Title :
Bunch lengthening recently observed at PF-AR
Author :
Ieiri, T. ; Kasuga, T. ; Minagawa, Y. ; Obina, T. ; Fujita, T.
Author_Institution :
KEK, Tsukuba
Abstract :
The PF-AR (Photon Factory Advanced Ring for pulse X-rays) at KEK has been renewed to upgrade the performance. In this project, new vacuum ducts were installed with shielding bellows instead of non-shielding aluminium bellows. Thus, the coupling impedance of the ring was improved due to the shields. Measuring the bunch lengthening before and after the installation, we evaluated the longitudinal impedance of the bellows in a low bunch current. When the bunch current was high enough, a longitudinal instability was observed, accompanied by higher-order coherent synchrotron oscillations. We discuss the instability and the impedance issues based on various phenomena and calculations
Keywords :
beam handling equipment; electron accelerators; particle beam bunching; particle beam stability; storage rings; Photon Factory Advanced Ring; bellow longitudinal impedance; bunch current; bunch lengthening; coupling impedance; higher-order coherent synchrotron oscillations; longitudinal instability; pulse X-rays; shielding bellows; vacuum ducts; Acceleration; Bellows; Damping; Ducts; Hysteresis; Impedance; Length measurement; Storage rings; Synchrotrons; X-rays;
Conference_Titel :
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the
Conference_Location :
Portland, OR
Print_ISBN :
0-7803-7738-9
DOI :
10.1109/PAC.2003.1289819
