multipole girders - alignment & stability (multipole girder alignment technology & r&d)...
TRANSCRIPT
Multipole Girders - Alignment & Stability
(Multipole Girder Alignment technology & R&D)
S. Sharma
ASD: J. Skaritka, D. Hseuh, V. Ravindranath, G. Miglionico, C. Longo, R. MeierMagnet Division: G. Ganetis, A. Jain, P. He, P. Kovach Cornell: A. Temnykh APS: H. Friedsam
Outline:
Alignment Technique and R&D
Reference Designs of the Magnets
Mechanical Stability of the Multipole Girders
Summary and Conclusions
Multipole Girder with Stretched Wire
Magnet Alignment Technique
Magnet alignment will be done with a vibrating wire alignment technique developed at the Cornell University by Prof. Alexander Temnykh.
Alignment tolerances:Magnets: 30 μm, 0.2 mrad
Girders: 100 μm, 0.5 mrad
Magnet Alignment Procedure
Accepted magnets and vacuum components shall be assembled (roughly aligned) on to the girder in an assembly station.
The girder assembly will be moved and installed into the temperature-controlled (± 0.1 ºC) alignment facility.
The girder will be aligned using a laser tracker. All electrical and water connections will be made to the magnets.
Magnet movers are installed beneath each magnet.
Magnet coils will be brought to their operating temperatures.
A clean wire will be inserted through the vacuum chamber.
The wire will be secured to wire movers located at either end of the girder assembly and a controlled constant tension will be applied.
A Laser tracker will used to locate the two ends of the wire at the correct height relative to survey targets on the girder to within +/- 100 microns.
Magnet Alignment Procedure – contd.
The magnets and the stretched wire shall be systematically powered.
Resultant wire vibration shall be monitored and analyzed.
The wire height can be adjusted vertically by the wire mover to correct for wire sag at each magnet location along the girder and can be reproducible to +/- 1 micron.
The magnet movers shall be used to locate the magnetic center of each quadrupole and sextupole to the wire to <25 microns
Magnetic Alignment Procedure – contd.
Vibrating Wire Technique - R&D
Wire Mover
Magnet Mover
Experimental Setup (Magnet Division)
Magnets will be setup will be on an existing 15 ft. granite surface plate. The wire movers will be mounted on two small separate granite surface
plates on either side of the magnet setup. The wire movers will be 22 ft. apart. SLS magnets are on site. Design work to mount them on magnet
positioners will begin soon.
Vibrating Wire Alignment R&D Wire Mover
Targets
Insulated V-notch
Wire
Mirror
Camera Lens
Small DovetailStages
Wire Finder
Photo Interrupters
Detailed design of major components are well under way.
Wire movers, magnet positioners and 3 Motorized X/Y Stages on order.
One set of 4 indicators with 1 um resolution is available.
Cornell data acquisition system has been duplicated.
weight
pulley
X-Y Stage
Digitalindicator
RHIC spare
Quadrupole
Other end of wire on a table ~6m away
Fixed end of wire
Photo Detectors
Digitalindicator
Lasers
Vibrating Wire Alignment R&D – contd.
Girder Alignment
Approach:
(1) Use precise alignment mechanisms that are removable.
(2) Simple hardware to lock the components in place
stiff system with high natural frequencies.
lower and predictable thermal deformations.
Storage Ring Multipole Magnets
Magnet designs must be robust. Field quality (harmonic contents) should remain within specified tolerances after repeated disassembly and reassembly.
Several different designs (SPEAR, SLS, APS) are being evaluated.
A 2-segment sextupole design is being developed.
Quadrupole Magnet
Tolerance Limits ΔX RMS Quads ΔY RMS Quads
Random magnet motion < 0.15 μm < 0.025 μm
Random girder motion <0.6 μm < 0.07 μm
Tolerances on Magnets’ Motion
Thermal: relative thermal displacement between magnets on the same girder: < 0.025 μm.
Vibration: no magnification of ambient floor motion up to 50 Hz.
• Below 4 Hz girder motions are highly correlated• Above 50 Hz the rms floor motion is < 0.001 μm
Mechanical Stability of the Multipole Girders
Thermal Deformations
Magnets:Relative displacement on a girder: 0.01 μm
Vacuum Chamber:Near fixed and flexible supports (SS plates): ~0.3 μm
• Chamber deformations near the supports are ~ 0.17 μm with Invar plates. • BPMs need to be located near the fixed or flexible supports.
Displacement PSDs at locations near the NSLS-II site(Source: N. Simos)
RMS Displacements at CFN
( 0.5-4) Hz : 200 nm (4-50) Hz : 20 nm(50-100) Hz : 0.4 nm
Ambient Floor Motion
Natural modes of vibration for the girder-magnets assembly: (a) rolling mode = 63 Hz, (b) twisting mode = 79 Hz
RMS (2-50) Hz Displacements:Floor: 20 nm
Magnets: 21 nm
(b)(a)
Mode Shapes of the Girder-Magnets Assembly
Summary and Conclusions
The magnets on the girder will be aligned with a vibrating wire technique.
Girders will be aligned with precise but removable alignment mechanisms.
Reference designs for the SR magnets are being developed that are consistent with the vibrating wire alignment technique.
The multipole magnets-girder assembly (with removable alignment mechanism) will meet the stability specifications.