update on ilc ml lattice design alexander valishev, for the fnal let group fnal ap dept. meeting...
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Update on ILC ML Lattice Design
Alexander Valishev,for the FNAL LET group
FNAL
AP Dept. Meeting March 7, 2007
2APD meeting March 7, 07
ML Lattice design
Outline
• Basic layout• Curvature implementation• Matching• Summary and problems
3APD meeting March 7, 07
ML Lattice design
Lattice Design
• Defined by cryo segmentation• Versions of segmentation
» 8-8-8 scheme, Nov 21 2006» 9-8-9 scheme, Dec 28 2006
• Basic segmentations:
Main Linac
RF Unit
Cryogenic Unit
5APD meeting March 7, 07
ML Lattice design
Lattice Revision HistoryDate Cav/
CMQ/CM Comments
1/06 12 1/2 USColdLC by PT, TESLA-like, straight
3/06 8 1/4 PT + curved
5/06 8 1/3 BCD-like, simple periodic lattice
5/06 8 1/3 Added cryo boxes and warm straights
6/06 8 1/3 May 31 (ver. 3) cryo layout
9/06 8 1/3 SBEND version *)
10/06 8 1/3 M.Woodley RTML-ML-BDS **)
1/07 8 1/3 “8-8-8” Nov 21. cryo layout (ver. 4)
2/07 9-8-9 1/3 “9-8-9” Dec 28. cryo layout
**) http://www.slac.stanford.edu/~mdw/ILC/2006e/
*) http://tdserver1.fnal.gov/project/ILC/ARCHIVE/ILC-ML-SbendCurvature.zip
6APD meeting March 7, 07
ML Lattice design
Curvature Implementation
• Beam line geometry definition differs for MatLIAR/Lucretia and MAD.
• A method to have one set of decks and still be able to work with two codes was proposed by M.Woodley:» One common XSIF file, defining beam line, all common
elements, and ‘KINK’ elements at the ends of cryomodules.
» Two different files defining KINK elements to be used in MatLIAR and MAD. One of the files is called from the main file depending on the software used.
» Beam trajectory in both cases is changed by VKICK elements
• Another approach is to use vertical SBENDs» In this case one deck is compatible with both codes
8APD meeting March 7, 07
ML Lattice design
Implementation of ‘KINKs’
• MatLIAR/Lucretia: Thin ‘dispersion-free kick’ GKICK, which pitches the coordinate system.
• MAD: Combination of» General thin multipole n=0, changes both
the beam trajectory and the coordinate system
» VKICK of the opposite sign
12APD meeting March 7, 07
ML Lattice design
Emittance Preservation LIAR Simulation: CURVED LINAC: ILC BCD-Like LATTICE
Orb
it a
t th
e Y
CO
Rs
(m
)
Perfect Lattice - No misalignments
Zoom
No
rma
lize
d E
mit
tan
ce
(n
m)
Static Tuning: Dispersion Matched Steering (DMS) - Misalign the beamline components and perform the steering
Average of 50 machines
Straight
Curved
Co
rre
cte
d n
orm
ali
zed
em
itta
nc
e
(nm
)
Mean: 5.0 ± 0.4 nm
90%: 8.7 nm
Laser Straight
Mean: 5.3 ± 0.5 nm
90%: 9.5 nm
Curved
Distribution of emittance growth for 50 seeds
BPM index
BPM index
13APD meeting March 7, 07
ML Lattice design
Summary
• ML lattices based on two cryogenic layouts have been developed
• Two versions of ILC2006e (8-8-8) ML lattice (GKICK/MULT and SBEND) were studied» Both versions work well in Lucretia and show similar
emittance growth» It was decided at the Daresbury meeting in January
that only GKICK/MULT lattice will be supported
• Static alignment simulations show acceptable emittance growth in the curved ML lattice
• Dynamic simulations in progress
14APD meeting March 7, 07
ML Lattice design
TODO
• Create set of decks suitable for simulations of bunch propagation from RTML to the end
• Improve dispersion matching between curved and straight sections» The way it was implemented in ILC2006e suggests
large orbit kinks with angles of ~3e-4. At 250 GeV, this leads to energy losses of 100MeV and synchrotron radiation power of 4kW
» Angle of steering to the Earth’s curvature is 6e-6. Eloss=37keV, Ploss=1.6W
» One possible solution – make smooth transition from curved to straight beam line.
15APD meeting March 7, 07
ML Lattice design
Synchrotron Radiation in a Single Corrector
L
EB
3.0
L
EU SR
2441085.8
IavUP SRSR
E – particle energy [GeV]
– bending angle
L – corrector length [m]
B – corrector field [T]
USR – particle energy loss [eV]
Iav – average beam current [A]
PSR – average radiated power [W]
E=250L=0.335Iav=4e-5 for 1s beam at 5Hz
USR [keV] PSR [W]
5e-6 26 1.1
1e-5 100 4.5
5e-5 2600 110
1e-4 10300 450