h. tarawneh, c. steier, a. madur, d. robin. l.e. workshop, july 9, 2013 low emittance rings...
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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.
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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 bunches
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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
• 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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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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)
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
Beamsize and Beam Dynamics Measurements
-400 -200 0 200 400-100
-50
0
50
100October 24, 2012 October24_2012.opj
z (
m)
y (m)
-400 -200 0 200 400-100
-50
0
50
100spot_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
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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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H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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.
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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
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-9
-8
-7
-6
-5
-4
-3
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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
H. Tarawneh, C. Steier, A. Madur, D. Robin. L.E. Workshop, July 9, 2013
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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