Radio frequency (rf) photoguns are widely used in modern particle accelerator facilities, particularly in free electron lasers (FELs), as they provide very low-emittance, high-brightness electron bunches. Presently, the rf technology mostly used for photoguns is the S-band ($\sim 3$ GHz), with typical cathode peak fields of 80–120 MV/m and maximum repetition rates of $\sim 100$ Hz. According to beam dynamics studies, the higher the peak electric fields on the cathode, the better the quality of the beam emerging from the gun. In this respect, S-band rf guns represent the state-of-the-art, both in terms of reachable cathode peak fields and repetition rates. An innovative C-band rf gun, operating at 5.712 GHz and aiming at reaching cathode peak fields larger than 160 MV/m, with repetition rates exceeding 400 Hz, has been designed, realized, and high-power tested. Its device consists of a 2.5-cell standing wave (SW) cavity with a four-port mode launcher whose overcoupled design allows it to operate with short rf pulses (300 ns). Its realization has been based on the new brazing-free technology developed and successfully tested at the Frascati Laboratories of the National Institute of Nuclear Physics (INFN-LNF, Italy). In the paper, we illustrate the design and realization performed by INFN-LNF, and its high-power rf test, which was conducted at the C-band test facility at the Paul Scherrer Institute (Switzerland).

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• Electromagnetic field calculations
• Radio frequency techniques
• Room temperature RF