1 brookhaven science associates nsls-ii asac-2007, april. 23, 2007 nslsii footprint f. willeke,...

1 BROOKHAVEN SCIENCE ASSOCIATES

NSLS-II ASAC-2007, April. 23, 2007

NSLSII Footprint

F. Willeke, April 23, 07

• Accomodation of Extra Long Straights

• Considerations for Accommodating a possible ERL Upgrade into NSLSII



Outline

Extra Long Straights• reducing symmetry• quasi symmetry preserving solutions• footprint preserving solutions

Accommodating a possible ERL Upgrade into the NSLSII site• Requirements and constraints for an ERL• Performance of an ERL using the NSLSII Ring to distribute the Beams• A possible Parameter Set• Beam Loss and Shielding• Considerations which determine S.C. Linac Overall Length• A possible Footprint of a NSLSII-ERL Facility• Items to be included in present planning to ease later upgrade of an ERL



CD-1 Footprint

15-fold Lattice symmetry

27 Beam lines from Insertion devices

30 Beam lines from bends

3 Utility straight sections

15 of which see hard x-rays from 3-pole wiggler

Symmetry will be weakly broken to 3-or-5 fold

Because of large aperture dipoles in 3/5 locations



Integrations of Extra-Long Straights

Several Possibilities to implement:

Reducing the lattice super-periodicity from 15 to 3 or 5 by introducing different achromats with extra long straights

Inserting just two long straights optically matched to the achromat with a transparent lattice x,y = n x 2 Bengtsson

Impact on footprint

Extra-Long Straight Motivation: Nano-focussed beam and experiments with inelastically scattered soft X-rays would profit from extra long straight sections with an active undulator lengths of 10m-12m

3-foldor 5-fold symmetry

Quasi 15-fold symmetry



A solution based on Transparent Insertion

x=-1.039, y=-3.01 Total length: 23.73 m, free length 3 x 5.83 m x/y: 1.8/1.4 , 3.0/1.3, 1.8/1.4

23m Insert

On-Energy Transparent Opticsx, y = n x 2

Courtesy Guo Wei Ming

Requires verification for realistic conditions, (6D-beam, imperfections, ….)

Needs time



A Possible Strategy of Providing extra long Straights

Problem:

Lattice Design effort has been centered in optimizing the achromatic super-period.

Still to do: Integration of the entire ring with damping wigglers and insertion devices

and verification of the stability and dynamic aperture

Deadline for freezing the foot print: End of May (driven by start of CF Title I design )

There is not sufficient time to work out a well thought through concept of X-long straights, integrate it and assure stability of the entire ring.

Desirable to base long straights on solutions which are compatible with the food print of a 15-fold symmetric lattice

Can finalize the symmetric lattice in a timely fashion to start building design and engineering design

Can continue to work on way to implement extra long straights and on assurance of single particle stability without time pressure of CD2



Two examples of implementation of extra-long straightsin 15-fold symmetric footprint

Shorten Straights

Shorten Arcs

T = T015 T = T0

13 T1 ≈ T014

T1 = T120+T1

21+T130+T1

22+ T140 +T1

h.o ≈ T0

= T020 =T0

21=0 =T022=0 =T0

40 ≠T0h.o=T0

30=0

Require(breaks symmetry)

Decomposition of lattice map in linear, nonlinear and chromatic parts



Making a longer Long-Straights by Shortening two Short-Straights

Lengthening long straight = 2 x shortening the short shtraight

Maximum long : 18m



Geometry and Optics

90

-80 -60 -40 -20 0 20 40 60 80

Geometry of the Lattice

Possible Beam Optics



ERL Integration Considerations

(Nota bene: this is no attempt to lay out an ERL)



Requirements and Constraints

Ī• Beam Losses critical, present Shielding insufficient• Should go for significantly larger brightness• should plan for higher energy than storage ring• Should allow for sufficient Linac length• Planning for ERL should minimize the additional effort for NSLSII• Bending for returns and injection into the ring should be minimized• Preserve an FEL option• No planning which modifies the site appearance in an unfavorable way• Necessary additional tunnels necessary should stay clear from existing buildings• ERL should be planned such, that construction and commissioning can be parallel to NSLSII running• Stay clear from road North of the site• Stay clear from road West of the site



Beam Losses ERL

Beam Energy 4 GeV

Beam Current 0.2 A

Loss level 1E-6

Power Loss 400 W

Particle Loss rate 1.25E12 Hz

Storage Ring

Beam Energy 3.6 GeV

Beam Current 0.6 A

lifetime 2 h

Particle Loss rate 1.35E9 Hz

Ratio off losses 831

Necessary increase in Shielding 1.56 m



Short Parameter List

Energy 4 GeV

Beam Current 200 mA

Normalized Emittance 0.5 m

Energy Spread 10 -4

Bunch Length 0.5 mm

Linac gradient 10 MV/mLinac Length 723 m



Comparison of Brightness

• NSLS NSLS-II ERL• Energy, GeV 2.8 3 4• Current, mA 275 500 200• Emittance X, nm 53 0.5 0.1• Emittance Y, nm 0.117 0.005 0.1• Energy spread, % 0.084 0.1 0.01• BetaX, m 1.114 3.3 7 • BetaY, m 0.407 1 7• Dispersion X, m 0.15 0 0• • Undulator • • Period, cm 1.25 1.4 14• Length, m 0.3375 2 18• K 1.1 2 2



Brightness

1013

10

15

10

17

10

19

10

21

Pho

t/s/

0.1%

bw/m

m2 /m

r2

2 3 4 5 6 7 8 910keV

2 3 4 5 6 7 8 9100keV

Photon Energy

ERLNSLS-IINSLS

Courtesy Timur Shaftan



Flux Calculation

1010

1011

1012

1013

1014

1015

1016

1017

Pho

t/s/

0.1%

bw

2 3 4 5 6 7 8 910keV

2 3 4 5 6 7 8 9100keV

Photon Energy

Courtesy Timur Shaftan



Possible Site Layout Compatible with NSLSII as planned

Possible Footprint

Vertical cut through the site

source

Dump

Linac I

Linac II

Return Arc

FEL Hall

~7m

Scale in [m]



Detail Footprint

Commissioning loop

FEL

Exp Hall

Possible Injection Scheme

Horizontally separated vertical bends

Lambertson septa

s

s

D

Scale in [m]

Scale in [m]



What needs to be done now:

• Include a small radial vault underneath the Eastside of the Ring• Rotate the facility footprint clockwise by ~25 Degree

25degree



Conclusions

Due to a compressed schedule and limited resources it might not be possible to include extra long straights in a timely fashion in the NSLSII footprint

Intend to base a later upgrade to extra long straights on a footprint with 15-fold lattice symmetry

need to select potential positions soon, because we need

- to enlarge the tunnel at these locations somewhat

- to build-in some flexibility into the ratchet wall

In order to ease the later integration of an ERL/FEL driven by a superconducting LINAC as a major upgrade project, some small modifications of the NSLSII footprint appear to be advisable:

• A small clockwise rotation

• A small piece of tunnel underneath the East-side of NSLSII

• shielding issue cannot be resolved, would have to be addressed in a different way

1 brookhaven science associates nsls-ii asac-2007, april. 23, 2007 nslsii footprint f. willeke,...

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