Design, realization and test of C-band accelerating structures for the SPARC_LAB linac energy upgrade

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• 作者：D. Alesini^a ; M. Bellaveglia^a ; M.E. Biagini^a ; R. Boni^a ; M. Brö ; nnimann^b ; F. Cardelli^c ; ^d ; P. Chimenti^a ; R. Clementi^a ; G. Di Pirro^a ; R. Di Raddo^a ; M. Ferrario^a ; L. Ficcadenti^c ; ^d ; A. Gallo^a ; R. Kalt^b ; V. Lollo^a ; L. Palumbo^c ; ^d ; L. Piersanti^c ; ^d ; ^{luca.piersanti@lnf.infn.it" class="auth_mail" title="E-mail the corresponding author} ; T. Schilcher^b
• 关键词：C-band ; High gradient ; Constant impedance ; Tuning ; Breakdown rate ; Rf breakdown
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2016
• 出版时间：21 November 2016
• 年：2016
• 卷：837
• 期：Complete
• 页码：161-170
• 全文大小：4124 K

文摘

The energy upgrade of the SPARC_LAB photo-injector at LNF-INFN (Frascati, Italy) has been originally conceived replacing one low gradient (13 MV/m) 3 m long SLAC type S-band traveling wave (TW) section with two 1.4 m long C-band accelerating sections. Due to the higher gradients reached by such structures, a higher energy beam can be obtained within the same accelerator footprint length. The use of C-band structures for electron acceleration has been adopted in a few FEL linacs in the world, among others, the Japanese Free Electron Laser at SPring-8 and the SwissFEL at Paul Scherrer Institute (PSI). The C-band sections are traveling wave, constant impedance structures with symmetric input and output axial couplers. Their design has been optimized for the operation with a SLED RF pulse compressor. In this paper we briefly review their design criteria and we focus on the construction, tuning, low and high-power RF tests. We also illustrate the design and realization of the dedicated low level RF system that has been done in collaboration with PSI in the framework of the EU TIARA project. Preliminary experimental results appear to confirm the operation of such structures with accelerating gradients larger than 35 MV/m.