A Future Light Source for LBNL Facility Vision and R&D plan John Corlett

1. A Future Light Source for LBNL Facility Vision and R&D plan John Corlett ALS Scientific Advisory Committee Meeting June 16, 2006

2. A variety of synchrotron radiation source concepts to pursue • Storage rings • Energy recovery linac (ERL) • Free electron laser (FEL) • Laser wakefield accelerator • Optical manipulation of electron beams Performance metrics • Wavelength range • Average and peak flux • Average and peak brightness • Pulse repetition rate • Temporal coherence • Spatial coherence • Pulse duration • Synchronization • Tunability • # beamlines • Beam stability • … Future generations of light sources will likely utilize novel techniques for producing photons tailored to application needs Different operating modes Work with users to define performance parameters

3. Evolution of light sources - coherence offers next orders magnitude improvement Dominates if sz < l • Free Electron Laser (FEL) • Enhance coherence at shorter wavelengths by modulation of the charge within a bunch • PLUS optical manipulations • Control of pulse duration • Temporal coherence • Harmonic generation of shorter wavelengths • Precise synchronization • Shorter gain length

4. Vision for future light source at LBNL - a high rep-rate, flexible FEL facility • Independent tuned FELs: • Wavelength • Pulse duration • Polarization • FEL configuration: • SASE • Seeded • long pulse • short pulse • Complementary to ALS & LCLS • Wavelength: ~200 nm to 1 nm • Peak flux: 1010-1012 ph/pulse • Short pulse: 10-100 fs or 100 as • Narrow bandwidth: ∆l/l ~10-5 Low-emittance, high rep-rate gun 2-3 GeV CW superconducting linac Beam conditioning Beam distribution Multiple independent beamlines up to ~100 kHz rep rate

5. N ALS Bevatron site 50 m

6. N ALS Injector Beam switchyard Beamlines & experimental hall FEL farm 50 m

7. Spectrum Pulse profile Comparison of seeded and SASE characteristics SASE, 20 m undulator 25 fs seed, 30 m undulator 500 fs seed, 30 m undulator Electron beam is 1.5 GeV, energy spread 100 keV, 250 A current, 0.25 micron emittance; laser seed is 100 kW at 32 nm; undulator period 1 cm

8. High-gain harmonic generation (HGHG) energy -p p phase e- bunch radiator modulator laser pulse dispersive chicane e- beam phase space: Input Output np -np Bunched beam radiates strongly at harmonic in a downstream undulator resonant at l0/n, Laser modulates e-beam energy Dispersive section introduces bunching L.-H. Yu et al, Science 289 932-934 (2000) L.-H. Yu et al, Phys. Rev. Let. Vol 91, No. 7, (2003)

9. Optical manipulation 1 - ESASE SASE Bunching Modulation Acceleration 20-25 kA Peak current, I/I0 z /lL • Precise synchronization of the x-ray output with the modulating laser • Variable output pulse train duration by adjusting the modulating laser pulse • Capability to produce a solitary ~100-attosecond duration x-ray pulse • Increased peak output power • Shorter x-ray undulator length to achieve saturation A. A. Zholents, Phys. Rev. ST Accel. Beams 8, 040701 (2005)

10. Optical manipulation 2 - attosecond pulses • Attosecond x-ray pulse using energy modulation with two lasers 1.5Å output pulse Energy modulation with two lasers (1.2, 1.6 µm) ~ 100 as A.Zholents, W.M. Fawley, Phys. Rev. Lett. 92, 224801 (2004) A.Zholents, G. Penn, Phys. Rev. ST Accel. Beams 8, 050704 (2005)

11. Performance goals

12. LBNL FEL facility Attosecond mode High resolution mode Short pulse mode ALS Top-off 0.0001 Performance comparisons

13. R&D to address FEL performance (& cost) drivers • Electron beam energy g • High gradient accelerator • Electron beam emittance e • High brightness gun, minimize emittance growth in accelerator • High gradient accelerator • Manipulate and condition beam for FEL process • Peak current Ipeak • Bunch compression, minimize distortion from acceleration and longitudinal wakefield • Energy spread sE • High brightness gun, minimize distortion from longitudinal wakefield Power/ undulator length

14. Emittance sensitivity - cost effective to use low emittance beams lx=1 nm, Ipeak=250 A, sE=100 keV

15. Beam switching and transport Bunch manipulation and conditioning Low emittance, high rep rate source High gradient CW superconducting accelerator Advanced undulators and FEL radiators Critical systems

16. Low emittance, high rep rate gun Cathode Laser RF field R&D plan outline - (1) low emittance, high rep rate electron gun Low emittance, high quantum efficiency cathodes Photocathode laser systems Electron beam

17. High gradient CW accelerator R&D plan outline - (2) CW SCRF cryomodules from Stanford FEL & bunch manipulations • Develop robust high gradient SCRF • Collaborate with Cornell, J-Lab, etc • Re-locate Stanford FEL? • 40 MeV • TESLA cavities • 10 MV/m CW mode Electron beam emittance control and manipulations

18. R&D plan outline - (3) accelerator physics and modeling • Detailed computer modeling of the electron beam in all stages of the accelerator • Highly parallelized code development • Emittance compensation • Design of transport optics • Design of beam switchyard • Design experimental program to demonstrate high rep rate low emittance beams • SASE / Seeded / Cascade / Attosecond … FEL configurations • LBNL expertise exists in the AFRD division

19. Timeline • July/August 2006 • Present vision and R&D plan to DOE • FY’07 • Begin R&D studies • LDRD support and some DOE funding • FY’08-FY’12 • Vigorous R&D program • Cathodes, gun, lasers, emittance control, beam switchyard, superconducting RF, FELs • FY’09 - CD0 • FY’11-12 opportunity for construction project • Following successful operations of LCLS and peak of NSLSII spend