Low Emittance Rings Workshop, Oxford, UK - PowerPoint Presentation

Slide1

Low Emittance Rings Workshop, Oxford, UKJuly 8, 2013

ALS Brightness Upgrade & Future PlanH. 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.

OutlineIntroduction - ALS UpgradesBrightness UpgradeLattice ChoiceMagnet DesignInstallation/Commissioning

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

2

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 6/2010Magnet Installation 10/2012-3/2013 Migration to low emittance 4/2013

Brightness Upgrade

223 microns (FWHM)

68 microns (FWHM)

Superbend

Sourcepoints

3

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 chromaticityStrengthening them would dramatically reduce dynamic aperture (lifetime, injection efficiency)Need additional degrees of freedom‘Harmonic’ SextupolesALS lattice already full – needed to replace existing corrector magnets with multi-magnetsPossibility for low alpha operationTHz, short bunches

4

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

b

x

lattice would optimize brightness for the insertion devices further

Current Lattice

New Large

b

x

Lattice

New Small

b

x

Lattice

5

Baseline Lattice: Dynamic Aperture

Dynamic aperture is fairly large (larger than current lattice)Dynamic Momentum Aperture largerTouschek Lifetime longer than present latticeDespite higher density

6

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

7

Top-off calculations with new magnets

Re-analysis necessary, new field profilesNo 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 slicingShorter pulses

Supporting analysis of magnet test results – Reducing Commissioning RiskHysteresisBandwidthMultipole contentContinuing work to explore low

bx lattices

Accelerator

Physics Work

8

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

9

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

Beamsize and Beam Dynamics Measurements

10

BL 6.3.1

BL 6.3.1

Confirmed larger dynamic and momentum aperture than high

emittance

lattice

Beamsize

Reduction

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 limit100x increase

in brightness

angle

Diffraction Limit upgrade on a 200m circumference ring

enables

nanoscale

microscopes with chemical, magnetic, and electronic resolution

Chemical Maps

From 20 nm to 2 nm; from 2D to 3D

Resolve

nano

-interfaces in a cathode

Observe the flux in a catalytic network

Electronic MapsnanoARPES of complex phases at 25 nm resolutionMagnetic Maps

Thermally-driven domain fluctuations imprinted in speckle at nm resolution

new magnets

old magnets

13

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

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/m

Pole Tip Flux:

1.0

T

3000

T/m

2

Pole Tip Flux 0.45T

80

T/m

Pole 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

Storage

Ring

Accumulator

Ring

injecting

0.1*

I

beam

Bunch

Trains

S

tored

train

S

tored

train

Injected

train

SummaryBiggest challenge (as well as opportunity) for ALS – Continuous RenewalWell balanced plan between machine/facilities upgrades and beamline

/endstation renewalMajor Machine Renewal example: Brightness upgrade reduced horizontal emittance from 6.3 to 2.0 nmBeamlines can resolve brightness increase and realize (full) benefitDramatic performance improvements beyond ALS are possible (at moderate cost) and are now being actively studied.

18