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Yamamoto, Kazami; Shibata, Takeo*; Ogiwara, Norio; Kinsho, Michikazu
Vacuum, 81(6), p.788 - 792, 2007/02
Times Cited Count：13 Percentile：46.87(Materials Science, Multidisciplinary)The J-PARC 3GeV Rapid-Cycling Synchrotron (RCS) is required to provide 1MW pulsed protons to the spallation neutron target and the 50 GeV main ring. Since the acceleration period is set at a repetition rate of 25Hz, the eddy current effect due to such rapid repetition magnetic field is a big issue (i.e. the perturbation of the magnetic field and the heating owing to the ohmic loss) in the metal duct. Therefore, we choose the ceramics duct in the magnets in order to avoid the eddy current effect. But the total secondary electron emission yield (SEY) from the ceramics surface is larger than the metal one. In order to reduce these undesirable electron emitted from the chamber surface, Titanium Nitride (TiN) is coated on the inside surface of the chambers. We measured SEY from TiN coating surface with various conditions. We further investigated Diamond Like Carbon coating to search the possibility of another coating. The results of these measurements are shown.
Kinsho, Michikazu; Saito, Yoshio*; Kabeya, Zenzaburo*; Ogiwara, Norio
Vacuum, 81(6), p.808 - 811, 2007/02
Times Cited Count：7 Percentile：30.11(Materials Science, Multidisciplinary)It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section of 378 mm inner diamater for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. The radio-frequency shield is designed as a high frequency pass filter, where eddy currents cannot be generated. In this shield one end of each strope is connected to a titanium flange with a capacitor to interrupt the eddy current loop. With this, the impedance of the duct with the radio-frequency shield was reduced within an allowable desgin limit. In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.
