Light Sources and Future ProspectsLight Sources and Future Prospects
R. Bartolini
Diamond Light Source Ltdand
John Adams Institute, University of Oxford
IoP NPPDGlasgow, 06 April 2011
OutlineOutline
• Introduction
synchrotron radiation properties and users’ requirements
• 3rd generation light sources
performance, trends and limitations
• 4th generation light sources
AP and FEL challenges and enabling R&D
• beyond 4th generation
Laser plasma accelerators driven light sources
• Conclusions
IoP NPPDGlasgow, 06 April 2011
Broad Spectrum which covers from microwaves to hard X-rays (tunable with IDs)
High Flux: high intensity photon beam
High Brilliance (Spectral Brightness): highly collimated photon beam generated by a small divergence and small size source
Polarisation: both linear and circular (with IDs)
Pulsed Time Structure: pulsed length down to
High Stability: submicron source stability in SR
Flux = Photons / ( s BW)
Synchrotron radiation propertiesSynchrotron radiation properties
Brilliance = Photons / ( s mm2 mrad2 BW )
IoP NPPDGlasgow, 06 April 2011
Partial coherence in SRs
Full T coherence in FELs
10s ps in SRs
10s fs in FELs
1992 ESRF, France (EU) 6 GeVALS, US 1.5-1.9 GeV
1993 TLS, Taiwan 1.5 GeV1994 ELETTRA, Italy 2.4 GeV
PLS, Korea 2 GeVMAX II, Sweden 1.5 GeV
1996 APS, US 7 GeVLNLS, Brazil 1.35 GeV
1997 Spring-8, Japan 8 GeV1998 BESSY II, Germany 1.9 GeV2000 ANKA, Germany 2.5 GeV
SLS, Switzerland 2.4 GeV2004 SPEAR3, US 3 GeV
CLS, Canada 2.9 GeV2006: SOLEIL, France 2.8 GeV
DIAMOND, UK 3 GeV ASP, Australia 3
GeVMAX III, Sweden 700 MeVIndus-II, India 2.5 GeV
2008 SSRF, China 3.4 GeV2009 PETRA-III, D 6 GeV 2011 ALBA, E 3 GeV
33rdrd generation storage ring light sources generation storage ring light sources
ESRF
SSRF
> 2011 NSLS-II, US 3 GeV SESAME, Jordan 2.5 GeVMAX-IV, Sweden 1.5-3 GeV
TPS, Taiwan 3 GeV CANDLE, Armenia 3 GeV
33rdrd generation storage ring light sources generation storage ring light sources
under construction or planned NLSL-II
Max-IV
IoP NPPDGlasgow, 06 April 2011
Photon energy
Brilliance
Flux
Stability
Polarisation
Time structure
Ring energy
Small Emittance
Insertion Devices
High Current; Feedbacks
Vibrations; Orbit Feedbacks; Top-Up
Short bunches; Short pulses
Accelerator physics and technology challengesAccelerator physics and technology challenges
IoP NPPDGlasgow, 06 April 2011
The brilliance of the photon beam is determined (mostly) by the electron beam emittance that defines the source size and divergence
Brilliance and low emittanceBrilliance and low emittance
''24 yyxx
fluxbrilliance
2,
2, ephexx
2,
2,'' ' ephexx
2)( xxxx D
2' )'( xxxx D
Brilliance with IDsBrilliance with IDs
Medium energy storage rings with In-vacuum undulators operated at low gaps (e.g. 5-7 mm) can reach 10 keV with a brilliance of 1020 ph/s/0.1%BW/mm2/mrad2
Thanks to the progress with IDs technology storage ring light sources can cover a photon range from few tens of eV to tens 10 keV or more with high brilliance
IoP NPPDGlasgow, 06 April 2011
Diamond aerial view with the new I13 beamlineDiamond aerial view with the new I13 beamline
Diamond is a third generation light source open for users since January 2007
100 MeV LINAC; 3 GeV Booster; 3 GeV storage ring
2.7 nm emittance – 300 mA – 18 beamlines in operation (12 in-vacuum small gap IDs)
Diamond storage ring main parametersDiamond storage ring main parametersnon-zero dispersion latticenon-zero dispersion lattice
Energy 3 GeV
Circumference 561.6 m
No. cells 24
Symmetry 6
Straight sections 6 x 8m, 18 x 5m
Insertion devices 4 x 8m, 18 x 5m
Beam current 300 mA (500 mA)
Emittance (h, v) 2.7, 0.03 nm rad
Lifetime > 10 h
Min. ID gap 7 mm (5 mm)
Beam size (h, v) 123, 6.4 m
Beam divergence (h, v) 24, 4.2 rad
(at centre of 5 m ID)
IoP NPPDGlasgow, 06 April 2011
48 Dipoles; 240 Quadrupoles; 168 Sextupoles (+ H and V orbit correctors + Skew Quadrupoles ); 3 SC
RF cavities; 168 BPMs
Quads + Sexts have independent power supplies
All BPMS have t-b-t- capabilities
Linear optics modelling and correctionLinear optics modelling and correction
0 100 200 300 400 500 600-1
-0.5
0
0.5
1
S (m)
Hor
. Bet
a Bea
t (%
)
0 100 200 300 400 500 600-2
-1
0
1
2
S (m)
Ver
. Bet
a Bea
t (%
)
Hor. - beating < 1% ptp
Ver. - beating < 1 % ptp
Very good control of the linear optics with LOCO
Emittance [2.78 - 2.74] (2.75) nm
Energy spread [1.1e-3 - 1.0-e3] (1.0e-3)
Coupling correction to below 0.1%
V beam size at source point 6 μm
V emittance 2.2 pm
Top-Up modeTop-Up mode
17th-19th September 2009: 112 h of uninterrupted beam:
25th January 2011 first full operating week (144 hours )
0.64%
= 26 h
IoP NPPDGlasgow, 06 April 2011
dzVdf
c
RFsz /2
3
Short bunches at DiamondShort bunches at Diamond
(low_alpha_optics) (nominal) /100
6101 ds
D
Lx
z(low alpha optics) z(nominal)/10
We can modify the electron optics to reduce
The equilibrium bunch length at low current is
Comparison of measured pulse length for normal and low momentum compaction
2.5 ps is the resolution of the streak camera
Shorter bunch length confirmed by synchrotron tune measurements
fs = 340Hz => α1 = 3.4×10-6, σL = 1.5ps
fs = 260Hz => α1 = 1.7×10-6, σL = 0.98ps
I09 and I13: “Double mini-beta” I09 and I13: “Double mini-beta” andand Horizontally Horizontally Focusing OpticsFocusing Optics
I13 October 2010
I09 April 2011
4 new quadrupoles
new mid-straight girder
existing girders modified
in-vacuum undulators
Trends in 3Trends in 3rdrd generation light sources generation light sources
Striving to meet advanced user’s requirements
more beamlines (canted undulator from single straight sections)
customised optics
higher brightness (low emittance – low coupling)
higher flux (higher current)
short pulses
New machine designs or upgrades are targeting 100 pm or less in the horizontal plane
… but peak brightness and pulses length cannot compete with FELs
IoP NPPDGlasgow, 06 April 2011
Transverse coherence
Users’ requirements - 4Users’ requirements - 4thth generation light sources generation light sources
SASE
direct seeding - seeding + HGTemporal coherence
High repetition rates / Time structure SC/NC RF
Polarisation control
Synchronisation to external lasers VUV and THz
Ultra short pulses (<100 fs down to sub-fs)
IDs technology or novel schemes
Tunability
Higher peak brightness
Many projects target Soft X-rays (here 40 – 1 nm) . Soft X-rays FELs require 1-3 GeV Linacs. Hard X-rays project will also provide Soft X-rays beamlines (Swiss FEL – LCLS)
FEL radiation propertiesFEL radiation properties
FELs provide peak brilliance 8 order of magnitudes larger than storage ring light sources
Average brilliance is 2-4 order of magnitude larger and radiation pulse lengths are of the order of 100s fs or less
Slicing or low charge
X-rays FELsX-rays FELs
FLASH 47-6.5 nm 1 GeV SC L-band 1MHz (5Hz) SASE
FERMI 40-4 nm 1.2 GeV NC S-band 50 Hz seeded HGHG
SPARX 40-3 nm 1.5 GeV NC S-band 100 Hz SASE/seeded
Wisconsin 1 nm 2.2 GeV SC/CW L-band 1 MHz seeded HHG
LBNL 100-1 nm 2.5 GeV SC/CW L-band 1 MHz seeded
MAX-LAB 5-1 nm 3.0 GeV NC S-band 200 Hz SASE/seeded
Shanghai 10 nm 0.8-1.3 GeV NC S-band 10 Hz seeded HGHG
NLS 20-1 nm 2.2 GeV SC/CW L-band 1-1000 kHz seeded HHG
LCLS 0.15 nm 14 GeV S-band 120 Hz SASE
SCSS 0.1 nm 8 GeV C-band 60 Hz SASE
XFEL 0.1 nm 17.5 GeV SC L-band CW (10 Hz) SASE
Swiss-FEL 0.1 nm 5.8 GeV C-band 120 Hz SASE
Swiss-FEL 10 nm 2.1 GeV NC S-band 120 Hz SASE/seeded
LCLS-II 4 nm 4 GeV NC S-band 120 Hz seeded
LCLS lasing at 1.5 LCLS lasing at 1.5 ÅÅ (April 2009) (April 2009)
High brightness beam at LCLSHigh brightness beam at LCLS
MEASURED SLICE EMITTANCE at 20 pCMEASURED SLICE EMITTANCE at 20 pC
Managing collective effects with high brightness beams is a non trivial AP task
CSR effects at BC2CSR effects at BC2
NLS Conceptual Design Report (May 2010)NLS Conceptual Design Report (May 2010)
The science case requires a light source with
• photon energies from THz to X-rays
• high brightness
• high repetition rate (1 kHz to 100 kHz or more)
• short pulses: 1011 ppp - 20 fs upgrade to sub-fs pulses
• full coherence
The technical solution proposed is based on a combination of advanced conventional lasers and FELs
• 2.25 GeV SC linac
• seeded harmonic cascaded FEL (50 eV to 1 keV)
IoP NPPDGlasgow, 06 April 2011
photoinjector
3rd harmonic cavity
BC1
BC2 BC3
laser heateraccelerating modules
collimation
diagnostics
spreader
FELs
IR/THzundulators
gas filters
experimental stations
UK New Light Source (NLS)UK New Light Source (NLS)
High brightness electron gun operating (initially) at 1 kHz
2.25 GeV SC CW linac L- band
50-200 pC
3 FELS covering the photon energy range 50 eV – 1 keV (50-300; 250-800; 430-1000)
• GW power level in 20 fs pulses• laser HHG seeded for temporal coherence• cascade harmonic FEL• synchronised to conventional lasers (60 meV – 50 eV) and IR/THz sources for pump probe experiments
Soft X-ray are driven by high brightness electron beam
1 – 3 GeV n 1 m
~ 1 kA / 10–4
This requires:
a low emittance gun (norm. emittance cannot be improved in the linac)
acceleration and compression through the linac keeping the low emittance
The operation of seeded FELs requires in addition
e- pulse shape control (flat slice parameters flat gain length over ~100s fs)
careful reduction of jitter of e- beam properties
Accelerator Physics challengesAccelerator Physics challenges
Astra/PARMELAImpact-T
Elegant/IMPACT/CSRTrack GENESIS/GINGER
Gun A01 LH A02A39 A03 A04 A05 A06 A07 A08 BC3 A09 A10 A11 A12 A13 A14BC1 BC2SPDR FELs
Optimisation validated by start-to-end simulation Gun to FEL
Seeding improves
longitudinal coherence shorter saturation length
stability (shot to shot power, spectrum, ...) control of pulse length
allows synchronisation to external lasers
FEL physics challenges: need for seedingFEL physics challenges: need for seeding
Advantage of seeded operation vs SASE
SASE has a very spiky output: each cooperation length behaves independently: no phase relation among spikes
SASE >> 1 Seeded ~ few TFL
Seed source are not available down to 1 keV. Frequency up-conversion done with FEL itself (HGHG, HGHG cascade, EEHG most unproven yet)
FEL physics challenges: harmonic cascadeFEL physics challenges: harmonic cascade
Optimisation of cascaded harmonic FEL for highest power and highest contrast ratio
Conflicting requirements:
generate bunching at higher harmonics of interest
keep the induced energy spread low
Courtesy N. Thompson
u,seed n
2seed2
u,2
but
Sub-fs radiation pulsesSub-fs radiation pulses
Slicing +
wavelengthSlicing +current
Slicing + Energy chirp
Single spike
Mode-Locking
Pulse length 300 as 250 as200 asor less
300 as23 as
every 150 as
Photon energy 12 keV 12 keV 12 keV 12 keV 8.6keV
Photon per pulse 108 109 1010 108 108
Peak Power 5 GW 50 GW 100 GW 5 GW 5 GW
contrast poor poor good excellent good
Rep rate Laser seedLaser seed
Laser seed LINAC Laser seed
synchronisation YES YES YES NO YES
• laser slicing (Zholents, Saldin, Fawley)
• mode locking (Thompson, McNeil)
• single spike (Bonifacio, Pellegrini)
• echo – based (Xiang –Huang-Stupakov)
Generation of sub-fs radiation pulses has been proposed with a variety of mechanisms
e-beam ~ 100 fs
)t(E
NLS – recirculating linac optionNLS – recirculating linac option
High brightness electron gun operating (initially) at 1 kHz
2.25 GeV SC CW linac L- band
50-200 pC
Option with recirculating linac (10 modules instead of 18 modules)
Linac8 modules
The ALICE layout and main parametersThe ALICE layout and main parameters
Parameter Value
Gun Energy 350 keV
Injector Energy 8.35 MeV
Max. Energy 35 MeV
Linac RF Frequency 1.3 GHz
Max Bunch Charge 80 pC Courtesy J. Clarke
Accelerator and Laser In Combined Experiments
The ALICE electron test acceleratorsThe ALICE electron test accelerators
IoP NPPDGlasgow, 06 April 2011
An R&D facility dedicated to accelerator science and technology
Offers a unique combination of accelerator, laser and free-electron laser sources Enabling studies of electron and photon beam combination techniques
Provides a range of photon sources for development of scientific programmes and techniques
Highlights of the scientific programme include
R&D on SC DC photoinjectors and on SC RF for CW L-band Linacs
Diagnostics (e.g. ultrashort pulses) timing and synchronisation
Energy recovery - Emma injector
Compton backscattering - THz radiation
and IR-FEL
FIR wavelength FEL (8 FIR wavelength FEL (8 6 6 mm))
First Lasing Data: 23/10/10 Simulation (FELO code)
-5 0 5 10 15 20 250
2
4
6
8
10
12
14
Cavity Length Detuning (m)
Out
coup
led
Ave
rage
Po
wer
(m
W)
-5 0 5 10 15 20 250
10
20
30
40
50
Cavity Length Detuning (m)
Out
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Possible future directions for 4Possible future directions for 4thth generation generation light sourceslight sources
• Ultracold injectors: low emittance, low charge, to shorten the saturation length
• Insertion Devices: development of new undulators beyond Apple-II, compact, shorter periods, higher fields, wakefield control, compact (e.g. Superconducting U)
• RF: Optimise performance and reduce cost of SC RF (gradient choices 13-15 MV/m for LBNL, NLS, BESSY) or use simple low risk design with high gradient (possibly high repetition rate based on C-band X-band)
• FEL physics: Critical assessment of various seeding schemes, non-seeding and slicing options, HHG, HGHG cascade and sub fs pulses
• AP Physics: alternative compression schemes to avoid the limits posed by microbunching (velocity bunching)
• Diagnostics: New diagnostics for ultra short bunches, arrival time, low charge but also dealing with COTR
• Timing and synhcronisation: sub 10-fs resolution over 100s m; long term stability
• Stability and feedbacks: positions (sub m over large frequency range), energy, charge, …
The progress with laser plasma accelerators in the last years have open the possibility if using them for the generation for synchrotron radiation and even to drive a FELs
First observation of undulator radiation achieved in Soft X-ray
FEL type beam can be achieved with relatively modest improvements on what presently achieved and significant improvement on the stability of these beams
Beyond fourth generation light sourcesBeyond fourth generation light sources
Layout of a compact light source driven by a LPWA
LBNL-Oxford experiment (2006)LBNL-Oxford experiment (2006)
W. P. Leemans et al. Nature Physics 2 696 (2006) E = 1.0 +/-0.06 GeVΔE = 2.5% r.m.sΔθ = 1.6 mrad r.m.s.Q = 30 pC charge
Capillary: 310 μmLaser: 40 TWDensity: 4.3 ×1018 cm-3
Density 4.3 1018 cm–3
Laser Power > 38 TW (73 fs) to 18 TW (40 fs)
IoP NPPDGlasgow, 06 April 2011
Laser plasma wakefield accelerators demonstrated the possibility of generating GeV beam with promising electron beam qualities
Undulator radiation from LPWAUndulator radiation from LPWA
First combination of a laser-plasma wakefield accelerator, producing 55–75MeV electron bunches, with an undulator to generate visible synchrotron radiation
Undulator radiation Soft Xrays Undulator radiation Soft Xrays MPQ experimentMPQ experiment
22
2
2u
2
K1
2
Spontaneous undulator radiation and off-axis dependence
M. Fuchs et al, Nature Physics (2009)
Electron spectrum
radiation spectrum
Undualtor radiation Soft Xrays – MPQ experimentUndualtor radiation Soft Xrays – MPQ experiment
Stability of the electron beam quality is crucial for a successful FEL operation
IoP NPPDGlasgow, 06 April 2011
Alpha - X ProjectAlpha - X Project
Courtesy M. Wiggins
IoP NPPDGlasgow, 06 April 2011
Diagnostics development Diagnostics development
Can LPWA beam drive a Free Electron Laser (e.g. in the Soft X-rays) ?
Activity on diagnostics to characterise such electron pulses
Energy - Energy spread – Emittance - Pointing stability
Courtesy M. Wiggins
125 MeVdivergence 2-4 mradAverage emittance 2 um – best emtittance 1 umResolution limted
IoP NPPDGlasgow, 06 April 2011
Alpha X - Summary Alpha X - Summary
Beam quality appear to be close to the one required for driving FEL in the UV - XUV:
170 MeV beam
Measured emittance below 1 m
Charge 1 – 5 pC in 2 fs corresponding to 1-2 kA
Measured energy spread better 1%
should be sufficient at least to measure FEL gain in the XUV range
Progress is advancing nicely towards a working compact soft X-ray driven by a LPWA electron beam based on gas jet or capillary accelerator
talk by D: Jarosinsky tomorrow
IoP NPPDGlasgow, 06 April 2011
Users’ requirements pose difficult challenges for storage ring and FEL design and operation
The methods and solutions developed show that these challenges can be met.
Experimental tests of seeding in the coming future will confirm the extent of seeding capabilities to cover the whole Soft X-ray spectrum down to 1 nm
However, more compact and economic solutions to meet the present challenges are needed:
Injectors – IDs – LINACs RF technology …. LPWA
ConclusionsConclusions
Thank you for your attention.
IoP NPPDGlasgow, 06 April 2011
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