Observations of collective effects at the Advanced Light Source

摘要

We present a summary of measurements of single beam collective effects in the Advanced Light Source (ALS). We describe measurements of coupled-bunch instabilities, including some recent results using the newly commissioned feedback systems and the results of an initial search for the fast ion instability. Single bunch effects include bunch lengthening, energy spread increase, HOM loss measurements, head-tail damping rates, current dependent tune shifts, and transverse mode coupling instability threshold. The longitudinal measurements are consistent with a broadband impedance (vert bar)(Zeta)(sub (parallel))/(eta)(vert bar)(sub eff) = 0.22(plus minus)0.07 (Omega) and transverse measurements indicate broadband impedances of (Zeta)(sub y,eff) = 155 k(Omega)/m and Z(sub x,eff) = 58 k(Omega)/m.