NSLS-II Injection System update

1 BROOKHAVEN SCIENCE ASSOCIATES

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

NSLS-II Injection System update

T. ShaftanInjection System group leader

NSLS-II Accelerator Systems Advisory CommitteeMarch 26-27, 2009


Acknowledgements

R. Heese, J. Rose, R. Fliller, B. Parker, M. Rehak, S. Ozaki, F. Willeke, E. Weihreter, Y. Li, S. Kramer,

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, H. Ma,T. Shaftan, O. Singh, J. Skaritka, N. Tsoupas,

J. O’Connor, C. Lavelle, I. Pinayev, E. Trakhtenberg,P.K. Job, B. Casey, T. Mennona, G. Woods, J. Zipper

NSLS-II Accelerator Systems Advisory Committee, March 26-27, 2009


Outline

• Injector design specifications and requirements• Linac • Booster• Transport lines• Storage Ring injection straight section• Pulsed Magnet lab• Summary



Introduction-Requirements

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

• Top-off mode of injection is required • Specifications for NSLS-II injector

• Storage ring: 3 GeV, 0.5 A, 1080 bunches in 1320 RF buckets, 3 hr lifetime• Top-off: deliver 80…150 bunches with 7.3 nC total charge once a minute total

stability of ring current 0.55%, bunch-to-bunch charge deviation 20%• Repetition rate of 1 Hz is sufficient with multibunch injection:

Initial fill 00.5 A in 3 min• Supported Storage Ring Bunch patterns:

• Baseline: uniform fill with 20% ion-clearing gap or 4-5 bunch trains with short gaps• Future upgrade: camshaft bunch(es), uniform fill• Future upgrade: Bunch cleaning, Empty/Full RF bucket charge ratio 0.01%• Last year’s work: analysis of ring bunch pattern uniformity and calculation of

contamination of empty ring buckets • Dialog with NSLS-II users on injection requirements


NSLS-II Injector


R. Meier



Injector building

12

345

67

8

9

10

11

13

12

14

15

1617 18

N

Supplemental shieldingPenetration

Safetydevice

Cabling

Entrance

•Multiple iterations on building layout: no conflicts with injector

•100% Title II Design complete

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

•Injector BOD is moved up in schedule to May 2011

• Construction starts soon!


Linac

• Design and Modeling• THALES linac model is in studies; charge/ bunch

scaled up• Linac Front-End beam dynamics completed• Linac Front-End diagnostics station design is assessed• Overall linac design is nearly complete

• Next steps:• Set-points and tolerances• Initial conditions for transport line • Diagnostics performance

90 keV

15 MeV

R. Fliller

Linac FEAn option

R. Fliller

J. Rose



Booster• Tests of injection efficiency• Injection modeling with CD2 booster

lattice at injection energy• “Square” magnet model• Magnet errors• Misalignments• RF cavity• Orbit/Tune correction

• Conclusions: • SC aperture of CD2 lattice (X:15mm/1.7mrad; Y:

5.6mm/1.4mrad) • Substantially smaller than that in ASP• Tighter tolerance for injection errors• Prohibits concept of beam stacking considered

before• “4-bump” concept of beam stacking is under

consideration

R. Fliller

X Y



Booster• Finalizing preliminary lattice design• CD-2 lattice

– High y High y

– Small footprint of large DA in tune space– High sensitivity to errors– Small stay-clear aperture– Straight-section length 7.05m– Strong quadrupole– High dispersion in straights– Long BD magnets (3.6 GeV)

• Several new lattice versions have been developed


CD-2

new

S. Kramer, R. Fliller


Booster• Booster magnetic element analysis

• Models of all dipoles, quadrupoles, sextupoles, correctors are created

• Coil models developed• R, L, UPS, IPS, P are calculated• Compared with the ASP values

• “Build-in-house” booster cost estimate

• Cost/labor of subsystems (accelerator design, magnets, PS, vacuum, controls, instrumentation/ diagnostics) were estimated

• Compared with vendors’ cost estimates

• Work on preparation of procurement documents is ongoing

• Booster RF cavities arrived and being tested(see J. Rose’s talk)

M. Rehak

OPERA-3D

MERMAID

Analytic

estimate



Extraction system design

• Extraction septum design• Geometry of extraction straight: DC

septum is close to booster chamber• Septum design (shielding) leads to field

of only ~1Gs inside booster chamber• Ramping DC septum is a possibility

• Extraction magnet tolerances• Booster emittance is small (~35 nm)• Tolerances (<20% of x):

– extraction kicker -- 0.2% amplitude– extraction septum – 0.02% amplitude Extraction septum: B. Parker



Transport lines• Optimization of TL elements• Revision of instrumentation• Consideration of commissioning

scenarioTL equipment LTB BSRDipole 4 4Quad 17 16Corrector 10 17Dipole PS 1+1 4Quad PS 12+6 12+4Corrector PS 9x2 9x2ICT 2 2FCT 2 2BPM 6 7Flag 9 9Energy slit 1 1Pumps 10 11Gauges 3 4Valves 5 6dipole chambers 2 3chamber to dump - Y 2 1quadrupole pipes with BPM 8 7BPM block machining 8 7Drift pipes 18 27



Kicker tolerances in 4-kicker bump• Tolerance analysis focusing on:

• Tilt of kickers• Kicker amplitude mismatch

• Calculations cross-checked via• Analytic calculation• Tracking particles in complete SR model• Assuming realistic waveforms and multiple

turns• Observing orbit shift and angle in source

points (centers of straight sections)• Conclusions: to maintain x,x’ <0.1x,x’

• Kicker amplitude mismatch A< 0.810-4

• Kicker roll y<1.2 10-5 rad• Discussing tolerances with users• Developing Pulsed Magnet lab


orbit shift

orbit angle

RMS beam size

1st SS2nd SS3rd SS


Storage ring injection straight section• We are considering injection via pulsed

multipole magnet• Both quadrupole and sextupole schemes

were analyzed; sextupole is chosen• Geometry layout with PSM is developed

• Guidelines for PSM design:• Angle/coordinate at injection point are same

as for baseline (4k) scheme• Same (or close) angle/coordinate at

entrance of injection straight section• Same requirements on DA of storage ring

for injection• Waveform 2 revolutions (5.2 µs) long

septum

PSM

xs

xk

L

Lk

F. Willeke

Normalized phase space

1

2

3

1

2

3



Pulsed Sextupole magnet

• Pulsed Sextupole magnet design• 0.5 m long, field 0.5 T pole tip, half-sine pulse 5.2

µs long• Design goal: minimize inductance and, thus, PS

voltage• Current magnet layout is close to the that of PF in

Japan (H. Takaki et al., PAC-2007)• PS voltage 30 kV, current 3 kA• OPERA 3D with time dependence

• PSM tolerances• Considered PSM transverse translations and tilt• Conditions x,x’ <0.1x,x’ for stored beam orbit• Conclusion: vertical alignment tolerance <10 µm!

• Impact on stored beam size/shape• Insignificant

50 µH 30.75 µH 14 µH

PSM optimization: M. Rehak

Distortion of beam shape in horizontal phase space (PSM)

no PSM

PSM



PSM: Summary• Advantages

• Replacing 4 pulsed magnets• Increasing reliability• Decreasing cost• Beam dumps less risky

• Challenges• Tight tolerances on vertical alignment • PS (27 kV, 3.2 kA)• Tight arrangement of injection straight to

maximize distance septum-PSM• PSM induces strong focusing for injected beam

– Difficult to match BSR TL (large beam size)– BSR TL requires more magnets

• This injection scheme requires high stability of both injected and stored beams

• Conclusions:• Build prototype of PSM and PS in Pulsed

Magnet lab• Work out feasible scheme for PSM alignment

and trajectory controls

x=6mm

y=1.5mm

R. Fliller

R. Meier

PSMseptum



Pulsed Magnet Lab Status• Pulsed Magnet lab is being set up for

• performance evaluation and calibration of final magnets

• test innovations and concepts required to make top-off operation transparent to NSLS-II users

• Tolerances required to have non-invasive top-off injection will be difficult to meet and maintain, some innovation is required

• Present funding is inadequate, request for additional funding has been presented

• PML status• Lab space assigned, materials/tools on order• 35 ft. x 15 ft. caged, interlocked test area under

construction• Sr. Scientist on board full time• Experienced Head Technician hired• Post-Doc starting in mid-April• Engineering candidate in interview process• First order of business: Pulsed sextupole prototype

construction and evaluation

Bldg. 832

R. Heese


Summary

• Injector design is on-going• Injector is entering procurement stage; expediting procurements of linac

and booster• In the past few months work was focused on:

• Setting injector specifications• Preparation of linac and booster procurements documents• Meeting with vendors• Designing injector magnets• Revising diagnostics for TLs and considering commissioning scenario• Developing injection scheme via Pulsed Sextupole magnet• Starting set up of Pulsed Magnet lab• Studying tolerances for pulsed magnets




Extra


Comparison 4K PSM


Parameter DC sept. Pulsed sept.

Kicker Weak kick.

Length, m 1.8 2 0.5 0.2Field, T 0.833 0.42 0.165 0.053Poletip field, T 0.833 0.42 0.165 0.053Angle, mrad 150 80 8.5 1Aperture X/Y, mm/mm 50/20 20/15 60/27 60/30

Design ¼ SiS lam.

¼ SiS lam.

CMD5005

CMD5005

Inductance, µH n/a 3.35 1.396 0.5027

Parameter DC sept. Pulsed sept. PSM

Length, m 1.5 1 0.5

Field, T or else 1.5 0.4 1550 Tm-3

Poletip field, T 1.5 0.4 0.484

Angle, mrad 225 40 2.8

Half aperture, mm x mm 5/20 20/15 25/25

Design ¼ SiS lam. ¼ SiS lam. CMD5005

Inductance, µH n/a 14

4 Kickers PSMMagnets

Power Supplies

R. Heese, E. Weihreter


Response to the ASAC-2008 comments• Expedite injector procurements

• Accelerated schedules for linac/booster are prepared• Procurement documents are getting ready • Funds may available for accelerated procurement• Injector building BOD is moved up by 6 months

• Group tenders for linac and linac FE into one• Yes; early procurement for linac FE. See J. Rose’s talk.

• Do not procure linac FE in advance• Need to test and commission LFE early to prove feasibility of the design• Need to test performance in flexible bunch pattern mode still planning on procuring LFE in advance

• Insufficient labor resources for pulsed magnets development• Actively hiring personnel, postdoc and tech is onboard• Looking for a skilled electrical engineer



Response to the ASAC-2008 comments Cont’d

• Including RF system into booster contract?• Under consideration

• Analyze the Pulsed Sextupole option as the ring injection scheme• In progress; decision to be made in Dec. 2009

• Standard pumps and gauges across the project• Yes

• High bunch purity implies special diagnostics/ cleaning system• Not included into the baseline scope• Will not be precluded by the current design; provisions for stripline and scraper are

made (spool pieces)• Will be implemented as a future upgrade



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


Injection System Hardware Changes Since Baseline

• Thick septum magnets have been replaced by special DC magnets

• Pulsed septa for ring injection and booster extraction have been made as short as possible

• Booster injection septum moved to upstream end of injection straight to adapt to more capable transport line

Changes under investigation• Ring injection with pulsed sextupole magnet• Double Lambertson septum PSM for ring injection

• Can septum magnets can be built similar to NSLS

septum magnets


Where we are

• Necessarily a snapshot of work in progress• Booster baseline injection and extraction systems with matched transport lines are

designed (beware extraction kicker and extraction hardware stability) • Injection into Storage ring tricky due to stability requirements – injection transient

restricted only to injection straight• Baseline injection system uses four kickers, injection septum, but with DC injection

bender and pulsed Ht correction windings in bump magnets.• Six PUE’s will be installed - not necessarily instrumented at first.• Beam based correction and feed-forward on magnetic field pulses will ultimately

be used.• Investigate different approach to septum construction, à la NSLS, with no current

carrying feed-through into vacuum

• Injection with pulsed sextupole appears feasible, measured magnet prototype due to be completed by December this year.

• Possibility exists of using two Lambertson septa with PSM, resulting in only one pulsed component in the ring injection process (under investigation, geometrically it is feasible)

NSLS-II Injection System update

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