Transient Beam Loading Calculations and Experiment at the Saclay Electron Linac

The transformation of the Saclay electron linac (ALS) into an injector for a 2 GeV stretcher ring is under study. One of the problems associated with this transformation is the use of the existing sections in a new mode of operation. The sections were ontimized for low current operation (high attenuation, high internal resistance), they will be used in a high current, short pulse(1¿s) mode resulting in a prohibitive transient beam loading energy spectrum broadening. The compensation method used at SLAC, wich consists in delaying the turn-on of some klystrons, has been studied theoretically and an experiment has been performed with a 1¿s pulse, at the same beam loadinq level as for the future plans.