Kem Edward Robinson

Laser induced bunch lengthening on the ACO storage ring FEL

Laser induced bunch lengthening has been measured on the ACO storage ring FEL. The experimental data at low current generally confirm the existing theoretical models, while the high-current data is dominated by anomalous effects.

Measurement of stimulated transverse mode mixing in a free electron laser

We report the first measurement of the off-diagonal terms in the transverse gain matrix in a free electron laser. We show that the higher order transverse modes stimulated in the FEL interaction diminish in amplitude as the electron beam size is increased, that the far field and the near field effects of the excited modes are not equivalent, and that in this low divergence case, the mode mixing is insensitive to the resonance parameter. Remarkably close agreement is demonstrated with the theory [1]. The effects of a multiple mode input beam are also observed, and the theoretical expression is derived.

Characterization of Free-Electron Laser bunch lengthening on the ACO Storage Ring

This paper summarizes the basic low-current, laser-induced bunch-lengthening measurements that have been made on the ACO Storage-Ring Free-Electron Laser (SRFEL). The measurements provide verification of both the functional dependence and absolute magnitude of SRFEL theoretical models. The method of measurement, which is is explained, exploits frequency-domain techniques and is capable of accuracies comparable to those of a streak camara. The measurements are in good agreement with existing SRFEL theory and provide an important base for future work.

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.

Free Electron Laser Experiment on the ACO Storage Ring (Orsay)

Since the first demonstration of the Free Electron Laser (FEL) in Stanford [1], several experiments have been proposed using various types of relativistic electron beam sources. The purpose of our experiment in Orsay (LURE-Stanford Collaboration) is to use the electron beam of the ACO storage ring (140 MeV to 540 MeV) to build a F.E.L. in the 5000 A range.