Low Emittance Rings Workshop, Oxford, UK July 8, 2013

H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013

Low Emittance Rings Workshop, Oxford, UKJuly 8, 2013

ALS Brightness Upgrade & Future Plan

H. Tarawneh, C. Steier, A. Madur, D. RobinLawrence Berkeley National Laboratory

B. Bailey, A. Biocca, A. Black, K. Berg, D. Colomb, N. Li, S Marks, H. Nishimura, E. Norum, C. Pappas, G. Portmann, S. Prestemon, A. Rawlins, D. Robin, S. Rossi, F. Sannibale, T. Scarvie, R. Schlueter, C. Sun, W. Wan, E. Williams.


Outline• Introduction - ALS Upgrades• Brightness Upgrade

– Lattice Choice– Magnet Design– Installation/Commissioning

• Future directions (ALS-II) - Pre-conceptual: Lattice, Magnets, Injection.• Summary

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Brightness Upgrade Scope:Replacement of the current 46 dipole corrector magnets with 48 combined function magnets (sextupole+HCM+VCM+skew), as well as associated power supplies, controls, interlocks, chamber modifications Project Schedule:- Magnet RFP 6/2010- Magnet Installation 10/2012-3/2013 - Migration to low emittance 4/2013

Brightness Upgrade

223 microns (FWHM)

68 microns (FWHM)

Superbend Sourcepoints

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ALS for 20 years has been extremely successful in (soft) x-ray science and newer Facilities could provide potentially better performance and better tools


Why do we add sextupoles?• Reducing the equilibrium emittance is achieved

changing settings of existing quadrupoles • Problem is nonlinear dynamics:

– Sextupoles are too weak to correct chromaticity– Strengthening them would dramatically reduce dynamic

aperture (lifetime, injection efficiency)• Need additional degrees of freedom

– ‘Harmonic’ Sextupoles– ALS lattice already full – needed to replace existing

corrector magnets with multi-magnets• Possibility for low alpha operation

– THz, short bunches4


Lattices for ALS upgrade

• There are several possible lattices with ~2 nm rad emittance– 3x smaller than the nominal ALS (~6.3 nmrad)

• Large bx lattice optimizes brightness for the central bends

• Small bx lattice would optimize brightness for the insertion devices further

Current Lattice New Large bx Lattice New Small bx Lattice

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Baseline Lattice: Dynamic Aperture• Dynamic aperture is fairly large (larger than current lattice)• Dynamic Momentum Aperture larger• Touschek Lifetime longer than present lattice

• Despite higher density

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• Received funding (summer 09)• Comprehensive project review (12/09)• Awarded magnet contract (9/10)• Detailed magnet design review (3/11) • Prototypes of 3 magnet types complete (12/11)• First set of 13 production magnets shipped (4/12)• All magnets received (8/12)• Pre-Installed 13 of 48 sextupoles (1/13)• Remaining magnets and power supplies installed (3/13)• User operation in high brightness mode (2.0 nm emittance) – since (4/13)

Project History

Existing Correctors

Sextupole / Corrector Multimagnets

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Top-off calculations with new magnets– Re-analysis necessary, new field profiles– No hardware changes necessary– Wider ranges on topoff interlocks

New fs-slicing bump for new lattice– Using MOGA optimization techniques– Making use of new skew quadrupoles– Also evaluating to switch to horizontal

slicing– Shorter pulses

Supporting analysis of magnet test results – Reducing Commissioning Risk– Hysteresis– Bandwidth– Multipole content

Continuing work to explore low bx lattices

Accelerator Physics Work

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Commissioning Results

Measured horizontal photon beam profiles showing the reduction in size and increase in brightness. Above: BL 12.3.2, Below: BL 6.3.1

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• Installation completed on time (Mar/Apr 2013)

• Quick Commissioning Progress– Benefit of pre-installation and

commissioning: orbit feedbacks, detuned upgrade lattice

• Managed to deliver low emittance beam during BLC shifts – and continue into user operations– 3 months ahead of schedule

• Beamlines able to resolve brightness increase

• Reliable operation (no faults due to new lattice or hardware so far)


Beamsize and Beam Dynamics Measurements

-400 -200 0 200 400-100-50

050

100 October 24, 2012 October24_2012.opjz

(m

)

y (m)

-400 -200 0 200 400-100

-500

50100 spot_size_April16_2013.opjApril 19, 2013

z (

m)

y (m)

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BL 6.3.1

BL 6.3.1

Confirmed larger dynamic and momentum aperture than high emittance lattice

Beamsize Reduction

H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013 11

Brightness Comparison• Comparison to

existing and future light sources (and upgrades)

• Below 1 keV (soft x-ray) ALS is competitive now

• Future: NSLS-II and Max-4 will outperform ALS above 100 eV

Triple Bend Achromat provides very bright bend and Superbend source points from center bend magnets – ALS (2 nm) above NSLS-II 3PW


Looking beyond completed Brightness Upgrade: Assuring world class capabilities for the future

Potential upgrade of ALS ring to diffraction limit

100x increase in brightness

angle

Diffraction Limit upgrade on a 200m circumference ringenables nanoscale microscopes with chemical, magnetic, and electronic resolutionChemical Maps

From 20 nm to 2 nm; from 2D to 3DResolve nano-interfaces in a cathodeObserve the flux in a catalytic network

Electronic MapsnanoARPES of complex phases at 25 nm resolution

Magnetic MapsThermally-driven domain fluctuations imprinted in speckle at nm resolution

new magnets

old magnets

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Diffraction Limited Light Sources Recent realization: Still large potential for storage ring

sources• Smaller vacuum+magnet aperture – Multi bend achromat lattices with low

emittance.• Actively pursued: MAX-IV, SIRIUS, ESRF-2, Spring8-2, BAPS, … Transverse diffraction limited to 2 keV for ALS size is possible

– ALS-II• Using the ALS tunnel to achieve moderate low emittance with moderate

cost.


Ongoing Conceptual Machine Design Work

Active Areas of Conceptual Machine Design:• Lattice Optimization• Injection• Collective Effects• Engineering

Considerations (Magnets-DC/pulsed, RF, Vacuum)

• Cost/Schedule

-3 -2 -1 0 1 2 30

0.5

1

1.5

2

2.5

x position [mm] (injection straight)

y po

sitio

n [m

m]

ALS-II lattice frequency map, x = 0cm, x = 41.1265

-10

-9

-8

-7

-6

-5

-4

-3


Third generation light sources = generous physical apertures (except for IDs which define much smaller admittance) – smaller apertures (factor 3) = much stronger magnets

Nowadays field quality with smaller magnet apertures achievable

MBA lattices provide smaller natural emittances NEG coating - distributed pumping in small

chambers (cheaper)

ALS-II Magnet System

0.78 T & 50 T/mPole Tip Flux: 1.0 T

3000 T/m2 Pole Tip Flux 0.45T

80 T/mPole Tip Flux: 0.9 T


ALS-II Injection Scheme

Brightness evolution

On-axis injection into SR due to small DA Accumulator Ring (AC).

Accumulator ring shares the SR tunnel. AC Lattice Req. (a) DA of ±10 mm. (b) Lifetime ≥2 h. (c) Minimum 4 Straight sections.

Partial Swap-out injection is foreseen Relax requirements on AC ring & pulsed magnets, I=100 mA

𝜖𝑥5𝜖𝑥 𝜖𝑥 Storage

Ring

AccumulatorRing

injecting0.1*Ibeam

BunchTrains

Storedtrain

Storedtrain

Injectedtrain


Summary• Biggest challenge (as well as opportunity) for ALS –

Continuous Renewal– Well balanced plan between machine/facilities upgrades and

beamline/endstation renewal• Major Machine Renewal example: Brightness upgrade

reduced horizontal emittance from 6.3 to 2.0 nm• Beamlines can resolve brightness increase and realize (full)

benefit• Dramatic performance improvements beyond ALS are

possible (at moderate cost) and are now being actively studied.

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Low Emittance Rings Workshop, Oxford, UK July 8, 2013

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