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Journal Articles

Non-destructive beam spatial profile measurement using a gas sheet monitor for a high-intensity ion beam

Yamada, Ippei; Wada, Motoi*; Kamiya, Junichiro; Kinsho, Michikazu

Journal of Physics; Conference Series, 2244, p.012077_1 - 012077_6, 2022/04

no abstracts in English

Journal Articles

Effect of a 2-MHz RF source on the H$$^-$$ beam extracted from an RF-driven high-intensity H$$^-$$ ion source

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

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.230 - 233, 2021/10

In most proton accelerator facilities such as J-PARC, SNS, CERN, a H$$^-$$ ion source equipped with a 2-MHz rf driver for plasma generation produces H$$^-$$ beams. We have reported H$$^-$$ beam characteristics extracted from the J-PARC rf-driven high-intensity H$$^-$$ ion source. We have been developing an emittance measurement apparatus equipped with a highly time-resolved data acquisition system in order to observe fluctuation of the beam emittance in association with the frequency of the rf driver. By using this apparatus, we found that the beam emittance is fluctuated with the frequency with the rf driver and higher harmonics. We will show some obtained results of the emittance fluctuation.

Journal Articles

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

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 $$pi$$ mm-mrad, while the amplitude of the 2 MHz oscillation is around 0.04 $$pi$$ 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.

Journal Articles

High-intensity beam profile measurement using a gas sheet monitor by beam induced fluorescence detection

Yamada, Ippei; Wada, Motoi*; Moriya, Katsuhiro; Kamiya, Junichiro; Saha, P. K.; Kinsho, Michikazu

Physical Review Accelerators and Beams (Internet), 24(4), p.042801_1 - 042801_13, 2021/04

 Times Cited Count:1 Percentile:46.35(Physics, Nuclear)

A transverse beam profile monitor that visualizes a two-dimensional beam-induced fluorescent image was developed. The monitor employs a sheet-shaped gas flow formed by a technique of rarefied gas dynamics. A simplified analysis method was developed to reconstruct the beam intensity profile from the obtained image. The developed profile monitor and the analysis method were applied to measure the J-PARC 3 MeV H$$^-$$ beam profile. The root mean square values of the profiles were consistent with the ones obtained by a wire-scanning-type beam profile monitor. The beam loss due to the gas sheet injection was measured as a beam-current reduction. The amount of the beam current decreased in proportion to the gas sheet flux and the reduction ranged from 0.004 to 2.5%. The assembled system was capable of reconstructing a beam profile from a single shot beam pulse (1.7$$times$$10$$^{13}$$ protons in 50 $$mu$$s).

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:1 Percentile:13.9(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

Observation of beam current fluctuation extracted from an RF-driven H$$^-$$ ion source

Shinto, Katsuhiro; Shibata, Takanori*; Miura, Akihiko; Miyao, Tomoaki*; Wada, Motoi*

AIP Conference Proceedings 2011, p.080016_1 - 080016_3, 2018/09

 Times Cited Count:3 Percentile:87.63

Journal Articles

Effect due to RF discharge from a high intensity H$$^-$$ ion source upon the extracted beam

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

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.648 - 650, 2017/12

In J-PARC, peak H$$^-$$ current of several tens mA is extracted from an ion source driven by a solid-state rf amplifier with the frequency of 2 MHz for production of a cesiated hydrogen plasma. In case of the rf-driven ion source for producing the high-intensity H$$^-$$ current, the plasma density in the source chamber is so high that the ion sheath around the beam extraction area can follow the rf oscillation. The H$$^-$$ beam current fluctuation as large as approximately 1 mA was observed at the average beam current of 44 mA measured by a Faraday cup installed downstream of the ion source. The beam exhibited some fluctuation to the transverse motion as well. To further clarify this high frequency oscillation of the beam extraction sheath, we propose a measurement system using a time-resolved and highly sensitive emittance monitor in order to observe the real-time beam fluctuation in the phase space.

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Development of a negative hydrogen ion source for spatial beam profile measurement of a high intensity positive ion beam

Shinto, Katsuhiro; Wada, Motoi*; Nishida, Tomoaki*; Demura, Yasuhiro*; Sasaki, Daichi*; Tsumori, Katsuyoshi*; Nishiura, Masaki*; Kaneko, Osamu*; Kisaki, Masashi*; Sasao, Mamiko*

AIP Conference Proceedings 1390, p.675 - 683, 2011/09

 Times Cited Count:0 Percentile:0.19

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:164 Percentile:99.44(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:51.82(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

A Negative ion beam probe for diagnostics of a high intensity ion beam

Shinto, Katsuhiro; Wada, Motoi*; Kaneko, Osamu*; Tsumori, Katsuyoshi*; Nishiura, Masaki*; Sasao, Mamiko*; Kisaki, Masashi*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.999 - 1001, 2010/05

We propose a negative ion beam probe system as a new scheme to diagnose beam profile of high power positive ion beams. Two RF linacs of IFMIF have to drive the neutron source by providing continuous-wave (CW) positive deuterium ion beams with the intensity of 125 mA each at the beam energy of 40 MeV. During the CW beam operations, the extreme intensity of the beam and the severe radiation levels make the beam diagnostics with conventional techniques in the transport lines terribly difficult. A beam of negative ions liable to lose the additional electron at the occasion of impact with a high energy particle can work as a probe to measure the positive ion beam profile. On possible configuration to achieve high intensity beam profile measurement is to inject a negative ion probe beam into the target beam perpendicularly, and measure the attenuation of the negative ion beam by beam-beam interaction at each position. We have started an experimental study for the proof-of-principle of the new beam profile monitoring system. The paper presents the status quo of this beam profile monitor system development and the prospects to apply the system to the IFMIF beam line controls.

Journal Articles

Negative ion production in cesium seeded high electron temperature plasmas

Inoue, Takashi; Tobari, Hiroyuki; Takado, Naoyuki*; Hanada, Masaya; Kashiwagi, Mieko; Hatayama, Akiyoshi*; Wada, Motoi*; Sakamoto, Keishi

Review of Scientific Instruments, 79(2), p.02C112_1 - 02C112_4, 2008/02

 Times Cited Count:2 Percentile:15.15(Instruments & Instrumentation)

In experiments on uniformity improvement in a large negative ion source, steep gradients have been observed in the profiles of electron temperature and H$$^{-}$$ ion beam intensity. It has been observed that the gradient in the H$$^{-}$$ ion beam intensity is altered by seeding Cesium, though the electron temperature distribution is not affected by the Cs. Thus in the Cs seeded condition, the H$$^{-}$$ ion beam intensity is enhanced in local area illuminated by high-electron temperature plasmas. A brief analysis suggests possible advantages of high-electron temperature plasmas for the negative ion surface production, by enhancement of dissociation to yield proton or atoms as parent particles of the negative ions.

Journal Articles

Probe measurements; Fundamentals to advanced applications

Amemiya, Hiroshi*; Wada, Motoi*; Toyoda, Hirotaka*; Nakamura, Keiji*; Ando, Akira*; Uehara, Kazuya; Oyama, Koichiro*; Sakai, Osamu*; Tachibana, Kunihide*

Purazuma, Kaku Yugo Gakkai-Shi, 81(7), p.482 - 525, 2005/07

This article is asked to write by the Japan Society of Plasma Science and Nuclear Fusion Research. The probe diagnostics in fusion plasma is explaind for many readers of the Journal of Plasma and Fusion Research, who have much concerned on various aspects.In section one, the method to estimate the electron temperature and the density as well as the electron energy distribution function with the single probe is given. In section two, the method to estimate the ion temperature and the flow velocity with the double probe is given. The practical measurements are explained introducing the data obtained at JFT-2, JFT-2a and JFT-2M in JAERI tokamak.

JAEA Reports

Effect of electrode materials on a negative ion production in a cesium seeded negative ion source

Shimizu, Takashi; Morishita, Takatoshi; Kashiwagi, Mieko; Hanada, Masaya; Iga, Takashi*; Inoue, Takashi; Watanabe, Kazuhiro; Wada, Motoi*; Imai, Tsuyoshi

JAERI-Tech 2003-006, 26 Pages, 2003/03

JAERI-Tech-2003-006.pdf:1.12MB

no abstracts in English

Journal Articles

Effect of electrode materials on the production of negative ions

Shimizu, Takashi; Wada, Motoi*; Watanabe, Kazuhiro; Hanada, Masaya; Kashiwagi, Mieko; Iga, Takashi*; Inoue, Takashi; Morishita, Takatoshi; Amemiya, Toru*; Imai, Tsuyoshi

Dai-12-Kai Ryushisen No Sentanteki Oyo Gijutsu Ni Kansuru Shimpojiumu (BEAMS 2001) Hobunshu, p.25 - 28, 2001/11

no abstracts in English

Journal Articles

Correlation between negative hydrogen ion production and work function of plasma grid in a cesium-introduced volume-production-type negative hydrogen ion source

Shinto, Katsuhiro*; Okumura, Yoshikazu; *; Wada, Motoi*; *; Inoue, Takashi; Miyamoto, Kenji; Nagase, Akihito*

Japanese Journal of Applied Physics, 35(3), p.1894 - 1900, 1996/00

 Times Cited Count:20 Percentile:68.75(Physics, Applied)

no abstracts in English

Oral presentation

Development of a beam monitor for high intensity positive ion beams using negative ion beam injection

Shinto, Katsuhiro; Wada, Motoi*; Imakita, Shinsuke*; Kaneko, Osamu*; Tsumori, Katsuyoshi*

no journal, , 

no abstracts in English

Oral presentation

Molecular mass spectrum of vacuum evaporated DNA bases

Nakagawa, Atsuhiro*; Hiroyasu, Tomoyuki*; Moribayashi, Kengo; Kenmotsu, Takahiro*; Wada, Motoi*

no journal, , 

no abstracts in English

Oral presentation

Spectra of solid laser materials for the small high intensity laser

Tajiri, Nobuhiro*; Hiroyasu, Tomoyuki*; Wada, Motoi*; Kenmotsu, Takahiro*; Kiriyama, Hiromitsu; Daito, Izuru; Sasao, Hajime*; Suzuki, Masayuki; Okada, Hajime

no journal, , 

no abstracts in English

27 (Records 1-20 displayed on this page)