Engineering design of a pets tank prototype for CTF3 test beam line

In the CLIC concept, PETS (Power Extraction and Transfer Structure) role is to decelerate the drive beam and transfer RF power to the main beam. One of the CTF3 test beam line (TBL) aims is to study the decelerated beam stability and evaluate PETS performance. The PETS core is made of eight 800 mm long copper rods, with very tight tolerances for shape (+/-20 micron), roughness (less than 0.4 micron) and alignment (+/- 0.1 mm). Indeed, they are the most challenging components of the tank. This paper reports about the methods of fabrication and control quality of these bars. A special test bench has been designed and manufactured to check the rod geometry by measuring the RF fields with an electric probe. Other parts of the PETS tank are the power extractor, the waveguides and the vacuum tank itself. Industry is partially involved in the prototype development, as the series production consists of 15 additional units, and some concepts could be even applicable to series production of CLIC modules.