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Iwai, Haruki*; Naoi, Norihiro*; Asai, Keisuke*; Iguchi, Tetsuo*; Isobe, Mitsutaka*; Yukawa, Kyohei*; Kawarabayashi, Jun*; Konno, Chikara
no journal, ,
For ion temperature measurement in DD plasma experiments, we are developing a high energy resolution neutron spectrometer based on the associated particle detection using a proton recoil telescope and a time-of-flight spectrometer. To verify the operational principle and the basic performance of this system, we have set up a prototype system through Monte Carlo simulations and carried out a preliminary experiment with a DD neutron beam at the Fusion Neutronics Source (FNS), JAEA. The results have demonstrated that the energy resolution could be achieved around 5.0% (in FWHM) for DD neutrons
Yukawa, Kyohei*; Asai, Keisuke*; Tomita, Hideki*; Iguchi, Tetsuo*; Iwai, Haruki*; Kawarabayashi, Jun*; Konno, Chikara
no journal, ,
We are developing a new neutron spectrometer to apply to the measurement of the D/T burning ratio in the ITER high-power operation region. This system is based on the conventional double crystal TOF method and consists of a water cell and several pairs of scintillators. A water cell is inserted before the first scintillator of the TOF system and acts as a radiator or neutron scattering material. Because DD neutrons have a larger cross section of elastic scattering with hydrogen than DT neutrons, the elastic scattering in the radiator enhances the relative ratio of DD/DT intensity by approximately three times before entering the TOF system. The enhancement of the relative intensity of DD neutrons makes the detection of DD neutrons easier. The feasibility of this method as a neutron spectrometer has been verified through a preliminary experiment using a DT neutron beam (20 mm) at the Fusion Neutronics Source, Japan Atomic Energy Agency, which includes a small amount of DD neutrons.
Tomita, Hideki*; Iwai, Haruki*; Iguchi, Tetsuo*; Kawarabayashi, Jun*; Isobe, Mitsutaka*; Konno, Chikara
no journal, ,
Neutron spectrometer based on coincident counting of associated particles has been developed for deuterium plasma diagnostics on Large Helical Device (LHD) at National Institute for Fusion Science. Efficient detection of 2.5 MeV neutron with high energy resolution would achievable by coincident detection of a scattered neutron and a recoiled proton associated to a elastic scattering of incident neutron in a plastic scintillator as a radiator. Calculated neutron spectra from deuterium plasma heated by neutral beam injection indicate that the energy resolution of less than 7% is required for the spectrometer to evaluate energetic deuterium confinement. By using a prototype of the proposed spectrometer, the energy resolution of 6.3% and the detection efficiency of 3.310 counts/neutron were experimentally demonstrated for 2.5 MeV mono-energetic neutron, respectively.