Design, status and roadmap of next generation low emittance ring R. Bartolini Diamond Light Source...

Design, status and roadmap of next generation low emittance ring

R. Bartolini

Diamond Light Sourceand

John Adams Institute, University of Oxford

Thanks to B. Hettel and M. Borland

ESLS XXII WorkshopGrenoble, 25 November 2014

OutlineOutline

• Overview of machine upgrade programmes (2010 vs 2014)

• Short survey of new ring desing

• Challenges in design and technology of ultra low emittance rings

• Matching users requests and conclusions


New rings and upgrades R&D programmes (2014)New rings and upgrades R&D programmes (2014)

MAX-IV 330 pm 3 GeV 7BASpring-8 II 70 pm (48) 6 GeV 6BAPEP-X 5 pm 6 GeV 7BAAPS 100 pm (25) 7 GeV 7BAUSR 3 pm 9 GeV 7BA

SIRIUS 280 nm 3 GeV TBAESRF II 140 pm (28) 6 GeV 7BA-hybridDiamond II 140-270 pm (20-10) 3 GeV (270 pm DDBA - 140 pm 5BA)ALS 100 pm (20) 2 GeV 9BABAPS 50 pm 5 GeV 10BA

SOLEIL 430 pm (10) 2.7 GeV DB-splitSLS 250 pm (20) 2.4 GeV Longitudinal gradient bendELETTRA 250 pm (28) 2 GeV 6BAANKA 5000 pm (18) 2.5 GeV split-TMECLS 800 pm (22) 2 GeV 7BASPEAR III 750 pm (13) 3 GeV DQBA

IPAC 11-12

USR Beijing 12

IPAC13-14


Upgrade programmes ~ 2010Upgrade programmes ~ 2010

Up until ~2010 upgrade of existing third generation light sources targeted

e.g .ESRF purple book

• Lower vertical emittance (lower coupling)• Longer straight sections (longer IDs or canted Ids)• Higher current (from 200 mA to 300 mA)• Top Up for 16 and 4 bunches modes• New technology: CPMU, RF NC HOM free cavities, SS amplifiers, BPMs.

e.g. APS studies

• ERL option• other intermediate upgrades options (not precluding the ERL option):• Longer straight sections (longer IDs, customized optics, canted Ids)• Higher current (from 100 mA to 200 mA)• Short pulses programme with crab cavities, • Increase BW of orbit feedback system to achieve sub-m stability up to 200 Hz


Why now ?Why now ?

• Science case is growing: NSLS-II, MAX-IV, APS, Spring-8, ESRF, …

science enabled by better photon properties

• Growing confidence in “aggressive” low emittance lattice designs

from DBA to MBA

injection in smaller apertures (…eventually on axis)

• Excellent control of the beam properties proven at many light sources

orbit, optics, stability, lifetime, losses, customised optics…

beam based tuning tools

• Key enabling technologies appear to be mature

no showstoppers in magnets, vacuum, diagnostics, RF, …


Science caseScience case

High brilliance and transversely coherent x-rays

- Uniform phase wavefronts: coherent imaging, holography, speckle, etc.

- Focusable to smallest spot size: nano-focus

- High flux (~1014-1015 photons/sec) in small spot: slits may not be required, etc.

- Round beams: H-V symmetric optics, circular zone plates, flexibility in optics

XDL 2011 Workshops for ERLs and DLSRs, Cornell, June 2011Beijing USR Workshop, Huairou, October 2012DLSR Workshop, SPring-8, December 2012DOE BESAC Subcommittee on Future Light Sources, July 2013SLAC DLSR Workshop, SLAC, December 2013DLSR Workshop, Argonne, November 2014

A number of workshop have discussed the science case for ultra low emittance lattices

A dedicated issue in Journal of Synchrotron Radiation is in publication


Lattice designLattice design

Growing confidence in “aggressive” low emittance lattice design

• Lattice design evolution from DBA, TBA to 4BA,…MBA:

• Lattice optimisation tools improved (linear and nonlinear dynamics)

Low emittance lattice require small angle bending

3d

32qx

N

1FC MBA lattices (large rings favoured)

dipolex

2

x HJ

22 'D'DD2D)s(H

Minimise and D and be close to a waist in the dipole


Multiple bend achromatsMultiple bend achromats

DBA 7BA

Simplified explanation– Emittance is driven by randomness of photon emission in presence of dispersive (energy-dependent) orbits – electron recoils randomly– Breaking up dipoles and putting focusing (quadrupoles) between the parts allows reducing the amplitude of dispersive orbits – smaller electron recoils


Design challengesDesign challenges

Linear optics– To reduce the amplitude of dispersive orbits, must bend more gently (small

bending angles) and focus more frequently and more strongly– Finding good optics with existing layout constraints is non trivial

Focusing (quadrupole) elements have chromatic aberrations– Sextupole magnets added to correct these– Introduces higher order aberrations that must be corrected– Require magnets with small bore radia

Stronger focusing leads to difficult non-linear dynamics– Poor “momentum aperture” reduced lifetime frequent injection– Poor “dynamic aperture” greater difficulty injecting – Some designs are considering on-axis injection

Collective instabilities are amplified with short bunches


Optimisation of beam dynamicsOptimisation of beam dynamics


Lattice designsLattice designs

MAX–IV (Sweden) is taking the first pioneering step with 7BA, under construction

3 GeV, 528 m, 0.25 nm

Sirius (Brazil) just started construction of 5BA with superbend

3 GeV, 518 m, 0.28 nm

L. Liu, LNLS.


ESRF (France)

6 GeV, 844 m, 4 nm → 150 pm

• Dispersion bumps for efficient sextupoles

• Longitudinal gradient dipoles (D1, D2, D6, D7) to further reduce emittance

• Combined dipole-quadrupoles D3-4-5

• 3-pole wiggler as hard X-ray source

now - ESRF DBA

future - ESRF 7BAAPS (US - preliminary)

7 → 6 GeV, 1104 m, 3.1 nm → ~65 pm• ESRF-style lattice, 3-pole wiggler

• Swap-out injection

• Superconducting undulators

SPring-8 (Japan)

8 → 6 GeV, 1436 m, 2.8 nm → <100 pm•lattice under development


ALS-U (US - LBNL)

1.9 GeV, 200 m, 2 nm → 52x52 pm• 9BA

• Swap-out injection from accumulator ring

• 3-T PM superbend insertions

ALS-II swap-out/accumulator

ALS-U 24-mm ID chamber

Other rings:

•SLS (Switzerland - PSI)

2.4 GeV, 288 m, 5 nm → 0.25 nm

•Soleil (France)

2.75 GeV, 354 m, 3.9 nm → 0.5 nm

…..


• Increase dispersion at chromatic sextupoles• Optimize magnets positions and length leaving more distance between dipoles

(no coil clash)• removed sextupoles in the new straight• Longer mid-cell straight section from 3m to 3.4 m – longer is unmanageable

A modified 4BA lattice for Diamond-IIA modified 4BA lattice for Diamond-II


upgrade with Diamond-II (200pm): upgrade with Diamond-II (200pm): 300mA and 1%K300mA and 1%K

Tuning curves computed with Spectra 8.0

Brilliance plot using U27 – 72 periods 2 m long with Kmax = 2.02


Survey of low emittance latticesSurvey of low emittance lattices


Experimental control of the beam opticsExperimental control of the beam optics

Growing confidence in the experimental control of the electron optics

Proven correction strategies

beam based tuning techniques

(better instrumentation: diagnostics, power supplies, …)

e.g. Diamond operates with a very good control of the beam optics • Optics deviation (beta-beating) redecue to 1% level• Emittance [2.78 - 2.74] (2.75) nm• Energy spread [1.1e-3 - 1.0-e3] (1.0e-3)• Emittance coupling ~0.08% achieved → vertical emittance ~ 2.0 pm (2009 WR)

6 m rms vertical

Records for smallest vertical emittance (2011-2014)Records for smallest vertical emittance (2011-2014)

APS

0.35 pm

Courtesy L. RivkinPSI and EPFL

SLS

0.9 pm


Comparison machine/model andComparison machine/model andLowest vertical emittance (back in 2011)Lowest vertical emittance (back in 2011)

Model emittance

Measured emittance

-beating (rms) Coupling*

(y/ x)

Vertical emittance

ALS 6.7 nm 6.7 nm 0.5 % 0.1% 4-7 pm

ASP 10 nm 10 nm 1 % 0.01% 1-2 pm

Diamond 2.74 nm 2.7-2.8 nm 0.4 % 0.08% 2.0 pm

ESRF 4 nm 4 nm 1% 0.1% 3.7 pm

SLS 5.6 nm 5.4-7 nm 4.5% H; 1.3% V 0.04% 2.0 pm

SOLEIL 3.73 nm 3.70-3.75 nm 0.3 % 0.1% 4 pm

SPEAR3 9.8 nm 9.8 nm < 1% 0.05% 5 pm

SSRF 3.9 nm 3.8-4.0 nm <1% 0.13% 5 pm

* best achieved 2011Since these early studies

SLS reached 0.9 pm V emittanceDiamond is providing 8 pm V emittance in users’ operationESRF is providing 8 pm V (and lower) emittance in users’ operation

Enabling technologyEnabling technology

Diamond, 11 July 2014

Compact magnet and vacuum technology• Precision magnet pole machining for small aperture magnets, combined function magnets, tolerance for magnet crosstalk (e.g. MAX-Lab)

• NEG-coated vacuum chambers enable small apertures to enable high magnet gradients

Pioneered at CERN, used extensively at Soleil, and adopted for MAX-IV and Sirius MBA lattices

MAX-IVCourtesy S. Leemans

SPring-8conceptK. Soutome

heater tape for in-situ NEG

bake-out Sirius

Enabling technologyEnabling technology

Other advances in accelerator and light source technology:

• High performance IDs (superconducting, Delta, RF, etc.)

SC undulator development at LBNL (S. Prestemon et al.), APS (E. Gluskin et al.) and elsewhere

Delta undulator prototype - A. Temnykh

Fast kickers (KEK ATF)

• Fast kickers for on-axis injection

• Accelerator and beam line component mechanical positioning and stabilizing systems

SPring-8 concept based on NSLS-II vibrating wire method - K. Soutome

• “In-situ” and beam-based magnet measurement and alignment methods

• Mode-damped RF cavities (fundamental and harmonic)

• Highly stable solid state RF power sources

Higher order resonances detected by

turn-turn BPMs (A. Franchi)

• Sub-micron e- BPMs with micron resolution single pass capability: non-linear lattice tuning

• Advances in X-ray optics and detectorsstart-to-end beam line system simulations, SC

detectors, cryo-cooled mirrors, etc.

ConclusionsConclusions

Many 3GLS operates since 2000’s with nominal parameters

• few nm H emittance

• 300-500 mA

• 8pm V emittance

However:

– 2010 Petra-III was commissioned 1 nm H emittance

– 2011-12 SLS and ASP ~1 pm V emittance (best achieved)

– 2012 ESRF et al. operate with 8pm V emittance

– 2013 ALS upgraded to a 2 nm H emittance lattice

– 2014 NSLS-II started operation 0.5 nm H emittance

– 2014 Petra III has tested a 160 pm lattice at 3GeV

– 2016 MAX IV 300 pm H emittance lattice

– 2019 ESRF II 140 pm H emittance lattice


ConclusionsConclusions

Man 3GLS are investigating a full ring upgrade (Diamond–II, SLS-II, SOLEIL, …)

Various MBA options are under analysis.

Some of the designs have still lots of flexibility in the technical choices

Need input from PBSs and Userswhat emittance?are round beams needed?alternate high beta – low beta ? operating modes (e.g. low alpha, …)?… open for any exotic ideas?

AP should explore tailoring the design to their specific beamlines


Low emittance ring communityLow emittance ring community

• ICFA Low Emittance Rings Workshops (LowERing)

• XDL 2011 Workshops for ERLs and DLSRs, Cornell, June 2011

• Beijing USR Workshop, Huairou, October 2012

• DLSR Workshop, SPring-8, December 2012

• Low Emittance Ring Workshop, Oxford, July 2013

• SLAC DLSR Workshop, SLAC, December 2013

• Workshop on Low Emittance Rings Technology (ALERT 2014), Valencia, 2014

• Low Emittance Rings Workshop (LER2014), Frascati, September 2014

• DLSR Workshop, Argonne, November 2014

The development of ultra low emittance rings is now seriously tackled by a large community, including damping rings and HEP colliders meeting regularly in workshop discussing general or dedicated topics (beam

dynamics, collective effects, technology for low emittance rings


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Design, status and roadmap of next generation low emittance ring R. Bartolini Diamond Light Source...

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