1. Status of ATF2 FD Magnets and Info on their FFTB supports & mover
Cherrill Spencer, SLAC
Member of ATF2 Magnet Team
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

2. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Consider designs of final doublet quads & sextupoles and dimensions of FFTB movers
With goals of answering these questions:
Will the 4 FD magnets and their S band BPMs fit on the CLIC table?
Can they have FFTB magnet movers under them and have centers of their apertures match the 1.2m beam height off ground? [will be discussed more on Weds morning]
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

3. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Suggested spacing of 2 quads & 2 sextupoles on special CLIC table 26 Sept 06
NOTE: 450mm is QD0 core length. Overall length = 546.1mm.
BPM fits at one end only. At other end coils, fittings & terminals stick out 72.5mm.
FD quads, QD0, QF1 using old FFTB quad “QC-3” style.
Quad bore value under discussion- will be less than 60mm
Sextupoles being designed. Bore ?
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

4. Cherrill Spencer, SLAC Status ATF2 FD Magnets
At February 2006 ATF2 project meeting my design suggestion for Final Doublet Quads was accepted
QF1 and QD0 requirements:
Definition of K1 :
Gradient = K1 x Brho / Effective length
At 1.3 GeV, Brho = Tesla-meter
Latest requirements are:
QF1 K1 = and QD0 K1=
These can be met using the “QC3” style FFTB quad [1.38Q17.72] of which 2 are available
Original aperture: 35.06mm diameter ; Eff L= m;
Aperture needs to be larger to match S band BPM
Effective length varies with aperture value
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

5. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Views of both ends of QC-3 as sits in SLAC warehouse waiting for modification
LCW fittings prevent BPM being installed this end
Old beampipe will be removed. G10 coil supports stay.
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

6. Cherrill Spencer, SLAC Status ATF2 FD Magnets
FFTB “QC3” as it was in SLAC FFTB beamline Sitting on a FFTB magnet mover
This support has to be re-designed to be much shorter, so magnet center will be at desired height in ATF2.
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

7. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Shape of pole tip and coil in the 1.38Q17.72 quad. Possibility to machine pole tip to make larger aperture
“Dog-eared” shape of coil ends starts at 56mm, but have also G10 coil support, uses ~25.4mm of the 56mm space. This is not enough for the S band BPM, so adapter needs to be designed.
The 35 mm aperture is not compatible with S band BPM.
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

8. Proposed connection between QD0/QF1 and S band BPM – from Honda
Coil end shape prevents S band BPM from directly attaching to magnet core; so an adaptor has been designed to avoid coils. Makes cavity sit 82.5mm from magnet end.
Outstanding question: what is thickness of beampipe coming out of BPM? Spencer wants to minimize.
40mm ID is fixed. Make pipe 3.5mm thick.
Does adaptor design account for G10 coil support?
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

9. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Two old FFTB quads: 1.38Q are ready to have their poletips machined back to become QD0 & QF1
FFTB “QC3” style = 1.38Q Made in Protvino, Russia, Three of this style made.
Bore = 1.38” = mm; Core length = 17.72” = cm. Overall length=54.61cm
Solid steel core
Water cooled coils, 24 turns of 0.255” sq hollow Cu conductor; 2 water circuits per coil.
Maximum current capability: ~320 amps -ample
To minimize operating current and amount of machining by EDM (at LBNL machine shop): Spencer proposes to make quad bore diameter= x x 1 = 49mm mm=Cu beampipe thickness; 1mm= free space
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

10. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Implications of QD0 & QF1 bore value: increase from 35mm to ? (60mm was considered)
If bore = 49mm, rather than 60mm, then:
Operating currents much lower, power supply rating less and so cheaper
Less steel has to be removed and so pole tip machining costs less
(Any Multipole)/quad decreases as aperture increases. [12 pole/quad varies slowly with aperture]
Multipole values at r=1cm predicted by 2-D POISSON model
With 35mm diameter: 12-pole/quad = 1.22 x10-4
With 69mm diameter: 12-pole/quad = 1.10 x10-4
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

11. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Compare predictions of multipole content with tolerances from James Jones & S. Kuroda
Magnet Name
Tolerance
6 pole/quad
At r=1cm
12 pole/quad
POISSON
Prediction
12pole/quad
20pole/quad
QF1
9.5x10-5
2.46x10-4
1.09x10-4
1.19x10-3
1.16x10-6
QD0
5.26x10-5
3.08x10-3
1.10x10-4
5.98x10-1
Tightest tolerance is 12pole/quad for QF1. POISSON often under-predicts multipole value, we have 2.3 times margin. But if 12pole is too large we have at least 2 ways to reduce it: by chamfering poletip ends or by adding steel buttons on poletip end; Determine the button size and position by experiment (Spencer has done this successfully for SLC DR quadrupole)
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

12. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Conceptual Sketch of an FFTB magnet mover- using V blocks to connect quad directly with mover
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

13. FFTB installation drawing showing QC-3 sitting on wider FFTB mover
Special plate & Z restraint could be redesigned
296mm
T-1 plate
406.4mm
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

14. FFTB MOVER: was under QC3
Free space for magnet to sit determined by distance between LVDT on left and middle stand of LVDT on right ~200mm
Width of this QC3 mover is 609.6mm
There is only ONE QC3 style mover. Need 2.
Will have to make a 2nd one with a new T plate and use mover parts from a standard mover
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

15. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Close-up of QC3 Mover showing LVDT parts not shown on installation drawings
LVDT=Linear Variable Differential Transformer
These 3 position sensors and their supports, not shown on main installation drawing.
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

16. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Side view of the QC-3 quad on its mover, showing extra restraint- will have to be re-designed
This drawing not showing the overall QC-3 length, it overhangs the T-plate to the right.
Note that motor sticks out beyond the T-plate by about 4.25 cm
Restraining bracket attached to special plate on bottom of quad
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

17. Cherrill Spencer, SLAC Status ATF2 FD Magnets
T-1 plate for QC-3, sits under FFTB mover. We have only one QC-3 T plate
609.6 mm WIDE
482.6mm LONG
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

18. Old FFTB mover: was under 0.9Q17.2 quad (call this a standard mover)
Planned to use this style mover under SD0 & SF1
Standard mover is less wide than QC3 mover: mm wide
Free space between LVDTs is 140mm
Not done SD0 design yet, but predict 140mm is not enough room for lower part of SD0/SF1 sextupole
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

19. Cherrill Spencer, SLAC Status ATF2 FD Magnets
Drawings of smaller T-plate that we will be using under QEAs and FF sextupoles
Width 457.2mm
Length 482.6mm
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets

20. Originally planned to make all ATF2 sextupoles similar to SLC FF “SX3”
SX3 aperture =41.3mm
Now realize need 2 different designs, one for SD0&SF1, other for SD4,SF5, SF6
89.6mm long
213.6mm wide, poor fit to less wide mover
LAPP, Annecy, 9th Oct 2006
Cherrill Spencer, SLAC Status ATF2 FD Magnets