Experimental study of the E.L.S.A. electron‐beam halo

An experimental study of the transverse spatial distribution of the ELSA‐linac electron beam has been initiated to investigate halo‐producing mechanisms in the generation, acceleration and transport of high‐intensity, high‐brightness charged‐particle beams. In an experiment presented here the beam profile has been analysed over four decades using an imaging technique. This technique consists in putting an optical transition radiation screen on the beam path. The emitted light is transported through conventional optics to an intensified video camera. The beam‐profile behaviour is shown to be dependent on the current, the initial size and shape of the beam and on the transport configuration.