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Design Considerations for the NGLS (Next Generation Light Source)

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

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Design Considerations for the NGLS (Next Generation Light Source)

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

  2. What are the new facility directions? • High-rate and ContinuousWave(CW) operation • FEL seedingfor narrow BW & full coherence • Femtosecondx-ray pulses (~ 10-15 sec) • Multiple FELs with independently tunablewavelengths • Pulse length and BW controlat FT-limit • Two-Colorpulses with variable relative timing & color • Expandablefacility well into the future •  A Next Generation Light Source (NGLS)

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

  4. An Array of Unique Free-Electron Lasers FEL-2 2-Stage HGHG (100-600 eV) FEL-1 Self-Seeded (250-1250 eV) FEL-3 Two-Color (250-1000 eV)

  5. NGLS Layout e- diagnostics compressors e- diagnostics collimation FELs (1-9) injector linac spreader 1 MHz CW e- injector ( = 0.6 m, Q = 300 pC) 1.3-GHz CW SRF @ 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) exp. halls beam stops

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

  7. NGLS Photo-Cathode Gun (APEX) 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 Cs2Te cathode generating 100’s of pC/bunch @ 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) 186 MHz e- F. Sannibale, D. Filippetto, C. Papadopoulos, R. Wells

  8. NGLS High-Rate Injector (R&D at APEX - LBNL) F. Sannibale, D. Filippetto, C. Papadopoulos, R. Wells warm cold 0.8 MeV velocity bunching ( 1/6) 94 MeV Eight 9-cell TESLA cavities (1.3 GHz) 186 MHz UV first beam 1.3-GHz buncher RF Gun solenoids Ipk 45 A APEX Parameters (done): Mar. 18 ’13 gex,y < 0.6 mm APEX Gun (1 MHz CW) sE/E 20 keV Cs2Te 8

  9. 650-MHz booster for the injector? Possible layout for injector and first linac section No need for 3.9 GHz RF linearizer at end of linac moderate ( RF compression beam is close to parabolic. 1.5-2 kA M. Venturini

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

  11. Linac and Compressor Layout for 4 GeV (cathode to undulator) L0 j 0 V0 94 MV L1 j = -17.0° V0= 195 MV HL j = 180° V0 = 0 L2 j = -18° V0= 600MV L3 j = 0 V0= 3150 MV CM01 CM2,3 CM08 CM34 CM04 CM09 3.9GHz LH 94 MeV R56 = -5 mm Ipk = 46 A Lb = 1.5 mm sd = 0.02 % BC1 280 MeV R56 = -85 mm Ipk = 100 A Lb = 0.75 mm sd = 0.62 % BC2 850 MeV R56 = -80 mm Ipk = 500 A Lb = 0.13 mm sd = 0.50 % Spreader 4.0 GeV R56 = 0 Ipk = 500 A Lb = 0.13 mm sd 0.008 % GUN 0.75 MeV 300 pC; Machine layout 2013-08-27; Bunch length Lb is FWHM

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

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

  14. Superconducting Undulator Technology Use Nb3Sn SC-undulators for efficiency & rad. hardness Nb3Sn NGLS NbTi Perm. Mag. LCLS • Magnetic gap = 7.5 mm. • Vacuum chamber  5.5 mm 80% of short sample limit S. Prestemon, D. Arbelaez

  15. FEL-1 (SASE/Self-Seeded) 8.8 m 4.4 m Based on SXRSS 4.4 m 3 mm P Lmag= 36.3 m, Nu = 11 Lmag = 26.4 m, Nu = 8 1 MHz 230-1250 eV To 2 keV SASE Near FT-limit 4.4 m mono. 20000 mod-1 Lmag= 33 m, Nu = 10 mod-2 P Lmag= 33 m, Nu = 10 P rad-1 rad-2 mod1 mod2 35.2 m 52.8 m 97 m P 0.5 mr 48.4 m 48.4 m FEL-2 (2-Stage HGHG) 6 6 6 6 123 m Lmag = 26.4 m, Nu = 8 Based on Fermi Results in Trieste 6.0 m 58 m 0.1 MHz 100-600 eV + 3rd stage option FT-limited pulses (7 - 70 fs) FEL-3 (Two-Color FEL) Based on SPARC Chirp/Taper Results in Frascati 0.1 MHz, 230-1000 eV, two 1-fs pulses, variable color, pol., & timing

  16. Chirped/Tapered 2-Color FEL chirped SASE e- Few cycle 2-5 mm laser pulse chirps very short section of e-beam add taper 8 fs ΔtFWHM ≈ 1.7 fs Two 1-fs pulses at 0.1 MHz, 250-1000 eV, var. color, pol., & timing Possible attosec. pulse with ESASE 21010at 1.0 keV G. Marcus, A. Zholents

  17. 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

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