The The LCLSLCLS--II II DesignDesign(and other Horror Stories)(and other Horror Stories)(and other Horror Stories)(and other Horror Stories)

Paul Emma et al.May 5, 2011

LCLS Operations Meeting

γεγεγεγεx,y ≈≈≈≈ 0.4 µµµµm (slice)Ipk ≈≈≈≈ 3.0 kAσσσσE/E ≈≈≈≈ 0.01% (slice)

April 2009(25 of 33 undulators)

L ≈≈≈≈ 3.3 m

Saturation at 60 m (design was 90 m)

LCLS Achieves FEL Saturation at 1.5ALCLS Achieves FEL Saturation at 1.5A

Lg ≈≈≈≈ 3.3 m

Slide 2

LCLS AchievementsLCLS Achievements

Exceptional e−−−− beam quality from RF gun (γεγεγεγεx,y ≈≈≈≈ 0.4 µm)

Pulse length easily adjustable for users (60 - 500 fs FWHM)

Low-charge mode (20 pC) allows <5 fs pulses (~0.15 mJ)

Wider photon energy range: 480 - 10000 eV (design was: 830 - 8300 eV)

Peak FEL power >70 GW (design was 15 GW)

Pulse energy up to 4 mJ (3.7 mJ with 150 pC @ 9.4 keV)

Slotted foil produces 5-fs pulses, or double pulses

96.7% accelerator availability, 94.8% photon availability

Slide 3

Machine Requirements for LCLSMachine Requirements for LCLS--IIII

Build two adjacent, adjustable-gap, SASE-FEL undulators (HXR & SXR) in a new tunnelPhoton energy range: SXR: 0.25-2 keV, HXR: 2-13 keV

LCLSLCLS--I works quite well.I works quite well.

Don’t change too much!Don’t change too much!

Reserve space for seeding, polarization control, taper…Provide up to 14 GeV electron energy at 3 kAPulse repetition rate: 120 Hz (one e−−−− bunch per RF pulse)Bunch charge 0.01-1.0 nC (0.25 nC nominal)

Slide 4

Differences with respect to LCLSDifferences with respect to LCLS--II

Two adjacent, adjustable gap FEL undulators (hard & soft x-rays) in new tunnel1200-m bypass line to deliver e−−−− around existing LCLS-I

New horizontal bend system (2.4°) diverts e- into new undulator hallTransport line is split with pulsed bend in order to feed two Transport line is split with pulsed bend in order to feed two parallel undulators at 60 Hz each (2.5 meters apart)Two separate electron beam dumps and front ends (FE’s) neededFour fewer klystrons available than in LCLS-I (slightly lower energy )Many smaller differences, such as fewer OTR screens, soft bends in e−−−− dump, etc – see later slides

Slide 5

LCLSLCLS--II Machine LayoutII Machine Layout

LCLS-IXXXX

L1L1 L2L2 L3L3BC1BC1 BC2BC2

RFgun-1

RFgun-1

L0L0

3-15 GeV3-15 GeV

existingexisting und-hall-1und-hall-1

LCLSLCLS--II

L3L3′′

RFRFgungun--22

L1L1′′ L2L2′′BC1BC1′′ BC2BC2′′

L0L0′′

one more one more km of linackm of linac

44--14 14 GeV bypass GeV bypass lineline

XX

LCLS-II

SectorSector--20 wall20 wall

Use same injector design at sector-10 (1 km upstream)Two new bunch compressors and 4-14 GeV linac (~1 km)1200-m long bypass (old PEP-II 9-GeV line) goes around LCLS-I

Slide 6

HXRHXR44--14 14 GeV bypass GeV bypass lineline

SXRSXR

undund--hallhall--22undund--hallhall--22

LCLSLCLS--II Accelerator ParametersII Accelerator Parameters

Parameter symbol nominal range unit

Electron energy Ef 13.5 4.2 - 14 GeV

Electron bunch charge Q 0.25 0.01 - 1.0 nC

Pulse repetition rate f 120 SS*, 1 - 120 Hz

Transverse slice emittance γεx,y 0.6** 0.1 - 1.2 µm

Peak current Ipk 3.0 0.5 - 5.0 kA

Slide 7

Peak current Ipk 3.0 0.5 - 5.0 kA

Slice energy spread (rms) σE 1.4 0.1 - 1.5 MeV

* “SS” = single shot on demand

** Note that LCLS-I slice emittance is 0.4 µm at best, but we design somewhat conservatively for a 0.6-µm level (at 0.25 nC).

Inside Linac Tunnel - Looking Downstream

47”47”120”120” LINACLINAC

25.610”25.610”

25.570”25.570”

99--GeV (PEPGeV (PEP--II)II)17”17” 33--GeVGeV

(PEP(PEP--II)II)

Use existing PEP-II bypass line on linac tunnel ceiling(FODO cells with one quad every 101.6 m)

Slide 8DOE CD-1 Review of the LCLS-II Project, April 26-28, 2011

66”66”

132”132”

((IDID--344344--013013--30)30)

Moves LCLS-II 25.57” higher than LCLS-I

Existing Bypass Line in Linac Tunnel

LCLSLCLS--II bypass lineII bypass line

Slide 9

LCLS-II Bypass Line

∆x = 25.6”

PLAN VIEWNN

17-m thick µ-plug wall

LCLS-I

LCLS-II

Slide 10DOE CD-1 Review of the LCLS-II Project, April 26-28, 2011

ELEVATION VIEW

NNLinacSector 20-5

∆y = 25.6”

LCLS-I

LCLS-II

LCLS-II Layout After Linac

LTUHLTUH (LCLS(LCLS--II)II)LCLSLCLS--II (approx.)(approx.)

Slide 11DOE CD-1 Review of the LCLS-II Project, April 26-28, 2011

LTUSLTUS (LCLS(LCLS--II)II)pulsed bendpulsed bend

2.42.4--deg bends (4)deg bends (4)

Head-House Port (South Side)

LCLSLCLS--IIII--HHLCLSLCLS--IIII--SS

LCLSLCLS--II

Wall face at Z’(LCLS) = 346.24 m

LCLSLCLS--IIX’X’ = = --1.25 m1.25 mY’Y’ = = --0.90 m0.90 m

LCLS-II Line Fits Close to LCLS-I in BTH

LCLSLCLS--IIII

Slide 13DOE CD-1 Review of the LCLS-II Project, April 26-28, 2011

LCLSLCLS--II

LCLSLCLS--II Beam Transport LayoutII Beam Transport Layout

LCLSLCLS--IILCLSLCLS--II FEE1LTU1

Undulator Hall, LCLS-I

e− dump

LINAC

Exp. Hall

Slide 14

2.4°Exp. Hall

LCLS-II BTH (3D view)

Armin Busse

120-Hz Switching from HXR to SXR

kicker(-0.13 mrad)

Lambertsonentrance face

←←←←Kicked y-orbit for transport to SXR

Required kicker stability ~0.01%

Slide 16DOE CD-1 Review of the LCLS-II Project, April 26-28, 2011

Existing Lambertson Septum →→→→

−−−−7.1 mm

vertical trajectory after kicker

LCLSLCLS--II Accelerator for 250 pC, 120 HzII Accelerator for 250 pC, 120 Hz

Linac-0’L ≈ 6 m

Linac-1’L ≈ 9 m

ϕrf ≈ −20°

Linac-2’L ≈ 326 m

ϕrf ≈ −32°

Linac-3’L ≈ 582 m

ϕrf ≈ 0°

undulatorsL ≈ 120 m

6 MeV

σz ≈ 0.62 mm

σδ ≈ 0.05 %

135 MeV

σz ≈ 0.62 mm

σδ ≈ 0.07 %

250 MeV

σz ≈ 0.13 mm

σδ ≈ 1.1 %

4.2 GeV

σz ≈ 7 µm

σδ ≈ 0.43 %

13.5 GeV

σz ≈ 7 µm

σδ ≈ 0.01 %

Linac-X’L ≈ 0.6 m

ϕrf ≈ −160°V0 ≈ −19 MV

SXR

1-km bypass

line2-13 keVrf

gun HXR

Slide 17

SLAC linac tunnelSLAC linac tunnel BTH & UBTH & U--HallHall

ϕrf ≈ −20° ϕrf ≈ −32° ϕrf ≈ 0°

BC1’L ≈ 6.5 m

R56≈ −46 mm

BC2’L ≈ 23 m

R56≈ −29 mm

DL1’L ≈12 m

R56 ≈ 6.3 mm

11-3b14-4dX11-1

b,c,d...existing

linac14-7b20-4d

LCLS-I

LCLS-I

0.24-2 keV

0.5-10 keV

Injector, linac, and compression parameters are all very similar to LCLS-I, but not exact

StartStart--22--End Tracking with LCLSEnd Tracking with LCLS--II OpticsII Optics

BC1 BC2

bypass line2.4°

bends

Slide 18

HXR und.

SXR not shown

LCLSLCLS--II Longitudinal Phase Space (w/ CSR)II Longitudinal Phase Space (w/ CSR)

Output from Parmela at135 MeV

35 A35 A250 pC

Slide 19

Elegant output at 13.5 GeV (HXR start)

3 kA3 kA…with CSR

0.01% rms

RF Stations & Spares for LCLS-II

Slide 20DOE CD-1 Review of the LCLS-II Project, April 26-28, 2011

Two spare klystrons in L2-linac with worst case -40° phase (nominal is 32°) and 3 spares in L3-linac (plus feedback over-head) – assumes 18.5 MV/m

LCLSLCLS--II: Hard and Soft XII: Hard and Soft X--Ray SASERay SASE

FEE

LCLSLCLS--II (112 m)(112 m)0.5 0.5 -- 10 10 keVkeV

Existing Tunnel

SectorSector--20 20 gun; 3.4 gun; 3.4 -- 15 GeV15 GeV

DMP

gap = 6.8 mm (K = 3.5)

Slide 21

FEE2 2 -- 13 13 keVkeV

New Tunnel

0.25 0.25 -- 2 2 keVkeVSectorSector--10 10 gun; 4.2 gun; 4.2 -- 13.513.5--GeVGeV

DMP

LCLSLCLS--IIII HXRHXR variable gap (109 m)variable gap (109 m)

reserved for self-seeding (95 m)

reservedfor power

taper space reserved forpolarization control

gap : 7.2 - 20.4 mm (K = 0.8 - 3.8)

gap : 7.2 - 35.5 mm (K = 1.2 - 9.9)

2.5 m

The concept of the LCLS-II undulator design is takenFrom the European XFEL.

SXR and HXR undulators will only

LCLSLCLS--II Undulators Based on EuroII Undulators Based on Euro--XFELXFEL

undulators will only differ in their magnetic arrays

H.-D. Nuhn

LCLSLCLS--II AdjustableII Adjustable--Gap UndulatorsGap UndulatorsH.-D. Nuhn

+=

21

2

2

2

Kur γ

λλ

Schematic layout of two individual undulator segmen ts and intermediate break sections for the HXR and SXR undulators.

phase shifter is a small 3-dipole chicane

LCLSLCLS--II Undulators are Much LargerII Undulators are Much Larger

Components OverviewComponents OverviewUndulator System, PreliminaryUndulator System, Preliminary

Vacuum Chamber & Strongback

Beam

Undulator Interspace ComponentsUndulator Interspace Components

PedestalVacuum Chamber Strongback

W. Olson

XX--ray Transport to Experimental Hallray Transport to Experimental Hall--22

Slide 26J. WelchJ. Welch

LCLSLCLS--II FEL Operational RangesII FEL Operational Ranges

Slide 27

both undulators always have same e− energy

H.H.--D. NuhnD. Nuhn

LCLSLCLS--IIII Electron Beam DiagnosticsElectron Beam Diagnostics

L1L1L1L1 L2L2L2L2 L3L3L3L3µµ

BC2BC1

YAG screensYAG screensOTR screensOTR screensWire Wire scannersscannersBunch length Bunch length monmon..

gun

DL1 DL211-3 to 14-4 14-7 to 20-4

11-1ε ε ε

ε ε

εσδ

σδ σδ

σδ

σδ

σδ

σδ

σδ

σz σzσz

2 Transverse RF cavities (135 2 Transverse RF cavities (135 MeVMeV & 5 & 5 GeVGeV))6 6 YAG YAG screensscreens8 OTR screens8 OTR screens19 wire scanners (each with 19 wire scanners (each with xx & & yy wires)wires)3 bunch length monitors3 bunch length monitorsGun spectrometer, injector spectrometer, dump spectrometerGun spectrometer, injector spectrometer, dump spectrometerBC1 stopper, abort kicker, BSY stopper, undulator stoppersBC1 stopper, abort kicker, BSY stopper, undulator stoppers

σδ

Removed and Added Components Removed and Added Components wrtwrt LCLSLCLS--II

No YAG01 (ion pump instead)No YAG01 (ion pump instead)

No QG02 or QG03 (gun No QG02 or QG03 (gun spectspect. quads) & no XCG1,2, YCG2, BPMG1. quads) & no XCG1,2, YCG2, BPMG1

No SOL2 (not useful)No SOL2 (not useful)

No XC03/YC03 (offline)No XC03/YC03 (offline)

No OTR1, OTR3, or WS01, WS03 (only OTR2 & WS02)No OTR1, OTR3, or WS01, WS03 (only OTR2 & WS02)

No WS04 (not used)No WS04 (not used)

No WS11 or WS13 (only WS12)No WS11 or WS13 (only WS12)

No YAG03 (between L0a & L0b No YAG03 (between L0a & L0b –– not used)not used)

Ion pumps on L0a/b, L1S loadsIon pumps on L0a/b, L1S loads

New New pyropyro--based bunch length based bunch length monmon. in LTU2 bends?. in LTU2 bends?

Improved mirror control on heater IR beam steeringImproved mirror control on heater IR beam steering

Improved VCC?Improved VCC?

4 new wire scanners in sec4 new wire scanners in sec--14 (before BC2’)14 (before BC2’)

4 new wire scanners in bypass line (old PEP4 new wire scanners in bypass line (old PEP--II 9II 9--GeV line)GeV line)

BYKIK’ and TDKIK’ moved to BSY (near new D2’, ST60’, and ST61’)BYKIK’ and TDKIK’ moved to BSY (near new D2’, ST60’, and ST61’)

Slide 29

New Features New Features wrtwrt LCLSLCLS--II

2 new 2 new xx and 2 new and 2 new yy adjustable collimator jaw pairs in bypass lineadjustable collimator jaw pairs in bypass line

YY--kicker + HLAM kicker + HLAM magnets magnets in BTHin BTH to split beam into HXR & SXR @ 60 Hz eachto split beam into HXR & SXR @ 60 Hz each

LTUH line has 4 LTULTUH line has 4 LTU--like wirelike wire--scannersscanners and 2/2 final and 2/2 final xx//yy collimatorscollimators

LTUS line has 3 BC1LTUS line has 3 BC1--like wirelike wire--scanners and 2/2 final scanners and 2/2 final xx//yy collimatorscollimators

Each undulator line has anEach undulator line has an insertable stopper (TDUNDH & TDUNDS)insertable stopper (TDUNDH & TDUNDS)

Future selfFuture self--seeding sections leads each new undulator (30seeding sections leads each new undulator (30--100 m)100 m)

Two separate electronTwo separate electron beam dumpsbeam dumps

Soft bends start each dump bend (no Be foil needed?)Soft bends start each dump bend (no Be foil needed?)

Two separate xTwo separate x--ray frontray front--ends (diagnostics ends (diagnostics –– J. Welch, P. J. Welch, P. HeimannHeimann, J. Frisch), J. Frisch)

SummarySummary

LCLSLCLS--II accelerator and FEL design is reasonably well II accelerator and FEL design is reasonably well advancedadvanced

Design is closely based on very successful LCLSDesign is closely based on very successful LCLS--II

Automated commissioning and operations software already Automated commissioning and operations software already being extendedbeing extendedbeing extendedbeing extended

Many details to finish (power supply specs, dump design, Many details to finish (power supply specs, dump design, steering simulations, etc)steering simulations, etc)

Slide 31