CERN, Geneva
LAL, Orsay
INFN/LNF, Frascati (Roma)
Installation of the new photo-injector for the CTF3 drive beam (PHIN) has been completed on a stand-alone test bench. The photo-injector operates with a 2.5 cell RF gun at 3 GHz, using a Cs2Te photocathode illuminated by a UV laser beam. The test bench is equipped with different beam monitoring devices as well as a 90-degree spectrometer. A grid of 200 micrometer wide slits can be inserted for emittance measurements. The laser used to trigger the photo-emission process is a Nd:YLF system consisting of an oscillator and a preamplifier operating at 1.5 GHz and two powerful amplifier stages. The infrared radiation produced is frequency quadrupled in two stages to obtain the UV. A Pockels cell allows adjusting the length of the pulse train between 50 nanoseconds and 50 microseconds. The nominal train length for CTF3 is 1.272 microseconds (1908 bunches). The first electron beam in PHIN was produced in November 2008. In this paper, results concerning the operation of the laser system and measurements performed to characterize the electron beam are presented.
CERN, Geneva
The aim of the last CLIC test facility CTF3, built at CERN by an international collaboration, is to prove the main feasibility issues of the CLIC two-beam acceleration technology. The main points which CTF3 should demonstrate by 2010 are the generation of a very high current drive beam and its use to efficiently produce and transfer RF power to high-gradient accelerating structures. To prove the first point a delay loop and a combiner ring have been built, following a linac, in order to multiply the current by a factor two and four, respectively. The power generation and transfer and the high gradient acceleration are instead demonstrated in the CLIC experimental area (CLEX), where the drive beam is decelerated in special power extraction structures(PETS). In this paper we describe the results of the combination in the ring, properly working after the cure of the vertical instability which limited high current operation, and the commissioning of the new beam lines installed in the second half of 2008, including response matrix analysis and dispersion measurements used to validate the optics model. The results of the energy transfer will be also briefly described.
