Title :
A coupled-bunch ion instability in the SLC electron damping ring
Author_Institution :
Linear Accel. Center, Stanford Univ., CA, USA
Abstract :
Under abnormally poor vacuum conditions in the electron damping ring, described in a companion paper at this conference, an emittance blowup was observed related to a transverse instability. The instability was only observed with two bunches in the ring, and could not be seen with single bunch operation, even at the same total beam current as for the two bunches. Measurements of the transverse beam transfer function indicate strong coupling between the two bunches when ions are present. This is described in terms of a simple model where the oscillating ion cloud provides the coupling between the two bunches. The frequency shift due to coupling can also cause the ion cloud to become unstable, and disappear, when the betatron tune of the electron bunch is just below the 1/2 integer
Keywords :
electron accelerators; linear colliders; particle beam bunching; particle beam stability; storage rings; SLC electron damping ring; Stanford Linear Collider; abnormally poor vacuum conditions; betatron tune; bunch operation; coupled-bunch ion instability; emittance blowup; oscillating ion cloud; transverse beam transfer function; transverse instability; Clouds; Contamination; Damping; Electron emission; Frequency; Linear accelerators; Optical coupling; Pollution measurement; Stripline; Transfer functions;
Conference_Titel :
Particle Accelerator Conference, 1997. Proceedings of the 1997
Conference_Location :
Vancouver, BC
Print_ISBN :
0-7803-4376-X
DOI :
10.1109/PAC.1997.750779
