Clic Test Facility Developments and Results

The objectives of the CLIC Test Facility (CTF) are to study the generation of short intense electron bunches using a laser driven photocathode in an RF gun, to generate 30 GHz RF power for high gradient tests of prototype CLIC components, and to test beam position monitors. The performance of the CTF has improved dramatically in the course of the past year and highlights are presented here. The layout of the CTF is shown in Fig. 1. The RF gun now has a Cs2Te photocathode, enabling the use of the fourth harmonic of the YLF laser system (262 nm). Laser pulse lengths down to 8 ps full-width-halfheight (FWHH) and energies of 0.5 mJ have been produced. The CTF operates with a repetition rate of 10 Hz with either single bunches or trains of up to 48 bunches. Trains are produced by splitting the laser pulse. The RF gun consists of a 1 1/2 cell cavity, a photocathode, a focusing solenoid and a 4 cell booster cavity. The beam exits the gun with a momentum of 4.5 MeV/c and is then accelerated up to 92 MeV/c by the S-band travelling wave accelerating section. 30 GHz power is generated when the beam is passed through the un-powered prototype CLIC main linac accelerating section [1]. The power is fed to the second prototype main linac accelerating section and the accelerating gradient produced in it is directly measured by reaccelerating the lead bunch of the drive train.