1. LCLS Injector Commissioning P
LCLS Injector Commissioning P. Emma, for the LCLS Commissioning Team LCLS DOE Review July 10, 2007
LCLS

2. LCLS Injector Layout 6 MeV 135 MeV 250 MeV OTR screens (7)
YAG screens (7)
RF Gun
Wire scanners (7)
Dipole magnets (8)
Beam stoppers (2)
L0a
S-band RF acc. sections (5)
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
(not to scale)

3. Electron Beam Transported to All Areas
April 5: First e- from gun (6 MeV)
April 5: First e- to gun spectrometer (6 MeV)
April 8: First e- to inj-spectrometer (135 MeV)
April 14: First e- through BC1 (250 MeV)
June 20: First e- through main linac (16 GeV)

4. Parameters and Highlights
Up to 500 pC of charge (500 µJ laser energy)
10 Hz beam & 30 Hz RF (30 Hz e- also tested)
RF Gun is quite reliable and performing well
Transverse RF deflector working (×2)
X-band RF (4th harmonic) up and running
Emittance diagnostics (OTR + wires) and software working very well (gex,y  nC)
Bunch compression & possible COTR observed
RF feedback systems operational
Commissioning ends Sep. 4 (BC2 starts Dec. ‘07)

5. Pre-Beam Tunnel Check List Complete
40 pages, ~2000 checks – all DONE
Polarity conventions
Field type (quad, dipole)
Serial numbers
Installation orientation
etc.
etc.

6. RF Gun Installed in March 2007
D. Dowell breakout

7. e- e- Q  0.5 nC fRF = 30 Hz G  110 MV/m gex,y  1.2 mm DtFW  6.5 ps
Ipk  75 A
E  5.8 MeV
QE  1×10-5
spec. dipole e-
UV laser
YAG screens
solenoid
Cathode
(Cu)
Dual RF feed
RF gun

8. Laser Spatial and Temporal Shaping
R = 0.7 mm
7.1 ps
Spatial shape on cathode using iris
Temporal shape (7.1 ps FWHM)
Good up time and energy on cathode above spec .(500 μJ)
W. White breakout

9. Beam on YAG02 Screen (80 cm from gun)
First electron beam on April 5, 2007
20 mm

10. Injector Trajectory (BPMs) – Good Alignment

11. EPICS Controls - Vacuum
H. Shoaee

12. EPICS Controls - Magnets

13. Emittance Measurements with Quad-Scans and with Multiple Profile Monitors (OTR & Wire-Scanners)
H. Loos
breakout
Q  450 pC
gex = 0.91 μm
quad scan

14. Repetitive Emittance Measurements

15. Transverse RF Deflector as Diagnostic
RF deflector OFF
RF deflector ON
RF deflector ON
head
 high E
tail
Screen image with RF deflector OFF (left) and ON (middle), for measuring sliced emittance. A 2nd screen after a bend (right), with deflector ON, shows longitudinal phase space.

16. Measured Temporal Distribution of Bunch
Temporal distribution of e- beam measured with the transverse RF deflector upstream of BC1.

17. Time-sliced Emittance Measured Routinely
gex
~1 ps
C. Limborg
breakout
Time-sliced x-emittance measured on pre-BC1 OTR screen using quad-scan at 0.2 nC and 0.7-mm cathode spot radius. Each slice is about 1 ps wide.

18. motor controlled translation stage
X-Band RF (11.4 GHz) and BC1 Chicane are Fully Operational
BPM for energy feedback (20 mm resolution)
Offset: 0 to 26 cm (23 cm nominal)
collimator
BPM
tweaker
quadrupoles
OTR
screen
motor controlled translation stage
J. Frisch breakout
RF deflector OFF
RF deflector ON
Deflector ON & X-band ON
X-band correction
energy chirp only

19. Residual Dispersion Measurements & Correction
BPM
Scan energy…
BPM B2 B3
BPM
BPM B1 B4
S-band acc.
CQ11
CQ12
Read BPMs…
…set quads
BC1
Assumes e0 = 1 μm & sd = 1.6%
Before correction
After CQ11/CQ12 correction

20. BC1 Dipole Field Quality Poor
quads use to correct
‘CQ’ quads off
nominal x-position
dipoles need work

21. Bunch Compression Observed with CER
L1S-linac RF phase:
j = 0º
j = 15º
j = 20º
j = 25º
j = 30º
j = 35º
j = 40º
Coherent edge radiation (CER)
detector after BC1

22. Hor. emittance growth in X-band RF
L1S
X-band RF
acc. section
BC1
stopper
gex
Dx = 1.2 mm
gey
~65 μrad pk
(1.3 keV)
X-band RF ON
X-band RF OFF
x kick at downstream BPM

23. Transverse Wakefield in X-Band Structure
Q  500 pC
BC1 OFF
X-band RF OFF
gex (μm)
Dx = +0.6 mm

24. LCLS Beam Down SLAC Linac with 500 pC and up to 16 GeV
end of linac screen
1 km

25. 2007 Injector Commissioning Goals
DONE
DONE
DONE
DONE
~DONE
DONE
CONTINUES
STARTED

26. LCLS Installation and Commissioning Time-Line
June 29, 2007
linac/BC2 Install
LTU/Und/Dump
FEE/NEH Install
First Spont. Light
X-Ray tunnel/FEH Install
now
CD-4a J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D
2007
2008
2009
PPS
PPS
Controls checkout & re-commission injector
Re-commission Inj/BC2 to SL2
…Injector
Commissioning
Linac/BC2 Commissioning
LTU/Und/FEE Commissioning
FEL Commissioning

27. Problems/Issues Gun Faraday cup & toroid not functioning
BC1 motion control limited (300 mm  260 mm)
Cathode QE 3-10 times below design (improving!)
Some controls tools late (orbit displays, fitting, magnet control & alarms)
Laser phase drift and lock trouble until mid-June
Hor. emittance growth from X-band RF (?)
BC1 dipole field quality poor

28. Summary Beam transported to all areas (no major problems)
No obstructions or ‘backwards’ components (except laser alignment mirror)
BC1 & X-band emittance preservation problems
Controls still developing, but working well and improving fast – great cooperation and effort
Matlab control tools are indispensable
Communication with laser group excellent
BC2/Linac commissioning starts in Dec. ’07
GREAT commissioning team! (see breakout talks)
Thanks to all – results are quite positive (in spite of my constant whining)