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A compact, soft X-ray FEL at KVI. Hans Beijers Kernfysisch Versneller Instituut University of Groningen, The Netherlands. Introduction Science drivers ZFEL characteristics Roadmap to ZFEL. Introduction. atomic, nuclear and (astro-) particle physics
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A compact, soft X-ray FEL at KVI Hans Beijers Kernfysisch Versneller Instituut University of Groningen, The Netherlands • Introduction • Science drivers • ZFEL characteristics • Roadmap to ZFEL
Introduction • atomic, nuclear and (astro-) particle physics • accelerator /radiation physics • theoretical physics Kernfysisch Versneller Instituut F. Zernike (1888-1966) • biomolecular and bio-inspired functionality • nanostructured materials for electromagnetic functionality Zernike Institute for Advanced Materials
SCSS Hard and soft X-ray FELs Hard X-ray FEL’s • LCLS: 15 GeV, NC, S-band • SCSS: 8 GeV, NC, C-band • SwissFEL: 5.8 GeV, NC, C-band • Eur-XFEL: 20 GeV, SC, L-band • FLASH: 1.2 GeV, SC, L-band • FERMI@Elettra: 1.5 GeV, NC, S-band EU-XFEL Swiss-FEL Soft X-ray FEL’s FLASH FERMI@Elettra
Gaffney et al., Science 316 (2007) 1444 Explosion of T4 lysozyme (C,N,O,S) induced by radiation damage. R. Neutze, et al, Nature 406, 752 (2000). XFEL properties • Short wavelengths: < 1 Å – 100 nm (10 keV – 10 eV) • High transversal coherence and, when seeded, also longitudinal coherence • Very intense: 1010 – 1013 photons/pulse • Short pulse lengths: < 1 – 100 fs
Science drivers Hierarchical biology Protein folding, ‘biological’ water, structure and function, membranes, viruses, cells Chemical reactions Catalysis, interfaces, combustion, molecular movies Matter in extreme conditions Phase diagram borders, end of scales Atoms to materials Inorganic/bio clusters Emergence of solid state properties from atom clusters Fundamental interactions QED and symmetries, axions, dark matter Correlated materials Phase transitions, emergent phenomena, high Tc superconductivity, magnetism Mesoscale physics Fatigue, fracture, strain, radiation damage, nucleation, disordered materials Complex materials New battery and photovoltaic materials, phase transitions
ZFEL characteristics • Wavelength range: 0.8 – 50 nm Emax= 2.1 GeV • Repitition rate: 10 Hz – 1 kHz • Total length: < 200 m high accel-grad. structures
XFEL: lasing • Self-Amplified Spontaneous Emission (SASE) • EM wave – electron interaction (m-bunching) ZFEL
SASE • SASE has nolongitudinal coherence ! • Longitudinal coherence can be realized by • Seeding at l1 or n x l1 using e.g. HGHG • Making very short electron bunches, i.e. < 1 fs
XFEL: e- beam requirements • FEL power gain length (1 D): • High peak current: Ie~ 1 – 3 kA (bunch compression) • Excellent e- - g transverse overlap: small transversal emittance • Small wavelength/energy bandwidth: • Regular-spaced e- bunches with rep.rate up to 1 kHz • High acceleration gradient (X-band linac) • Small emittance and energy spread must be preserved during acceleration !
XFEL linac courtesy R. Bakker
Courtesy: Chr. Adolphsen Generic ZFEL layout SLAC scheme • 3 S-band injector sections • X-band linac section: 8 x 0.5 m TW = 400 MeV energy gain per section • 2 X-band linearizer cavities • Stage 1: 2 X-band linac sections Stage 2: 5 X-band linac sections
Courtesy: Jom Luiten ZFEL RF Photogun • Collaboration with TU Eindhoven (J. Luiten) 266 nm, 10 ps, 1 kHz rep. rate > 0.2 mJ/pulse E = 6.9 MeV Q = 0.1 – 1 nC en 1 mm mrad
X-band accel. structures • High-gradient accelerating structures for ZFEL • SLAC T53 or H60 structures • high acceleration gradient and low breakdown rate • design optimization (e.g. a/l)
Design studies • Single-particle dynamics: • B-field errors, magnet misalignments and chromatic aberrations • Maximum-allowed emittance growth determines tolerances • Collective effects: • short-range wakefields, CSR emission and beam instabilities • S2E simulations • Basic problem: no designs as yet for 1 kHz, high-power X-band klystrons and modulators
Road to ZFEL • Submitting ZFEL proposal in 2011 • RF photogun and diagnostics, X-band test stand • Build up expertise and setting up collaborations • Design studies and developing subsystems, e.g. seed lasers, diagnostics, timing and synchronization systems, alignment and feedback etc. • Construction • First light 5 years after start project
Thanks • The CLIC group for having me here • Many colleagues from the X-band and XFEL communities for very useful discussions and advice (Walter Wuensch, Sami Tantawi, Chris Adolphsen, Hans Braun, …….. Thank you for your attention