An Attempt to estimate the migration pathway of slab-derived fluid using shear wave splitting analysis

Hiratsuka, Shinya; Asamori, Koichi; Saiga, Atsushi

JAEA-Research 2022-002, 38 Pages, 2022/06

JAEA-Research-2022-002.pdf:4.49MB

Deep groundwater originates from dehydration of Pacific and Philippine Sea slab subducting beneath Japanese islands, which has characteristics of high temperature and is rich in carbonate species. In this respect, it is very important for geological disposal of high-level radioactive waste to estimate reservoir and migration pathway of deep groundwater. The region where cracks are densely distributed can be regarded as the migration pathway of slab-derived fluid. It is highly probable that the region has strong anisotropy. Shear wave propagating through anisotropic media splits into two mutually orthogonally polarized waves due to shear wave polarization anisotropy. In this report, we applied shear wave splitting analysis to Hongu area of Tanabe City, Wakayama Prefecture and estimated the spatial distribution of leading shear wave polarization direction (LSPD) and arrival time difference between leading and lagging shear waves (dt). Based on comparison with helium isotope ratio of ground water and bubbling gas samples and two-dimensional resistivity structure estimated by previous study, we attempt to estimate migration pathway of slab-derived fluid in Hongu area of Tanabe City, Wakayama Prefecture. The main results are summarized as follows. When helium isotope ratio of groundwater and bubbling gas samples is high, dt value tends to be large. Shear wave propagating through high and low resistivity anomaly zone show small and large dt values, respectively. Previous study suggested that slab-derived fluid migrates from deeper part of western side of Hongu area and wells out in Yunomine and Kawayu hot springs. This is consistent with spatial distribution of dt values estimated by this study.

Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator

Hiratsuka, Junichi; Hanada, Masaya; Kojima, Atsushi; Umeda, Naotaka; Kashiwagi, Mieko; Miyamoto, Kenji*; Yoshida, Masafumi; Nishikiori, Ryo; Ichikawa, Masahiro; Watanabe, Kazuhiro; et al.

Review of Scientific Instruments, 87(2), p.02B137_1 - 02B137_3, 2016/02

https://doi.org/10.1063/1.4935636

To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of 16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

Development of design technique for vacuum insulation in large size multi-aperture multi-grid accelerator for nuclear fusion

Kojima, Atsushi; Hanada, Masaya; Tobari, Hiroyuki; Nishikiori, Ryo; Hiratsuka, Junichi; Kashiwagi, Mieko; Umeda, Naotaka; Yoshida, Masafumi; Ichikawa, Masahiro; Watanabe, Kazuhiro; et al.

Review of Scientific Instruments, 87(2), p.02B304_1 - 02B304_5, 2016/02

https://doi.org/10.1063/1.4931803

Optimization techniques of the vacuum insulation design have been developed in order to realize a reliable voltage holding capability of Multi-Aperture Multi-Grid accelerators for giant negative ion sources for nuclear fusion. In this method, the nested multilayer configuration of each acceleration stage in the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages were based on the past experimental results of the area effect and the multi-aperture effect on the voltage holding capability. Moreover, total voltage holding capability of multi-stage was estimated by taking the multi-stage effect into account, which was experimentally obtained in this time. In this experiment, the multi-stage effect appeared as the superposition of breakdown probabilities in each acceleration stage, which suggested that multi-stage effect can be considered as the voltage holding capability of the single acceleration gap having the total area and aperture. The analysis on the MAMuG accelerator for JT-60SA agreed with the past gap-scan experiments with an accuracy of less than 10% variation.

Long-pulse production of high current negative ion beam by using actively temperature controlled plasma grid for JT-60SA negative ion source

Kojima, Atsushi; Hanada, Masaya; Yoshida, Masafumi; Umeda, Naotaka; Hiratsuka, Junichi; Kashiwagi, Mieko; Tobari, Hiroyuki; Watanabe, Kazuhiro; Grisham, L. R.*; NB Heating Technology Group

AIP Conference Proceedings 1655, p.060002_1 - 060002_10, 2015/04

https://doi.org/10.1063/1.4916471

In this paper, the recent activities on the new test stand are reported toward demonstration of the long pulse production for 22A, 100s negative ion beams. As for the temperature control of the plasma grid, a prototype of the grid with cooling/heating by circulating a high-temperature fluorinated fluid has been improved to cover the full extraction area by using 5 segments of the PG. These grids were found to have a capability to control the temperature with a time constant of 10s as well as the prototype grid. As a result, 15A negative ion beams for 100s have been achieved.

Non-linear dependence of deflection angle on beam steering control grid displacement in accelerator for N-NBI

Hiratsuka, Junichi; Hanada, Masaya; Umeda, Naotaka; Kojima, Atsushi; Kashiwagi, Mieko; Watanabe, Kazuhiro; Tobari, Hiroyuki; Yoshida, Masafumi

Plasma and Fusion Research (Internet), 10(Sp.2), p.3405045_1 - 3405045_4, 2015/04

https://doi.org/10.1585/pfr.10.3405045

To produce high current density ( 200 A/m), high-energy ( 1 MeV) negative ion beams for long pulse duration time (1 hour) for International Thermo-nuclear Experimental Reactor (ITER), the suppression of the direct interception of the negative ions with the grids has been carefully investigated with studying the deflection angle by aperture displacement technique. The non-linear dependence of the deflection angle appears at the aperture diameter of 14 mm on a steering control grid (SCG). From this dependence, the aperture diameter and the offset distance of the SCG has been designed to be 16 mm and 0.7 mm, respectively and tested in a prototype accelerator for ITER. Each of the beamlets on the multiple apertures is properly steered with compensation of the deflection due to the residual magnetic field in the accelerator and the grid power loading was significantly reduced. It resulted in a 10% enhancement of the accelerated beam current.

Promotion of the gas analysis technology by Breath-Mass

Hiratsuka, Hajime; Hatano, Toshihisa; Abe, Tetsuya

Heisei-24-Nendo Kyoto Daigaku Sogo Gijutsu Kenkyukai Hokokusho (CD-ROM), 3 Pages, 2013/03

no abstracts in English

First measurement of electron temperature from signal ratios in a double-pass Thomson scattering system

Tojo, Hiroshi; Ejiri, Akira*; Hiratsuka, Junichi*; Yamaguchi, Takashi*; Takase, Yuichi*; Itami, Kiyoshi; Hatae, Takaki

Review of Scientific Instruments, 83(2), p.023507_1 - 023507_4, 2012/02

https://doi.org/10.1063/1.3685612

Development of gas analyzer to aim for speed and high sensitivity and shaping of mass spectrum

Hatano, Toshihisa; Hiratsuka, Hajime; Abe, Tetsuya

Journal of the Vacuum Society of Japan, 54(9), p.474 - 477, 2011/09

https://doi.org/10.3131/jvsj2.54.474

Licensable Patent Information Database

Patent publication (In Japanese)

This study focused on more reproducible pumping time constant of vacuum devices. The mass spectrum measured in non-steady state was corrected with a mathematical technique corresponding to constant pressure in steady state. The correction mass spectrum was evaluated from the viewpoint of the gas analysis. In measuring the sample gas was a pulse gas injection. After injection the gas pressure decreases exponentially. Here was confirmed reproducible pumping time constant by pulsing gas injection and investigated influence of the pumping time constant to the correction mass spectrum. N, O, Ar, CO were measured the above method and analyzed. The correction mass spectrum showed use from the comparison with mass spectrum in The National Institute of Standards and Technology (NIST) mass spectra library as for the analysis enough.

Response of fusion gain to density in burning plasma simulation on JT-60U

Takenaga, Hidenobu; Kubo, Hirotaka; Sueoka, Michiharu; Kawamata, Yoichi; Yoshida, Maiko; Kobayashi, Shinji*; Sakamoto, Yoshiteru; Iio, Shunji*; Shimomura, Koji*; Ichige, Hisashi; et al.

Nuclear Fusion, 48(3), p.035011_1 - 035011_6, 2008/03

https://doi.org/10.1088/0029-5515/48/3/035011

A burning plasma simulation scheme has been developed with consideration for temperature dependence of the DT fusion reaction rate in JT-60U. The heating power for the simulation of alpha particle heating was calculated using real-time measurements of density and ion temperature. Response of a simulated fusion gain to the density was investigated in this scheme with constant heating power for the simulation of external heating, in order to understand burn controllability by the fuel density in a fusion reactor. When temperature dependence of the fusion reaction rate was assumed as square of ion temperature, density dependence of the simulated fusion gain stronger than square of density was observed. Transport analysis using a 1.5 dimension transport code indicated that the strong density dependence is induced due to both change in a confinement improvement factor and change in a pressure profile.

Measurement of expiratory alcohol by QMS gas analyzer

Arai, Takashi; Hiratsuka, Hajime; Hasegawa, Koichi; Hatano, Toshihisa; Nemoto, Masahiro; Abe, Tetsuya

Heisei-18-Nendo Nagoya Daigaku Sogo Gijutsu Kenkyukai Sochi Gijutsu Kenkyukai Hokokushu, p.76 - 79, 2007/03

Recently, the accident because of drunken driving is taken up in the topic of news, and the concern is had at the amount of the drinking and the drinking time etc. of the inside of the body. It is said that there is a correlation in the alcoholic density included in an alcoholic amount and the expiration in blood so far, and is reported on the equipment that measures an alcoholic density of the expiration based on this. We also are executing the breath analysis as an example of applying QMS (four pile polar mass spectrometer) gas analyzer "Gravimas". This time, an alcoholic density in the expiration was measured, the performance of this device to alcoholic detection was examined, and the change at the time of an alcoholic density in the expiration high sensitivity was measured. These results suggest the utility of the breath analysis that uses QMS.