Cyclotrons2013 - List of Authors (Ohnishi, J.)

Paper

Title

Page

Acceleration of Intense Heavy Ion Beams in RIBF Cascaded-Cyclotrons

1

N. Fukunishi, T. Dantsuka, M. Fujimaki, T. Fujinawa, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, T. Kageyama, O. Kamigaito, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, M. Nakamura, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa
RIKEN Nishina Center, Wako, Japan

The RIBF cascaded-cyclotrons have obtained, as of December 2012, uranium ion beams with an intensity of as high as 15 pnA (1 kW of power). This was achieved owing to deployment of a 28 GHz ECRIS, a new injector linac, a gas stripper and a bending-power upgrade of RIKEN fixed-frequency Ring Cyclotron as well as improvement of transmission efficiencies through cyclotrons and stability, etc.

Slides MO1PB01 [12.793 MB]

MOPPT022

Design of New Superconducting Ring Cyclotron for the RIBF

79

J. Ohnishi, M. Nakamura, H. Okuno
RIKEN Nishina Center, Wako, Japan

At the RIBF, uranium beams are accelerated up to the energy of 345 MeV per nucleon with a RFQ linac, DTL, and four ring cyclotrons (RRC, fRC, IRC, SRC). However, the present beam current of the uranium is 10-15 pnA at the exit of the SRC, still low, because we have to use two charge strippers located upstream and downstream of the fRC to convert the U³⁵⁺ ions extraced from the 28 GHz ECR ion source to U⁶⁴⁺ and U⁸⁶⁺, respectively. Accordingly, in order to increase the beam current more than tenfold, we performed the design study of the new superconducting ring cyclotron with the K-value of 2200 which can accelerate the U³⁵⁺ ions from 11 MeV/u to 48 MeV/u without the first charge stripper. The number of sector magnets is four and the RF frequency is fixed. The maximum magnetic field strength on the beam orbit is 3.2 T, and the superconducting main coils of the dense winding of NbTi and the trim coils of normal-conducting Cu are used. The total weight of the iron yokes is approximately 4800 t. This paper also describes the beam injection and extraction system which includes one superconducting magnetic channel.

TU1PB04

Status of the RIKEN 28-GHz SC-ECRIS

139

Y. Higurashi, M. Kidera, T. Nakagawa, J. Ohnishi, K. Ozeki
RIKEN Nishina Center, Wako, Japan

Since we obtained first beam from RIKEN 28GHz SC-ECRIS in 2009, we tried to increase the beam intensity using various methods. Recently, we observed that the use of Al chamber strongly enhanced the beam intensity of highly charged U ion beam. Using this method, we obtained ~180e μA of U³⁵⁺ and ~230e μA of U³³⁺ at the injected RF power of ~3kW with sputtering method. Advantage of this method is that we can insert the large amount of material into the plasma chamber, therefore, we can produce the beam for long term without break. Actually, we already produced intense U beams for the RIBF experiments longer than month without break. For the long term operation, we observed that the consumption rate of the U metal was ~4mg/h. In this spring, we also produced U beam with high temperature oven and two frequencies injection. In these test experiments, we observed that the beam intensity of highly charged U ions is strongly enhanced. In this contribution, we report the various results of the test experiments for production of highly charged U ion beam. We also report the experience of the long term production of the U ion beam for RIKEN RIBF experiments.

Slides TU1PB04 [6.949 MB]

Paper	Title	Page
MO1PB01	Acceleration of Intense Heavy Ion Beams in RIBF Cascaded-Cyclotrons	1
	N. Fukunishi, T. Dantsuka, M. Fujimaki, T. Fujinawa, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, T. Kageyama, O. Kamigaito, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, M. Nakamura, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa RIKEN Nishina Center, Wako, Japan
	The RIBF cascaded-cyclotrons have obtained, as of December 2012, uranium ion beams with an intensity of as high as 15 pnA (1 kW of power). This was achieved owing to deployment of a 28 GHz ECRIS, a new injector linac, a gas stripper and a bending-power upgrade of RIKEN fixed-frequency Ring Cyclotron as well as improvement of transmission efficiencies through cyclotrons and stability, etc.
	Slides MO1PB01 [12.793 MB]

MOPPT022	Design of New Superconducting Ring Cyclotron for the RIBF	79
	J. Ohnishi, M. Nakamura, H. Okuno RIKEN Nishina Center, Wako, Japan
	At the RIBF, uranium beams are accelerated up to the energy of 345 MeV per nucleon with a RFQ linac, DTL, and four ring cyclotrons (RRC, fRC, IRC, SRC). However, the present beam current of the uranium is 10-15 pnA at the exit of the SRC, still low, because we have to use two charge strippers located upstream and downstream of the fRC to convert the U³⁵⁺ ions extraced from the 28 GHz ECR ion source to U⁶⁴⁺ and U⁸⁶⁺, respectively. Accordingly, in order to increase the beam current more than tenfold, we performed the design study of the new superconducting ring cyclotron with the K-value of 2200 which can accelerate the U³⁵⁺ ions from 11 MeV/u to 48 MeV/u without the first charge stripper. The number of sector magnets is four and the RF frequency is fixed. The maximum magnetic field strength on the beam orbit is 3.2 T, and the superconducting main coils of the dense winding of NbTi and the trim coils of normal-conducting Cu are used. The total weight of the iron yokes is approximately 4800 t. This paper also describes the beam injection and extraction system which includes one superconducting magnetic channel.

TU1PB04	Status of the RIKEN 28-GHz SC-ECRIS	139
	Y. Higurashi, M. Kidera, T. Nakagawa, J. Ohnishi, K. Ozeki RIKEN Nishina Center, Wako, Japan
	Since we obtained first beam from RIKEN 28GHz SC-ECRIS in 2009, we tried to increase the beam intensity using various methods. Recently, we observed that the use of Al chamber strongly enhanced the beam intensity of highly charged U ion beam. Using this method, we obtained ~180e μA of U³⁵⁺ and ~230e μA of U³³⁺ at the injected RF power of ~3kW with sputtering method. Advantage of this method is that we can insert the large amount of material into the plasma chamber, therefore, we can produce the beam for long term without break. Actually, we already produced intense U beams for the RIBF experiments longer than month without break. For the long term operation, we observed that the consumption rate of the U metal was ~4mg/h. In this spring, we also produced U beam with high temperature oven and two frequencies injection. In these test experiments, we observed that the beam intensity of highly charged U ions is strongly enhanced. In this contribution, we report the various results of the test experiments for production of highly charged U ion beam. We also report the experience of the long term production of the U ion beam for RIKEN RIBF experiments.
	Slides TU1PB04 [6.949 MB]