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Ohnishi, J.

Paper Title Page
MOPD046 Construction of New Injector Linac for RI Beam Factory at RIKEN Nishina Center 789
 
  • K. Yamada, S. Arai, M.K. Fujimaki, T. Fujinawa, N. Fukunishi, A. Goto, Y. Higurashi, E. Ikezawa, O. Kamigaito, M. Kase, M. Komiyama, K. Kumagai, T. Maie, T. Nakagawa, J. Ohnishi, H. Okuno, N. Sakamoto, Y. Sato, K. Suda, H. Watanabe, Y. Watanabe, Y. Yano, S. Yokouchi
    RIKEN Nishina Center, Wako
  • H. Fujisawa
    Kyoto ICR, Uji, Kyoto
 
 

A new additional injector (RILAC2) is constructed at RIKEN Nishina Center in order to enable the independent operation of the RIBF experiments and super-heavy element synthesis. The RILAC2 consists of a 28 GHz superconducting ECR ion source, a low-energy beam transport with a pre-buncher, a four-rod RFQ linac, a rebuncher, three DTL tanks, and strong Q-magnets between the rf resonators for the transverse focusing. Very heavy ions with m/q of 7 such as 136Xe20+ and 238U35+ will be accelerated up to the energy of 680 keV/u in the cw mode and be injected to the RIKEN Ring Cyclotron without charge stripping. The RFQ linac, the last tank of the DTL, and the bunchers have been converted from old ones in order to save the cost. Construction of the RILAC2 started at the end of the fiscal 2008. The RFQ and DTLs will be installed in the AVF cyclotron vault and be tested in March 2010. The ECR ion source and low-energy beam transport will be set on the RILAC2 in 2010 summer, and the first beam will be accelerated in 2010 autumn. We will present the details of the linac part of RILAC2 as well as the progress of construction which includes the result of high power test of resonators.

 
THPEB023 Design of the Low Energy Beam Transport in RIKEN New Injector 3936
 
  • Y. Sato, M.K. Fujimaki, N. Fukunishi, A. Goto, Y. Higurashi, E. Ikezawa, O. Kamigaito, M. Kase, T. Nakagawa, J. Ohnishi, H. Okuno, H. Watanabe, Y. Watanabe, S. Yokouchi
    RIKEN Nishina Center, Wako
 
 

The RI beam factory at RIKEN Nishina Center needs high intensity of uranium ion beams. We constructed a new injector, RILAC2, which would provide several hundred times higher intensity. As a part of the RILAC2, we designed the low energy beam transport, LEBT, from the superconducting ECR ion source to the RFQ entrance. In this paper we present its requirements and problems, and show our design as the solutions to them. Especially we focus a technique of a pair of two solenoids to treat a rotational operation and a focusing operation independently. Based on this design, the LEBT was completed in March 2010. The RILAC2 will be operational this fall.

 
THPEB024 Design of the Medium Energy Beam Transport from High-voltage Terminal 3939
 
  • Y. Sato, M.K. Fujimaki, N. Fukunishi, A. Goto, Y. Higurashi, E. Ikezawa, O. Kamigaito, M. Kase, T. Nakagawa, J. Ohnishi, H. Okuno, H. Watanabe, Y. Watanabe, S. Yokouchi
    RIKEN Nishina Center, Wako
 
 

The RI beam factory at RIKEN Nishina Center needs high intensity of uranium ion beams. We have used so far the RFQ pre-injector upstream of the linac system, in which the extraction voltage of the ECR ion source is as low as 5.7 kV for the uranium beam. However, for much higher intensity beams from a newly developed superconducting ECR ion source, such a low voltage was expected to significantly increase their emittance due to the space charge effect. To reduce this effect, we prepared a new pre-injector line of 127 kV for uranium beams by placing the ion source on a high-voltage terminal. In this paper we present the design of the 127 kV medium energy beam transport, MEBT, and show the measured results through the line.

 
THPEC060 Developments of RIKEN New Superconducting ECR Ion Source 4191
 
  • Y. Higurashi, M.K. Fujimaki, A. Goto, E. Ikezawa, O. Kamigaito, M. Kase, M. Komiyama, T. Nakagawa, J. Ohnishi, Y. Watanabe
    RIKEN Nishina Center, Wako
  • T. Aihara, M. Tamura, A. Uchiyama
    SHI Accelerator Service Ltd., Tokyo
 
 

The next generation heavy ion accelerator facility, such as the RIKEN RIBF, requires great variety of high charged heavy ions with a magnitude higher beam intensity than currently achievable. In the last decade, performance of the ECR ion sources has been dramatically improved with increasing the magnetic field and RF frequency to enhance the density and confinement time of plasma. Furthermore, the effects of the key components (magnetic field configuration, gas pressure etc) on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and the technology, we successfully constructed the new 28GHz SC-ECRIS which has a flexible magnetic field configuration to enlarge the ECR zone and to optimize the field gradient at ECR point. In the test experiment, we obtained the direct evidence that the field gradient and the zone size strongly affect the beam intensity. It concludes that the gentler field gradient and large ECR zone size gives intense beam of highly charged heavy ions from ECR plasma. In this contribution, we report the systematic study of these effects on the beam intensity of highly charged heavy ions.

 
THPEC061 Extraction System and Beam Qualities of the RIKEN Full Superconducting ECR Ion source 4194
 
  • J. Ohnishi, Y. Higurashi, O. Kamigaito, T. Nakagawa
    RIKEN Nishina Center, Wako
 
 

The superconducting ECR ion source enabled to use a 28 GHz microwave source had been developed to provide intense beam of highly charged heavy ions like U35+ to the RIKEN RI-beam factory (RIBF) since 2007. The first plasma was lit in May of 2009 and it was succeeded in providing the uranium beam to the RIBF in December. In this operation, uranium ions were supplied with sputter method and two 18 GHz microwave sources were used. The beam intensity of the uranium ion exceeded 14μAmps, which was more than five times larger than that for 18 GHz ECR ion source of a usual type. The extraction system consists of the accel-decel electrode system, a solenoid coil and a 90 degreeanalyzing magnet. We measured the profiles and emittances of the extracted beams for several ion species and compared with the calculated results with 'OPERA-3d' including space charge effect. And we shall discuss the beam dynamics at the extraction region such as the relationship between the beam emittance and the operating parameters.