First Results From Beam Tests of the CLIC Drive Beam Phase Feedforward Prototype at CTF3

In the CLIC two beam acceleration scheme 100 MV/m normal conducting cavities are fed with RF power extracted from a secondary high power but low energy drive beam. To ensure the efficiency and luminosity performance of CLIC the phase synchronisation between the high energy main beam and the drive beam must be maintained to within 0.2 degrees of 12 GHz. To reduce the drive beam phase jitter to this level a low-latency drive beam phase feedforward correction with bandwidth above 17.5 MHz is required. A prototype of this system has been installed at the CLIC test facility CTF3 to prove its feasibility, in particular the challenges of high bandwidth, high power and low latency hardware. The final commissioning and first results from operation of the complete phase feedforward system are presented here.