IMP, Lanzhou
Advancement of nuclear physics and high power heavy ion accelerator is always a driving force for persistent development of highly charged ECR ion source. Increasing demands for more intense and higher charge state heavy ion beams have dramatically promoted development of ECR ion source technology and physics. This talk provides an overview of intense highly charged superconducting ECR ion sources built by the world-wide laboratories in the last years. The key technologies, challenges and main issues related to construction and operation of high performance superconducting ECR ion source are reviewed. The latest results of intense highly charged ion beam production from the superconducting ECR ion sources are presented. Future development and the next generation highly charged ECR ion source are discussed.
KEK, Ibaraki
Nagaoka University of Technology, Nagaoka, Niigata
Sokendai, Ibaraki
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
KEK digital accelerator (DA) capable of accelerating all species of ion* is an induction synchrotron employing no large scale injectors. At the beginning of its operation, Ar ions from the ECR ion source (ECRIS) embedded in the 200 kV high voltage terminal (HVT) are directly injected into KEK-DA though the low energy BT line (LEBT). The permanent magnet ECRIS was assembled at KEK. Its characteristics such as a charge-state spectrum, emittance, and intensity are presented. The 200 kV HVT has been also assembled at KEK. Its voltage stability in the pulse mode operation, where a plasma of 1 msec is created by x-band microwaves at 10 Hz, is discussed. The LEBT consists of the Eintzel lens, momentum analyzer, B magnets with edge focusing, electrostatic chopper**, and a combination of Q magnets. In the upper LEBT from the ion extraction hall to the entrance of the analyzer, possible charge-state ions are contaminated in the space-charge limit and beam focusing is realized through the Eintzel lens and tandem acceleration gaps. In the lower LEBT from the analyzer to the KEK-DA injection point, the lattice has been optimized so as to meet optics matching at the injection point.
*K. Takayama, J. of Appl. Phys. 101 063304(2007), "KEK digital accelerator for material and biological sciences" in this conference
**T.Adachi, "Injection and extraction system" in this conference
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.
RIKEN Nishina Center, Wako
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.