
U fission chambers which are used as neutron monitors in JT-60U, neutron yield measured by micro fission chamber has a good linearity with them. The influence of the magnetic field on the micro fission chamber has not been observed. However improper signals caused by plasma disruption and breakdown event of Neutral Beam Injection were observed, probably due to long wiring between the detector and the preamplifier. Therefore, by enhancement of noise protections, micro fission chambers can be available as neutron monitor for ITER.
Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi
JAERI-Tech 2002-032, 41 Pages, 2002/03
JAERI-Tech-2002-032.pdf:2.62MB
A micro-fission chamber and a dummy chamber without uranium were fabricated and the performance was tested. They are designed to be installed inside the vacuum vessel of compact ITER (ITER-FEAT) for neutron monitoring. Vacuum leak rate of the chamber, resistances between central conductor and outer sheath, and mechanical strength up to 50G acceleration were confirmed to meet design criteria. Gamma-ray sensitivity was measured with 
Co gamma-ray irradiation facility at JAERI Takasaki. The output signals for gamma-rays in Campbelling mode were estimated to be less than 0.1% those by neutrons at the location behind the blanket module in ITER-FEAT. Detector response for 14 MeV neutrons was investigated with the FNS facility. Excellent linearity between count rates and neutron fluxes was confirmed. According to the test for the change of surrounding materials, the sensitivity was enhanced by slow-downed neutrons, which agreed with the calculation result by MCNP-4C code. As a result, it was concluded that the developed micro-fission chamber is applicable for ITER-FEAT.
Nishitani, Takeo; Ebisawa, Katsuyuki*; Walker, C.*; Kasai, Satoshi
JAERI-Tech 2001-066, 57 Pages, 2001/10
JAERI-Tech-2001-066.pdf:1.89MB
no abstracts in English
Nishitani, Takeo; L.C.Johnson*; Ebisawa, Katsuyuki*; C.Walker*; Ando, Toshiro; Kasai, Satoshi
Review of Scientific Instruments, 70(1), p.1141 - 1144, 1999/01
Times Cited Count：15 Percentile：68.21(Instruments & Instrumentation)no abstracts in English
Nishitani, Takeo; Ebisawa, Katsuyuki*; C.Walker*; *; Kasai, Satoshi; L.C.Johnson*
Proc. of Int. Workshop on Diagnostics for Experimental Fusion Reactors, p.491 - 500, 1998/00
no abstracts in English
Nishitani, Takeo; Ebisawa, Katsuyuki*; Iguchi, Tetsuo*; Matoba, Toru
Fusion Engineering and Design, 34-35, p.567 - 571, 1997/00
Times Cited Count：13 Percentile：70.31(Nuclear Science & Technology)no abstracts in English
