Contributions to ELI-NP on RF accelerator activities Andrea Mostacci Università di Roma, Sapienza The joint Sapienza/INFN-LNF group is active in the field of S-band, C-band, Xband accelerator devices design and construction. The group is interested both in designing beam generation and manipulation devices as well as the technological issues related to the construction of devices standing the high RF power needed in modern accelerators. Through numerical simulation, we study and optimize the electron beam dynamics in a single device as well as in the whole machine. Moreover we are commissioning the LNF photoinjector (SPARC), the first S-band/C-band high brilliance linear accelerator. As a university based group, we have also experience in training students in their first steps in the accelerator physics and technology.
Goal Show our experience and ongoing activities on RF issues of accelerator physics which can be useful for ELI-NP Group L. Palumbo (Sapienza) and its group M. Ferrario, B. Spataro, L. Serafini (INFN/LNF) and researchers from INFN/LNF accelerator division High brightness photo-injector (SPARC) commissioning. R&D activities on RF issues ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities Outline S-band devices: installation and operation of S-band accelerator and in-house RF gun construction. C-band devices: high gradient accelerating sections and RF guns, installation and commissioning. X-band devices: beam manipulation devices (e. g. harmonic cavities) and beam generation devices (hybrid SW/TW gun). Beam dynamics studies and optimisation (S-band, C-band, X -band mixed solutions). Training and educational experience. Contribution to ELI-NP. Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Commissioning of SPARC High Brilliance photo-injector Undulators Diagnostic and Matching 150 Me. V S-band linac Contributions to ELI-NP on RF accelerator activities u = 2. 8 cm Velocity Bunching 10 m Kmax = 2. 2 r = 500 nm 15 m Long Solenoids S-band Gun Seeding THz Source Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities S-band devices (~ 3 GHz) We presently are runnig a S-band linear accelerator producing high brightness 180 Me. V electorons. We design, built and operate RF deflectors for beam length measurement. Our device, first tested at SPARC, has been rebilt and installed in PSI SWISS-FEL and FERMI FEL injectors. A novel improved RF gun is at the executive design stage (design scalable to higher frequencies). SPARC RF Deflector RF gun Beam Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities C-band devices (~ 6 GHz) For SPARC energy upgrade (180 250 Me. V), we will install and operate inhouse built TW sections. (>35 MV/m accelerating field) S-band injector in a C-band linac will be tested next year @ SPARC and it is the solution adopted by SWISS-FEL @ PSI. After the succesful Spring 8 FEL, the C-band seems a mature and reliable technology. For a given bunch charge, wake fields and beam loading are relaxed with respect to higher frequency solutions. The same arguments holds for timing, synchronization and jitters issues. We are investigating a fully C-band linac design, including C-band RF gun. Power test @ KEK Symmetric input coupler Output couplers 48 MV/m Beam RF power Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities X-band devices: design & production X-band (11. 424 GHz) harmonic cavities for longitudinal phase space compensation in high brilliance photo-injectors Accelerating cells RF CAD design T U N E R Beam RF power Low power test and multi-cell cavity tuning Coupling cells Technological issues (high power test @ SLAC), novel materials Cu z axis (cm) Mo Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 X-band devices: design & production X-band (11. 424 GHz) harmonic cavities for longitudinal phase space compensation in high brilliance photo-injectors Accelerating cells RF power 9 cells T U N E R Contributions to ELI-NP on RF accelerator activities Beam ~ 17 cm Low power test and multi-cell cavity tuning Coupling cells Technological issues (high power test @ SLAC), novel materials Cu z axis (cm) Mo Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities X-band devices: R&D on manufacturing We join the world wide effort to avoid hot brazing to Photographs of three manufactured X band cavities: (a) Cu brazed; (b) Mo brazed; (c) Cu electroformed. V. Dolgachev, SLAC B. Spataro, invited contribution to X-Band Structures, Beam Dynamics and Sources, December 2010 Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities X-band hybrid gun (Sapienza/INFN/UCLA) SW RF gun section fed on-axis from coupling cell that also feeds (the majority of the power) to a lower gradient downstream TW section (no circulators needed). The gun strongly longitudinally focuses, from velocity bunching due to 90° phase shift between SW cell and input coupler. Emittance. Compensating Solenoids RF power Photocathode Electrons Laser ) (266 nm TW structure (lower field) Device under study RF input RF Input coupler 1. 6 SW structure (higher field) TW structure 2. 5 SW structure RF input coupler RF output coupler Next steps: RF design optimisation (with beam dynamics), hot tests … The S-band version will be commissioned in 2011 @ UCLA (J. Rosenzweig) The hybrid gun is part of the CRISP proposal. Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Beam dynamics studies Simulations of particle beam evolution in linear and circular accelerators based on macro-particle models. Beam optimisation in S-band, C-band, X-band linac and for mixed frequency machines (SPARC is the first linac operating at two frequencies) Micro-bunching instability due to coherent synchrotron radiation (CSR) and space charge in linear or in circular machines (e. g. RF and/or magnetic compressors). Beam dynamics optimization of accelerator devices (e. g. hybrid gun). CSR in a ring Bunch Length in hybrid gun 1 OC temperature shift energy Contributions to ELI-NP on RF accelerator activities Study of collective effect due the particle wake fields. time Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Beam dynamics studies for SPARX is a mixed frequency machine (S-band/C-band) to be commissioned before 2015 (C-band gun is under investigation). C-band has been chosen for reliability consideration (as SWISS-FEL @ PSI). SPARX has a nominal energy of 750 Me. V (FEL operation) to 900 Me. V (on crest operation, corresponding to 18 Me. V Compton photons). Contributions to ELI-NP on RF accelerator activities Thermal emittance 0. 6 um/mm, minimum emittance (Ferrario) working point. Parmela/Astra simulation + scaling laws Q (p. C) Luminosity/spectral density ε (μm) E peak (MV/m) Brightness (A/m 2) Q/ε 2 (p. C/μm 2) S-band 1000 1. 0 120 1. 9 1014 (90 A) 1000 S-band 500 0. 54 120 1. 5 1014 (70 A) 1720 S-band 100 0. 19 240 0. 9 1014 (40 A) 2770 C-band 500 0. 49 240 7. 7 1014 (92 A) 2080 C-band (scaled) 250 0. 37 240 6. 1 1014 (73 A) 1830 X-band 250 0. 27 480 2. 5 1015 (90 A) 3400 X-band 250 0. 28 350 1. 5 1015 (58 A) 3400 X-band (Hyb. gun) 6. 7 0. 08 200 2. 8 1016 (90 A) 1050 Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities Educational and training experience All the previous activities are pursued with the aid of students, either master thesis or Ph. D level, that every year get their diploma at Sapienza (Faculty of Engineering). At the moment we have Ph. D and master students working on accelerator physics topics. The core topics where most of the students have been trained range from beam dynamics in linear and circular machines (including collective effects) to design methodology and bench measurements of RF devices in particle accelerators at frequencies from S-band (3 GHz) to X-band (12 GHz). In the framework of our long standing collaboration with INFN/LNF accelerator physics division, we can also profit of the experience gained at SPARC (an accelerator physics research machine) where many talented Ph. D students from our university have been trained. We give lectures in international accelerator schools, such as Joint Universities Accelerator School (JUAS) or Cern Accelerator School (CAS). We give also a course on Physics and Technology of Accelerators at the University of Rome, Faculty of Engineering and Faculty of Physics. Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities Conclusions We design and construct RF devices for beam generation (photo -gun) and beam manipulation (IV harm. cavity, RF deflectors, …) in the 3 -12 GHz frequency range. We have experience in beam dynamics optimisation of linear/circular machines We take part to commissioning of High Brilliance photo-injector SPARC We train Ph. Ds and technical engineers in accelerator physics We are interested in sharing our experience in design and the realization of RF devices for the ELINP accelerator We are interested in contributing to beam dynamics studies and commissioning of the accelerator in ELI-NP We are interested in contributing to the setting up of accelerator physics expertise in ELI-NP Ongoing collaborations: INFN (other labs/sections), UCLA, CERN, LULI, Euro. FEL (IRUVX FEL), SLAC, KEK Andrea. Mostacci@uniroma 1. it
Contributions to ELI-NP on RF accelerator activities Additional material Andrea. Mostacci@uniroma 1. it ELI-NP: the way ahead Bucharest, 10 -12 March 2011
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities X-band hybrid gun (Sapienza/INFN/UCLA) SW RF gun section fed on-axis from coupling cell that also feeds (the majority of the power) to a lower gradient downstream TW section (no circulators needed). The gun strongly longitudinally focuses, from velocity bunching due to 90° phase shift between SW cell and input coupler. Emittance. Compensating Solenoids RF power Photocathode Electrons Laser TW structure (lower field) Device under study RF input RF Input coupler 1. 6 SW structure (higher field) TW structure 2. 5 SW structure RF input coupler RF output coupler Next steps: RF design optimisation (with beam dynamics), hot tests … The S-band version will be commissioned in 2011 @ UCLA (J. Rosenzweig) The hybrid gun is part of the CRISP proposal. Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities X-band hybrid gun (Sapienza/INFN/UCLA) SW RF gun section fed on-axis from coupling cell that also feeds (the majority of the power) to a lower gradient downstream TW section (no circulators needed). The gun strongly longitudinally focuses, from velocity bunching due to 90° phase shift between SW cell and input coupler. Emittance. Compensating Solenoids RF input coupler Photocathode Electrons Laser TW structure (lower field) Device under study RF input RF Input coupler 1. 6 SW structure (higher field) 2. 5 SW structure Temperature sensitivity 200 k. Hz/o. C Next steps: RF design optimisation (with beam dynamics), hot tests … The S-band version will be commissioned in 2011 @ UCLA The hybrid gun is part of the CRISP proposal. Andrea. Mostacci@uniroma 1. it
ELI-NP: the way ahead Bucharest, 10 -12 March 2011 Contributions to ELI-NP on RF accelerator activities X-band hybrid gun (Sapienza/INFN/UCLA) SW RF gun section fed on-axis from coupling cell that also feeds (the majority of the power) to a lower gradient downstream TW section (no circulators needed). The gun strongly longitudinally focuses, from velocity bunching due to 90° phase shift between SW cell and input coupler. Emittance. Compensating Solenoids @z=30 cm σz< 10 mm (90 A) εn, x< 0. 08 mm-mrad Photocathode Electrons Laser TW structure (lower field) Device under study RF input RF Input coupler 1. 6 SW structure (higher field) σx< 80 mm Brilliance=2. 8 1016 A/m 2 6. 7 p. C Solenoid @ 6 k. G Next steps: RF design optimisation (with beam dynamics), hot tests … The S-band version will be commissioned in 2011 @ UCLA The hybrid gun is part of the CRISP proposal. Andrea. Mostacci@uniroma 1. it
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