NSLSII Footprint

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NSLSII Footprint

• F. Willeke, April 23, 07

• Accomodation of Extra Long Straights
• Considerations for Accommodating a possible ERL
  Upgrade into NSLSII

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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

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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
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Integrations of Extra-Long Straights
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

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 Dfx,y n x 2 p (Bengtsson)
3-fold or 5-fold symmetry
Quasi 15-fold symmetry

• ? Impact on footprint

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A solution based on Transparent Insertion
On-Energy Transparent Optics Dfx, Dfy n x 2p
23m Insert

• xx-1.039, xy-3.01
• Total length 23.73 m, free length 3 x 5.83 m
• bx/by 1.8/1.4 , 3.0/1.3, 1.8/1.4

Courtesy Guo Wei Ming
Requires verification for realistic conditions,
(6D-beam, imperfections, .) ? Needs time
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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

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Two examples of implementation of extra-long
straightsin 15-fold symmetric footprint
Shorten Straights
Shorten Arcs
T T015 ? T T013? T1
T014
Decomposition of lattice map in linear, nonlinear
and chromatic parts
T1 T120T121T130T122 T140 T1h.o T0
Require
(breaks symmetry)
T020
T0210
T0220
T040
?T0h.o
T0300
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Making a longer Long-Straights by Shortening two
Short-Straights
Lengthening long straight 2 x shortening the
short shtraight ? Maximum long 18m
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Geometry and Optics
Geometry of the
Lattice
Possible Beam Optics
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ERL Integration Considerations
(Nota bene this is no attempt to lay out an ERL)
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Requirements and Constraints
I

• 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

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Beam Losses
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Short Parameter List
Energy 4 GeV Beam Current 200 mA Normalized
Emittance 0.5 mm Energy Spread
10 -4 Bunch Length
0.5 mm Linac gradient 10
MV/m Linac Length
723 m                                 
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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

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Brightness
Courtesy Timur Shaftan
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Flux Calculation
Courtesy Timur Shaftan
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Possible Site Layout Compatible with NSLSII as
planned
Linac I
Return Arc
source
Linac II
FEL Hall
Dump
Possible Footprint
Scale in m
Vertical cut through the site
7m
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Detail Footprint
FEL Exp Hall
s
Commissioning loop
D
s
Scale in m
Scale in m
Possible Injection Scheme
Lambertson septa
Horizontally separated vertical bends
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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
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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