Drift velocity measurements in relativistic electron beams

Abstract
A novel experimental method to measure the average drift velocity of relativistic electron beams is presented. The method is based on simultaneous measurements of the beam current and the radial electrostatic potential induced by the space charge of the beam. The method was applied to analyze the beam at different diode voltages and guide fields. The average drift velocity was found to be always considerably less than that corresponding to the diode voltage.