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

https://doi.org/10.1063/1.5128015

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.

ITPA meeting report, 43

Kawano, Yasunori; Itami, Kiyoshi; Kawahata, Kazuo*; Kusama, Yoshinori; Sasao, Mamiko*; Peterson, B.*; Mase, Atsushi*

Purazuma, Kaku Yugo Gakkai-Shi, 90(2), P. 164, 2014/02

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2014_02/jspf2014_02-164.pdf

no abstracts in English

Issues on the absolute neutron emission measurement at ITER

Sasao, Mamiko*; Ishikawa, Masao; Yuan, G.*; Patel, K.*; Jakhar, S.*; Kashchuk, Y.*; Bertalot, L.*

Plasma and Fusion Research (Internet), 8(Sp.1), p.2402127_1 - 2402127_3, 2013/09

https://doi.org/10.1585/pfr.8.2402127

Fusion power output of ITER is measured by a group of neutron flux monitors combined with a neutron activation system and neutron profile monitors. These systems should be absolutely calibrated by use of DD/DT generators moving inside the ITER vacuum vessel (in-situ calibration). Each neutron monitor has a limited measurement range of emission rate, but the ranges are connected by cross-calibration using the ITER plasma with at least one decade overlapping. The over all dynamic range covered by the group of neutron flux monitors is 10 n/sec to 10 n/sec. Effects of vertical/radial movement of plasma on the measurement accuracy were reviewed. It was found that cross-calibration using specially planned jog shots, and a vertical neutron camera is important to minimize the inaccuracy caused by the plasma movement.

Temporal contrast enhancement of petawatt-class laser pulses

Kiriyama, Hiromitsu; Shimomura, Takuya; Sasao, Hajime; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Pirozhkov, A. S.; Mori, Michiaki; Fukuda, Yuji; et al.

Optics Letters, 37(16), p.3363 - 3365, 2012/08

https://doi.org/10.1364/OL.37.003363

We demonstrate the temporal contrast enhancement in a petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser system. An extra saturable absorber, introduced downstream a low gain optical parametric chirped-pulse amplification (OPCPA) preamplifier, has improved the temporal contrast in the system to 1.410 on the sub-nanosecond time scale at 70 TW power level. We have achieved 28 J of uncompressed broadband output energy with this system, indicating the potential for reaching peak powers near 600 TW.

Report on ITPA meetings, 37

Hayashi, Nobuhiko; Ide, Shunsuke; Suzuki, Takahiro; Itami, Kiyoshi; Kawano, Yasunori; Sasao, Mamiko*; Kusama, Yoshinori

Purazuma, Kaku Yugo Gakkai-Shi, 88(7), p.392 - 393, 2012/07

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2012_07/jspf2012_07-392.pdf

no abstracts in English

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

https://doi.org/10.1063/1.3637440

Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline

Yogo, Akifumi; Maeda, Takuya; Hori, Toshihiko; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Kiriyama, Hiromitsu; Okada, Hajime; Kanazawa, Shuhei; et al.

Applied Physics Letters, 98(5), p.053701_1 - 053701_3, 2011/02

https://doi.org/10.1063/1.3551623

Strategy for the absolute neutron emission measurement on ITER

Sasao, Mamiko*; Bertalot, L.*; Ishikawa, Masao; Popovichev, S.*

Review of Scientific Instruments, 81(10), p.10D329_1 - 10D329_3, 2010/10

https://doi.org/10.1063/1.3491049

Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement sub-system, cross calibration among them, and in-situ calibration, are needed. Neutron transport calculations show that a suitable calibration source is a DT/DD neutron generator of source strength higher than 10 n/s for DT and 10 n/s for DD. It will take 8 weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

Test beam-line for laser-driven proton therapy

Sakaki, Hironao; Nishiuchi, Mamiko; Hori, Toshihiko; Bolton, P.; Yogo, Akifumi; Ogura, Koichi; Sagisaka, Akito; Pirozhkov, A. S.; Orimo, Satoshi; Kondo, Kiminori; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.312 - 315, 2010/08

http://www.pasj.jp/web_publish/pasj7/proceedings/SH_6AM_2/FRSH09.pdf

The beam transport test is carried out through the test beam line of the laser-driven proton accelerator which consists of the phase rotation cavity, PMQ, and bending magnet. The laser system used is J-KAREN at JAEA. The final transmitted bunch duration and transverse profile are well predicted by the PARMILA particle transport code by assuming relatively low initial current of the proton beam. The most probable explanation for this is the space charge neutralization by the laser-plasma-electrons.

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

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/mope018.pdf

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.