Progress of the general control system for the Materials and Life Science Experimental Facility in J-PARC

Sakai, Kenji; Oi, Motoki; Watanabe, Akihiko; Kai, Tetsuya; Kato, Yuko; Meigo, Shinichiro; Takada, Hiroshi

JAEA-Conf 2015-002, p.593 - 598, 2016/02

https://doi.org/10.11484/jaea-conf-2015-002

For safe and stable beam operation, a MLF general control system (GCS) consists of several subsystems such as an integral control, interlock, server, network, and timing distribution systems. Since the first beam injection in 2008, the GCS has operated stably without any serious troubles in comparison with upgrade of target devices for ramping up beam power and increment of user apparatuses year by year. In recent years, however, it has been improved significantly in view of sustainable long-term operation and maintenance. The monitor and operation system of the GCS has been upgraded by changing its framework software to improve potential flexibility in its maintenance. Its interlock system was also modified in accordance with the re-examination of the risk management system of J-PARC. This paper reports recent progress of the MLF-GCS.

In-situ structural integrity evaluation for high-power pulsed spallation neutron source by using a laser Doppler method

Wan, T.; Naoe, Takashi; Wakui, Takashi; Haga, Katsuhiro; Kogawa, Hiroyuki; Futakawa, Masatoshi

JAEA-Conf 2015-002, p.76 - 87, 2016/02

https://doi.org/10.11484/jaea-conf-2015-002

High power accelerator driven pulsed spallation neutron sources are being developed in the world. Mercury is used as a target material to produce neutrons via the spallation reaction induced by injected protons. At the moment of the proton injection, the mercury vessel with a double wall structure is impulsively excited by the interaction between mercury and solid wall. The vibrational signals were measured in noncontact and remotely by using a Laser Doppler Vibrometer (LDV) system to evaluate the structure integrity. The extreme damages were assumed as the first step, i.e., the inner structure was partly broken by erosion. The dependency of vibrational behaviors on the damage was systematically investigated through numerical simulations and experiments. A LDV was installed to monitor the dependency of an electro-Magnetic Impact Testing Machine (MIMTM) vibration on the damage size. Through the numerical simulation, it was found that the target vessel vibration depends on the damage size. A technique referred to a Wavelet Differential Analysis (WDA) has been developed to enhance the effect of damages on the impulsive vibration behavior. However, the vibration signals obtained from MIMTM contain considerable noise. In order to reduce the noise effect on the impulsive vibration behavior, the statistical methods referred to an Analysis of Variance (ANOVA) and an Analysis of Covariance (ANCOVA) was applied. Numerical simulation results that obtained from controlling the damage size, were firstly added to random noise with various levels manually, and then were analyzed by the statistic methods. Then, the field data that measured from the real mercury target was analyzed. The results represent that the combination of WDA and ANOVA/ANCOVA could effectively indicate the damage dependency.

Localization of the beam loss caused by the foil scattering for high-intensity routine operation in the J-PARC 3-GeV Rapid Cycling Synchrotron

Kato, Shinichi; Yamamoto, Kazami; Harada, Hiroyuki; Hotchi, Hideaki; Kinsho, Michikazu

no journal, , 

The J-PARC 3-GeV rapid cycling synchrotron (RCS) accelerates proton beams from 400 MeV to 3 GeV and the designed output beam power is 1 MW. To achieve a high-intensity output beam power, the RCS adapts H charge-exchange multi-turn injection. The H beam from the Linac is delivered to the RCS injection point, where it is injected through a carbon stripper foil in order to strip two electrons and to convert into proton. This injection is divided into 308 turns. Therefore, the both injection and circulating beams hit the foil repeatedly and scattering occur during the injection. Especially, large-scattered particles cause uncontrolled beam losses at downstream area. Thus, a new collimation system was developed and installed downstream of the foil to localize these losses in 2011. In the beam commissioning at 181 MeV and 400 MeV injection energy, unique tuning method of the collimator has been established and consequently these uncontrolled beam losses were localized successfully.

Magnetic shield design of in-situ SEOP polarized He neutron spin filter for high magnetic field sample environment accessories at J-PARC

Kira, Hiroshi*; Hayashida, Hirotoshi*; Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Suzuki, Junichi*; et al.

no journal, , 

Recent status of a cold neutron disk chopper spectrometer AMATERAS

Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Kawakita, Yukinobu; Inamura, Yasuhiro; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Soyama, Kazuhiko; Harada, Masahide; Oikawa, Kenichi; et al.

no journal, , 

Thermal hydraulic design of double-walled mercury target vessel

Haga, Katsuhiro; Naoe, Takashi; Wakui, Takashi; Kogawa, Hiroyuki; Kinoshita, Hidetaka; Futakawa, Masatoshi

no journal, , 

For the mercury target of a pulsed spallation neutron source of J-PARC, cavitation damage of the target vessel wall which is caused by the pressure wave in mercury induced by high power pulsed proton beam of 1 MW is the crucial issue. So far, the analytical and experimental studies and the operational experiences of SNS suggest that the rapid mercury flow can mitigate the cavitation damages. In order to include this effect into the target design of J-PARC, we adopted doubled-walled structure to the beam window of the target vessel. The mercury flow channel with a narrow gap of 2 mm was made by adding an inner wall to just inside of the beam window. In order to investigate the mercury flow distribution and flow field, numerical simulations were carried out using the conventional code, ANSYS FLUENT. While the mercury velocity outside of the narrow channel was 1.2 m/s, the mercury velocity in the narrow channel increased to almost 4 m/s, which was promising to suppress the cavitation damages. The effect of the inner wall failure of the narrow channel on the mercury flow was also evaluated. The round hole was created on the inner wall at the center of the beam window. The simulation results and the water experimental results showed that the mercury flow velocity in the narrow channel was almost the same with the case without a hole if the hole diameter is around 10 mm.

Current status of the small and wide angle neutron scattering instrument TAIKAN at J-PARC

Takata, Shinichi; Suzuki, Junichi*; Oishi, Kazuki*; Iwase, Hiroki*; Shinohara, Takenao; Oku, Takayuki; Nakatani, Takeshi; Inamura, Yasuhiro; Ito, Takayoshi*; Tominaga, Taiki*; et al.

no journal, , 

The small and wide angle neutron scattering instrument, , was installed at the 15 in the Materials and Life Science Experimental Facility, , of . is designed for efficient measurement in wide-q range by using of the wide wavelength and the four detector banks which cover small-, middle-, high-, and backward-angle. At the present stage, 1,216 s are mounted on , where the number is about 50% of the installable total s number. On beam commissioning started in January 2012, and user program began in March 2012. The software of data reduction has newly developed and some sample environment devices such as a sample changer, tension tester, and refrigerator have been improved. In this presentation, we present the current status of about the new software, sample environment devices, and the results on some samples to show the instrument performance of .

The First energy-resolved neutron imaging system in the world; RADEN at J-PARC MLF

Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Segawa, Mariko; Harada, Masahide; Nakatani, Takeshi; Oi, Motoki; Sato, Hirotaka*; Kamiyama, Takashi*; Yokota, Hideo*; et al.

no journal, , 

no abstracts in English

Transformation of S(Q,E) to G(r,t) with MEM

Kikuchi, Tatsuya

no journal, , 

Dynamic structure factor, S(Q,E), which can be obtained by Inelastic neutron scattering directly, is a function of scattering vector, Q, and energy transfer, E. In recent years, importance of the studies on dynamics that cannot be well described by Q and E in substances such as battery materials has increased. S(Q,E) is defined as a Fourier-transformed function from van Hove's space-time correlation function, G(r,t), which is a function in real space and time. G(r,t) is important to express local motions of atoms and molecules directly on these substances. However, the calculation of G(r,t) has been hardly performed even though it is so easy mathematically, because it requires spectrum in both high resolution and wide range in Q-E space. By the progress of the recent neutron sources and spectrometers, the measurements with wide range and high resolution in Q-E space are becoming easy. We measured high-resolution S(Q,E)s using AMATERAS spectrometer installed at J-PARC and calculated G(r,t)s. We used the maximum entropy method to lower the bias of truncation errors for the calculation of G(r,t).

Very high-cycle fatigue behavior in mercury target vessel for high-power pulsed spallation neutron source

Xiong, Z.; Naoe, Takashi; Futakawa, Masatoshi; Wakui, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Maekawa, Katsuhiro*

no journal, , 

An enclosure vessel of liquid mercury spallation target, which is made of 316L stainless steel, is suffered from the cyclic loading due to the proton beam-induced pressure waves. The number of loading cycles will be beyond 10 to giga-cycle region throughout the expected service life. In and around giga-cycle region, the fatigue failure occurs under the conventionally defined fatigue limit. In addition to the cyclic loading, the strain rate at the beam window of the target vessel reaches to 50 1/s at the maximum, which is much higher than the conventional fatigues. In this work, ultrasonic fatigue tests were conducted with controlling specimen surface temperature to investigate effects of the temperature and the work hardening that simulates the irradiation embrittlement on very high-cycle fatigue strength of 316L SS. The experimental result showed that the obvious fatigue limit was not observed up to 10 cycles, and the fatigue strength was reduced about 75% of R.T. around 250 C regardless of the work hardening, which was the conceivable maximum temperature of the beam window at the 1 MW operation.