ATF2 Magnets ATF2 Magnets 11Mar '08, Weekly MtgCherrill Spencer Status Report ATF2 FD quads 1 Status...

11Mar '08, Weekly Mtg Cherrill Spencer Status Report ATF2 FD quads

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ATF2

Magnets

ATF2

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Status Report on the ATF2 “Final Doublet” quads being made at SLAC from old FFTB

“QC3” style quads: 11th March 2008

Cherrill Spencer, SLACMember of ATF2 Magnet Team


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ATF2

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Concern about affect of nearby steel H beam on the QD0 field

Shintake monitor’s support structure, closest approach to QD0


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ATF2

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ATF2

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Plan view of Shintake support & magnet support table showing about 40 cm from middle of H steel beam to

closest edge of QD0 steel core

Closest approach here

QD0


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ATF2

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ATF2

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Use a ~60cm long steel H beam of approx correct dimensions and put it 40 cm from core edge, stand it up

vertically for ease of installation & is worst case.

Size & shape of H beam: A=B=15cm

T1=0.7cm

Steel H beam QD0 being measured


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ATF2

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ATF2

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Measure QD0’s integrated strength & multipoles at 132 amps, 5 times without H

beam & 5 times with H beam

• Calculate averages of ∫G.dl/amp without and with H beam:

• Without: 0.04490776 +/- 0.0000016 T/A• With: 0.04490860 +/- 0.0000000 T/A

– Delta=0.0019% -> insignificant• 12-pole without with as % of quad at 1cm

0.03411 0.03410

0.03410 0.03411

0.03411 0.03411

0.03412 0.03410

0.03411 0.03410 -> NO change in multipoles


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ATF2

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ATF2

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Chosen method for enlarging the FFTB “QC3” quad’s bore diameter

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

Hyperbolic pole-tip is moved, along a radius, further out than it’s equation says it should be.

XY= r2/2.

Consequence: the 12-pole component increases, ~17 times predicts POISSON.

ATF2 has very tight tolerances on the multipoles in QD0 & QF1


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ATF2

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ATF2

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Drawings of the modified core with ground shims in place

Sextupole component is very sensitive to poletip being at wrong radius or the poletip being offset “azimuthally”

GOAL :Adjacent pole distances (red arrow above) adjusted to be same to +/- 0.013mm. Then cores pieces pinned –BUT DOWEL PIN HOLES TOO SMALL, so achieved +/-0.031mm


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ATF2

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Close up view of modified quad

Shim added at split plane

Large bolts keep 4 core quadrants attached to each other


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ATF2

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POLE SIDE SHIMS IN PLACE- reduce the 12-pole to below tolerance


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ATF2

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ATF2

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Sextupole/quad values did not change when installed pole side-shims

• 12 pole/quad at 1cm reduced from 0.17% to 0.034% [tolerance was <0.05%]

• Sextupole/quad still at 0.038% at 1cm• Much too large said Glenn White. The spot size

at the IP is very sensitive to the sextupole components in QD0 and QF1– The unwanted sextupole is mostly a skew sextupole,

it affects the spot size, we have to improve the adjacent pole distance symmetry. The pole side-shims having some asymmetry [ ~0.3 mm] did not increase the sextupole component.


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ATF2

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ATF2

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Worked with technician to improve adjacent pole symmetry

• Had to enlarge the dowel pin holes so could adjust the quadrant positions- first try did not improve the symmetry on quad #1, so worked on quad #2 – bolt torque settings adjusted iteratively, distances re-measured

• Have achieved much closer distances, largest difference is 0.0178mm, or +/-0.0089mm, other differences are smaller.

• Measured field without pole-side shims: sextupole/quad at 1cm = 0.013%– i.e. one-third its previous value.


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ATF2

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ATF2

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Magnetic measurements also measure the angle of the first south pole of any

multipole, relative to horizontal axis

• The angle measurements indicate there is significant skew sextupole mixed in with the normal sextupole.

• Glen White has modelled the beam passing through QF1 & QD0 with the smallest multipoles I have achieved, at their measured angles, and the spot size is still “too large”.

• But when the FD sextupoles strength and roll (using their magnet movers) are adjusted to compensate for the unwanted sextupoles in QF1 & QD0 then the spot size is below 40 nm.


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ATF2

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ATF2

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How to maintain the best positions of the 4 quadrants, e.g. after quad been

split for SBPM to be installed?• Problem: when the pole side-shims are installed

you cannot access the ends of the hyperbolic poletip to measure the adjacent pole distances anymore. The shim to shim distances don’t tell you how good the poletip distances are.

• But need these poletip distances to be correct to better than 0.010mm

• We will shorten the pole-side shims by about 1cm at each end so gauge blocks can still be used to adjust the adjacent pole distances. 12-pole will increase a little- but we are sufficiently below the 12-pole tolerance we can afford to let it increase.


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ATF2

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ATF2

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Thermal behaviour & integrated strength

• Thermal tests : run at 150 amps for ~ 1 hour with 2.5 gpm total in 8 water circuits– Cooling water temperature increased by ~1.3°C [will

be less at operating current]

• Will run at 132.1 amps to get required nominal ∫G.dl. In order to shift the IP spot onto the Honda monitor, QD0 needs to run much stronger- will need 220 amps.

• Did a thermal test at 220 amps also. LCW temp increased by ~1.8°C- acceptable increase.


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ATF2

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ATF2

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ATF2 FD quad run at 150 amps for 45 minutes

FD quad thermal test at 150 amps

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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45

measurement # (every minute)

Var

iou

s te

mp

erat

ure

s, d

egre

e C

Magnet Coil

Poletip

Input LCW

Return LCW


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ATF2

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ATF2

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ATF2 FD quad run at 220 amps for 2 hours

FD Quad Thermal test at 220 amps

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1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116

Measurement #, every minute

Var

iou

s te

mp

erat

ure

s, d

egre

e C

Magnet Coil

Poletip

Input LCW

Return LCW

ATF2 Magnets ATF2 Magnets 11Mar '08, Weekly MtgCherrill Spencer Status Report ATF2 FD quads 1 Status...

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