Paul Emma, et. al. Sep. 18, 2013 Paul Emma, et. al. Sep. 18, 2013 Design Considerations for the NGLS (Next Generation Light Source) NGLS

What are the new facility directions ? High-rate and Continuous Wave (CW) operation FEL seeding for narrow BW & full coherence Femtosecond x-ray pulses (~ 10  15 sec) Multiple FELs with independently tunable wavelengths Pulse length and BW control at FT-limit Two-Color pulses with variable relative timing & color Expandable facility well into the future  A Next Generation Light Source (NGLS)

A High Repetition Rate CW X-Ray FEL Array CW Superconducting Linac X-Ray Beamlines and End-stations 3-9 FELs ~10 ms ~100 ms 600  s 1  s (CW) BC1 BC2 2.4 GeV 1 MHz injector

An Array of Unique Free-Electron Lasers FEL-1Self-Seeded ( eV) FEL-3Two-Color ( eV) FEL-2 2-Stage HGHG ( eV)

NGLS Layout 1 MHz CW e  injector (  = 0.6  m, Q = 300 pC) 1.3-GHz CW 15 MV/m (24 CM’s, 0.3 mA) Two bunch compressors + heater (500 A) Beam spreader using RF deflectors (  9 FELs) Three (initial) very diverse FEL designs Diagnostics and collimation sections 720-kW main beam stops (  3) 1 MHz CW e  injector (  = 0.6  m, Q = 300 pC) 1.3-GHz CW 15 MV/m (24 CM’s, 0.3 mA) Two bunch compressors + heater (500 A) Beam spreader using RF deflectors (  9 FELs) Three (initial) very diverse FEL designs Diagnostics and collimation sections 720-kW main beam stops (  3) injector linacspreader FELs (1-9) beam stops compressors e - diagnostics exp. halls collimation

Parameters for the CW SC-Linac (2.4 GeV) J. Corlett, L. Doolittle, A. Ratti, R. Wells, et al. Average current = 0.3 mA

Achieved: Successful CW operation Excellent RF design performance at full power (20 MV/m) E-beam design energy (0.75 MeV) < 10  10 gun vac. pressure Cs 2 Te cathode generating 100’s of 1 MHz 40 C in 4 days: QE goes from 10% to 4% (promising lifetime) Next Steps: Test CsK2Sb cathodes (green laser) 6D phase space characterization at gun energy (and later at 30 MeV) NGLS Photo-Cathode Gun (APEX) F. Sannibale, D. Filippetto, C. Papadopoulos, R. Wells 186MHz eeee

NGLS High-Rate Injector (R&D at APEX - LBNL) RF Gun 0.8 MeV warm UV solenoids 1.3-GHz buncher 8  x,y  m I pk  45 A  E /E  20 keV APEX Gun (1 MHz CW) Cs 2 Te F. Sannibale, D. Filippetto, C. Papadopoulos, R. Wells APEX Parameters (done): first beam Mar. 18 ’13 velocity bunching (  1/6) 186MHz

650-MHz booster for the injector? Possible layout for injector and first linac section at end of linac No need for 3.9 GHz RF linearizer kA M. Venturini

Removing Energy Chirp with a Wakefield add 5-m long de-chirper (2a = 6 mm) L3 on crest …or 35-deg off crest 5-m long dechirper NGLS Longitudinal Phase Space K. Bane, P. Emma, H.-S. Kang, G. Stupakov, M. Venturini point-charge wake PAL-ITF Dechirper Simulations dechirper off a = 4-15 mm p = 0.5 mm h = 0.6 mm g = 0.3 mm L = 1 m dechirper on PAL-ITF (Korea) corrugated pipe Aug. ‘13 experiment

Linac and Compressor Layout for 4 GeV (cathode to undulator) CM01 CM2,3 CM04 CM08 CM09 CM34 BC1 280 MeV R 56 = -85 mm I pk = 100 A L b = 0.75 mm   = 0.62 %BC2 850 MeV R 56 = -80 mm I pk = 500 A L b = 0.13 mm   = 0.50 % GUN 0.75 MeV LH 94 MeV R 56 = -5 mm I pk = 46 A L b = 1.5 mm   = 0.02 % L0   0 V 0  94 MVL1  =  17.0° V 0 = 195 MVHL  = 180 ° V 0 = 0L2  =  18° V 0 = 600MVL3  = 0 V 0 = 3150 MV Spreader 4.0 GeV R 56 = 0 I pk = 500 A L b = 0.13 mm    % 300 pC ; Machine layout ; Bunch length L b is FWHM 3.9 GHz

t V MHz = 3/4  186 MHz (7.2 ns) z DC bend septum Beam Spreader System RFdeflector Split again 3 times with 3 more deflectors at 151 MHz = 13/16  186 MHz (6.6 ns) yxyxyx x RF gun frequency = 1300/7 MHz  186 MHz ( 5.4 ns) end of linac Phase-I (3 FELs) needs only one RF deflector Keep long (139 MHz)  t = 5.4 ns collide two x-ray pulses distribute e  bunches to 3-9 FELs M. Placidi, C. Sun 5.4 ns

Pulse-Stealing Diagnostics (BC1, BC2, EOL) 250-W dump 1200-W dump 1 MHz Linac Intercepting diagnostics used only at low rate Measure at 1 kHz: Energy Energy Proj. energy spread Proj. energy spread Slice energy spread Slice energy spread Proj. emittance Proj. emittance Slice emittance Slice emittance Bunch length Bunch length Charge… Charge… 1 kHz Kicker (<1  s) TCAV Screens/wires 100-W dump

Superconducting Undulator Technology LCLS Nb 3 Sn Perm. Mag. NbTi NGLS S. Prestemon, D. Arbelaez 80% of short sample limit Use Nb 3 Sn SC-undulators for efficiency & rad. hardness  Magnetic gap = 7.5 mm.  Vacuum chamber  5.5 mm

97 m L mag = 26.4 m, N u = 8 L mag = 36.3 m, N u = 11 P 35.2 m52.8 m 8.8 m mono m FEL-1 (SASE/Self-Seeded) 1 MHz eV To 2 keV SASE Near FT-limit 58 m P rad-1 mod-1 rad-2 mod m 6.0 m L mag = 26.4 m, N u = 8 FEL-2 (2-Stage HGHG) 0.1 MHz eV + 3 rd stage option FT-limited pulses ( fs) 123 m L mag = 33 m, N u = 10 P 4.4 m mod m L mag = 33 m, N u = 10 P 48.4 m mod2 0.5 mr 3 mm FEL-3 (Two-Color FEL) 0.1 MHz, eV, two 1-fs pulses, variable color, pol., & timing Based on Fermi Results in Trieste Based on SXRSS Based on SPARC Chirp/Taper Results in Frascati

Chirped/Tapered 2-Color FEL Two 1-fs pulses at 0.1 MHz, eV, var. color, pol., & timing Possible attosec. pulse with ESASE Few cycle 2-5  m laser pulse chirps very short section of e-beam G. Marcus, A. Zholents Δt FWHM ≈ 1.7 fs 2  at 1.0 keV addtaper 8 fs chirpedSASE ee

More LBNL Presentations Soon Wed. Sep. 25 (13:30) G. Penn - Three Unique FEL’s for NGLS J. Byrd - Longitudinal Feedback for SRF Linac Thurs. Sep. 26 (09:00) M. Venturini – Bunch Compression and Dynamics F. Sannibale – High-Rate, High-Brightness Injector Wed. Oct. 2 (13:30)? J. Corlett - Superconducting RF Linac Design C. Steier - Collimation