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Journal Articles

Estimation of eddy current loss for a turbo-molecular pump in the J-PARC rapid cycling synchrotron

Ogiwara, Norio; Kanazawa, Kenichiro

Journal of the Vacuum Society of Japan, 53(3), p.148 - 150, 2010/04

Magnetically suspended turbomolecular pumps (TMPs) have been widely used in nuclear fusion devices and sometimes used in particle accelerators, because it is much easier for the TMPs with dry backing pumps to achieve and maintain UHV without oil contamination. In these devices the TMPs are influenced by a quasi static magnetic field; the eddy current is induced on the rotating rotor and then forces the rotor to thermally expand. In order to use the TMPs safely we attempted to establish a standard procedure for determining the influence of magnetic fields on TMPs. First of all, this influence was investigated in detail through the experiment with a rather small TMP. As a result, the following are found. (1) The parallel magnetic field has no influence, on the other hand, the driving power and the rotor temperature are greatly affected by the vertical magnetic fields. (2) The eddy current loss is formulated and well estimated with a model where a localized magnetic field and current flow exist within the rotor into the region down to a substantial skin depth $$delta$$ from the surface. This time we applied the above conclusions to the TMPs with high radioactive resistance which were employed in the RCS (3-GeV rapid cycling synchrotron) in J-PARC (Japan Proton Accelerator Research Complex). With the evaluation equation of eddy current loss established through the experiment in a uniform magnetic field, the rise of rotor temperature is estimated to be less than 100 $$^{circ}$$C even in the orthogonal magnetic field of 0.003 T. Thus, we concluded that the TMPs are safely operated in the RCS, as the leakage magnetic field at the floor where the TMPs are set is less than 0.001 T.

Journal Articles

Influence of magnetic fields on turbo-molucular pumps

Ogiwara, Norio; Kanazawa, Kenichiro; Inohara, Takashi*; Wada, Kaoru*

Vacuum, 84(5), p.718 - 722, 2009/12

 Times Cited Count:7 Percentile:30.25(Materials Science, Multidisciplinary)

Recently turbo-molecular pumps (TMPs) have been widely used in nuclear fusion devices and sometimes in particle accelerators. Therefore, in order to use them in a quasi-static magnetic field the influence of the fields on TMPs has been exactly investigated. First of all, the influence for the two special magnetic fields has been examined: one is due to the vertical magnetic field, and the other due to the parallel component. The parallel magnetic field has no influence of the operation of the TMP. On the contrary, the driving power and the rotor temperature were largely affected by the vertical magnetic field. The eddy current loss in the vertical field increases rapidly with the field strength. It is proportional to the square of the field strength. The eddy current loss also increases as the revolution frequency, however, it has quite different dependence from the magnetic field strength. These dependences are well explained by the skin depth, which referred to the region where a localized magnetic field and current flow exists. Then we have successfully evaluated the influence of the magnetic field with an arbitrary direction by means of adding the contributions from the two magnetic components. Furthermore, from the demonstration experiment, it is generally found that the magnetic field with the symmetry around the rotor axis does not affect the operation of the TMP.

Journal Articles

Vacuum system of the 3-GeV RCS in J-PARC

Ogiwara, Norio; Kinsho, Michikazu; Kamiya, Junichiro; Yamamoto, Kazami; Yoshimoto, Masahiro; Hikichi, Yusuke; Kanazawa, Kenichiro; Mio, Keigo; Takiyama, Yoichi; Suganuma, Kazuaki; et al.

Vacuum, 84(5), p.723 - 728, 2009/12

 Times Cited Count:7 Percentile:30.25(Materials Science, Multidisciplinary)

To minimize the radiation exposure during maintenance, it is necessary to compose the 3-GeV RCS vacuum system with reliable components which have long life time in such a high level of radiation. In addition, it is necessary to keep the operating pressure with beam in ultra high vacuum for suppressing the pressure instability. Thus we should think of not only the outgassing mainly due to ion desorption but also the pumping efficiency. From the above, the vacuum system was designed. The ring is divided by the isolation valves into 6 sections, which can be pumped down independently. For avoiding any eddy current loss ceramic ducts are used in the bending and focusing magnets. These ducts are connected to the Ti ducts, putting the Ti bellows between. Here, we adopt pure Ti as a material for the ducts and bellows because of its small residual radioactivity. The ring is evacuated with 20 ion pumps (0.7 m$$^{3}$$/s) and 24 turbomolecular pumps (TMPs) (1.3 m$$^{3}$$/s), which are attached to the Ti ducts. The TMPs are used for not only rough pumping but also evacuation during the beam operation. Especially a collimator system for localizing beam losses in a restricted area is evacuated with the TMPs, because the outgassing from this region will be probably the largest. On the other hand, each arc section is pumped by 4 ion pumps and 2 TMPs. To realize the above system, we have developed some components such as large aperture ceramic ducts and TMPs with high radioactive-resistance, as well as several kinds of heat treatment to reduce the outgassing. Finally, we have realized the UHV without baking in the RCS and the beam operation has been succeeded until now.

Journal Articles

Improvement of the shift bump magnetic field for a closed bump orbit of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Kanazawa, Kenichiro; Ueno, Tomoaki; Someya, Hirohiko*; Harada, Hiroyuki*; Irie, Yoshiro; Kinsho, Michikazu; Yamazaki, Yoshishige; Yoshimoto, Masahiro; Kamiya, Junichiro; et al.

IEEE Transactions on Applied Superconductivity, 18(2), p.306 - 309, 2008/06

 Times Cited Count:10 Percentile:50.83(Engineering, Electrical & Electronic)

The four shift bump magnets (BUHS01-04) of the 3-GeV RCS in J-PARC, which are located at the long straight section, produce a fixed main bump orbit to merge the injection beam into the circulating beam. They are realized with four magnets connected in series to form the accurate closed bump orbit. However, the total integrated magnetic field of the four magnets is not zero because of the magnetic field interferences between the shift bump magnet and the adjacent quadrupole magnet (Q magnet). In order to decrease the imbalance of the integrated magnetic field, 0.3mm insulators were inserted at the median plane of the return yoke of the second and third shift bump magnets (BUHS02 and BUHS03). The integrated field has been decreased from 2358.0 Gauss-cm to -71.6 Gauss-cm, resulting in the closed orbit distortion of the beam to be decreases from 6.0 mm to less than 1.0 mm.

Journal Articles

Measurement of the paint magnets for the beam painting injection system in the J-PARC 3-GeV RCS

Takayanagi, Tomohiro; Kanazawa, Kenichiro; Ueno, Tomoaki; Someya, Hirohiko*; Harada, Hiroyuki*; Irie, Yoshiro; Kinsho, Michikazu; Yamazaki, Yoshishige; Yoshimoto, Masahiro; Kamiya, Junichiro; et al.

IEEE Transactions on Applied Superconductivity, 18(2), p.310 - 313, 2008/06

 Times Cited Count:2 Percentile:20.21(Engineering, Electrical & Electronic)

The beam painting injection system of the 3-GeV RCS in J-PARC, which realizes the uniform beam distributions in the ring, consists of four horizontal paint bump magnets and two vertical paint magnets. Each paint bump magnet power supply is required to excite the current with high accuracy that varies from 17.6 kA to zero during 0.5 msec. The IGBT chopper units, the switching frequency of which is 50 kHz each, are multiple connected to achieve the effective carrier frequency of 600 kHz. The output accuracy is then achieved to be less than 1 %. The measurements of the magnetic field with the actual current waveform were performed and the good performance was confirmed.

Journal Articles

Design and construction of septum magnets at 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Ueno, Tomoaki; Togashi, Tomohito; Takeda, Osamu; Kanazawa, Kenichiro; Watanabe, Masao; Yamazaki, Yoshio; Kamiya, Junichiro; Takayanagi, Tomohiro; Kuramochi, Masaya; et al.

IEEE Transactions on Applied Superconductivity, 18(2), p.297 - 300, 2008/06

 Times Cited Count:4 Percentile:30.92(Engineering, Electrical & Electronic)

Journal Articles

Field measurement of DC magnets at 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Ueno, Tomoaki; Togashi, Tomohito; Toyokawa, Ryoji; Takeda, Osamu; Watanabe, Masao; Yamazaki, Yoshio; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; et al.

IEEE Transactions on Applied Superconductivity, 18(2), p.301 - 305, 2008/06

 Times Cited Count:1 Percentile:12.91(Engineering, Electrical & Electronic)

Journal Articles

Influence of magnetic field on turbomolecular pumps

Kanazawa, Kenichiro; Ogiwara, Norio; Suganuma, Kazuaki; Inohara, Takashi*; Wada, Kaoru*

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.391 - 393, 2008/00

no abstracts in English

Journal Articles

Roundness and straightness measurement of ceramic beam ducts for the 3GeV-synchrotron of Japan-Proton Accelerator Research Complex

Nishizawa, Daiji*; Kinsho, Michikazu; Kanazawa, Kenichiro; Ogiwara, Norio; Saito, Yoshio*; Kubo, Tomio*; Sato, Yoshihiro*

Shinku, 47(4), p.339 - 343, 2004/05

no abstracts in English

Journal Articles

Roundness and straightness measurement of ceramic beam ducts for the 3GeV-synchrotron of Japan-proton accelerator research complex

Nishizawa, Daiji*; Kinsho, Michikazu; Kanazawa, Kenichiro; Ogiwara, Norio; Saito, Yoshio*; Kubo, Tomio*; Sato, Yoshihiro*

Shinku, 47(4), p.339 - 343, 2004/02

Large aperture cylindrical beam ducts consisting of alumina ceramics will be used for the first time in the 3GeV-synchrotron of High Intensity Proton Accelerator Facility. It is necessary to evaluate roundness and straightness of ceramic ducts because we have to compensate contact area of the connected beam duct large as well as we have to compensate large enough beam aperture. We developed an apparatus of measuring roundness and straightness, and we completed data analysis method as well as measuring method. Then we are measuring and evaluating roundness and straightness of ceramic beam ducts. Now, we have newly made an ellipse ceramic duct for the 3GeV-synchrotron BM. This duct has ellipse cross-sections to satisfy with larger aperture that the beam dynamics requires. In this conference, we are going to present taken data and findings regarding form accuracy including roundness and straightness of the ellipse ceramic duct.

Journal Articles

Design of a dipole magnet for the 3-GeV proton synchrotron of the JAERI/KEK joint project

Tani, Norio; Kanazawa, Kenichiro; Shimada, Taihei; Suzuki, Hiromitsu; Watanabe, Yasuhiro; Adachi, Toshikazu*; Someya, Hirohiko*

Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.2376 - 2378, 2002/00

The 3-GeV synchrotron proposed in the JAERI/KEK Joint Project is a rapid-cycling synchrotron (RCS), which accelerates a high-intensity proton beam from 400 MeV to 3 GeV at a repetition rate of 25 Hz. The 3-GeV synchrotron is used to produce pulsed spallation neutrons and muons. It also works as an injector for a 50-GeV synchrotron. Since the magnets for the 3-GeV synchrotron are required to have a large aperture in order to realize the large beam power of 1 MW, there is a large leakage field at an end part than a usual synchrotron magnet. In addition, 25-Hz ac field induces an eddy current in magnet components: e.g. a coil, magnet end plates and etc. We intend to use a stranded conductor as a coil conductor so that the eddy current induced in the coil can be reduced. On the other hand, the eddy current induced in the end plates is expected to be large. Therefore, it is important to investigate an effect of the large leakage field and the eddy current to the beam motion around the magnet end part. We have constructed a prototype dipole magnet and field measurement system for this purpose. This paper reports the results of the design and the preliminary test about this magnet.

JAEA Reports

Roundness and straightness measurement of ceramic beam ducts for the 3GeV-synchrotron

Nishizawa, Daiji*; Kinsho, Michikazu; Kanazawa, Kenichiro; Kubo, Tomio*; Sato, Yoshihiro*; Saito, Yoshio*

JAERI-Tech 2001-081, 117 Pages, 2001/12

JAERI-Tech-2001-081.pdf:6.84MB

no abstracts in English

Oral presentation

Simulation of eddy current on the turbo-molecular pump in a magnetic field

Ogiwara, Norio; Kanazawa, Kenichiro; Yanagibashi, Toru

no journal, , 

Oral presentation

Alpha-ray measurement of dissolved plutonium particle on the TIMS filament

Yasuda, Kenichiro; Suzuki, Daisuke; Kanazawa, Kazuhito; Miyamoto, Yutaka; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

In order to detect of undeclared activities in nuclear facilities, we develop to technique of safeguards environmental sample analysis in JAEA. As part of this effort, isotope ratio analysis of individual MOX particle was performed using by TIMS without chemical treatment. It is possible to estimate an age determination of plutonium purification by a combination of the plutonium isotope ratios and (Pu-238+Am-241)/(Pu-239+Pu-240) alpha activity ratios were obtained by the alpha spectrometry. Since the plutonium particle size is more than 1$$mu$$m due to the influence of self-absorption, exactly measurement of the activity ratios has been difficult. Therefore, we were examining how to acid dissolution in the plutonium particles on the TIMS filament before alpha spectrometry.

Oral presentation

Feasibility study of americium determination method in plutonium particles using alpha spectrometry

Yasuda, Kenichiro; Suzuki, Daisuke; Kanazawa, Kazuhito; Miyamoto, Yutaka; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

We are applying a screening technique with alpha spectrometry to the analysis of particles containing nuclear materials in swipe samples. In this presentation, individual plutonium particles with known purification dates prepared from a standard reference material (NBS SRM947) were measured with alpha spectrometry. The obtained $$frac{^{238}Pu+^{241}Am}{^{(239+240)}Pu}$$ activity ratios for the particles with the diameters of more than 1 micrometer were consistent with the reference values within the uncertainties. These results indicate that alpha spectrometry can be applied to the quantitative analysis of $$^{241}$$Am in individual plutonium particles.

Oral presentation

Feasibility study of americium estimation method by alpha-ray measurement for age dating of individual plutonium particles

Yasuda, Kenichiro; Suzuki, Daisuke; Kanazawa, Kazuhito; Miyamoto, Yutaka; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

We are applying a screening technique with alpha-ray measurement to the analysis of particles containing nuclear materials in swipe samples. In the present study, individual plutonium particles with known purification dates prepared from a standard reference material (NBS SRM947) were measured with alpha-ray spectrometry. The obtained ($$^{241}$$Am+$$^{238}$$Pu)/$$^{239+240}$$Pu activity ratios for the particles with the diameters of less than 2 micrometers were consistent with the reference values within the uncertainties. These results indicate that alpha spectrometry can be applied to the quantitative analysis of $$^{241}$$Am in individual plutonium particles.

16 (Records 1-16 displayed on this page)
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