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![Undulator Alignment Diagnostics (Stretched Wires & Hydraulic Levels)
Girder Numbers
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x[microns]
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Calculated orbit change
Measured und. & quad moves
H.-D. Nuhn, THOA02
undulator
alignment drift
over 3 days](https://image.slidesharecdn.com/aea6340d-4344-41cf-a34c-e27c5e0b6ae3-161023143933/85/TUDORTMUND1-52-320.jpg)
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TUDORTMUND1
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- 2. Bholat@slac.stanford.edu Outline • Scientific motivationfor FEL (one example) • Principal of FEL • Important parameters of FEL • Systematic tuning the FEL parameters • User’s requirements • Improvement and future plans • Conclusion and Q&A.
- 3. Bholat@slac.stanford.edu Protein before andafter folding Amyloidoses Alzheimer�s disease Prion diseases Misfolding and cancer Protein folding diseases
- 4. t = 0 Bholat@slac.stanford.edu t= 25 fs t = 50 fs …which is being imaged with intense x-rays BEFORE its destruction Coulomb Explosion of Lysozyme (50 fs) J. Hajdu, Uppsala 1-Å spatial resolution with hard x-rays femtosecond short pulses to resolve atomic and molecular dynamics
- 5. Bholat@slac.stanford.edu Experimental Hutches atLinac Coherent Light Source •AMO: Atomic, Molecular & Optical Science This instrument will enable the study of the interaction between the extremely intense LCLS X-ray pulses and the basic constituents of matter: atoms and molecules. • CXI: Coherent X-ray Imaging This instrument will take advantage of the extremely bright, ultrashort LCLS pulses of hard X-rays to allow imaging of non-periodic nanoscale objects, including single or small clusters of biomolecules at or near atomic resolution. • MEC: Matter in Extreme Conditions This proposed instrument will observe matter at temperatures exceeding 10,000 Kelvin and at pressures 10 million times the earth's atmospheric pressure at sea-level, enabling unprecedented understanding of exotic states of matter. •SXR: Soft X-ray Materials Science This instrument will enable the high brightness and timing capability of the LCLS to be applied to scattering and imaging experiments that require the use of soft X-rays. •XCS: X-ray Correlation Spectroscopy This instrument will observe dynamical changes of large groups of atoms in condensed matter systems over a wide range of time scales. • XPP: X-ray Pump Probe This instrument will predominantly use a fast optical laser to generate transient states of matter, and the hard X-ray pulse from the LCLS to probe the structural dynamics initiated by the laser excitation. •
- 6. Bholat@slac.stanford.edu Experimental Hutches atLinac Coherent Light Source Techniques Electron time-of-flight spectroscopy Ion time-of-flight spectroscopy Ion imaging Ion momentum spectroscopy X-ray scattering Sample Environment A variety of pulsed and continuous gas, liquid and particle injectors pulsed Proch-Trickl, Even-Lavie or Parker gas valves with heating and cooling options single or double skimmer chambers for gas beams motorized XYZ paddle for solid samples liquid jet for biological samples aerosol jet of particulate samples Scientific Applications Coherent X-ray imaging on single sub-micron particles Macromolecular Nanocrystallography High Fluence X-ray interactions with matter Time-resolved imaging and scattering with hard x-rays Techniques and Scattering Geometry Forward scattering on target-mounted samples andfree-standing injected particles Back-scattering Ion Time-of-flight
- 7. Bholat@slac.stanford.edu Scientific Application Time-resolvedspectroscopy and scattering with ultrafast and ultraintense soft X-rays at the LCLS Techniques X-ray Emission Spectroscopy (XES) X-ray Photoelectron Spectroscopy (XPS) X-ray Absorption Spectroscopy (XAS) Coherent Imaging Fourier Transform Holography Diffraction Sample Environment A wide range of experimental setups in UHV and HV conditions Experimental Hutches at Linac Coherent Light Source Scientific Applications X-ray PhotonCorrelation Spectroscopy (XPCS) Coherent X-ray Scattering (CXS) Scattering Geometries Small Angle X-ray Scattering (SAXS) Grazing incidence Scattering (GI-SAXS,GID) Wide Angle X-ray Scattering/Diffraction Scientific Applications Femtosecond Structural Dynamics X-ray Interactions with Matter X-ray Techniques Wide Angle X-ray Scattering/Diffraction Small Angle X-rays Scattering X-ray Absorption Spectroscopy X-ray Emission Spectroscopy
- 8. Bholat@slac.stanford.edu LightSourcesat~0.1nm 1010 H.-D. Nuhn, H. Winnick storage rings Free- Electron Lasers representa huge technical advance with: 1010 increase of peak brightness, coherent x-rays, Femtosec pulses, and Angstrom wavelengths LCLS I LCLS II
- 9. Bholat@slac.stanford.edu Why a Linac-BasedFree-Electron Laser* ? •“Recent” advances in high-brightness RF photocathode guns •Longitudinal emittance from linac is ~103 smaller than ring •Bunch length can be <100 fs and with small energy spread •Experience from linear collider operation and study (SLC, TESLA, JLC, NLC, CLIC) •The last 1-km of the SLAC linac is available •FEL produces unprecedented brightness and fsec pulses Use SASE** (Self-Amplified Spontaneous Emission) no mirrors or seed-lasers at 1-Å wavelengths * Motz 1950; Phillips 1960; Madey 1970 ** Kondratenko, Saldin 1980; Bonifacio, Pellegrini 1984
- 10. Why a LinearAccelerator (Linac)? ex ~ g 2 sz 5 mm, sE/E 0.1% (1 GeV), gez = szsE/mc2 10000 mm Storage ring… Higher energy means larger emittance Longitudinal emittance, gez , is much too large! Much smaller gez Emittance scaling (1/g )! But lower repetition rate ex ~ 1/ggez < 10 mm RF Photocathode Gun (or SCSS gun) Linac zyx e e N B eee ~ sz 1 mm, sE/E 0.05% (5 MeV), gez = szsE/mc2 5 mm
- 11. Linac Coherent LightSource at SLAC Injector (35º) at 2-km point Existing 1/3 Linac (1 km) (with modifications) Near Experiment Hall (NEH) AMO,SXR,XPP Far Experiment Hall(FEH) XCS,CXI,MEC Undulator (130 m) X-FEL based on last 1-km of existing 3-km linac New e- Transfer Line (340 m) 1.2-25 Å (15-3.3 GeV) X-ray Transport Line (200 m)
- 12. BC2 4.3 GeV BSY 14 GeV TCAV3 5.0GeV BC1 250 MeV L1S 3 wires 2 OTR L1X 4 wire scanners + 8 coll’s L2-linac L3-linacDL1 135 MeV L0 gun TCAV0 old screen3 OTR sz1 sz2 3 wires 3 OTR stopper heater mwall DL2 14 GeV undulator 14 GeV 4 wire scanners + 6 coll’s vert. dumpstopper LCLS Machine Layout Accelerator is last 1-km of SLAC linac (14 GeV) RF photocathode gun and off-axis injector Two bunch compressors + ‘laser heater’ Two transverse RF deflectors for time-resolved beam measurements X-band (12 GHz) compression linearizer 4 emittance diagnostic stations + 4 spectrometers Primary and secondary collimation sections Fixed gap, planar, 132-m undulator at 14 GeV + 1-mm res. RF BPMs Near and Far Experimental Halls + 500 m of x-ray transport
- 13. LCLS Accelerator Requiredfor SASE X-Ray FEL SLAC linac tunnel research yard Linac-0 L =6 m Linac-1 L 9 m rf -20° Linac-2 L 330 m rf -36° Linac-3 L 550 m rf 0° BC1 L 6 m R56 -45 mm BC2 L 22 m R56 -25 mm DL2 L =275 m R56 0 DL1 L 12 m R56 0 undulator L =130 m 6 MeV sz 0.6 mm s 0.05 % 135 MeV sz 0.6 mm s 0.10 % 250 MeV sz 0.10 mm s 1.3 % 4.30 GeV sz 7 mm s 0.32 % 13.6 GeV sz 7 mm s 0.01 % Linac-X L =0.6 m rf= -160 V0 = -20 MV rf gun 21-3b 24-6d X 25-1a 30-8c ...existing linac undulator Most of accelerator existed (1960’s), but new electron source, new bunch compressors, and new undulator were added Entire machine is >2000 m long 21-1 b,c,d
- 14. Gun-Solenoid Assembly Cut-awayview of gun (1.6 RF cells) New Radio Frequency Photo-Cathode Gun 10 cmD. Dowell, E. Jongewaard copper cathode Copper cathode (low QE, but stable) UV laser illumination extracts electrons Radio Frequency acc. fields (3 GHz) Accelerate before space-charge blow up Can produce very bright electron beam 3 GHz RF 120 MV/m e- UV
- 15. Injector Transverse Emittance<0.5 mm 135 MeV 0.25 nC 35 A gex 0.43 mm gey 0.46 mm D. Dowell ,et al. Exceptional beam quality from S- band Cu-cath. RF gun… Time-sliced emittance is even less: 0.4 mm
- 16. RF Photo-Cathode Gun& Spectrometer e- (6 MeV) e- focusing solenoid RF gun cathode (Cu) UV Drive Laser spectrometer dipole Q 0.25 nC frep 120 Hz Ecath 120 MV/m fRF = 2856 MHz gex,y 0.5 mm Dt 3 ps
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- 18. Need a verybright, high-energy, bunched electron beam → linear accelerator provides MUCH brighter beam than a ring Electron bunch is injected into a long undulator → an array of periodic alternating dipole magnets Stimulated emission is resonantly amplified by interaction of radiation with electron bunch What is a SASE* Free-Electron Laser (FEL)? * Self-Amplified Spontaneous Emission X-rays ~100 m
- 19. z x Due to sustainedinteraction, some electrons lose energy, while others gain energy modulation at 1 e- losing energy slow down, and e- gaining energy catch up density modulation at 1 (microbunching) Micro-bunched beam radiates coherently at 1, enhancing the process exponential growth of radiation power u e- 1 x-ray Electrons slip behind EM wave by 1 per undulator period (u) Z. Huang + - + - + - - + - + - + K/g vxEx > 0 + - Resonant Interaction of Field with Electrons E t E t vxEx > 0 vxEx > 0vxEx > 0 vxEx > 0 undulator
- 20. FEL Micro-Bunching AlongUndulator SASE* FEL starts up from noise * Self-Amplified Spontaneous Emission log (radiation power) distance electron beam undulator photon beam e-beam dump S. Reiche Electrons form micro-bunches at the radiation wavelength (~1.5 Å)
- 21. ~10 kW (beam noise) ~1MW ~0.1 GW ~10 GW SASE-FEL startup from e- beam noise BW ≈ 0.60% BW ≈ 0.15% BW ≈ 0.10% 2r ≈ BW ≈ 0.08% spiky temporal structure narrow band- width All vertical axes are log scale 70 fs 2% FEL saturation undulator distance, z (m) FELPower(W)
- 22. + - +- + - - + - + - + + - Slippage and coherence length Light overtakes e- beam by one radiation wavelength 1 per undulator period (interaction length = undulator length) z Slippage length = 1 × N undulator periods: (at 1.5 Å, LCLS slippage is: ls ≈ 1.5 fs << 100-fs pulse length) Each part of optical pulse is amplified by those electrons within a slippage length (an FEL slice) Coherence length is slippage over ~2LG (lc << ls) ML ≈ Dz/lc independent radiation sources (modes) N1 e-x-rays slippage length Dz ~1 µm
- 23. Electron Beam Requirementsfor SASE FEL eN < 1 µm at 1 Å, 15 GeV <0.04% at Ipk = 3 kA, K 3, u 3 cm, … 18LG ≈ 100 m for eN 1.5 µm Need high peak current, low emittance, and small energy spread so that the x-ray radiation power grows exponentially with undulator distance, z P(z) = P0∙exp(z/LG) FEL power reaches saturation at ~18LG SASE performance depends exponentially on e- beam quality ! (challenge) transverse emittance: (volume occupied in phase space) radiation wavelength (e.g., 1 Å) relative energy spread: peak current undulator period beta function undulator ‘field’ = 0.93∙Bu FEL gain length: FEL parameter
- 24. sz0 DE/E z sz under- compressed V = V0sin(kz) RFAccelerating Voltage Dz = R56DE/E (g >> 1) Path Length-Energy Dependent Beamline DE/E z sE/E DE/E z energy chirp over- compressed chicane Magnetic Bunch Compression Peak Current ~ q/sz
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- 26. Injector summary LCLS summary Undulatorsummary FEL power in real time Jitter summary 10/23/2016 26 MCC (Main Control Center)
- 27. Bholat@slac.stanford.edu Controls software: EPICS,Matlab, XAL, SLC legacy (SCP, Fortran) LCLS Feedback system Overview Measurements: BPMs Actuators: Xcor and Ycor Measurements: BPMs and BL monitor Actuators: RF phase and Amplitude
- 28. LCLS interface software LCLSinterface software Alarm handler propagate OOT devices
- 29. Bholat@slac.stanford.edu Operator dashboardFeedbacks summary Machineprotection and Beam Containment summary Tuning Matlab gui Beam destination Photon attenuations
- 30. Bholat@slac.stanford.edu RF Phase scans Afterphase scans, LEM (scaling the LINAC lattice) will follow •L1S phase is set at 22 degree to give the beam head and tail energy chirp. So at what phase and Amplitude of L1X does Cs=-Cx; where Cs is Beam curvature after L1S, and Cx is Beam curvature caused by L1X RF. LiTrack simulation is used, set L1X need to be almost back phase to ~- 160 degree. L1X setting
- 31. Bholat@slac.stanford.edu Emittance measurement Atdifferent part of the LCLS machine
- 32. SLAC linac tunnelresearch yard Linac-0 L =6 m Linac-1 L 9 m rf -25° Linac-2 L 330 m rf -41° Linac-3 L 550 m rf 0° BC1 L 6 m R56 -39 mm BC2 L 22 m R56 -25 mm DL2 L =275 m R56 0 DL1 L 12 m R56 0 undulator L =130 m 6 MeV sz 0.83 mm s 0.05 % 135 MeV sz 0.83 mm s 0.10 % 250 MeV sz 0.19 mm s 1.6 % 4.30 GeV sz 0.022 mm s 0.71 % 13.6 GeV sz 0.022 mm s 0.01 % Linac-X L =0.6 m rf= -160 21-1 b,c,d ...existing linac rf gun 21-3b 24-6d X 25-1a 30-8c undulator Bholat@slac.stanford.edu Injector match guiSector 21 match guiSector 28 match guiLTU match gui These match Quads talk heavily to FEL power Undulator match gui
- 33. Bholat@slac.stanford.edu Correlation GUI Most importanttuning tool for the Operators! Fast control PV Control PV Read PV list Formula for Y axis
- 34. Bholat@slac.stanford.edu Emittance tuning andMatching.. Match Quads Emittance tuning set points
- 35. Bholat@slac.stanford.edu Emittance tuning andMatching.. Match Quads Emittance tuning Quads Emittance tuning set points
- 36. Bholat@slac.stanford.edu Emittance tuning andMatching.. Li28 Match Quads Emittance tuning set point for Li28 Emittance tuning set points for Li28
- 37. Bholat@slac.stanford.edu Emittance tuning andMatching.. LTU Matching Quads FEL tuning knobs. Emittance tuning set points for LTU Emittance tuning set points
- 38. Bholat@slac.stanford.edu Emittance tuning andMatching.. Undulator match Quads FEL tuning knobs.
- 39. e- sz sy RF ‘streak’ V(t) S-band (2856 MHz) transverseRF deflector off-axis screen single-shot, absolute bunch length measurement e- Bunch Length Measured with Transverse RF Deflector Deflector used to measure: absolute bunch length, time-sliced x-emittance, time-sliced energy spread, electron arrival time jitter deflector OFF deflector ON time …one deflector at 135 MeV & another at 5 GeV
- 40. And slotted FoilControl gui Bunch length GUI Bunch length Measurement gui
- 41. P. Emma, M.Cornacchia, K. Bane, Z. Huang, H. Schlarb (DESY), G. Stupakov, D. Walz Narrow or Double X-Ray Pulses from a Slotted Foil PRL 92, 074801 (2004). time (fs) Power(GW) 0 10 5 0-150 fs 2 fs 0-6 mm 0.25 mm pulses not coherent
- 42. OTR screen inBC2 (30 cm up-beam of foil) FELX-rayPulseEnergy(mJ) Scan only the single-slot section… FEL power is proportional to slot width (short pulses?) 3-mm thick moveable Aluminum foil
- 43. Few ways tochange energy of the machine Energy ramp, Energy change and Charge change GUI Charge change gui
- 44. 132-m Long Undulatorwith 5-DOF Motion Control Girders + IN/OUT 33 undulator segments and room for a second undulator (LCLS- II) cavity beam position monitor (BPM) quadrupole magnet 3.4-m undulator magnet cam-based 5-DOF motion control slider stage hydrostatic leveling monitor support girderstretched wire system
- 45. Beam-Based Undulator Alignment Measureundulator trajectory at 4 energies (4, 7, 9, & 14 GeV) Scale all upstream magnets each time Do not change anything in the undulator Calculate quadrupole and BPM alignment… (Matlab GUI) Move quads and adjust BPM offsets for dispersion free trajectory Iterate… RESULT: vary energy by factor of 3 trajectory changes by <10 mm H. Loos
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- 47. Also monitor and calibrate gasdetector readings vary FEL power with oscillations & record e- energy loss 1.5 Å FEL e- Energy-Loss Shows >2 mJ per X-ray Pulse Horizontal Dog-Leg BPMs Dumpline BPMs Vertical Bend 10 MeV/e- (2.4 mJ) ~100 meters initial DEi final DEf DE = DEf - DEi
- 48. FELON Electron Energy Loss& Spread Induced by FEL Gain 4.3 GeV, r = 15 Å, Ipk = 500 A FEL OFFFEL ON suppress FEL with oscillationallow FEL with straight orbit FELOFF 0.05% 50MeV Undulator, Dump-Line, and Screen 10 MeV loss/e- 2.6 mJ @ 830 eV
- 49. Bholat@slac.stanford.edu Gain Length measurementGUI Move horizontal correctors in front of each undulators.
- 50. Undulator Gain LengthMeasurement at 1.5 Å gex,y = 0.4 mm (slice) Ipk = 3.0 kA sE/E = 0.01% (slice) (25 of 33 undulators installed) Lg = 3.3 m Saturation length of 60 m in 112-m und.
- 51. <1 mm UndulatorQuadrupole Remote Position Control ±4 mm 3-parameter fit to 20 BPMs along undulator (y0, y0, and Dy) Dy = 30 nrad kick due to quad (y0, y0) 0.7 mm backlash <0.5 µm res.
- 52. Undulator Alignment Diagnostics(Stretched Wires & Hydraulic Levels) Girder Numbers 6 -6 -4 -2 0 2 4 x[microns] 0 5 10 15 20 25 30 35 Calculated orbit change Measured und. & quad moves H.-D. Nuhn, THOA02 undulator alignment drift over 3 days
- 53. Undulator Taper ControlGui. Bholat@slac.stanford.edu Taper control options, Set e- beam parameter
- 54. Undulator Taper morethan Doubles Power 1% 1.5 Å 5-mrad pole cant angle unmeasured range (>5 mm) measured range (|x| 5 mm) Wake (3 kA) 40 MeV Spont. (13.6 GeV) 20 MeV Post Sat. Taper 70 MeV H.-D. Nuhn, THOA02
- 55. FEL Energy (YAG) FEL-induced EnergyLoss (BPMs) ~100 meters 4.6 MeV Vary the FEL power and record e- energy loss Total x-ray screen signal vs. undulator K-taper (yaw) 4.6 MeV at 0.25 nC = 1.1 mJ or 0.8×1012 photons/pulse (15 GW at 75-fs FWHM pulse length) 1.5 Å Dumpline BPMs Undulator ‘Taper Scan’ Shows 1.1 mJ per X-ray Pulse Dog-Leg BPMs
- 56. FEL Intensity Jitter9.6% rms at 1.5 Å over >1 hr 1.87 ± 0.18 mJ 30 Hz beam rate, 5 Hz sample rate, 10000 data points, SASE saturation klystrontrips > 1 hr
- 57. LCLS Parameter Changes MachinePulse Rate (1, 10, 30, 60, 120 Hz & one-shot)* changed in seconds with one button push. Wavelength (25 - 1.2 Å) changed in 5-60 minutes. Pulse Energy (0 - 4 mJ) easily lowered, but may take 1-2 hrs to achieve >2.5 mJ (depends on wavelength, etc). Pulse Length (60 - 500 fs FWHM – for soft x-rays) easily changed in 1 minute (closed loop control). Peak FEL Power (0 - 40 GW) set by pulse length (increases with peak current – see next slide). Ultra-Short Pulse Length (<10 fs FWHM?) 20 pC - requires 1-2 hours to establish (starting from nominal 250-pC conditions). * Single shot and burst mode can be control by the users
- 58. Pulse Length EasilyAdjusted (500-60 fs)* X-Ray Pulse Energy vs. Pulse Length (2.5 – 3.8 mJ) e- Peak Current vs. Pulse Length (500-4000 A) Peak FEL Power vs. Pulse Length (5-40 GW) e- bunch length is quickly adjustable (<1 min) from 60 to 500 fs (hard x-rays: 60 to 100 fs) 1.7 keV, 250 pC, 23 of 33 undulators inserted * for soft x-rays (0.5-2 keV)
- 59. Conclusions. • Routine tuningcan be and is done during beam “delivery”. User’s consent usually required. • Energy changes take away from “delivery” time. Smaller energy changes are accomplished by Energy ramp gui. Larger energy change require multiple steps, Load known good configuration close to desired energy. Activate Klystrons on the beam to match the configuration energy. LEM (scale LINAC lattice) Run energy ramp gui to get to the desired energy. Bholat@slac.stanford.edu
- 60. Conclusions. Steer to “gold”orbit. Standardize all the bend magnets • Known problems: Correctors don’t scale properly. Muon Shield wall generate multipole fields. BX01/BX02 correctors. 50B1 degauss. A4 BSY correctors remnant fields. Bholat@slac.stanford.edu
- 61. Conclusions. • One wayto speed up large energy change would be to establish every 500MeV “safe zone” configuration file during Machine Development (MD) • Going to low charge ultra short pulse take away time from delivery. There are many steps involved, some are automated others can’t be automated. (1-2hrs) • There is an ongoing effort to create new tools to configure LCLS machine efficiently and repeatable manner so as to satisfy user requirements. Bholat@slac.stanford.edu
- 62. Acknowledgements R.Akre, A.Brachmann,FJ. Decker,D. Dowell, P.Emma, S. Giliveich, Z. Huang, S.Khan, H. Loos, A.Novohatsky, HD. Nuhn, H.Smith, M.Stanek, S. Tantawi, S. Weathersby, and ALL THE OPERATORS. Bholat@slac.stanford.edu
- 63. Thank you foryour attention. bholat@slac.stanford.edu END
- 64. More slides • FELSummary • LASER Heater • LCLS II Bholat@slac.stanford.edu
- 65. SASE 1D Summary Radiationwavelength: Power gain length: Exponential growth: P(z) = P0 exp(z/LG) Startup noise power: P0 ≈ Kr2gmc3/1 (spontaneous radiation in two gain lengths) Saturation power: Psat ≈ r × e-beam power Saturation length: Lsat ≈ u/r ≈ 18LG FWHM bandwidth at saturation: ≈ 2r Coherence length at saturation: lc ≈ 1/(2pr) Z. Huang 3 m 2 kW 20 GW 60 m 0.1% 0.3 fs 1.5 Å -
- 66. EM radiation (radiowaves) is produced by electrons running up and down the antenna wire… If we accelerate the electrons to near light speed we get a Doppler shift producing x-rays (instead of radio waves), where here the up and down electron motion is caused by the FEL wiggler magnets. 1-Å Wavelengths? Doppler Shifted Radiation accelerator /g 2 Huge boost from high energy, E = gmc2
- 67. Micro-bunching Instability (canruin e- beam) Initial e- bunch current modulation induces energy modulation through impedance, Z(), converted to more current modulation by bunch compressor, R56 growth of slice energy spread (and emittance) time projection t t gain = 10 R56 Current t Energy t 1% 10%initial current modulation energy modulation more bunching amplified bunching Z. Huang Z() impedance FEL-like effect
- 68. Laser Heater SpatialAlignment e- IR Calculate and re-align laserpoor heating? good heating One button click (~1 minute) time energy After three iterations Dave is smilingP. Emma H. Loos
- 69. Micro-Bunching on LCLSElectron Beam (measurements with and without laser heater) Heater ONHeater OFF m-bunching on dump screen (after FEL) in over- compressionbunch length Heater’s energy spread Landau-damps micro-bunching before it can degrade the electron beam brightness (better FEL performance)
- 70. undulator X L1 L2 L3BC1BC2 LCLS-II - Second Injector/Linac RF gun-1 L0 3-15 GeV sector-11 sector-21 sector-24sector-14 existing und-hall L3 HXR4-14 GeV bypass line 4-14 GeV X RF gun-2 L1 L2BC1 BC2 L0 FACET wall Second injector & linac allows 2 independent FELs serving 2+ experiments simultaneously with completely flexible param’s (plus 1-km linac remains). New hard X-ray FEL with ~2 – 13 keV photons (+ self-seeding?) SXR New soft X-ray FEL with ~0.24 – 2 keV photons Just one step on the way to “LCLS-2025” with ~10 x-ray beamlines… one more km of linac