Tuning procedure for traveling wave structures and its application to the C-Band cavities for SPARC photo injector energy upgrade

In this paper we illustrate the tuning procedure we implemented to tune the traveling wave structures designed and constructed for the SPARC photo-injector energy upgrade. The procedure has been derived from that proposed and adopted for the CLIC structures at CERN (J. Shi et al., Tuning of clic accelerating structure prototypes at Cern, Proc. of LINAC 2010, Tsukuba, Japan, 2010). In the first part of the paper we go through the analytical formulas also illustrating and discussing an algorithm to tune the input and output couplers. A detailed description of the measurements we have done before and after the tuning of the SPARC C-band structure prototype is then illustrated.