MOPA32
RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
RIKEN Nishina Center, Wako, Japan
KEK, Tokai, Ibaraki, Japan
RIKEN Nishina Center, Wako, Japan
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MOPA32 |
Operation of Gas Strippers at RIBF; Thinning Effect of Gas Strippers for High-Intensity Very Heavy Ion Beams | |
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| Intensity upgrade of very-heavy ions such as U and Xe beams is one of the main concerns at the RIKEN Radioactive Isotope Beam Factory (RIBF). In the acceleration of them, the possible output intensities have been principally limited by the lifetime problem of the carbon foil strippers. In previous years, realization of the gas strippers was an important breakthrough for intensity upgrade of very heavy ion beams. The recirculating He gas stripper for uranium beams has been stably operated since 2012. The air stripper for xenon beams was also successfully operated in 2013. For pursuing further high intensities of very heavy ion beams, we need to understand the application limit of the present gas strippers. Density reduction of gas along the trajectories of the beams caused by the heat load (thinning effect) is a factor which will determine the application limit of the gas stripper. We will present the recent operational situation of gas strippers involving the study of the gas thinning effect. | ||
| MOA1C01 | History of Solid Disk Improvement for Rotating Charge Stripper | 1 |
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| In 2007, we installed a rotating disk stripper device at the final charge stripping section for the uranium (U) beam acceleration at RIKEN RI Beam Factory. The first rotating carbon disk (C-disk) stripper was useless because of its poor surface flatness and unexpected low density. In 2012, we started the stable U beam operation using beryllium (Be) as the disk material. We successfully improved the flatness of the Be-disk by special polishing technique in 2014, and the transmission efficiency was greatly improved as well. However, it seemed to be impossible that the Be-disk withstood the heat load of the expected intensity in future, considering its deformation. Then, the polishing technique for the Be-disk improvement was applied to the Glassy carbon (GC) disk. The GC-disk flatness was improved maintaining high density. In addition, a tested high-density highly oriented graphite sheet, which is fabricated from a high polymer film in high temperature and high pressure conditions, can be applied as the charge stripping disk since the better stripping efficiency and transmission value than those of Be and the C-disk were realized. | ||
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Slides MOA1C01 [3.376 MB] | |