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Meigo, Shinichiro
Proceedings of 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2018) (Internet), p.99 - 103, 2018/07
As the increase of beam power, beam instruments play an essential role in the Hadron accelerator facility. In J-PARC, the pitting erosion on the mercury target vessel for the spallation neutron source is one of a pivotal issue to operate with the high power of the beam operation. Since the erosion is proportional to the 4th power of the beam current density, the minimization of the peak current density is required. To achieve low current density, the beam-flattening system by nonlinear beam optics in J-PARC, by which the peak density was successfully reduced by 30% than the density with the conventional case optics. Since the ADS requires a very powerful accelerator with the beam power such as 30 MW, a robust beam profile monitor is required, especially for the observation of the beam status on the target continuously. A candidate material for the beam monitor was developed by using heavy-ion of Ar beam to give the damage efficiently.
Meigo, Shinichiro; Oi, Motoki; Ikezaki, Kiyomi*; Kawasaki, Tomoyuki; Kinoshita, Hidetaka; Akutsu, Atsushi*; Nishikawa, Masaaki*; Fukuda, Shimpei
Proceedings of 12th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '15), p.255 - 260, 2016/00
Meigo, Shinichiro; Oi, Motoki; Fujimori, Hiroshi*; Kawasaki, Tomoyuki; Nishikawa, Masaaki; Fukuda, Shimpei
no journal, ,
no abstracts in English
Meigo, Shinichiro; Oi, Motoki; Fujimori, Hiroshi*; Sakamoto, Shinichi*
no journal, ,
Since the damage of the neutron target depends on the beam current density, the beam current density on the target is required to be minimized for the stable operation. Using linear optics, the current density can be reduced by expanding the beamwidth, forbidden by the increase of heat at the vicinities. Because the beam shape cannot be changed from Gaussian by linear optics, a new technique changing the beam shape was required. The beam can be shaped flatly by nonlinear optics using an octupole magnet having a cubic magnetic field. It was known that the beam loss arose by the nonlinear optics. Therefore, a detailed technique is required. Solving the transport calculation exactly, we found that the beam shape can be specified by only two parameters and the optimum parameter to achieve both the flat distribution and the minimized beam loss. From this result, we succeeded in reducing the current density on the target by about 30% compared to the previous case without significant beam loss.
Meigo, Shinichiro
no journal, ,
A high-intensity proton beam transport facility (3NBT) at J-PARC provides the proton beam accelerated at 3 GeV synchrotron accelerator to the neutron source facility and muon facility installed at the Materials and Life Science Experimental Facility (MLF) supplying the secondary beam of neutron and muons to the users. A talk regarding the development of the instruments for high-intensity beam transport, and the beam flattening technology based on nonlinear beam optics will be given at the annual meeting of the Physical Society of Japan,
