In the recent years there has been an increasing push towards the development of high gradient normal conducting accelerating structures for electron accelerators. In high brightness photo-injector facilities, for instance, the beam quality is directly related to the peak electric field on the cathode, so that the higher the field the better the beam parameters (e.g. emittance).
Moreover, the interest towards ultra-high gradient structures (>50 MV/m) as building blocks of future particle accelerators has been historically driven by CERN and SLAC, but in the last years other Laboratories showed an increasing enthusiasm for this topic. A design study for an X-band driven FEL source (Compact Light), and the Eupraxia@SPARC_LAB project to name a few.
The seminar will introduce the different kind of accelerating structures commonly used in electron linacs, defining main features, efficiency parameters, construction and design limitations. The introduction will be completed with a short state of the art of accelerating structures currently in operation in other international laboratories.
Then, a complete overview of the past, present and future prototyping activities on normal conducting accelerating structures at LNF will be presented. In particular, the R&D activity and high-power tests on three different structure categories will be covered:
(i) high gradient C-band travelling wave structures (designed for SPARC_LAB energy upgrade and ELI-NP project); (ii) high gradient clamped photo-guns working in S-band (SPARC_LAB, UCLA, ELI-NP) and C-band (I-FAST); (iii) ultra-high gradient X-band travelling wave structures (EuPRAXIA@SPARC_LAB prototype).
Finally, a discussion on the future applications and challenges will close the seminar.