Transcript The LCLS at SLAC LCLS Linac Coherent Light Source J. B. Hastings

The LCLS at SLAC
Linac Coherent Light Source
J. B. Hastings
(for the LCLS group)
January 31, 2007
LCLS
LLNL
ANL
UCLA
X-FEL based on last 1-km of existing SLAC linac
1.5-15 Å
LCLS
2 compressors
one undulator
Beam Transport from Linac Through X-Ray Halls
Beam Transport Hall:
227-m, above-grade
facility to transport electron
beam
Undulator Hall:
Electron Beam Dump:
40-m long underground
facility to separate electron
and x-ray beams
Front End Enclosure:
40-m long underground facility housing
photon beam diagnostic equipment
170-m, underground
tunnel housing
undulators
Near Experimental Hall:
underground facility to
house 3 experimental
hutches, prep, and shops
X-Ray Trans. & Diag. Tunnel:
210-m long underground tunnel to
transport photon beams from NEH to FEH
Far Experimental Hall:
underground 46’ cavern
housing 3 experimental
hutches and prep space
LCLS Parameters
LCLS Accelerator Schematic
6 MeV
z  0.83 mm
  0.05 %
rf
gun
250 MeV
z  0.19 mm
  1.6 %
135 MeV
z  0.83 mm
  0.10 %
4.30 GeV
z  0.022 mm
  0.71 %
13.6 GeV
z  0.022 mm
  0.01 %
Linac-X
L =0.6 m
rf= -160
Linac-0
L =6 m
Linac-1
L 9 m
rf  -25°
...existing
linac
21-1
b,c,d
DL1
L 12 m
R56 0
Linac-2
L 330 m
rf  -41°
Linac-3
L 550 m
rf  0°
21-3b
24-6d
25-1a
30-8c
X
BC1
L 6 m
R56 -39 mm
Commission in Jan. 2007
BC2
L 22 m
R56 -25 mm
Commission in Jan. 2008
SLAC linac tunnel
undulator
L =130 m
DL2
L =275 m
R56  0
research yard
LCLS Installation and Commissioning
Time-Line
Drive-Laser
Commissioning
Drive-Laser
Installed
LTU/und. Install
LTU/und.
hall “ready”
Controls
Checkout
First Spont.
Light
ASOND J FMAM J J ASOND J FMAM J J
2006
Gun/Inj./BC1
Install
(8/21 – 2/20)
Oct. 19, 2006
2007
Gun/Inj./BC1
Commissioning
2008
Inj./Linac/BC2
Commissioning
linac/BC2 Install
LTU/und.
Commissioning
LCLS Installation and Commissioning
Time-Line
Drive-Laser
Commissioning
Drive-Laser
Installed
LTU/und. Install
LTU/und.
hall “ready”
Controls
Checkout
First Spont.
Light
ASOND J FMAM J J ASOND J FMAM J J
2006
Gun/Inj./BC1
Install
(8/21 – 2/20)
Oct. 19, 2006
2007
Gun/Inj./BC1
Commissioning
2008
Inj./Linac/BC2
Commissioning
linac/BC2 Install
LTU/und.
Commissioning
Emittance Measurements with ‘QuadScan’ on OTR Screen
gey = 1.06 μm
OTR screen
95%
area cut
Gaussian used only
as visual aid here
135 MeV, 1 nC, 100 A
Projected Emittance Below 1 μm at 0.7 nC
gex = 0.76 μm
Q = 700 pC
gey = 0.85 μm
Emittance Measured Over 8 Hours
gex
gey
0.7 nC, 135 MeV, 70 A
Commissioning Results
x & y emittance 1.2 μm at 1 nC charge (design)
<1.5% rms charge stability (design is 2%)
Drive laser 98% up-time with 500 μJ (250 design)
Bunch compression in BC1 fully demonstrated
Accelerated LCLS beam to 16 GeV (13.6 design)
X-band & 2 RF deflectors both operational
New RF performing within spec (e.g., <0.1º rms)
Feedback ON: launch, charge, energy, RF, & z
Robust, high-quality RF gun demonstrated
Science Opportunities
Atomic, molecular and optical
science (AMOS)
SLAC Report 611
Nano-particle and single molecule
coherent x-ray imaging (CXI)
Coherent-scattering studies of
nanoscale fluctuations (XCS)
t=
t=0
Diffraction studies of stimulated
dynamics (pump-probe) (XPP)
Aluminum plasma
classical plasma
G =1
dense plasma
10-4
10-2
1
G =10
G=100
high den.
matter
102
Density (g/cm-3)
104
High energy density science
(HEDS)
Atomic, molecular, and optical (AMO) physics
Very-intense, ultrashort x-ray pulses will interact with matter in new
ways.
Atomic strong-field effects may alter the properties of the materials.
Low-Frequency Physics → High Frequency
IR:
Low frequency regime
VUV FEL:
Intense photon source
XFEL FEL:
Highly ionizing source
- Ip
- Ip
- Ip
1015 W/cm2
1013 W/cm2
• Keldysh parameter g <<1
• Tunnel / over the barrier
ionisation
• Ponderomotive energy 10 –
100 eV
• Keldysh parameter g >>1
• Multi-photon ionisation
• Ponderomotive energy 10
meV
g
Optical Frequency
Tunneling Frequency
= (Ip/2Up)1/2 -1;
10x20 W/cm2
• Angstrom wavelength
• Direct multiphoton ionisation
• Secondary processes
Up=I/4ω2 (au)
Imaging with coherent x-rays
Microscopy
light
image
sample
•depth of field limit
•lens-limited
•direct
lens
Diffractive
imaging
Diffraction Microscopy
•No depth of field limit
•No lens-limited
•Computer-limited
Coherent-light
CCD
Known:
k-space amplitude: I
Support
(outline of the object)
in real space s
X-ray free-electron lasers may enable atomic-resolution imaging of
biological macromolecules
One pulse, one
measurement
Particle injection
10-fs
pulse
Noisy diffraction pattern
Combine 105-107 measurements
Classification
Averaging
Orientation
Reconstruction
H. Chapman
Motivation for even
shorter x-ray pulses
Coulomb Explosion
of Lysozyme (50 fs)
Further e- compression
difficult:
 CSR in bends
 Undulator wakefields
Radiation damage
interferes with atomic
positions and the atomic
scattering factors
Janos Hajdu
20%
30%
40%
Relec
1014
Relectronic
b
1013
40%
Initial LCLS
parameters
1012
Tolerable damage
(single exposures)
30%
1011
20%
1010
15%
1
10
Dt /fsec
100
1000
First image reconstructed from an ultrafast FEL diffraction pattern
1 micron
1st shot at full power
2nd shot at full power
SEM of structure etched into
silicon nitride membrane
Reconstructed Image – achieved
diffraction limited resolution!
Wavelength = 32 nm
Chapman et al. Nature Physics (2006)
1 micron
Edge of membrane support
also reconstructed
LCLS
Nanocrystal of
lysozyme
1 LYSOZYME
5x5x5
LYSOZYMES
Dynamics
Silica: 2610 Å, ΔR/R=0.03, 10 vol% in glycerol, T=-13.6C,   56000 cp
sample
22µm direct
illumination
1k x 1k CCD
CCD
today:  1 s
1 MHz ADC
1 s exposure
4 s overhead
V. Trappe and A. Robert
XPCS Science
LCLS Parameters
Transverse Coherence
Split & Delay
8 and 24 keV
High Time–average Brilliance
Rep. Rate 120 Hz
Sequential Mode
High Peak Brilliance
Short pulse duration 100fs
Dedicated 2D-Detector
Ultrafast XPCS
Peak Brilliance & Pulse Duration
pulse duration < tC< several ns
Large Q’s accessible
Split and Delay
Provided by DESY/SLAC MoU
Prototype existing
1st Commissioning May 2007
pulse duration < delay < 3 ns
based on Si (511) with 2θ = 90º
E=8.389 keV
Traditional Pump-probe
Delay will be achieved by optical delay and/or RF phase shift
Resolution limited by LCLS/laser jitter ~ 1 ps limit
Short Pulse Laser Excitation Impulsively Modifies Potential Energy
Surfaces
Non-thermal melting
of InSb
Coherent phonons
in Bi
Ultrafast X-ray Scattering Provides Direct Access to Atomic Motion on
non-Equilibrium Potential Energy Surfaces
…characterizes the shape of the potential
A. Lindenberg, et al. Science 308, 392 (2005).
D.M. Fritz, et al. Science 315, 633 (2007).
High brightness of LCLS will enable unique studies of in situ material
failure
Future:
Post Processing x-ray scattering
Measure during pressure pulse
Shocked and
incipiently
fractured
single crystal
Al slug
Simulated xray scattering
APS
Beam
RPA
SLFC
LFC
Te
Shift
Free e-
-300 -200 -100 0
100
Energy shift (eV)
LCLS
Multiple and single bunch
x-ray scattering from shock
recovered samples in
progress
• Diffraction  lattice compression and phase change
• SAXS  sub-micron defect scattering
• Diffuse  dislocation content and lattice disorder
R. Lee
Bound e-
Collective
3-D x-ray tomographic
reconstruction of
dynamic fracture
Particle data
Current:
SLFC
LFC
-60
RPA
-40
-20
0
• LCLS will provide unprecedented fidelity to
measure dynamics of the microstate with subpicosecond resolution
LCLS enables real-time, in situ study of deformation at high pressure and
strain rate
Current Status
Simulation Classical scattering
Future with LCLS
Unique capabilities
• Imaging capability
• Point projection imaging
• Phase contrast
• High resolution (sub-µm)
• Direct determination of density
contrast
• Diffraction & scattering
• MD simulation of FCC copper
Periodic
features
average
distance
between
faults
• Detection of high pressure phase
transitions
Diffuse
scattering from
stacking fault
0
0
Peak
diffraction
moves from 0,0
due to
relaxation of
lattice under
pressure
• X-ray diffraction image using LCLS probe of the
(002) shows in situ stacking fault information
• Lattice structure, including dislocation
& defects
• Liquid structure
• Electronic structure
• Ionization
• Te, f(v)
These complement the standard instruments,
e.g., VISAR and other optical diagnostics
Impact: X-ray pulses 500
times shorter than
nominal LCLS
(2-fsec already in
baseline)
Lag:
1 yr
Level:
Straightforward –
Spoiler wakefield
needs checking
Ref:
Attosecond Pulses
Be foil
in BC2
chicane
2109 photons
PRL 92:074801,2004,
SLAC-PUB-10712.
380 as
Parameters:
<400 attosecond pulses
2109 photons/pulse
100 pC bunch charge
SLAC Contacts: P. Emma, Z. Huang, et al.
LCLS with Multiple Beamlines
535 m
FFTB m-shielding
330 m
62 m
100 m
Note: Design Hall A and Hall B compatible with LCLS II Expansion
Impact: Converts LCLS
into a user facility
with extended
wavelength range,
shorter pulses,
and enhanced
power levels
Lag:
~10 yrs
Level:
Challenging –
need multi-bunch Ecompensation
(variable spacing)
Ref:
SLAC-PUB-10133.
Parameters:
1 to 60 bunches/RF pulse
Up to 8 undulators
Wavelengths below 1 Å?
Pulse lengths to 1 fsec
Multiple Undulators and
Fast Multi-Bunch Switching
4.9 ns
up to 60 bunches
(same again on North side)
SLAC Contacts: F.-J. Decker, P. Emma, et al.
Impact: Provide soft x-ray
FEL in addition to
hard x-rays
Lag:
13.6 GeV LongWavelength FEL
~5 yrs
250 MeV
Level:
Moderate
Ref:
(none yet)
Parameters:
I =3.4 kA
1.2 mm-mrad emittance
σδ = 1x10-4
β = 25m
λu = 10 cm
K = 5~12
B= 0.53~1.28 T
λr = 10 -50 Å
10-50 Å
1.5-15 Å
Adjustable-Gap Undulator
Simultaneous Operation with 1.5-Å, but ½-rate
SLAC Contacts: J. Arthur, J. Hastings, Z. Huang, PE
X-FEL based on last 1-km of existing SLAC linac
1.5-15 Å
LCLS
?
2 compressors
one undulator
27 GeV, ge = 0.8 mm, 6.0 kA:
14 GeV, ge = 1.2 mm, 3.4 kA:
The SLAC linac can explore and
reach the limits of FEL
performance:
Peak brightness
Fluence
Pulse duration
These limits are primarily
determined at LOW energy:
Gun
Bunch compression
This is an extraordinary scientific
opportunity
Near- and long-term payoff
Peak Brightness (phot./s/mrad2/mm2/0.1%-BW)
LCLS Future Options:
XFEL
27 GeV
LCLS
LCLS soft
LCLS nom.
Photon Energy (eV)
Impact: Provide soft x-ray
FEL in addition to
hard x-rays
Lag:
~5 yrs
Level:
Moderate (use e+
PEP-II by-pass line)
Ref:
(none yet)
Parameters:
By-Pass Line to LongWavelength FEL
PEP-II e+
by-pass line
250 MeV
ESA
10-50 Å
4.3 GeV
pulsed dipoles
10-50 Å
1.5-15 Å
ESB
Adjustable-Gap Undulator
Simultaneous Operation with 1.5-Å, but ½-rate
Possible after-burner undulator added
Possible locations:
Endstaion A or B
SLAC Contacts: J. Arthur, J. Hastings, Z. Huang, PE
Impact: Provide variable
polarization in the
1-5 nm wavelength
range
Lag:
~5 yrs
Level:
Moderate – new
undulator
Ref:
none yet
Circular Polarization for
Soft x-rays
~ 2 GW (linear polarized)
planar
Six 3.4m sections
Two sections
~ 20 GW (90% circular polarized)
Parameters:
Parameters:
Electron energy 4.3 GeV
1.2 mm-mrad emittance
Energy spread 1 MeV
Standard LCLS undulator
helical
Contacts: Y. Ding, Z. Huang
Impact: Short pulse, or
narrow bandwidth,
& wavelength is
more stable
Lag:
Two-Stage SASE FEL
~5 yrs
30
Level:
Moderate – new
undulator line or
upgrade
Ref:
SLAC-PUB-9370,
TESLA-FEL-97-06E,
SLAC-PUB-9633,
SLAC-PUB-10310
Parameters:
30 fs
Contacts: C. Pellegrini
Final Comments
For LCLS, slice emittance >1.8 mm will not saturate FEL…
eN = 1.2 mm
eN = 2.0 mm
P = P0
P = P0/100
courtesy S. Reiche
SASE FEL is not forgiving — instead of mild luminosity loss,
power nearly switches OFF
electron beam must meet brightness requirements