A thermionic electron gun for the preliminary phase of CTF3

A dedicated electron gun has been designed and built for the preliminary phase of the CLIC Test Facility 3 (CTF3). The gun is based on a thermionic gridded cathode and operates at 90 kV in the intensity range of 50 mA to 2A. The specific time structure of the beam is characterized by a burst of up to seven pulses of variable pulse width (4 to 10 ns) each separated by 420 ns, the revolution time of the former EPA (Electron Positron Accumulator) ring. The mechanical conception was specifically designed to be compatible with the existing front-end of the former LIL (LEP Injector Linac). We will describe the experimental results obtained with the beam on CTF3