Update on Xband FEL Studies and Plans A

Update on X-band FEL Studies and Plans A. Latina and G. D’Auria for the X-band FEL collaboration CLIC Project Meeting #20 – Mar 31, 2015

Status • Xb. FEL, updated plan – Widespread interest for X-band FEL R&D – SINAP commitment – Activities continue • Strategy – Work in parallel on the three different lines: • Design and parameters optimization • Hardware design, fabrication and tests • Photon production and user requirements – Keep dialog between the three packages • Regular meetings – Technical – Organizational 2

Survey (I) 3 A proposal for tests is under preparation

Survey (II) 4

(1) Design and parameters • Parameters definition, including new challenging schemes • Accelerator design • Performance optimization Contributions from: Australian Synchrotron, National Technical University of Athens, Turkish Accelerator Center, Oslo University 5

Design and parameters: Phase space linearization T. Charles 1. After gun 2. After first section 3. After next (decelerating) section S-band injector X-band linearizer BC 1 chicane Studies are ongoing of: - Optical linearization using sextupoles - X-band injector 4. Final section before BC 6

Design and parameters: Emittance growth due to misalignments • • • Quadrupoles: • σx, y =100 μm, σx’, y’ =0 BPMs: • σ x, y =100 μm, σx’, y’ =0 Dipoles: • σx, y =100 μm, σx’, y’ =100 μrad, roll= 100 μrad S-band structures are located on single girder: • • • One-to-One correction (simple) • Dispersion Free Steering (dfs) • Wakefield Free Steering (wfs) σx, y =100 μm, σx’, y’ =100 μrad • Linearizer: X-band structure located on single girder: σx, y =100 μm, σx’, y’ =100 μrad • Linac module, 4 X-band structures are located on single girder, which has • Three correction methods: A. Aksoy σx, y =100 μm, σx’, y’ =100 μrad Needs to be checked. . . Transverse beam size error Transverse beam jitter < 15% < 7? ?

Design and parameters: Simulations of X-ray production J. Pfingstner Basic layout of one undulator section: Parameter choice: • • • All length have to be chosen as multiples of λu in simulations. λu = 1. 5 cm λl = 1 Å (Ku ≈ 1. 4) Lu = 4 m Lg = 0. 72 m LQ = 0. 12 m βavg = 15 m BQ ≈ 16 T/m (dipole focusing not included yet). 13 Sections (length 57 m) GENESIS model: 1. No gap: Basic functionality; focusing and undulator field interleaved (not the case in reality) and repeated. 2. Gap: External magnet file: possibility to model undulator and focusing field separately. 8

Design and parameters: Simulation of X-ray production J. Pfingstner • B 5 is shorter than B 1, but current is mainly the same apart from head and tail. • At head and tail also energy spread has been increased (not efficient). • Shape of SASE curves are different than steady-state. • B 5 is slightly better than B 1. 9

(2) Hardware Commitment from SINAP: • SINAP will provide 4 X-band structures for Xb. FEL collaboration before 2018 • R&D of our X-band structure, which has also been discussed between us and Walter. – – – 2015 early : First X-band deflecting structure 2015 later : First dedicated X-band accelerating structure for FEL 2016 : First T 24 (12 GHz) for CLIC 2017 : Optimized X-band structure of FEL 2017, 2018 : 4 X-band structures for Xb. FEL Collaboration. Contributions from: CERN, SINAP, VDL, Fermi@ELETTRA, Jagiellonian University, ASTEC, Uppsala, IASA, Ankara, Lancaster, [others…] 10

(3) X-ray production and user requirements Objectives Starting from the FEL output specifications a fully self consistent FEL facility design will be established (in terms of accelerator layout, major hardware choices, and FEL system design) using X-band technology across three scenarios: – Hard X-ray FEL. – Soft X-ray FEL. – Upgrade of an existing FEL facility (FERMI). Contributions from: Australian Synchrotron, Ankara, Fermi@ELETTRA, Jagiellonian University, ASTEC 11

(3) X-Ray FEL User Requirements: UK Case Study for an Hard X-ray facility J. Clarke Extract from UK-FEL document: We are aiming for a machine enhanced for; (a) high temporal resolution, (b) synchronisation to external THz and a wide variety of ultra-fast laser sources, (c) with end-stations optimized for a wide range of basic and applied science activities, (d) high scientific throughput with multiple end-stations operating in parallel. 12

Hard X-Ray FEL User Requirements: UK Case Study J. Clarke 13

Soft X-Ray FEL User Requirements: Ankara Plans A. Aksoy 14

Soft X-Ray FEL: Ankara Plans 15

Fermi upgrade: G. D’Auria 1. 5 Ge. V l 4 -80 nm 2 1 S-band linac two e-bunches/RF pulse HF bunch separator 3. 5 Ge. V l < 1 nm Two separate linacs at 50 Hz S-band → 1. 5 Ge. V X-band → 3. 5 Ge. V FERMI energy upgrading scheme and HF bunch separation 16

Main topics for future activities Ø Linac design based on FEL users requirements (i. e. wavelength range, energy per pulse, pulse duration, pulse structure, etc. ). Ø Beam dynamics studies, bunch compressors, deflecting cavities, bunch spreaders. Ø Timing and synchronization schemes. Ø Identify and develop a common hardware solutions for the accelerating unit. Ø Component fabrication. Ø RF module assembly and high power tests. 17

Plans • Progress in the three work-packages independently – Have regular meetings, mostly technical – Exploit opportunities for face-to-face meetings (e. g. HG 2015, high-gradient workshop in Tsinghua University, June 16 -19 2015) – Keep dialog between work-packages: e. g. SINAP X-band design <--> beam dynamics requirements • Write proposal for testing the X-band FEL structures at X-boxes • Explore other possibilities of EU funding 18