BROOKHAVEN SCIENCE ASSOCIATES SR Chambers & RF Bellows ASAC Review, 3/26-27/2009 1 of 21 SR Chambers & RF Bellows H. Hseuh, Vacuum Group ASAC Review of

BROOKHAVEN SCIENCE ASSOCIATES

SR Chambers & RF BellowsASAC Review, 3/26-27/2009

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SR Chambers & RF Bellows

H. Hseuh, Vacuum GroupASAC Review of NSLS-II

Mar 26-27, 2009



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Acknowledgements

BNL: A. Blednykh, P. Cameron, C. De la Parra, S. DiStefano, L. Doom, M. Ferreira, E. Hu, F. Lincoln, C. Longo, S. Krinsky, V. Ravindranath, P. Settepani, S. Sharma, O. Singh, J. Skaritika, J. Sullivan, K. Wilson, ….

ANL: J. Gagliano, G. Goeppner, …

ESRF: R. Kersevan

Diamond: M. Cox

KEK: Y. Suetsugu

SLAC: N. Kurita, M. Sullivan, L. Wang, U. Wienands, …

TPS: J.R. Chen, G-Y. Hsiung, …

and many others.



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Outline• SR Vacuum Chambers and FY08 Effort

– Material, quantity, types, fabrication– Extrusions w/ two vendors– Weld development of multipole chambers at APS

• Prototyping and Testing Effort in FY09– Bending of dipole extrusions– Extrusion of new multipole cross section– Weld development at APS– Testing of NEG strips and cal rod heaters– Interface with Magnets, AP, Diag. etc

• RF Shielded Bellows- Design options and prototyping

• Recent Review Recommendations



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Cell Vacuum Chamber Layout

BM Beamline

ID Beamline

L.S.

S.S.

S2 S3S4

S5

S6

Stainless chambers

S1

S1

• 60 stainless steel chambers, 1-2 m long

• 5 types (cross sections, length, flanges, etc)

• Stainless sheets, rolled, welded and brazed w/ Cu absorbers

• 191 aluminum chambers, 3 – 6 m long

• Extruded, two cross sections (dipole and multipole)

• > 12 types (length, magnet cutouts, flanges, etc.)

• Precision machining & welding to meet beam requirement

Dipole

Multipole



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S3

S5

S3-DW

90mm S3 & S5

S2-DW

S2E

S2O

S4

S6E

S6O

Multipolealso for day-1 straight

Dipole

Cell Aluminum Chamber TypesE: even cell; O: odd cell; DW: canted by ± 1.8 mrad



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End adaptor

Multi-step Fabrication of Al Chambers

Extrusion Bending Machining Cleaning Welding Assembly…➾ ➾ ➾ ➾ ➾V #1,2 BNL BNL, V # 3,4,5. APS APS BNL

Extrusions

Machined extrusion

Machined end End adaptors

End assemblyBi-metal flanges

Robotic welding at APS

Pump port

Lewis DoomLewis Doom



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Prototyping in FY08

Prototype multipole chamber for alignment, BPM mounting, NEG carriers and bakeout

Test extrusions completed Fabrication process fully developed

for ‘old’ multipole chambers

4mm

X15

Micrographs of welds show• Full fusion, no micro cracks• No void and trapped gas• Step ≤ 0.5 mm

X50

APS/ANLAPS/ANL



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• 50 ton press break with 18-inch throat

• W/ garnet filler, w/o filler

• Change punch heights and load distributions – curvature to within 1 mm

• Little spring back w/ thermal cycling to 180C

• Gap reduction by 1 – 2.5 mm

Bending of Dipole Extrusion at BNL

BNL CS break

Spread the load outboard from the center will give more bending

toward the ends.

Fine tweaking the punch & shimms to get the exact bend!

Lewis Doom Phil Settepani




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New Multipole Extrusion & Weld Development

Test extrusion orders placed To be completed by

May

Increase wall from 12 to 16 mm for improved BPM dual buttons/flange

NewNew BPM flange Old

Short dipole chambers and flanges

Multipole extrusion w/ exit port cutout

Welding development at APS

dipole, new multipole & exit port

A multi-yr contract w/ APS is in place

CD-2 Design



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NEG Strips and Carriers

NEG carriers and feedthruNEG carriers and feedthru

NEG strips in antechamber

Two NEG strips in each aluminum chamber as main distributed pumping – total ~ 1,200mRiveted mounting every 10 cm

w/ ceramic insulators and carrier plates

Fully tested in prototype chambers

Modified carriers for BPM TE modes?

Activation at 4500C x 30 min with 70 A thru NEG strips

Feedthru





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FY09 – One Cal rod heater (10 mm φ) inserted in unused cooling channel> 120 C and ΔT < 5 C

simple & versatile – to be tested for easy of installation and reliability

In-situ Bake with External Heaters

Baseline design: 135oC x 150 psi water (as in APS and Spring-8) A major ES&H concern

FY08 - T < 150oC achieved with foil heaters and insulation attached to limited magnet-free space

(not a neat solution)

Marcelo FerreiraMarcelo Ferreira



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Interface with Magnets, AP and DiagnosticsProvide AP vacuum component models for impedance simulation and approval

Worked with Magnet Measurement and identified issues with invar chamber supports, and fast corrector response over RF bellows/Al chambers – separate and relocate SC & FC

Worked closely with AP on lattice improvement - 3rd family sextupoles, locations of 3PW, moving of sextupoles, etc

RF shielding to shift the resonance frequencies of multipole chambers to > 550 MHz

Interference from invar standsInterference from invar stands

Separate SC & FCSeparate SC & FC

Om SinghOm Singh

Animesh JainAnimesh Jain



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Resonant Frequencies in Multipole Chamber

400MHz 1400MHz

Resonant frequencies measured in a 3.4m multipole chamber.

Agreed well with calculated H101 modes in a rigid waveguide.

Can be shifted by altering the chamber cross sections

Electric field

To shift the frequencies to > 550 MHz :

- increase the slot height to > 15 mm - No

- chamber width to < 80mm - No

- ante-chamber height to 20 mm - No

H101 Mode in a Rigid Waveguide

Alexei BlednykhAlexei Blednykh



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Suppression of Rogue ModesUse modified NEG carriers to create shields in the ante-chamber

~ 150 mm from beam center, installed through end flanges

~ 500 mm long and ~ 300 mm spacing to shift Fo to > 550 MHz

exact lengths and locations to be decided for each chamber type

Fo ~ 385 MHz due to S4 absorber in extraction channel?

Shields to be outside of SR fan or d/s of absorbers

To be designed, prototyped and fully tested with NEG activations


S4 S4

150 mm



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inside fingersoutside fingers

Choice of RF Shielded Bellows

inconel springs

Be-Cu fingers

Inside fingers Outside fingers

(APS, LNLS) (PEP II, Soleil, DLS, …)

Simple, reliable Lower impedance

$$ $$$

NSLS-II approach - outside fingers, few & wider fingers

Solid sleeve

Lewis Doom Marcelo Ferreira


NSLS-II RF Bellows Requirements:

Max mis-alignment: ± 2 mm

Max comp/extension: -15/+10 mm

Max angle deviation: ±15 mrad

Low impedance and low loss

Consulted with many experts in other light sourcesConsulted with many experts in other light sources



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4 Inconel outer springs (Ag plated )

Prototype Bellows Design

Hydro formed bellows welded to flanges with cooling channels

4 stainless inner support (Rh plated)

6 GlipCop fingers (0.9 mm thick Ag plated )

2 stainless clamping plate w/ groove for

contact springs





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Simulation w/ and w/o offsets

At nominal positionKloss ≈ 2.0 x10-2 V/pC

With ± 2 mm offsetKloss ≈ 3.7 x10-2 V/pC

Simulations of narrow finger bellows:Inside fingers : Kloss ≈ 1.9 x10-2 V/pC ± 2 mm offset ≈ 21.4 x10-2 V/pCOutside fingers : Kloss ≈2.1 x10-2 V/pC ± 2 mm offset ≈ 8.7 x10-2 V/pC

With ± 2 mm offsetKloss ≈ 10 x10-2 V/pC

6” bellows

5” bellows

• Thermal analysis with possible heat loads

• Detailed production drawings and prototyping

• Test for ease of assembly, mechanical stability with thermal cycling, etc.




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• TE mode interference to BPM– Extensive studies by AP and Diag groups using chamber extrusions– Modify NEG carriers to shift the frequency to > 550 MHz

• Clearance between magnets and vacuum chambers– Increased from 1.5 mm to 2 mm at sextupole poles– No foil heaters and insulation – cal rod heater in cooling channel– To be tested with magnets

• RF shielded bellows design and RF fingers– Consulted with colleagues from other light sources– Preliminary design completed, being detailed and prototyped

• EPU gap (~ 8 mm) and maximum K values– EDM the top and bottom walls of extraction gap in the S3 dipole (&

S2 multipole) chambers to accommodate vertical photon fans

ASAC Recommendations – July 08



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• Insitu bakeout and temperature uniformity - improved (ΔT < 5oC) with cal rod heater

• Extrusion tolerance and stress relief – straightened by machining vendor, < 1 mm relaxation after thermal cycling of bended extrusion

• NEG supports and protection – will be fully tested and with ground fault protected PS

• Effect of the vacuum components to magnets – ion pumps ok, invar supports not ok

• Asymmetric load on chambers due to thermal and mechanical force – analysis continues

• BPM buttons by welding – long development effort, can’t meet our current schedule

• 10,000 l/s pumping required at canted DW absorbers – pressure decreases with conditioning, only 1-2 locations

• Fast valve, Be window & RGA at FE – FV and RGA in the budget, Be windows to be reviewed together with BL

Vacuum, FE & Support Review Recommendations – Aug 08



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• BPM position stability after repeated bakeouts

– To be tested using the prototype chambers

• Possible electron cloud

– Use CLOUDLAND by Lanfa Wang (SLAC) and NSLS-II staff with worst case parameters

– Ex & Ey mainly by electrons from reflected photons

– No multipacting, no instability, no emittance blowup

– H tune shift < -0.001, V tune shift < 0.0006

• Fast ion instability

– High pressure d/s of canted DW, small impact only be ≤ 2 locations

– Need to simulate with beam fill patterns for ion clearing

Construction Readiness Review Recommendations – Sept 08

-40 -20 0 20 40-0.5

0

0.5

1

1.5

2

2.5

3

3.5x 10

10

X/Y (mm)

Ex/

Ey

Total field

ExEy

Lanfa WangLanfa Wang



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Summary

• Cell vacuum chamber detail drawings continue – minor adjustment possible• Test extrusion of ‘new’ multipole cross sections continues• Machining and weld development of prototype chambers are underway• NEG strip supports developed and tested• Chamber bakeouts with cal rod heaters being tested• RF shielded bellows concept done, to be detailed, prototyped and tested• Work with AP & Diag. on shifting resonance frequencies using NEG carriers• Production of dipole chambers starts this summer, multipole by Dec• Next - Design and prototyping of absorbers and stainless chambers

Documents

BROOKHAVEN SCIENCE ASSOCIATES SR Chambers & RF Bellows ASAC Review, 3/26-27/2009 1 of 21 SR Chambers & RF Bellows H. Hseuh, Vacuum Group ASAC Review of