max cornacchia, slac lcls project overview besac, feb. 26-27, 2001 lcls project overview what is the...
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Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
LCLS Project Overview
• What is the LCLS ?• Transition from 3rd generation light sources to x-
ray free-electron lasers• The SASE principle and linac-driven free-electron
lasers• Performance• Accomplishments• R&D and construction plan
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
• Single pass Free-Electron Lasers• Uses SLAC Linac• 1.5 - 15 Å (0.5-5 Å in 3rd harmonic)• Peak brightness 10 orders of magnitude above Advanced
Photon Source (APS)• Time averaged brightness 2-4 orders of magnitude above APS• Sub-picosecond pulses• Fully transversely coherent radiation• Design and R&D studies, a ANL-BNL-LANL-LLNL-SLAC-UCLA
collaboration
The X-ray FEL is a powerful tool to explore matter and fundamental physics.
What is the LCLS ?
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
The transition from 3rd generation light sources to x-ray free-electron lasers
3rd generation X-ray FELs
High flux and brightness Many order of magnitude higher than in 3rd generation sources
Short pulses (tens of ps)
1-2 order of magnitude shorter (sub-ps)
Partially transversely coherent Fully transversely coherent (Degeneracy factor 109)
Bandwidth = 1/number of undulator periods
FELs
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
The SASE principle and linac-driven free-electron lasers
• Main components of a SASE FEL
– A bright electron source (photo-injector)
– A bunch compression system
– A linear accelerator– An undulator– The photon beamlines– The experimental areas
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2
2
2
Kw
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Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
LCLS layout
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
SASE FEL theory well developed
and verified by simulations and experiments•FEL radiation starts from noise in spontaneous radiation
•Transverse radiation electric field modulates the energy and bunches the electrons within an optical wavelength
•Exponential build-up of radiation along undulator length
SASE FELs
Undulator RegimeUndulator Regime
Exponential Gain Regime
Exponential Gain Regime
Saturation
Saturation
0.2 fs
0.9 fs
1 % of X-Ray Pulse1 % of X-Ray Pulse
Electron BunchMicro-Bunching
Electron BunchMicro-Bunching
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
• Wavelength 1.5 Å
(range 1.5-15 Å, 1st harm)
• Electron energy 14.35 GeV (range 14.35-4.54)
• Bunch length 230 fsec (full)
• 1012 coherent photons/pulse
• Undulator length 120 m
• Undulator gap 6 mm
• Saturation peak power
9 GW• Peak brightness
1.2 1033
• Average brightness
4.2 1022
Main parameters
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
Light source performance chart
Peak and time
averaged
brightness
of the LCLS and other
facilities,
operating or
planned
Average Peak
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
Other FEL based light sources are being tested, built or planned• The TESLA Test Facility (TTF) at DESY
– Lasing with gain ~3000 observed at 80-180 nm
• X-ray FEL TESLA at DESY (associated with the linear collider project)– CDR being written
• Source Development Laboratory (SDL) at BNL-NSLS– Electron beam testing
• Harmonic Generation (HGHG) experiment successful at BNL-ATF
• VISA experiment at BNL-ATF– Study the FEL radiation with beam characteristics and tolerances
close to those of the LCLS
• FELs under study in Japan, Italy, England and Germany (BESSY II)
• LEUTL at ANL-APS– First observation of saturation
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
FEL experiment
• A crucial milestone in FEL physics was reached when the LEUTL experiment measured large amplification and evidence of saturation last summer at 530 and 385 nm
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1.1
370380
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VLD2VLD3
VLD5VLD7
VLD9In
ten
sity [a
.u.]
Saturation
BeyondSaturation
ExponentialGain
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
6D particle tracking through LCLS accelerator6D particle tracking through LCLS accelerator
150 MeV150 MeV
250 MeV250 MeV
250 MeV250 MeV
4.54 GeV4.54 GeV
14.3 GeV14.3 GeV
Ene
rgy
devi
atio
n al
ong
elec
tron
bun
chE
nerg
y de
viat
ion
alon
g el
ectr
on b
unch
Tra
nsve
rse
cros
s se
ctio
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ele
ctro
n be
amT
rans
vers
e cr
oss
sect
ion
of e
lect
ron
beam
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
How to achieve a short bunch
• The simulation tool was used to optimize the electron beam in 6-dimensional phase space–Preservation of transverse electron brightness leads to shorter undulator and more relaxed tolerances–Mechanism for achieving short electron bunches (230 fs) confirmed by the simulations–Even shorter bunches can compromise transverse electron brightness
230 fs bunch length is the result of optimization in all 6 dimensions
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
X-ray optics transport simulations
0 150
GINGER output:
Tables of electric field valuesat undulator exitat different times
Time Domain
Frequency Domain
TemporalTransform
SpatialTransform
00
1.94
150-150Transverse position, microns
x 1015 wattsc m2
Power Density
0
1.94
x 1015 wattsc m2
0 6Time, femtoseconds
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Power Density
0w0w0-400/fs
1.73
x 1017 wattsc m2
w0+400/fs
frequency
Power Density
0-10
1.73
-325 304Wavenumber, mm-1
x 1017 wattsc m2
Power Density
viewer
Viewer
Transformation to Frequency Domain
Propagationto arbitrary
z
tit Ni ..1
R, mm
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
FFTB hall for undulator and diagnostics
LCLS Undulator Hall and Experimental Area Layout
Hall A:Atomic PhysicsWarm Dense MatterX-Ray Physics
Hall B:Nanoscale DynamicsFemtochemistryBiological Imaging
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
Conceptual Design Report
• Conceptual Design Report is on schedule• First draft contributions are being reviewed• Goal is to have it ready, in draft form, by early
summer 2001
Max Cornacchia, SLAC
LCLS Project Overview
BESAC, Feb. 26-27, 2001
Summary• Substantial progress made in most areas• Experimental confirmation of the photo-injector
brightness is the most important short term goal– Program is receiving strong support from SLAC
• Integration photo-injector/FEL physics/x-ray optics to continue– Realistic x-ray FEL characteristics, tolerances, match to the
experiments
• X-ray optics to address detailed requirements of the “first experiments”
• Focus on CDR for the next 6-8 months• Preparation for Lehman Review
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