Anomalous Laser Induced Bunch Lengthening on-The ACO Storage Ring Free Electron Laser

Laser induced bunch lengthening has been measured on the ACO Storage Ring Free Electron Laser (SRFEL) in the anomalous bunch lengthening regime. The experimental results show correlations between the appearance of coherent modes in the electron bunch and anomalous behavior in the presence of the laser. Simultaneous time resolved laser induced bunch lengthening, mode strength, bunch length, and synchrotron sideband measurements were made as anomalous thresholds were traversed several times by changing the RF accelerating voltage. Bunch shortening, multiple time constants, and oscillatory behavior are among the phenomena which have been observed.