Simple 3D PIC analysis for beam phase space oscillation in RF driven negative hydrogen ion source

Shibata, Takanori*; Shinto, Katsuhiro; Nakano, Haruhisa*; Hoshino, Kazuo*; Miyamoto, Kenji*; Okoshi, Kiyonori; Nammo, Kesao*; Ikegami, Kiyoshi*; Kawai, Isao*; Oguri, Hidetomo; et al.

Journal of Physics; Conference Series, 2743, p.012007_1 - 012007_5, 2024/05

https://doi.org/10.1088/1742-6596/2743/1/012007

Oscillation of the negative hydrogen ion (H) beam phase space in Radio Frequency (RF) ion source is investigated by a simple 3D Particle-In-Cell (PIC) model which takes into account the transport processes of electron, proton and H in the extraction region. The calculation domain is in vicinity of the single beam aperture in J-PARC ion source configuration. In order to understand relation between the plasma density oscillation and the extracted H beam characteristics, the input electron and proton fluxes from the driver region are varied parametrically with the 1st and the 2nd harmonics of the J-PARC RF frequency (2 or 4 MHz). The numerical results give an idea to the main physical processes between the oscillations of the plasma parameters and the extracted H ion trajectories in the different RF phases. Countermeasures to reduce the oscillation mechanisms are also discussed in the presentation.

Discoloration of RF antenna coil surface after long-term operation of J-PARC ion source

Shibata, Takanori*; Shinto, Katsuhiro; Nammo, Kesao*; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Oguri, Hidetomo; Ishida, Masaki*; Wada, Motoi*

Journal of Instrumentation (Internet), 19, p.C01009_1 - C01009_8, 2024/01

https://doi.org/10.1088/1748-0221/19/01/C01009

From Nov. 2020 to Apr. 2021, the continuous ion source operation for 3,651 hours (5 months) was achieved. As the lifetime of the RF ion source is mainly limited by failure on the enamel coating of the RF antenna, detailed evaluation of the antenna surface is required to ensure feasibility of the further extension of the operation time. In the present study, surface discoloration on the RF antenna coil observed after the 5 months operation is investigated by application of digital microscope and SEM/EDS analyses. The material mapping and the line spectrum obtained by the EDS analysis show that depositions of the sputtered source chamber wall materials and the injected cesium on to the enamel coating are the most possible candidate for the discoloration. The dimension measurements of the RF antenna thickness before and after the long-term operation support the idea that the discoloration is due to the deposited materials and hence insulation of the RF antenna coil by enamel coating is maintained. The emittance measurement after the operation also shows that the RF plasma and the beam formations are not affected by the deposition on the antenna.

High-speed emittance measurements for beams extracted from J-PARC RF ion source

Shibata, Takanori*; Shinto, Katsuhiro; Wada, Motoi*; Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*

AIP Conference Proceedings 2373, p.050002_1 - 050002_9, 2021/08

https://doi.org/10.1063/5.0057418

Oscillation of emittance and Twiss parameters in the negative ion beam from the J-PARC 2-MHz RF ion source is measured by applications of a double-slit emittance monitor located at the RFQ (Radio Frequency Quadrupole) entrance. The emittance monitor is equipped with a newly-developed 60 MS/s data acquisition system, so that beam current oscillation in a few MHz can be observed with enough time resolution. From the measurement, it is shown that the beam phase space consists of (1) a DC component in the beam core, (2) a 2-MHz oscillating component which takes place both in the beam core and the halo and (3) a doubled RF frequency (4 MHz) oscillation which slightly exists in the beam halo. The major component is the 2-MHz component, which resultantly decides the beam emittance oscillation frequency. A typical value of the beam emittance in the present experiment is 0.34 mm-mrad, while the amplitude of the 2 MHz oscillation is around 0.04 mm-mrad. The results indicate that the high-frequency oscillation component occupying about ten-percent of the beam from the RF source travels a few meters passing through a magnetic lens focusing system.

Enhancement of control rod drive mechanism seating position detector for JRR-3

Ouchi, Satoshi; Kurumada, Osamu; Kamiishi, Eigo; Sato, Masayuki; Ikekame, Yoshinori; Wada, Shigeru

JAEA-Technology 2016-015, 42 Pages, 2016/06

JAEA-Technology-2016-015.pdf:3.53MB

The purpose of the control rod drive mechanism seating position detector for JRR-3 is one of a method for confirming the shutdown condition of the reactor. The detector has been utilizing more than 25 years with maintenance regularly. However, it is occurred some trouble recently. Moreover, the detector has already been end of manufacture, and even in the successor detector, it unsuitable for the control rod drive mechanism of JRR-3 was confirmed. Therefore, it was necessary to select the adequate detector to the control rod drive mechanism of JRR-3. Accordingly, we built a test device with the aim of verify several detectors for integrity and function. At the time of the test for performance confirmation, it was occurred unexpected problems. Nevertheless, we devise improvement of the problems and took measures. Thus we were able to collect adequate detector for JRR-3 and replace to enhanced detector. This paper reports the Enhanced of Control rod drive mechanism seat position detector.

Status of JRR-3 after Great East Japan Earthquake

Arai, Masaji; Wada, Shigeru; Murayama, Yoji

Proceedings of International Topical Meeting on Research Reactor Fuel Management and Meeting of the International Group on Reactor Research (RRFM/IGORR 2016) (Internet), p.403 - 408, 2016/03

In response to the accident at Fukushima Daiichi NPS, the new safety standards for research and test reactor facilities came into force on December 18, 2013. The evaluation of natural disasters and prevention of spread of accidents beyond design basis mainly were enhanced in the standards. We have completed the necessary checks and assessments, and submitted an application for reviewing if JRR-3 complies with the new standards to the Nuclear Regulation Authority on September 26, 2014.

Current status of irradiation facilities in JRR-3, JRR-4 and NSRR

Kishi, Toshiaki; Ichimura, Shigeju; Kinase, Masami; Wada, Shigeru

JAEA-Conf 2008-010, p.146 - 158, 2008/12

https://jopss.jaea.go.jp/pdfdata/JAEA-Conf-2008-010-1.pdf

The Department of Research Reactor and Tandem Accelerator operates three research reactors, JRR-3, JRR-4 and NSRR. JRR-3 was operated for 180 days in Japanese Fiscal Year 2007. The neutron bender system was installed on the cold neutron guide tube. As a result, the cold beam intensity has increased by about 10 times. JRR-4 was operated for 93 days in Japanese Fiscal Year 2007. Boron neutron capture therapy was carried out 25 times. The trouble of reflector occurred in December 2007. At present, the reactor has stopped to replace the reflectors. NSRR has been built for the investigation of light water reactor fuel behavior during off-normal conditions such as reactivity-initiated accident. Recently the investigation is performed for the behavior of high burnup fuel and mixed oxide fuel. At present, the NSRR experiments with the new capsule are continuing for high burnup fuels of 59, 67 and 71 GWd/t.

Conceptual design of JRR-3 automated silicon irradiation device for Neutron-Transmutation-Doped Silicon Semiconductor (NTD-Si) production

Hirose, Akira; Wada, Shigeru; Kusunoki, Tsuyoshi

JAEA-Technology 2007-033, 87 Pages, 2007/03

JAEA-Technology-2007-033.pdf:4.44MB

Neutron-Transmutation-Doped Silicon Semiconductor (NTD-Si) has good properties for the power device. In recent years the demand of NTD-Si has increased significantly due to mass production of hybrid-cars. We have been investigated the expansion technology of the NTD-Si productivity using the research reactors JRR-3, JRR-4 and JMTR of JAEA in order to meet the demand. The conceptual design of the automated silicon irradiation device using the JRR-3 Uniformity Irradiation System was carried out as one of the effective measures. After a Si ingot is irradiated once, it is turned over manually and irradiated again in order to irradiate the ingot uniformly. With the conventional equipment, it is necessary to wait radioactivity of the ingot decrease less than the permissible level with holding the ingot in the irradiation equipment. The waiting procedure takes 48 hours or more. Because the automated NTD-Si irradiation device reduces the manual operation process and the waiting time, it is effective to shorten the waiting period. This report is concerning the conceptual design of the automated silicon irradiation device for the JRR-3 Uniformity Irradiation System.

Current status of irradiation facilities in JRR-3 and JRR-4

Hori, Naohiko; Wada, Shigeru; Sasajima, Fumio; Kusunoki, Tsuyoshi

JAEA-Conf 2006-003, p.15 - 23, 2006/05

https://jopss.jaea.go.jp/pdfdata/JAEA-Conf-2006-003.pdf

no abstracts in English

Ferroelectricity from iron valence ordering in the charge-frustrated system LuFeO

Ikeda, Naoshi*; Osumi, Hiroyuki*; Owada, Kenji; Ishii, Kenji; Inami, Toshiya; Kakurai, Kazuhisa; Murakami, Yoichi*; Yoshii, Kenji; Mori, Shigeo*; Horibe, Yoichi*; et al.

Nature, 436(7054), p.1136 - 1138, 2005/08

https://doi.org/10.1038/nature04039

By means of resonant X-ray scattering experiments using synchrotron radiation of SPring-8, it was found that a mixed-valence system LuFeO is a ferroelectric material owing to a real-space charge-ordering of Fe and Fe. This ordering is rooted in a charge frustration between the Fe ions on a triangular lattice. The new mechanism of ferroelectricity shown in the present paper offers great potential for designing future ferroelectric devices to be coupled or controlled with the degrees of freedom of electron: charge, spin and orbital.

Energetic protons from a few-micron metallic foil evaporated by an intense laser pulse

Matsukado, Koji*; Esirkepov, T. Z.; Kinoshita, Kenichi*; Daido, Hiroyuki; Utsumi, Takayuki*; Li, Z.*; Fukumi, Atsushi*; Hayashi, Yukio; Orimo, Satoshi; Nishiuchi, Mamiko; et al.

Physical Review Letters, 91(21), p.215001_1 - 215001_4, 2003/11

https://doi.org/10.1103/PhysRevLett.91.215001

no abstracts in English