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Journal Articles

The Energy-resolved neutron imaging system, RADEN

Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Nakatani, Takeshi; Segawa, Mariko; Hiroi, Kosuke; Su, Y.; Oi, Motoki; Harada, Masahide; Iikura, Hiroshi; et al.

Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04

 Times Cited Count:1 Percentile:28.29(Instruments & Instrumentation)

Journal Articles

Measurement of a time dependent spatial beam profile of an RF-driven H$$^-$$ ion source

Wada, Motoi*; Shinto, Katsuhiro; Shibata, Takanori*; Sasao, Mamiko*

Review of Scientific Instruments, 91(1), p.013330_1 - 013330_5, 2020/01

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

The ions are extracted from an ion source through a plasma sheath where a low frequency electromagnetic induction drives transport of charged particles including the target ions. High frequency alternating current commonly excites plasmas in sources for negative hydrogen (H$$^-$$) ions at a frequency in the MHz range. A high-speed beam current monitor system coupled to a narrow entrance slit enabled the investigation of the special distribution of the AC component intensity of the H$$^-$$ ion beam extracted from an ion source driven by a 2 MHz radio frequency (RF) power. The distribution showed a smaller oscillation of the beam at the center.

Journal Articles

Validation of measured microwave absorption and temperature change for development of a single-mode-type microwave heating thermogravimetry apparatus

Karisma, A. D.*; Hamaba, Taishu*; Fukasawa, Tomonori*; Huang, A.-N.*; Segawa, Tomoomi; Fukui, Kunihiro*

Review of Scientific Instruments, 88(2), p.024101_1 - 024101_8, 2017/02

 Times Cited Count:1 Percentile:88.77(Instruments & Instrumentation)

Microwave heating direct denitration method is used in the nuclear fuel reprocessing process. In order to develop a single-mode-type microwave heating thermogravimetry apparatus which can perform detailed analysis of the characteristics of microwave heating, the temperature dependence of microwave absorption is verified. The temperature distribution, microwave absorption efficiency, and dielectric properties of a CuO pellet that was heated by the microwave irradiation were investigated. The temperature distribution in the CuO pellet due to one-way travel of the microwave in the apparatus was accurately reproduced by a three-dimensional numerical simulation of the electromagnetic field. The numerically determined temperature dependency of the CuO absorption efficiency was found to be in very good agreement with published data.

Journal Articles

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

 Times Cited Count:1 Percentile:90.37(Instruments & Instrumentation)

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.

Journal Articles

Time evolution of negative ion profile in a large cesiated negative ion source applicable to fusion reactors

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Umeda, Naotaka; Hiratsuka, Junichi; Ichikawa, Masahiro; Watanabe, Kazuhiro; Grisham, L. R.*; Tsumori, Katsuyoshi*; et al.

Review of Scientific Instruments, 87(2), p.02B144_1 - 02B144_4, 2016/02

 Times Cited Count:5 Percentile:59.13(Instruments & Instrumentation)

Time evolution of spatial profile of negative ion production during an initial conditioning phase has been experimentally investigated in the JT-60 negative ion source. Up to 0.4 g Cs injection, there is no enhancement of the negative ion production and no observation of the Cs emission signal in the source, suggesting the injected Cs is mainly deposited on the water-cooled wall near the nozzle. After 0.4 g Cs injection, enhancement of the negative ion production appeared only at the central segment of the PG. The calculation of the Cs neutral/ion trajectories implied that a part of Cs was ionized near the nozzle and was transported to this area. The expansion of the area of the surface production was saturated after ~2 g Cs injection corresponding to 6000 s discharge time. From the results, it is found that Cs ionization and its transport plays an important role for the negative ion production.

Journal Articles

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

 Times Cited Count:5 Percentile:59.13(Instruments & Instrumentation)

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.

Journal Articles

Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency

Hanada, Masaya; Kojima, Atsushi; 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.02B322_1 - 02B322_4, 2016/02

 Times Cited Count:9 Percentile:39.01(Instruments & Instrumentation)

In International Thermo-nuclear Experimental Reactor (ITER) and JT-60 Super Advanced (JT-60 SA), the D$$^{-}$$ ion beams of 1 MeV, 40 A and 0.5 MeV, 22 A are required to produce 3600 s and 100 s for the neutral beam injection, respectively. In order to realize such as powerful D$$^{-}$$ ion beams for long duration time, Japan Atomic Energy Agency (JAEA) has energetically developed cesium (Cs)-seeded negative ion sources (CsNIS) and electro-static multi-aperture and multi-stage accelerators (MAMuG accelerator) which are chosen as the reference design of ITER and JT-60 SA. In the development of the CsNIS, a 100s production of the H$$^{-}$$ ion beam has been demonstrated with a beam current of 15 A by modifying the JT-60 negative ion source. At the higher current, the long pulse production of the negative ions has been tried by the mitigation of the arcing in the plasma inside the ion source. As for the long pulse acceleration of the negative ions in the MAMuG accelerator, the beam steering angle has been controlled to reduce the power loading of the acceleration grids A pulse duration time has been significantly extended from 0.4 s to 60 s at reasonable beam power for ITER requirement. The achieved pulse duration time is limited by the capacity of the power supplies in the test stand. In the range of $$<$$ 60 s, there are no degradations of beam optics and voltage holding capability in the accelerator. It leads to the further extension of the pulse duration time at higher power density. This paper reports the latest results of development on the negative ion source and accelerator at JAEA.

Journal Articles

Fine-tuning to minimize emittances of J-PARC RF-driven H$$^-$$ ion source

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki; Oguri, Hidetomo

Review of Scientific Instruments, 87(2), p.02B130_1 - 02B130_5, 2016/02

BB2015-0492.pdf:4.68MB

 Times Cited Count:6 Percentile:53.02(Instruments & Instrumentation)

The Japan Proton Accelerator Research Complex (J-PARC) cesiated rf-driven H$$^-$$ ion source (IS), whose requirements are a peak beam intensity of 60mA within normalized emittances of 1.5 $$pi$$mm$$cdot$$mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500 $$mu$$s$$ times$$ 25 Hz) and a life-time of longer than 1month, has been successfully operated for about one year. The results of the fine-tuning to minimize the emittances of the J-PARC-IS with plasma chamber #3, which had the largest emittances with initial settings among four plasma chambers, will be presented in this paper. The rod-filter-filed will be finely tuned by selecting magnets with slightly different field strengths and/or changing gap-lengths. The dependence of the beam-hole-diameter on the emittances will be also presented. The tuning procedure to improve the emittances is one of the most important technologies for the IS of the high-energy and high-intensity accelerator.

Journal Articles

Status of the RF-driven H$$^{-}$$ ion source for J-PARC linac

Oguri, Hidetomo; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki; Ueno, Akira; Shibata, Takanori*

Review of Scientific Instruments, 87(2), p.02B138_1 - 02B138_3, 2016/02

BB2015-0491.pdf:1.81MB

 Times Cited Count:3 Percentile:73.28(Instruments & Instrumentation)

For the upgrade of the Japan Proton Accelerator Research Complex (J-PARC) linac beam current, a cesiated RF-driven negative hydrogen ion source was installed in 2014 summer shutdown period, and started to operate on September 29, 2014. The ion source has been successfully operated with a beam current and a duty factor of 33 mA and 1.25% (0.5 ms and 25 Hz), respectively. The result of recent beam operation showed that the ion source is capable of continuous operation for approximately 1,100 h. The spark rate at the beam extractor was observed to be less than once a day, which is acceptable level for the user operation. Although the antenna failure occurred during the user operation on October 26, 2014, there were no further serious troubles since then. In this conference, we will present the some operation parameters and the beam stability of the RF-driven ion source through the long-term user operation.

Journal Articles

Operation and commissioning of IFMIF (International Fusion Materials Irradiation Facility) LIPAc injector

Okumura, Yoshikazu; Gobin, R.*; Knaster, J.*; Heidinger, R.*; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; et al.

Review of Scientific Instruments, 87(2), p.02A739_1 - 02A739_3, 2016/02

 Times Cited Count:6 Percentile:53.02(Instruments & Instrumentation)

IFMIF is an accelerator based neutron facility having two set of linear accelerators each producing 125mA/CW deuterium ion beams (250mA in total) at 40MeV. The LIPAc (Linear IFMIF Prototype Accelerator) being developed in the IFMIF-EVEDA project consists of an injector, a RFQ accelerator, and a part of superconducting Linac, whose target is to demonstrate 125mA/CW deuterium ion beam acceleration up to 9MeV. The injector has been developed in CEA Saclay and already demonstrated 140mA/100keV deuterium beam. The injector was disassembled and delivered to the International Fusion Energy Research Center (IFERC) in Rokkasho, Japan, and the commissioning has started after its reassembly 2014; the first beam production has been achieved in November 2014. Up to now, 100keV/120mA/CW hydrogen ion beam has been produced with a low beam emittance of 0.2 $$pi$$.mm.mrad (rms, normalized).

Journal Articles

Measurement of ion species in high current ECR H$$^+$$/D$$^+$$ ion source for IFMIF (International Fusion Materials Irradiation Facility)

Shinto, Katsuhiro; Sen$'e$e, F.*; Ayala, J.-M.*; Bolzon, B.*; Chauvin, N.*; Gobin, R.*; Ichimiya, Ryo; Ihara, Akira; Ikeda, Yukiharu; Kasugai, Atsushi; et al.

Review of Scientific Instruments, 87(2), p.02A727_1 - 02A727_3, 2016/02

 Times Cited Count:7 Percentile:47.62(Instruments & Instrumentation)

Journal Articles

Numerical study of plasma generation process and internal antenna heat loadings in J-PARC RF negative ion source

Shibata, Takanori*; Nishida, Kenjiro*; Mochizuki, Shintaro*; Mattei, S.*; Lettry, J.*; Hatayama, Akiyoshi*; Ueno, Akira; Oguri, Hidetomo; Okoshi, Kiyonori; Ikegami, Kiyoshi*; et al.

Review of Scientific Instruments, 87(2), p.02B128_1 - 02B128_3, 2016/02

BB2015-1473.pdf:4.28MB

 Times Cited Count:3 Percentile:73.28(Instruments & Instrumentation)

A numerical model of plasma transport and electromagnetic field in the J-PARC RF ion source has been developed to understand relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. The magnetic field line with absolute magnetic flux density 30-120 Gauss results in the magnetization of electron which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna.

Journal Articles

Development of real-time rotating waveplate Stokes polarimeter using multi-order retardation for ITER poloidal polarimeter

Imazawa, Ryota; Kawano, Yasunori; Ono, Takehiro; Itami, Kiyoshi

Review of Scientific Instruments, 87(1), p.013503_1 - 013503_7, 2016/01

AA2015-0219.pdf:1.34MB

 Times Cited Count:2 Percentile:81.86(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Demonstration of the high collection efficiency of a broadband Mo/Si multilayer mirror with a graded multilayer coating on an ellipsoidal substrate

Ichimaru, Satoshi*; Takenaka, Hisataka*; Namikawa, Kazumichi*; Gullikson, E. M.*; Maruyama, Momoko; Oku, Satoshi*

Review of Scientific Instruments, 86(9), p.093106_1 - 093106_7, 2015/09

 Times Cited Count:3 Percentile:78.36(Instruments & Instrumentation)

A graded and broadband Mo/Si multilayer mirror for EUV spectroscopy is demonstrated. This mirror has an average reflectivity profile of 16% in the wavelength region from 15 nm to 17 nm and an effective area of 1100 - 1500 mm$$^{2}$$. This reflectivity is about 4 times larger than that of a standard Mo/Si multilayer mirror on a 1 in. diameter substrate, showing that the mirror can be used for measuring EUV fluorescence at wavelengths in the region around 15 nm to 17 nm.

Journal Articles

Assessment of the accuracy of plasma shape reconstruction by the Cauchy condition surface method in JT-60SA

Miyata, Yoshiaki; Suzuki, Takahiro; Takechi, Manabu; Urano, Hajime; Ide, Shunsuke

Review of Scientific Instruments, 86(7), p.073511_1 - 073511_13, 2015/07

 Times Cited Count:3 Percentile:78.36(Instruments & Instrumentation)

It is essential for a stable plasma equilibrium control to reconstruct an accurate plasma boundary in tokamak devices. Cauchy Condition Surface (CCS) method is a numerical approach to calculate the spatial distribution of the magnetic flux outside a hypothetical plasma surface and reconstruct the plasma boundary from the magnetic measurements located outside the plasma. It is found that the optimum number of unknown parameters and shape of the CCS for minimizing errors in the reconstructed plasma shape increase in proportion to the plasma size. It is shown that the accuracy of the plasma shape reconstruction greatly improves by using the optimum number of unknown parameters. The assessment of accuracy of plasma shape reconstruction by CCS method in JT-60SA is reported.

Journal Articles

Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro*

Review of Scientific Instruments, 86(7), p.073311_1 - 073311_8, 2015/07

 Times Cited Count:9 Percentile:46.9(Instruments & Instrumentation)

The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was modified to improve the quality and intensity of the single-pulse beam with pulse intervals over 1 $$mu$$s at TIARA cyclotron facility of Japan Atomic Energy Agency. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. As a result, a contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1 %. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the TIARA cyclotron magnet. Provision of the high quality intense single-pulse beam contributes to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.

Journal Articles

A Fluorescence XAFS measurement instrument in the Soft X-ray region toward observation under operando conditions

Honda, Mitsunori; Baba, Yuji; Shimoyama, Iwao; Sekiguchi, Tetsuhiro

Review of Scientific Instruments, 86(3), p.035103_1 - 035103_5, 2015/03

 Times Cited Count:8 Percentile:55.24(Instruments & Instrumentation)

Journal Articles

Note: Proton microbeam formation with continuously variable kinetic energy using a compact system for three-dimensional proton beam writing

Okubo, Takeru; Ishii, Yasuyuki

Review of Scientific Instruments, 86(3), p.036102_1 - 036102_3, 2015/03

 Times Cited Count:2 Percentile:85.18(Instruments & Instrumentation)

Journal Articles

System for measuring temporal profiles of scintillation at high and different linear energy transfers by using pulsed ion beams

Koshimizu, Masanori*; Kurashima, Satoshi; Taguchi, Mitsumasa; Iwamatsu, Kazuhiro; Kimura, Atsushi; Asai, Keisuke*

Review of Scientific Instruments, 86(1), p.013101_1 - 013101_5, 2015/01

 Times Cited Count:8 Percentile:50.82(Instruments & Instrumentation)

We have developed a system for measuring the temporal profiles of scintillation at high linear energy transfer (LET) by using pulsed ion beams from a cyclotron. The half width at half maximum time resolution was estimated to be 1.5-2.2 ns, which we attributed mainly to the duration of the pulsed ion beam and timing jitter between the trigger signal and the arrival of the ion pulse. The temporal profiles of scintillation of BaF$$_{2}$$ at different LETs were successfully observed. These results indicate that the proposed system is a powerful tool for analyzing the LET effects in temporal profiles of scintillation.

Journal Articles

Signal evaluations using singular value decomposition for Thomson scattering diagnostics

Tojo, Hiroshi; Yamada, Ichihiro*; Yasuhara, Ryo*; Yatsuka, Eiichi; Funaba, Hisamichi*; Hatae, Takaki; Hayashi, Hiroshi*; Itami, Kiyoshi

Review of Scientific Instruments, 85(11), p.11D865_1 - 11D865_3, 2014/11

 Times Cited Count:1 Percentile:92.41(Instruments & Instrumentation)

356 (Records 1-20 displayed on this page)