1 BROOKHAVEN SCIENCE ASSOCIATES NSLS-II Accelerator Systems Advisory Committee, July 17-18, 2008 NSLS-II Injection System T. Shaftan Accelerator Physicist

1 BROOKHAVEN SCIENCE ASSOCIATES

NSLS-II Accelerator Systems Advisory Committee, July 17-18, 2008

NSLS-II Injection System

T. ShaftanAccelerator Physicist

NSLS-II Accelerator Systems Advisory CommitteeJuly 17-18, 2008



Acknowledgements

R. Heese, J. Rose, N. Tsoupas, I. Pinayev, S. Ozaki, F. Willeke, E. Weihreter, Y. Li, W. Guo, B. Nash,

M. Fallier, M. Ferreira, R. Alforque, S. Krinsky, E. Johnson, A. Blednykh, O. Dyling, R. Meier, S.

Sharma, D. Hseuh, G. Ganetis, T. Shaftan, O. Singh, J. Skaritka, M. Rehak, J. O’Connor, C. Lavelle,

P.K. Job, B. Casey, T. Mennona



Outline

• Introduction• Injector design specifications and main parameters• Injector layout

• Linac • Booster• Transport lines• Storage Ring injection straight section

• Summary• Future plans



Introduction

• NSLS-II requires reliable injector capable of filling and maintaining storage ring current

• Top-off mode of injection is required• More detailed design has been developed on preliminary

design of 200 MeV linac and 158 m 3 GeV booster presented at the ASAC in Oct. 2008

• Linac and booster are envisioned as semi-turnkey procurements

• Transport lines and ring injection straight are going to be built by BNL



Storage Ring Parameters Related to Injection

Parameters Value

Energy, GeV 3Circulating current, A 0.5Circumference, m 792Revolution period, s 2.6RF frequency, MHz 500Circulating charge, C 1.3Total number of RF-buckets 1320Number of filled buckets 13204/5108

0Charge per bunch, nC 1.25Beam lifetime, hours 3Top-up cycle time, min 1Beam current change between top-ups, % 0.55%Charge variation between top-up cycles, nC 7.3



Requirements for NSLS-II Injection

Discussed with users on their desired bunch patterns and top-off formats

Two bunch patterns are in NSLS-II baseline: 4 or 5 bunch trains with shorter gaps totaling

about 80% of the full buckets uniform fill with 20% ion-clearing gap

Complex bunch patterns (camshaft bunches or 100% uniform fill) are not precluded and foreseen as future upgrades.

Current stability and purity Relative current stability of 1% is the baseline

number. Charge in empty bucket <10-4 x nominal charge Minimum interval between two consecutive top-off

is 1 min. Gating signal to users is to be provided.

NSLS-II bunch patterns

4/5 1/5It

It

1 turn

Iinj

1min t

NSLS-II top-off format



• Many (~1000) bunches in the ring multi-bunch injection

• NM bunches in the injected train• Filling NM consecutive buckets in the

ring• Sequentially shift the injection timing• 1 Hz injector rep rate suffices with

pulse train injection• 1 minute between injector cycles for

top-off• Interacting with users on the requirements

for top-off and complex bunch patterns• Developed simulation on SR pattern

non-uniformity• Evaluated rate of contamination of

“empty” buckets by Touschek-scattered particles

Injected bunch train (NM=80-150)

t

#Ring bunch pattern

Ib

Top-Off Injection Scenario

0 200 400 600 800 1000 12000

20

40

60

80

100

120

SR bucket number

Sca

led

curre

nt p

er b

unch

, %

SR bunch pattern after 48 hours of continuous top-off

80 bunches in injected train




NSLS-II Injector Complex Overview

200-MeV linac

3-GeV booster

LB TL

B-SR TL

Injection straight



Linac

• SR injection: 7.3 nC/min10% loss at SR injection20% loss at booster extraction

30% beam loss at booster injection 15 nC per pulse

• NSLS-II: 200 MeV, 15 nC/train, ~0.5% energy spread

• Linac can be procured turn-key• January 2008 we visited SOLEIL and

THALES• Acquired information regarding linac

hardware, utilities and performance• Acquired information on beam

measurement data• Participated in linac studies

0 0.5 1 1.5-0.04

-0.035

-0.03

-0.025

-0.02

-0.015

-0.01

-0.005

0

0.005

Time, s

Booster bunch train

B-SR bunch train

SOLEIL measurement of injected bunch train

SOLEIL linac

J. Rose



Linac Configuration

3 GHz, 100 MeV linac is in operations at ASP (ACCEL) 3 GHz, 100 MeV linac is in operations at SOLEIL (THALES) Achieved parameters:

4/0.25 nC/pulse in LPM/SPM at ASP 10/0.5 nC/pulse in LPM/SPM at SOLEIL

Close to NSLS-II requirements Linac Front-End funding is planned in FY09 to procure and establish

gun performance

Thales linacJ. Rose, R. Meier



Booster

• Booster accelerates beam from 200 MeV 3 GeV

• Tracking studies have been carried out with nearly complete ring model: booster emittance of ~30 nm is adequate for low-loss injection

• Compact (158.4 m) and low-emittance (30 nm at 3 GeV) lattice

• Accelerates bunch trains • Repetition rate of 1 Hz• Charge per train 10 nC

• RF system (by BNL): PETRA cavity and IOT• Optimized injection and extraction systems:

DC septa• Semi turn-key procurement that is close to

existing solution

Lattice

Similar to Australian Synchrotron Project booster

Structure

Acknowledge work of W. Guo, Y. Li, B. Nash



Progress on booster lattice

• CD2 New lattice version• Similar magnet parameters as in CD2

lattice• Straight section length increased 7.05

7.7 m• Vertical tune (and chromaticity) is

decreased• DA (on- and off-energy) is increased to

larger than vacuum chamber aperture• Dispersion in straight decreased to 10 cm• Emittance is 33 nm at 3 GeV – needs

more work• Orbit correction scheme is adequate• 20 mA in the booster: study of collective

effects is under way

-30 -20 -10 0 10 20 300

5

10

15

20

25

p/p=-3%p/p=0%p/p=3%

Dynamic aperture

Dipole

physical aperture

x

y

Dynamic Aperture Scan [mm2]

10.15 10.2 10.25 10.3 10.35 10.44.15

4.2

4.25

4.3

4.35

4.4

4.45

200

250

300

350

400

450

500

550

600

650

700

Y. Li



Optimization of booster extraction and injection systems

0 1 2 3 4 5 6 7 8 9 10-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 1 2 3 4 5 6 7 8 9 10-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

CD-2• A single pulsed septum 150 mrad• Assume beam divergence of 80 urad

(horizontal) at extraction• RMS beam divergence = error at:

• Kicker stability (flatness) of 1.6%• Septum stability (flatness) of 0.05%

Reducing sensitivity to waveform jitter and noise

CD-3• Combination of weak pulsed septum (47 mrad) and DC septum (96 mrad)

• Kicker stability (flatness) of 1.6%• Septum stability (flatness) of 0.2%

QF QG QG QF

BB B

B

DC septum

kicker

pulsedseptum

BB B

B

kicker

pulsedseptum

QF QG QG QF



Magnet design

DC extraction septum

Transport line quadrupole

M. Rehak, R. Heese

• Magnet definition is in progress for injector:• LB TL: 4 dipoles, 14 quadrupoles• Booster injection and extraction system• BSR TL: 4 dipoles, 16 quadrupoles• Injection straight: pulsed magnets

• Transport lines:• Quadrupoles: 2 type of yokes, 3 types of

different coils• Dipoles: 3 types of yokes, 3 types of coils• Correctors: 2 types of yokes, 2 types of coils

• Complex magnets: DC extraction and SR injection septa

• Soon start magnetic design of pulsed magnets



Layout of LB TL In the past months:

SOLEIL experience: energy slit after linac is very helpful

Redesigning LB TL to increase dispersion at energy slit

New booster injection scheme is implemented

Beam optics is complete Local shielding design is under way Diagnostics beam lines are to be designed

ES

R. Heese, R. Meier



Booster to Storage Ring Transport Line

In the past months: Addressed all incompatibility between TL

and building New booster extraction scheme is

implemented in the BSR TL Beam optics complete Placement of corrector magnets, and beam

diagnostic devices complete Tolerance studies complete Diagnostics beam line is being designed

N. Tsoupas, R. Meier



Storage ring injection straight

• Quad-to-quad distance is 9.3 m• Combination of strong DC pre-septum

with pulsed septum• Closed bump of 15 mm• Kickers with 5.2 μs long pulse powered

separately• Pulsed magnets (3.15 GeV max) are

within vendors capabilities• Magnet and PS design is under way

• Development and optimization of pulsed magnets and PS (total of 13 magnets of 7 types for NSLS-II) in-house: Pulsed Magnet Lab in FY09

R. Heese, M. Ferreira, D. Hseuh



Pulsed magnet tolerance analysis• Study of the residual field errors in closed

bump (for the maximum stored beam displacement)

• Vertical error: random kicker roll of 0.5 mrad (3.75 µrad angular vertical kick)

• Horizontal error: 0.1% kicker-to-kicker random amplitude mismatch

• Consider combination of 4 kickers and scale total to the Source Points of Short and Long Straight sections

• Compare with RMS beam size and divergence at the Source Points

• Horizontal error is of order of RMS beam parameters

• Vertical error exceeds RMS parameters• Need set-up of Pulsed Magnet Lab to

develop methods of error reduction• Tolerance analysis is ongoing

Horizontal error scaling for kicker mismatch

Vertical error scaling for residual kicker roll

Orb

it an

gle

at S

P (

µra

d)

0 100 200 3000

10

20

30

40

50

xrpLS

xrpSS

xrSS xrLS

0 20 40 600

10

20

30

40

ypLSypSS

ySSyLS

Orb

it an

gle

at S

P (

µra

d)

Orbit shift at SP (µm)

Orbit shift at SP (µm)



Injector building

12

345

67

8

9

10

11

13

12

14

15

1617 18

N

Supplemental shieldingPenetration

Safetydevice

Cabling

Entrance



Utilities, injector components, safety

• Multiple iterations on building layout • 80% Title II Design complete

• Injector utilities (electric power, water, compressed gas) are specified

• Injector components• Booster Power Supplies performance specs

established• Injector element specification is in progress• Injector magnet design and PS specs are in

progress• Cable/signal list is compiled• Component naming convention to be

discussed• Safety review took place

• Assessed beam parameters envelope• Assessed beam confinement system• Design of safety devices is under way

NSLS-II beamdump design

APS safety shutter

R. Alforque



Procurements• Linac: visited THALES and SOLEIL in January• Linac Front-End to be procured in FY09• Booster RF: visited DESY in July• Booster: two potential vendors visited NSLS-II in

January and March• Booster Statement of Work completed in April • Information on:

• Scope of delivery• Timeline• Performance specifications• Acceptance testing• Conventional constructions• Mechanical and Electrical utilities• Diagnostics and Controls• Norms and Standards

• Booster SOW was sent to three potential vendors for budgetary quotes and schedules

• Expecting information from two vendors in August



Summary

• NSLS-II full energy injector will support top-off operations in presence of limited beam lifetime

• Multi-bunch injection with high charge per bunch train• Linac and booster are envisioned as major procurements• NSLS-II booster is based on existing design (low-emittance cost-effective solution) with

modifications• We are moving forward with design of injection straight section and transport lines• In the design process we use experience from other state-of-art light sources• In the past months injector development was focused on:

• Finalizing injector building specifications• Setting specifications on utilities, safety systems, interfaces with NSLS-II subsystems• Optimization of the booster lattice, injection/extraction systems• Transport line design and specification of components• Design of the storage ring injection straight• Interaction with vendors• Draft of CD-3 Design Report is nearly ready



Important dates for NSLS-II injector

• CD-2: injection system baseline design is developed• During FY08-FY09 we are refining design and perform value engineering effort, prepare

specs for procurements• Specifications are ready for procurement:

• Linac Oct 09• Booster Aug 09• Booster RF Aug 11• Utilities Dec 10• TL Mar 10

• At this point the design and specs by BNL are finalized• Procurement begins:

• Linac Oct 10 • Booster Mar 10 • TL Apr 10 • Utilities Nov 09

• Injector Building BOD end Nov 11



Extra



Uniformity of bunch pattern

• Requirement on SR bunch pattern uniformity is 20%

• Can we preserve the uniformity while executing top-off with bunch trains?

• “Hunt&Peck” mode of injection at SLS• Simulation with assumptions:

• Touschek-limited lifetime• Phase transient induced by harmonic cavity• Noisy (20%) injected bunch train• Filling consecutive N=80…150 buckets in one

top-off cycle• Results after 2 days of continuous top-off

show no deterioration of bunch pattern• “Hunt&Peck” mode with bunch trains to be

studied

0 200 400 600 800 1000 12000

20

40

60

80

100

120

SR bucket numberSc

aled

cur

rent

per

bun

ch, %

SR bunch pattern after 48 hours of continuous top-off





Maintaining purity of “empty” RF buckets

To maintain the purity of empty buckets on 1E-4 level we will need to do cleaning ~every 3 min

Very first energy band is located at 4.3% off the nominal energy.

This is a pessimistic estimate assuming no limits on machine energy acceptance. Real energy acceptance (limited by a scraper) will reduce migration rate.

This analysis includes only Touschek-scattered particles migrating from full to empty buckets. In reality there will be additional particles coming from injected beam every top-off cycle.

Needs an analysis of the bunch cleaner in the booster.

0 1 2 3 41 10

5

1 104

1 103

0.01

0.1

1

Fractional Migration Rate per hour

Bucket number



Booster RF System

• Signed MOU with DESY for two 5-cell PETRA cavities, to be delivered in early FY2009• Need to work out coupler interface

Documents

1 BROOKHAVEN SCIENCE ASSOCIATES NSLS-II Accelerator Systems Advisory Committee, July 17-18, 2008 NSLS-II Injection System T. Shaftan Accelerator Physicist