Commissioning Experience at SLAC
Linac Coherent Light Source (LCLS)
Commissioning Session
Workshop on Accelerator Operations 2010

Michael Stanek
Deputy Head, Accelerator Operations and Safety Division
SLAC National Accelerator Laboratory

Stanford Linear Accelerator CenterESB

LINAC

FFTB ESA• Operated by Stanford University for the U.S. Department of Energy.
• Approximately 1400 employees.
• 3000 users from universities and other labs world-wide.
• Established in 1962 to study high energy particle physics.

SLAC past
• High Energy and Particle Physics– 1966: 20+ GeV e- Fixed Target– 1972: 3 GeV e-/e+ Colliding beam storage ring (SPEARring  J/Psi particle )– 1980-1989: 14 GeV e-/e+ (PEP ring)– 1989-1998: 50 GeV e-/e+ SLAC Linear Collider (Z0)– 1999-2008: PEP2 “B-factory” 9 GeV e- on 3 GeV e+colliding beam storage rings

Latest addition: LCLS
Linac Coherent Light Source

1 km Linac(existing)

Injector

Near HallFEL Center
Far Hall~$300 M Project

LCLS X-ray FEL key elements
Low emittance RF Photo-cathode Injector• 250 pC  1 nC
• 30  120 pulse/sec

4.0 -13.6 GeV electron Linac• Multi-stage bunch compression• sub-picosecond electron bunches

130 meters of Undulator magnets

Coherent X-ray pulses
 0.8 – 8.0 KeV, < 100 fsec, 3 mJ/pulseSelf-Amplified Spontaneous Emission (SASE)

The electron beam and its synchrotron
radiation are so intense that the electron
motion is modified by the electromagnetic
fields of its own emitted synchrotron
light. Under the influence of both theundulator and its own synchrotron
radiation, the electron beam begins toform micro-bunches,separated bya distance equal to the wavelength of theemitted radiation.

SNSNS

N

S

N

S

N

S

N

S

N

S

N

S

NN

S

N

S

N

S

N

S

N

S

NS

N

S

NS

N

S

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

X-rays for Material Science• High brightness, ultra-fast, ultra-small X-raypulses– 800 nm – 1.5 A wavelength– Probe for Atomic, Molecular & Optical Science– X-ray Pump-Probe experiments– Coherent X-ray imaging– Matter in Extreme Conditions

RF Photo-Cathode Gun
Q = 1 nC
f = 120 Hz
G = 120 MV/mgex,y = 1 mm
Dt = 10 ps
I = 100 A
E = 6 MeV

spec. dipolee-e-

UV lasersolenoid

YAG screensRF guncathode8RF Gun
EN

V
AC
UU
M

TR
EA
TM

B
ERM
PS

HAMPUTC

Injector LayoutLO
A S NG
SE B
M EL
BL LO
Y WS
SP
SE O OL
AL S
FRO
MV
AL

L0a RF section

CATHO
DE

UH
GA V A
TE LL
V M
AL ET
VE AL
S

PO
H O RCULD PI
E R NEVE

6 MeV

62 MeVgunspectrometer

L0b RF section

135 MeVTransverse RF deflector
L1 RF section(21-1b)Existing off-axis tunnel

main SLAC Linac

injector spectrometer
sector 20

sector 21

Use 1 km of existing Linac• Legacy infrastructure &control system• Some upgrades:• 2 bunch compressionchicanes.
• New BPM
instrumentation• Magnet power supplies

New Civil Construction & Beamlines• Beam Transport Hall (above ground)• Undulator Hall (underground)– Tunnel under hill for temperature stability• Air temp +/- 0.5 deg C for Undulator field quality– 33 Undulator Magnet girders• 3.4 m long

– Integrated diagnostic instrumentation• BPM, Wire, Motion Control, Alignment• Beam Dump
• Front End Enclosure (X-ray diagnostics)

Undulator Girder with Motion Control + IN/OUT
Beam Finder Wire (BFW)
Cavity BPM (<0.5 mm)
Quadrupole
magnet3.4-mundulator
magnetsand-filled,
thermally
isolated
supports

Xtranslation(in/out)
Wire Position
MonitorHydraulic Level
System

CAM-based
5-DOF
motioncontrol

New X-ray user facilities
2 soft X-ray &4 hard X-ray hutches

Remodeled Control Room(see talk – P. Schuh - Control Room and Ergonomics session)

2009
Down

FEHNEH

Down

FEL/FEE2008

Project complete

First Light in FEHFirst Users

First Light in FEE
X-Rays in NEH

DOE Review

Install Undulators

First e- to dump
FEE/NEH Install

LTU/Und Sys Install

PEP-II ends

BC2 Install• Commissioning• Project Milestones• Installation Periods

LTU/Und

Down

Linac2007

Linac/BC2

Injector

Down

First e- from gun

Injector Install

Commissioning Time-LineFirst FEL LightD J FMAM J J
MJ J A SONDJ FMAM J J A SON D J FMAM J J A SON D J FMAM
2010

Success!
• First X-rays - April 2009
• Front End Enclosure & 1st Hutch – Sept 2009
• First X-ray user experiment – Sep-Dec 2009• 2nd user Hutch planned May 2010
– Alternate users every 12 hours

Undulator ‘Taper Scan’ Shows 1.1 mJ of X-rays
1.5 Å

FEL Energy (YAG)

Pixel sum of x-ray
YAG screen CCD
camera vs undulator
K-taper

4.6 MeV

FEL-induced
Energy Loss (BPMs)

4.6 MeV at 0.25 nC= 1.1 mJ or
0.8×1012
photons/pulse (15GW at 75-fs FWHM
pulse length)
Dumpline
BPMs

Dog-Leg BPMs

 ~100 meters Beam-Based Undulator Alignment
Measure undulator trajectory at 4 energies (4.3, 7.0, 9.2, & 13.6 GeV)
Scale all linac & upstream transport line magnets each time
Do not change anything in the undulator
Calculate… (Matlab GUI)
Move quads and adjust BPM offsets for dispersion free trajectory
Iterate…
H. Loos

RESULT: vary energy by factor of 3  trajectory changes by <10 mm

Undulator Gain Length Measurement at 1.5 Ågex,y = 0.4 mm (slice)
Ipk = 3.0 kA
sE/E = 0.01% (slice)(25 of 33 undulators
installed)

LG  3.3 m

What has worked well?
• Dedicated, organized Commissioning team– Paul Emma, et.al.

• Early Operator involvement– Lectures from System Experts– Assist commissioning team on shift– Share control room with PEP2 operation• (until PEP2 shutdown 2008)– Experienced PEP2 operations organization– Clearly defined roles, responsibilities

Detailed Staged Commissioning PlanCommissioning Definition and Strategy
All components installed, aligned, connected, and initially verified
by the system engineer, then commissioning starts.

Commissioning Sequence (1-4)
1. Pre-Beam Checkout (tunnel and MCC)
Controls/software testing, check cameras, „snail‟ hunt, etc
Magnet polarities, cable connections, verify motion-control, etc

2. Beam-based Hardware and Software Checkout
Establish beam transport, RF setup, MPS/BCS tests, etc
Checkout of all wires, screens, BPMs, toroids, magnets, etc

3. First-Order Optics: Measurement and Correction
Steering, transmission, oscillation data, feedback setup, etc
Beta and dispersion matching, beam-base align key quads, etc

4. Full Beam Characterization: Measurement and Correction
Measure emittance, energy spread, distributions - correct
Measure beam sensitivities, optimize tuning, beam experiments
No (serious) emittance measurements until all hardware/software checked out!
25

LCLS Injector Commissioning Day
24-Hour Cycle (7 days/week, 1/2/07 to 9/1/07, 32 total weeks)

DAY SHIFT (8:00-16:00)
1 lead physicist, 1 physicist,
1 controls eng.,
1 LCLS operator, 1 laser operator

SWING SHIFT (16:00-24:00)
1 lead physicist, 1 physicist,
1 LCLS operator, 1 laser op on-call

OWL SHIFT (0:00-8:00)
1 LCLS operator, 1 laser op on-call26

After PEP2-BaBar ended (2008),
Full attention of Operations crew
2-3 Ops, 1 Engineering op

Communication & Teamwork• Accelerator Physicist – Operator handoff– Owl Shift left to operators• Complete measurements started by physicists• Tune accelerator within guidelines• Practice routine measurements• Frequent commissioning team meetings– 08:00 (7 days/week), 16:00 (M-F)– Controls Deputy manages Software releases

Organizational foresight• Support group involvement in hardware:– Specification Development– Installation– Checkout– Commissioning• Natural transition to Maintenance & Repair

Control System support• Controls group provides infrastructure– EPICS, Network and IOC support• High-level Applications minimal for start-up• Heavy use of MatlabR(The MathWorksTM)– Commissioning Physicists– Operators• Internal training– Controls group provides support• Training for Ops in EPICS, EDM screensOperator Matlab GUI

Flexibility• Compromise between flexibility & discipline– Allow exploration by system experts during
Commissioning– Tighter configuration control for operators during
User runs• Add simple diagnostics when schedules slip
– Changing priorities for support groups• Ops take over routine tasks, Experts moveon to the next challenge

Challenges Ahead• Advertised X-ray availability 95%– Technical challenges• Aging infrastructure with Linac– Cultural challenges• Different Operational mindset than High Energy Physics
Experiments• Weekly (almost) shutdown days, short work list
• Availability „budget‟ for each system– First user run achieved goal (96%)• Additional complexity coming – multiple users

Thank you for your attention