Investigation and measures of abnormal events of helium refrigerator for cryogenic hydrogen system at J-PARC

Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Aoyagi, Katsuhiro*; Muto, Hideki*; Nomura, Kazutaka*; Takada, Hiroshi; Ikeda, Yujiro

JAEA-Technology 2017-021, 75 Pages, 2017/08

JAEA-Technology-2017-021.pdf:33.03MB

Liquid hydrogen is employed as a cold neutron moderator material at the spallation neutron source of Materials and Life science experimental Facility of Japan Proton Accelerator Research Complex (J-PARC). From January 2015, it became observable that the differential pressure between heat exchangers and an 80 K adsorber (ADS) in a helium refrigerator system increased with operating time. In November 2015, the differential pressure rise became more significant, leading to degrade the refrigerating performance in cooling liquid hydrogen. In order to investigate the cause of the abnormal differential pressure rise between the heat exchangers and the ADS, we carried out visual inspection inside the heat exchangers and analyzed the impurities contained in the helium gas. Unfortunately, we could not identify the impurities causing the performance degradation, but observed a trace of oil in the inlet piping of the heat exchanger. Based on investigations of the abnormal events occurred in the refrigerators with similar refrigerating capacity at other facilities, we took measures that cleaning the heat exchangers with Freon and replacing the ADS with new one. As a result, the differential pressure rise phenomenon was removed to recover the performance. We have detected oil from the Freon used for cleaning the heat exchangers and at a felt supporting charcoal packed in the ADS. In particular, oil was accumulated in membranous form onto the felt at the entrance side in the ADS. The amount of oil contained in the helium gas was about 10 ppb or so, less than the design value, in the helium refrigerator. However, the oil accumulated onto the felt in the ADS through long operating period may cause abnormal differential pressure rise, leading to the performance degradation of the helium refrigerator. Further study is needed to specify the cause more clearly.

Cooperative behavior of the random and correlated pinning in Er123 films with columnar defects

Awaji, Satoshi*; Namba, Masashi*; Watanabe, Kazuo*; Ito, Shun*; Aoyagi, Eiji*; Kai, Hideki*; Mukaida, Masashi*; Okayasu, Satoru

IEEE Transactions on Applied Superconductivity, 21(3), p.3192 - 3195, 2011/06

https://doi.org/10.1109/TASC.2010.2089588

The flux pinning behaviors for the heavy ion irradiated Er123 films are investigated based on the detailed (, , ) properties. The double peaks of curves for //c appear in case of the matching field of 0.3 T along -axis and 1.7 T tilted from -axis. In addition, the peaks on () at = 0 (B//c), which originate from the columnar defects, decrease with increasing magnetic field but increase again near the irreversibility field. We found that the cooperation model of the -axis correlated and random pinning centers can describe the observed double peak behavior of (B) and the angular dependence of related to the correlated pinning.

Study of beam fluctuation of high speed variably-polarizing undulator APPLE-2 in 2001 Dec.-2002 Nov.

Nakatani, Takeshi; Agui, Akane; Yoshigoe, Akitaka; Tanaka, Hitoshi*; Takao, Masaru*; Takeuchi, Masao*; Matsushita, Tomohiro*; Aoyagi, Hideki*

JAERI-Tech 2005-027, 29 Pages, 2005/05

JAERI-Tech-2005-027.pdf:5.14MB

We measured the orbit fluctuation caused by APPLE-2 type undulator (ID23) installed in the SPring-8 storage ring by using the developed real time measurement system of electron and photon beam position monitors. We quantitatively found two characteristic fluctuations correlating with the ID23 motion by wavelet transform which is a kind of frequency analysis. One originates from the variation of error field during the ID drive. The other originates from the stray magnetic field leaked from the servomotors for the phase drive. Using these results, we tried to get rid of the effect of error fields on the beam orbit by the precise feed-forward correction table and the stray field shield. Consequently we succeeded in suppressing the orbit fluctuation down to sub-micron during the gap drive, which is observed by photon beam position monitors installed in downstream 20m from each light source point.

Measurement of the orbit fluctuation caused by an insertion device with the amplitude modulation method

Nakatani, Takeshi; Agui, Akane; Yoshigoe, Akitaka; Matsushita, Tomohiro*; Takao, Masaru*; Aoyagi, Hideki*; Takeuchi, Masao*; Tanaka, Hitoshi*

AIP Conference Proceedings 705, p.290 - 293, 2004/00

https://doi.org/10.1063/1.1757791

We have developed a new method to extract only the orbit fluctuation caused by changing magnetic field error of an insertion device (ID). This method consists of two main parts. (i) The orbit fluctuation is measured with modulating the error field of the ID by using the real-time beam position measuring system. (ii) The orbit fluctuation depending on the variation of the error field of the ID is extracted by the filter applying the Wavelet Transform. We call this approach the amplitude modulation method. This analysis technique was applied to measure the orbit fluctuation caused by the error field of APPLE-2 type undulator (ID23) installed in the SPring-8 storage ring. We quantitatively measured two kinds of the orbit fluctuation which are the static term caused by the magnetic field error and the dynamic term caused by the eddy current on the ID23 chamber.

Four-blade-drive style X-ray beam position monitor for soft X-ray beamline BL23SU at SPring-8

Agui, Akane; Aoyagi, Hideki*; Yoshigoe, Akitaka; Nakatani, Takeshi

JAERI-Tech 2003-089, 23 Pages, 2003/12

JAERI-Tech-2003-089.pdf:1.33MB

no abstracts in English

Analysis of the orbit distortion caused by SPring-8 ID23 using the wavelet transformation

Matsushita, Tomohiro*; Agui, Akane; Yoshigoe, Akitaka; Nakatani, Takeshi; Tanaka, Hitoshi*; Takao, Masaru*; Aoyagi, Hideki*; Takeuchi, Masao*

Hoshako, 15(5), p.303 - 307, 2002/05

http://ci.nii.ac.jp/naid/10009629724

no abstracts in English

First operation of circular dichroism measurements with periodic photon-helicity switching by a variably polarizing undulator at BL23SU at SPring-8

Agui, Akane; Yoshigoe, Akitaka; Nakatani, Takeshi*; Matsushita, Tomohiro*; Saito, Yuji; Yokoya, Akinari; Tanaka, Hitoshi*; Miyahara, Yoshikazu*; Shimada, Taihei; Takeuchi, Masao*; et al.

Review of Scientific Instruments, 72(8), p.3191 - 3197, 2001/08

https://doi.org/10.1063/1.1382635

no abstracts in English

Efforts to recover performance of helium refrigerator for cryogenic hydrogen system at MLF

Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki; Aoyagi, Katsuhiro; Nomura, Kazutaka; Takada, Hiroshi

no journal, , 

no abstracts in English

Present status and test result of 1MW proton beam injection of liquid hydrogen circulation system of J-PARC high intensity neutron source

Aso, Tomokazu; Teshigawara, Makoto; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi

no journal, , 

Liquid hydrogen (20 K, 1.4 MPaG) is employed as a cold neutron moderator material at the 1 MW spallation neutron source of Japan Proton Accelerator Research Complex (J-PARC). The cryogenic hydrogen system, combined with a helium refrigerator, was adopted to generate a liquid hydrogen circulation flow (185 g/s). Since January 2015, a pressure drop gradually increased between heat exchangers HXs) and an adsorber (ADS) in the helium refrigerator for each operation, causing the refrigerator performance degradation. The performance of helium refrigerator could be recovered as a result of countermeasures focused on accumulated oil removal, such as cleaning the inside HXs and exchanging the ADS at 2016 summer shutdown, however the detailed cause is still in doubt. On the other hand, a long run stable operation could be secured over 175 days in 2018. Just end of long run operation, a first high-intensity-beam injection with 1MW beam power was also carried out for one hour aiming to confirm the refrigerator performance according to design requirement.

Performance degradation of helium refrigerator for liquid hydrogen circulation system of J-PARC high intensity neutron source; Key points to performance recover and future plan

Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro

no journal, , 

no abstracts in English