1. LCLS Commissioning: Results & Plans P
LCLS Commissioning: Results & Plans P. Emma, for the LCLS Commissioning Team DOE Status Meeting for the LCLS May 13, 2008
LCLS
Phys. Rev. publication:

2. LCLS Accelerator Layout
6 MeV
z  0.83 mm
  0.05 %
135 MeV
z  0.83 mm
  0.10 %
250 MeV
z  0.19 mm
  1.6 %
4.30 GeV
z  mm
  0.71 %
13.6 GeV
z  mm
  0.01 %
beam parked here
Linac-X
L =0.6 m
rf= -160
Linac-0
L =6 m rf
gun
L0-a,b
Linac-1
L 9 m
rf  -25°
Linac-2
L 330 m
rf  -41°
Linac-3
L 550 m
rf  0°
25-1a
30-8c
...existing
linac
21-3b
24-6d
21-1
b,c,d
undulator
L =130 m X
BC1
L 6 m
R56 -39 mm
BC2
L 22 m
R56 -25 mm
DL1
L 12 m
R56 0
DL2
L =275 m
R56  0
Injector Commissioned (‘07)
Commissioned in Jan. 2008
SLAC linac tunnel
research yard

3. LCLS Injector Layout Commissioned in ‘07 6 MeV 135 MeV 250 MeV
OTR screens (7)
YAG screens (7)
Wire scanners (7)
RF Gun
Dipole magnets (8)
Commissioned in ‘07
Solenoid
Beam stoppers (2)
S-band RF acc. sections (5)
L0a
Gun
Spectrometer
L0b
Emittance
Screens/Wires
Emittance
Screen/Wires RF
Deflector
2-km point in 3-km SLAC linac
L1S
X-band RF
acc. section
135-MeV
Spectrometer
BC1
TD11
stopper
135 MeV
250 MeV

4. LCLS BC2 Area Layout (sector 24/25)
OTR screens (3)
Collimator jaws (2
Phase monitor cavity (1)
New installation in fall ‘07
Dipole magnets (4)
Kicker magnet (1)
Transverse RF deflector (1)
S-band RF acc. sections
4 wire-scanners “de-scoped”
4 wire-scanners in sec-28
(300 m downstream)
CE21
BPMS21
OTR21
PH03
BXKIK
BC2
TCAV3
(25-2d)
OTR22
(25-3d)
OTR_TCAV
(25-9)
(not to scale)
4.3 GeV

5. Commissioning Highlights
Injector commissioning: April through August, 2007 (DONE)
Phase-II commissioning: Dec.  Complete 3/31/08 (BC2 + Linac)
Up to 1 nC of bunch charge now available (0.25 nC used)
Great laser uptime (99%) and good performance (again)
Emittances 1 mm after BC1 at 1 nC, 250 MeV (fairly routine)
Routine e- to 14 GeV (24/7 except Wed., ~90% up-time)
BC1 dipoles & chicane motion fixed!
No emittance growth in X-band RF cavity when best steered
BC2 compression demonstrated (no dipole field quality issues)
Long transverse RF deflector at 5 GeV fully operational
CSR effects measured in BC1 & BC2 – agree with codes so far
Many beam & RF feedback systems running well
Coherent OTR observed – compromises nearly all screen data
Gun RF probes changed in April ’08 (allows 120-Hz – D. Dowell)
More physicists involved in commissioning in 2008 (8  15)

6. Design and Typical Measured Parameters

7. “Problems/Issues” from July ‘07 DOE Review
Gun Faraday cup broken
Gun toroid shorted during installation
Some YAG screens not installed properly
BC1 motion control limited (300 mm  260 mm)
Cathode QE about 5-times lower than design
Some controls tools late (orbit displays, fitting, magnet control & alarms)
MCOR power supply ADC readback noise (fixed)
Laser phase drift and lock trouble until mid-June
ALL FIXED

8. Pre-Beam Check List for BC2/Linac
17 pages, 800 checks - all DONE
polarity
checks
DONE
installation
orientation
controls check
component bar codes
etc.
etc.

9. Laser Spatial and Temporal Shaping
2R = 1.4 mm
2008
2007
7.2 ps
6.9 ps
2008
7.2 ps
2007
Spatial shape on cathode using iris
Temporal shape (6.9 ps FWHM)
S. Gilevich, G. Hays, P. Hering, A. Miahnahri, W. White
99% Drive Laser up time!

10. Powerful Scanning/Correlation Application
Watch profiles as scan proceeds
H. Loos
Quickly minimize emittance by scanning any parameter

11. b-Matching GUI in Matlab Soon to be extended for undulator matching…
C. Limborg
before
xx = 1.08
sets quads
after
xx = 1.00
reads meas’d b & a
Soon to be extended for undulator matching…

12. Projected Emittance <1.2 μm at 1 nC (135 MeV)
s = 60 μm
gex = 1.07 μm
meets
injector
goals
gey = 1.11 μm

13. Injector Emittance Measured Over 3 Days (0.25 nC)
OTR screen at 135 MeV
gex = 0.91, gey = 1.01
gex
injector is stable
gey
wire-scanner at 250 MeV after BC1
gex = 0.83, gey = 0.83
J. Welch

14. Laser & Electron-Based Feedback Systems
Transverse Loops:
Laser spot on cathode (2)
Gun launch angle
Injector trajectory
X-band cavity position
Linac trajectory (2 old)
Undulator traj. (future)
Longitudinal Loops:
DL1 energy
BC1 energy
BC1 bunch length
BC2 energy
BC2 bunch length
Final energy (old loop)
now
running
Laser
(bunch length feedback still needs work)
BPMs
CSR detectors
Steering Loop
sz1
sz2 V0
gun d0 d3 d1 d2 L0 1 V1 2 V2 V3
D. Fairley J. Wu
J. Frisch L1 X L2 L3
DL1
BC1
BC2
DL2

15. BC1 Dipole Field Quality Fixed
Poles were milled off and wider poles were bolted on and then the fields were shimmed.
Nov. ‘07
fixed
Sext.
tolerance
Aug. ‘07
±3s beam
J. Welch, S. DeBarger, N. Li, et al.

16. BC1 Dispersion Measurement & Correction
Dex/e0 < 1%
Dey/e0  3%
hx = mm
hx = mrad
hy = 1.62 mm
hy = mrad
gex = 0.88 mm
No more BC1 emittance growth
Vary energy before BC1 and read BPMs after BC1  h, h
Dex/e0 (2nd-order) < 5%
Dex/e0 (1st-order) < 1%

17. BC2 Dipole Field Quality OK
Beam energy scans confirm BC2 dipole field quality meets requirements
No measurable quad field and
sextupole is just at tolerance
±3s beam OK

18. Operating Point Summary Display
Shows operators the main machine parameter targets and their present settings
&
includes save/restore files
H.-D. Nuhn

19. A Phase shift of -0.4 deg is added to the Elegant curves
Bunch length after BC1 measured with transverse RF
BPM-Measured CSR Energy Loss in BC1 at 0.25 nC (compares well with tracking)
BC2
OFF
BSY
(14 GeV)
TCAV
(5.0 GeV)
BC1
(250 MeV)
L1S
BPM e-
Elegant
CSR energy loss after BC1 measured with BPM
A Phase shift of -0.4 deg is added to the Elegant curves
Y. Ding, Z. Huang
operating
point g
Chicane Bend
BPM

20. Hor. CSR Emittance Growth after BC1 (250 MeV, 0.25 nC)
j = -22º
sx = 38 mm
sx = 55 mm
j = -26º
sx = 246 mm
j = -27º
Vertical emittance after BC1 is almost unaffected
Y. Ding, Z. Huang
Elegant
Horizontal emittance after BC1 vs. RF phase
Elegant
Meas-1
Meas-2
Data also exists at 1 nC and BC2 data (0.25 nC) also shows decent results
Elegant
operating
point

21. RF Phase and Amplitude Stability (e.g., L0a)
New inj. RF systems meet jitter tolerances
0.05% rms (<0.07%)
RF Feedback Running
20-second sample at 10 Hz
0.05º rms (<0.07º)
R. Akre,
D. Kotturi,
J. Craft,
V. Pacak, et al.

22. Stability is not so far off of our goals (~10%)
Normalized phase space centroid jitter after BC1 (~5% of rms beam size)
RMS AyN = 4.1%
RMS AxN = 4.9%
Stability is not so far off of our goals (~10%)
1-s beam size
D. Ratner
… near end of linac (~15% of rms beam size, but sometimes larger)
poor BPM resolution
RMS AxN = 19.9%
RMS AyN = 8.5%
Thanks to Controls group for new BPM electronics!
Q = 0.25 nC
DE/E jitter < 0.1%
DQ/Q jitter < 2%

23. Chicane length 24 m, 4.3 GeV, 2º bends
BC2 Chicane in the Linac at 4.3 GeV
Bob
Fuller
Chicane length 24 m, 4.3 GeV, 2º bends

24. old screen used – poor res.
Bunch Compression Measured after BC2 (0.25 nC)
Bunch length after BC2 measured with transverse RF
-2º shift applied to simulation
sz  10 mm
sz < 10 mm
old screen used – poor res.
sz > 25 mm
BC2
(4.3 GeV)
BSY
(14 GeV)
TCAV
(5.0 GeV)
550 m L2

25. Longitudinal Phase Space at 14 GeV
PR55
LiTrack
simulation
Bunch is Over-Compressed
L2 phase = -41 deg
Chirp knob = -450 MeV
measurement
Vertical scale only approx.
PR55
Bunch is Under-Compressed
L2 phase = -41 deg
Chirp knob = +450 MeV
LiTrack
simulation
Vertical scale only approx.
measurement
older screen has poor resolution

26. Results still variable – requires careful work
Emittance Measurements at End of Linac Using Wire Scanners
sx = 76 mm
sx = 38 mm
sx = 49 mm
sx = 47 mm
wire scans
F.-J. Decker
R. Iverson
Emittance measured 300 m after BC2 at 10 GeV with 10 mm bunch length
gey = 0.9 mm
Q = 0.25 nC
Results still variable – requires careful work

27. Poor Beam Conditions Also Arise…
bad X-profile at end of linac
Possibly the L2 phase drifted into a strong CSR regime – bunch length feedback not running
gex = 5.5 mm
Q = 0.25 nC

28. Emittance Near End of Linac Over a Weekend
gex
gey
Emittance near end of linac during weekend run at nC, with no tuning
gey stayed at ~1 mm for the next 3+ days

29. DONE DONE DONE DONE DONE DONE 2008 Commissioning Goals
DONE
DONE
DONE
DONE
DONE

30. LCLS Installation and Commissioning Time-Line
First Light
in FEE
First Light
in FEH
LTU/Und/Dump Install
PPS Cert. LTU/Dump
Und. Seg. Install
FEE/NEH Install
X-Rays in NEH
FEH Hutch BO
CD-4 (7/31/2010)
PEP-II run ends
FEH Install
now J F M A M J J A A S O N D J F M A A M M J J A S O N D J F M A M J J
Down
PPS
Linac/BC2 Commissioning
Re-commission Inj/BC2 to SL2
LTU/Und
Comm.
FEE
Comm.
NEH Operations/ Commissioning
May 2, 2008

31. LTU/Undulator/FEE/FEL Commissioning
H. Tompkins
See break-out presentations:
LTU & Undulator Commissioning Plans (H.-D. Nuhn)
FEL/FEE Overview Commissioning Plans (H. Tompkins)
FEE Diagnostics & Commissioning (R. Bionta)

32. Problems/Issues
End-of-linac x-emittance difficult to minimize and maintain, especially at 1 nC (needs more work – m-bunching?)
Some wire-scanner vibration issues (~fixed in April ‘08)
Most OTR screens are unusable due to COTR (laser heater should solve this in FY2009)
Most linac BPMs need upgrade – 16 of 83 done with great resolution improvement (on AIP list)
BC2 bunch length monitor noisy or real jitter – (need beam synchronous acquisition for RF & BPMs or m-bunching?)
Bunch length feedback loops need more wring-out (need more time + less noisy monitor)

33. Summary Drive laser very reliable – performs well (great team)
Injector in very good shape – runs well after setup
Many measurements made – getting to know machine
Emittances at end of linac difficult to tune and maintain, but nice results are possible with effort (gey is maybe there?)
We look forward to next phase (LTU, undulator, FEL, …) –preparations have begun (plans, software, checkout, …)
Thanks to dedicated Commissioning Team + Controls, RF, Engineering, Operations, ASD, maintenance, etc

34. DONE

35. m-Bunching in BC2 May Blow up X-Emittance
OTR screen in BC2
OTR21
gex,y measured with wire-scanners 500-m downbeam of BC2
gex
gey

36. COTR After BC2 OTR screen just after BC2 OTR22 OTR22
with BC2 screen inserted
(smoothes m-bunching)
with BC2 screen OUT
(m-bunching present – COTR!)

37. FY2009 Commissioning Activities
Pre-Beam Checkout (Nov-Dec ‘08) – check-list in prep.
Re-establish injector & linac beam quality (Nov-Dec ‘08) – have experience
First LTU Commissioning with beam (Jan-Mar ‘09) – lots of time
‘Undulator’/Dump Comm. without undulators (Jan-Mar ‘09)
Calibrate & commission: RF BPMs, Loss Monitors, BFWs, ADS
BBA algorithm testing (without segments)
Install undulator segments (Mar ’09, two wks) – optimize linac again
First Undulator Segments Commissioning (Mar-Apr ‘09)
Care with first transport to minimize radiation on segments
Full alignment process (BBA, BFW’s)
Commission FEE Diagnostics (Apr-Jun ‘09)
Direct Imager, Calorimeter, Slit, Solid Attenuator, Gas Attenuator, Gas Detector
Beam-Based K Measurement Components
Optimization & characterization of SASE (Jun-Jul ‘09)
Optimize linac beam quality (adjust compression, emittance tuning, BBA)
Measure gain length