1. 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

2. Introduction Kernfysisch Versneller Instituut Zernike Institute for
atomic, nuclear and (astro-) particle physics
accelerator /radiation physics
theoretical physics
Kernfysisch Versneller Instituut
F. Zernike ( )
biomolecular and bio-inspired functionality
nanostructured materials for electromagnetic functionality
Zernike Institute for
Advanced Materials

3. Hard and soft X-ray FELs
SCSS
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
1.5 GeV, NC, S-band
EU-XFEL
Swiss-FEL
Soft X-ray FEL’s
FLASH

4. Explosion of T4 lysozyme (C, N, O, S) induced by radiation damage.
XFEL properties
Short wavelengths: < 1 Å – 100 nm
High transversal coherence and, when seeded, also longitudinal coherence
Very intense: 1010 – 1013 photons/pulse
Short pulse lengths: < 1 – 100 fs
Explosion of T4 lysozyme (C, N, O, S) induced by radiation damage.
R. Neutze, et al, Nature 406, 752 (2000).
Gaffney et al., Science 316 (2007) 1444

5. Science drivers Hierarchical biology Chemical reactions
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

6. 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

7. XFEL: lasing
Self-Amplified Spontaneous Emission (SASE)
ZFEL

8. SASE SASE has no longitudinal coherence !
Longitudinal coherence can be realized by
Seeding at l1
Various schemes for harmonic generation
Making very short electron bunches, i.e. < 1 fs

9. XFEL linac
courtesy R. Bakker

10. XFEL: e- beam requirements
FEL power gain length (1 D):
High peak current: Ie~ 1 – 3 kA
Excellent e- - g transverse overlap: small transversal emittance:
Small energy spread:
Small emittance and energy spread must be preserved during acceleration !

11. ZFEL parameters Stage 1 Stage 2 Beam energy (GeV) 1.0 2.1
Bunch charge (pC)
Norm. emittance
(mm mrad)
Peak current (kA)
1.5
Energy spread (MeV)
0.9
Rep. Frequency (Hz)
Stage 1
Stage 2
Undulator period (mm) 15
Undulaor par. K
1.2
Pierce param. r
9.7e-4
4.6e-4
Gain length (m)
0.711
1.5
Saturation length (m)
13.3 27
Photon wavelength (nm)
3.4
0.8

12. ZFEL layout 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: Chr. Adolphsen

13. 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
Courtesy: Jom Luiten

14. X-band accel. structures
High-gradient accelerating structures for X-ray FEL
100 MV/m
breakdown rate
high beam quality has to be preserved during acceleration
sensitivity of single-particle dynamics to various errors
study of collective effects
design optimization

15. Design studies Error budget of X-band linac
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

16. Road to ZFEL Submitting ZFEL proposal in the beginning of 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

17. Thank you for your attention
ZFEL
Thank you for your attention