atf2 magnets atf2 magnets 2 oct 2007cherrill spencer info for atf2 magnet alignment discussion 1...

2 Oct 2007 Cherrill Spencer Info for ATF2 magnet alignment discussion

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ATF2Magnets

ATF2Magnets

Information on Alignment Issues for ATF2 magnets: for discussion

Cherrill Spencer, SLACMember of ATF2 Magnet Team


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ATF2Magnets

ATF2Magnets

Main issues to be brought up today- not expecting to find resolution today

• Are 3 sets of ATF2 magnets that are being “made from” old SLAC magnets: – Final doublet quads: QF1 and QD0– Final doublet sextupoles: SF1 and SD0– Final focus sextupoles: SD4,SF5 and SF6

• These 3 sets cannot be modified to fit in with the KEK way of aligning magnets (problem will be described in detail in this presentation)


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ATF2Magnets

ATF2Magnets

Main issues continued

• The magnet roll tolerances given in figure 3.6 on page 16 of chapter 3 of the ATF2 proposal are extremely tight and probably not achievable:– Approx 40 μrads for the FF quads & sexts– Approx 5 μrads for QF1 and QD0– Between 0.5 and 2 μrads for FF bends :B5,B2,B1

• Magnets must be aligned with smaller rolls than this else the spot size will increase by 2%

• I have been consulting with Glen White who is running detailed simulations of the ATF2 beamline and tracking 1000s of particles passing through the magnets which have a variety of alignment errors and then he sees if he can tune the beamline to get the desired spot size- will show his alignment errors/tolerances later


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ATF2Magnets

ATF2Magnets

Conventional Alignment

Optical tooling balls are secured on the magnet: at SLAC we “fiducialize” all the tooling balls: work out how far from each tooling ball center to the magnetic center or mechanical center.

Robert Ruland, SLAC


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ATF2Magnets

ATF2Magnets

SLAC’s process of aligning a magnet- more info

This sphere has a specially shaped reflector – center of reflector is at center of the sphere. Beam of laser light is bounced off reflector and can work out where ball is to a few microns. Spheres are placed without any precision on the outside of all magnets.

Using pulsed stretched wire to find magnetic center and a coordinate measuring machine (CMM) to make mechanical measurements, can relate the spheres’ positions to the magnetic center. This process is called FIDUCIALIZATION.

Every magnet has to be fiducialized BEFORE it is put in the beamline- each magnet has a unique identity. The fiducialization data is kept in a DATABASE “for ever”; alignment crew refer to it whenever they align a magnet.


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ATF2Magnets

ATF2Magnets

KEK’s method of aligning magnets uses a reference alignment base- is placed VERY PRECISELY on top of magnet so a target inserted in central hole lines up with the magnetic center to within the alignment tolerance

Drawings of alignment base made for the ATF2 QEA quads and DEA dipoles (are brand new magnets) .

Units are inches – so quite large item


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ATF2Magnets

ATF2Magnets

ATF2 QEA quad with alignment plate and target.


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ATF2Magnets

ATF2Magnets

Measurement system at KEK

Ceramic coil for rigidity, smaller thermal expansionBobbin is made of Macor.

Air bearing, forsmoother rotation

Reference plate （基準面）for alignment

Room & watertemperature arecontrolled.

Electronics (Integrator etc) are kept on all the time.


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ATF2Magnets

ATF2Magnets

Big problems with magnet & alignment basemachining : 3 cases –from Masuzawa talk on QEA measurements

Correct caseAlignment base center Split line between the coresBore centerMust be aligned.

(1) Magnet bore is not aligned.How could this happen??EDM process???

(2) Alignment base is not aligned.

(3) (1)&(2) mixed.


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ATF2Magnets

ATF2Magnets

2 mrad, we think this is not fake (coming from theSystem) but real difference from each magnet.

Quadruple phase (median plane) for 2nd batch 50 A magnets

水平

Alignment base is not parallel tothe magnet plane.

Variation too large


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ATF2Magnets

ATF2Magnets

The magnet core has to be designed from the start to use these plates in the

way KEK tends to use them

BUT :cannot add such a plate in the necessarily precise way after the magnet has been designed and made. The core pieces have to be toleranced to accommodate the base.

How these alignment bases might fit on the FD quads.


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ATF2Magnets

ATF2Magnets

How were these FD quads aligned in FFTB: with special apparatus

Invar tooling plates, so do not change size with temperature variation.

Aiming for < 30 micron errors.


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ATF2Magnets

ATF2Magnets

An FFTB quad in FFTB with its alignment apparatus

Invar tooling plate


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ATF2Magnets

ATF2Magnets

Problem because of the difference between KEK’s and SLAC’s alignment

techniques

• 2 sets of SLAC magnets will be fiducialized using SLAC style tooling ball and alignment process, then will be magnetically measured at SLAC– I think KEK does not have the equipment to measure them at KEK.

• HOW to align them in the ATF2 beamline?


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ATF2Magnets

ATF2Magnets

Brand new ATF2 FF dipole- just completed at IHEP, with 2 alignment bases


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ATF2Magnets

ATF2Magnets

From Glen White: Static Error Parameters

• Assume movers on all FF and FD quadrupoles and sextupoles.

• Cavity BPMs fixed to all FF Quads + Sexts.

• Also assume IP BPM with 5nm RMS resolution.

• Model for SM measurement: mean spot size from 90 consecutive pulses +/- RMS error.

Quad, Sext x/y transverse alignment

200 um

Quad, Sext roll alignment (including QF1 & QD0)

300 urad

Initial BPM-magnet field center alignment

30 um

dB/B for Quad, Sexts 1e-3 syst. + 1e-4 random

Mover resolution (x & y) 50 nm

BPM resolutions 100 nm

Power supply resolution 14 - bit

Shintake Monitor Resolution

2nm


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ATF2Magnets

ATF2Magnets

Tuning Results- from Glen White

3.4 3.6 3.8 4 4.2 4.4 4.6 4.8x 10-8

0

5

10

15

20

25

30

Post - Tuning IP Vertical Beam Size

No EXT SextWith EXT Sext

3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8x 10-8

0

5

10

15

20

25

30

IP Waist Vertical Size / m

InitialTuned -GM 'A'Tuned - GM'ATF'

Case Median Spot Size / nm

Initial EXT Tuned Lattice 36.2

FFS Errors + GM ‘A’ 37.6

GM ‘A’ (Turn off EXT Sexts) 38.6

ATF GM (EXT Sexts on) (no BEND errors) 38.2

As Above but: 600 urad magnet roll errors 40.9

As Above but: 150 urad magnet roll errors 37.8

As Above but: add 1mr RMS BEND roll errors

37.9

‘Nominal case’


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ATF2Magnets

ATF2Magnets

Conclusion from Glen’s simulations

• Can ignore the tolerances in fig 3.6 in proposal and use his much looser tolerances – still tight but do-able with SLAC’s alignment techniques.

• But what about when they have to be put into ATF2 beamline at KEK? How/can will KEK use our fiducialization data.


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ATF2Magnets

ATF2Magnets

FF sextupoles have SLAC tooling balls – how to align them at ATF2?

Sockets to hold SLAC tooling balls. This sextupole has 6 sockets.


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ATF2Magnets

ATF2Magnets

Same problem with the small sextupoles to be used in FD.

Sockets to hold SLAC tooling balls


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ATF2Magnets

ATF2Magnets

Another problem– fitting in the MONALISA apparatus on top of QD0!

Place a very flat and precise thickness shim in each split plane to “explode” the quad and enlarge the bore diameter.

Shim will be low carbon steel, ground to 0.0005” flatness


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ATF2Magnets

ATF2Magnets

Info from David Urner re putting MONALISA on top of QD0

• We will have to stabilize QD0. The stabilization will connect QD0 to• the Shintake monitor table.• Indeed we will not be ready by next January. More likely by January• 2009. We can of course bring a dummy system earlier if that would help.• We would indeed need the LCWS hoses moved so that we can extend our• platform.• Alignment transfer: I agree that this needs some thought. I could• imagine two different approaches:• 1. Assuming you would use two alignment plates. They look fairly• sturdy, so we could mount our base-plate on it and transfer the alignment• using external theodolites. (Although I'm not sure that they have those• available at KEK, we would have to inquire.)• 2. What about putting a rectangular tube on top of the magnet.• When we are ready we would slide our interferometer setup inside that• tube. And you could mount the ATF2 alignment base-plates on top of it?


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ATF2Magnets

ATF2Magnets

Space on poletip end is limited by the G10 clamps which exist on BOTH ends

of the final doublet quads• Urner et al want to mount a retro-reflector on a

QD0 poletip end , I suppose on the upstream end? BUT HOW TO FIT IN WITH BPM and its adapter which cover up the poletips ?

• At the “terminal end” the maximum space between the G10 piece and the tip of the pole is 0.6” At the non-terminal end this space is 1”. BUT THIS SPACE WILL HAVE SMALL STEEL BUTTONS TO REDUCE 12-pole component.

• THESE INTERFERENCES HAVE TO BE RESOLVED!

atf2 magnets atf2 magnets 2 oct 2007cherrill spencer info for atf2 magnet alignment discussion 1...

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