light sources and future prospects

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


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 )


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


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


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


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)


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


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


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)


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


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

coup

led

Ave

rage

Po

wer

(m

W)

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)


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


Alpha - X ProjectAlpha - X Project

Courtesy M. Wiggins


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


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


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.


light sources and future prospects

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