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High-power Test of Annular-ring Coupled Structures for the J-PARC Linac Energy Upgrade
Jun Tamura,Hiroyuki Ao,Yasuo Nemoto,Hiroyuki Asano,Takahiro Suzuki 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3
Annular-ring coupled structures (ACSs) will increase the beam energy of the Japan proton acceleratorresearch complex (J-PARC) linac from 181 to 400 MeV to achieve a beam power of 1MW for a materials and life science experimental facility. The mass production of the ACS cavitiescommenced in March 2009. Before the installation, all cavities require power testing. High-powertesting is essential not only for confirming the cavity’s design performance but also for preventingdelays in cavity conditioning schedule. However, the 2011 Tohoku earthquake damaged J-PARCfacilities, including the ACS power-test area, and cavity conditioning was interrupted for two years. After the facility’s restoration, two ACS cavities (M01 and M11) were conditioned. They performed15 − 20% above the designed accelerating field of 4.2 MV/m. As M01 was initially conditioned sixyears ago, the most recent conditioning time required for M01 was drastically reduced. From thisresult, we confirmed that long-term stored ACS cavities purged with nitrogen gas do not producecritical cavity performance issues. During high-power operation of M11, which is a unique cavityequipped with a capacitive iris in a waveguide, no significant increases in the temperature and thedischarge rate around the capacitive iris were observed. Even considering beam loss due to residualgas scattering, the vacuum pressure was sufficiently low (4 × 10−6 Pa). More stable operation canbe expected following a month-long conditioning process before the beam is commissioned. M11’sconditioning successfully demonstrated an auto-conditioning program, and we established the conditioningscheme using this auto-conditioning program for all ACS cavities in a limited time andwith limited manpower.
Tomofumi Maruta,Akihiko Miura,Hiroyuki Sako,Jun Tamura,Masanori Ikegami,Kenta Futatsukawa,Zhigao Fang,Tomoaki Miyao,Yong Liu 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.7
The Tohoku earthquake in March 2011 caused significant damage to the Japan Proton AcceleratorResearch Complex (J-PARC) linac and forced us to shutdown the accelerator for nearly nine months. After a significant effort for its restoration, we resumed beam operation of the J-PARC linac inDecember 2011. Since the resumption of beam operation, we have been suffering from beam-losseswhich were not observed before the earthquake. Tackling the beam-loss issues, we have finallyreached the same beam power for user operation as before the earthquake. In this paper, we presentour experience with the beam start-up tuning after the earthquake, with emphasis on beam-lossmitigation efforts.
Inada, Hiromi,Hirayama, Yoichi,Tamura, Keiji,Terauchi, Daisuke,Namekawa, Ryoji,Shichiji, Takeharu,Sato, Takahiro,Suzuki, Yuya,Ohtsu, Yoshihiro,Watanabe, Keitaro,Konno, Mitsuru,Tanaka, Hiroyuki,Saito, Korean Society of Microscopy 2015 Applied microscopy Vol.45 No.1
We have developed a new HD-2700 (Hitachi High-Technologies Corp., Japan) scanning transmission electron microscope (STEM) that includes an automatic aberration correction function, and a large-solid-angle energy-dispersive X-ray spectroscopy detector that enables high-resolution and sensitive analysis. For observation with atomic resolution, using spherical-aberration-corrected STEM, in order that satisfactory performance of the device can be achieved readily, and within a short time, irrespective of the operator's skill level, a spherical-aberration-correction device with an automatic aberration-correction function was developed. This automatic aberration-correction function carries out the entire correction-related process (aberration measurement, selection and correction) automatically, with automatic selection of the aberrations that require correction, and automatic measurement of the appropriate corrections.