Open AccessCoupling Impedance of the Collimator Without RF-Shields at the RCS in J-PARC
Author(s) -
Yoshihiro Shobuda,
Kota Okabe,
J. Kamiya,
K. Moriya
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1350/1/012113
Subject(s) - shields , collimator , synchrotron , synchrotron radiation , shield , radio frequency , coupling (piping) , optics , materials science , electromagnetic shielding , tin , electrical impedance , physics , electrical engineering , engineering , composite material , petrology , metallurgy , geology , quantum mechanics
All holes on the chamber walls of synchrotrons should be filled with the radiofrequency (RF)-shields to suppress coupling impedances that excite beam instabilities. In a synchrotron, titanium nitride (TiN)-coated RF-shields are installed with collimators. If the holes, through which the collimator jaw enters and exits the chamber, are filled with such RF-shields, the shields may break down as the dynamic coefficient of TiN increases in vacuum. At the Rapid Cycling Synchrotron (RCS), the RF-shields are eliminated from the collimator after demonstrating that the effect due to the RF-shields is negligible on the impedance at low frequencies.