1. Paolo Fessia, Ezio Todesco
WP1 status
INFN Milano, LASA
Franco Alessandria, Giovanni Bellomo, Francesco Broggi, Augusto Leone, Antonio Paccalini, Danilo Pedrini, Mauro Quadrio, Massimo Sorbi, Maurizio Todero, Carlo Uva, Giovanni Volpini
CERN, June 30th, 2015
CERN
Paolo Fessia, Ezio Todesco

2. Corrector magnet inventory
150
OD460
Mechanical
support
Iron yoke
SC Coils
Mechanical
support
Iron yoke
SC Coils
Mechanical
support
SC Coils
From 6-pole to 12-pole magnets exist in both normal and skew form (the latter is shown)
150
OD320
The superferric design was chosen for ease of construction, compact shape, modularity, following the good performance of earlier corrector prototype magnets developed by CIEMAT (Spain).
Giovanni Volpini, CERN 30 June 2015

3. LHC vs. HL-LHC corrector magnet
comparison chart
LHC
HL-LHC
Order
Type
Aperture
Stored energy
Operating Current
Inductance
Integrated field at r=50 mm
Magnetic Length
Differential Iop mm
[J]
[A]
[mH]
[mm]
[kJ]
[T.m]
[m]
[H] 2 S
MQSX 70
2,116
550 14
150
24.57
182
1.00
0.807
1.247 3 N
MCSX
MCSTX 39
100
4.7
1.28
132
0.06
0.111
0.118
MCSSX
MCSOX 6 50
7.8 4
MCOX 16
4.4
1.41
120
0.04
0.087
0.152
MCOSX 22
3.2 5
1.39
139
0.03
0.095
0.107
MCTX 94 80
29.2
4.35
167
0.086
0.430
0.229
0.92
163
0.017
0.089
0.052
187/II
Giovanni Volpini, CERN 30 June 2015
Rev 9 July 2014

4. Sextupole layout Yoke Coil D320 Wedge 194
5.8 mm thick iron laminations, machined by EDM
CuBe TieRods
194
Flux-return plates
Bridge
Yoke
Yoke
Coil
D320
Wedge

5. Flux Return Plate in Quadrupole
Iron yoke total length 801 mm
HX hole r = 185 mm
round bore
flux return plate

6. Quadrupole Fringe field for different choices for the flux return plate
Iron yoke half length
No flux return plate
symmetric flux return plate
Flux return 40 mm
round hole flux
return plate
Selected solution

7. Differential Inductance, a3/b3
«zero-current» inductance, from linear-iron case, L = 194 mH
Ld(I) = 1/I dU/dI = ns2 / At dU/d At
Operating point
Ld = 122 mH
Inductance [H]
Artifacts generated by numerical derivative
The marked change of inductance due to saturation must be carefully considered when designing the protection system
Ampere·turns [At]
263/III
Giovanni Volpini CERN, 30 June 2015

8. Giovanni Volpini CERN, 30 June 2014
Coil deformation σy σz
Wedge
End Plate
3 kN
3.6 kN
0.06 kN
0.25 kN
@ RT
@ 4K
w/ I
Giovanni Volpini CERN, 30 June 2014

9. SC wire
- Small wire (low operating current), but not too small (must be easy to handle, insulation should not reduce too much the Je)
High Cu content
(again, low operating current, 4-pole protection)
- Off the shelf product: small amount required (10’s of kg)
- Small filament: not a strict requirement, but these magnets are designed to operate in the whole range 0-Imax
SC wire procured
35 kg
SC wire required for series
~ 150 kg
Bruker-EAS
NbTi for Fusion application
Fine filaments ITER PF wire
Wire type 2
Cu:NbTi ≈ 2.30
Number of filaments 3282
Wire (filament diameter)
0.5 mm (5.5 µm)
0.7 mm (8 µm)
S2-glass insulation,
8 km + 8 km

10. Coil winding & impregnation tooling
Insulation scheme:
-wire w/ S2 glass 0.14 mm thick (on diameter)
-ground insulation:
G11, 2 mm thick plates on both sides of the coil, including the wire exits
G11 thin, flexible layer on the inner wall of the coil;
S2 tape on the outer wall
Resin inlet/outlet
Base plate
Closing cap (defines the impregnation chamber)
Top plate
mandrel
Resin inlet/outlet
Giovanni Volpini CERN, 26 February 2015

11. Controlled wire tension 10 N Telecentric camera system
Winding station
Controlled wire tension 10 N
(51 MPa)
Telecentric camera system

12. Giovanni Volpini CERN, 30 June 2015
Oven & impregnation
Temperature monitored with a PT100 on the mould, in agreement within +/- 1°C wrt the set temperature (in stationary conditions)
CTD-101K resin
Giovanni Volpini CERN, 30 June 2015

13. Giovanni Volpini, CERN 30 June 2015
Coil assessment
Coil assessment
Test protocol
Coil RT , typical values 9.2 ± ohm, coil temperature measured with 0.1 °C accuracy
Ground insulation test @ 5 kV
Dimensional measurements w/ gauge & optical measuring apparatus
Thermal LN on coil
Resistance & ground insulation test repeated after thermal shock
Inductance measurement
Non-destructive test list & procedures
will evolve into a formal Quality Control Plan, with well defined steps, goals and procedures.
Giovanni Volpini, CERN 30 June 2015

14. Giovanni Volpini CERN, 30 June 2015
Sextupole assembly
Iron laminations
Coil
Cu traces for coil-to-coil junctions
Duratron plate
s.s. rings
Giovanni Volpini CERN, 30 June 2015

15. Test Station 500 A current leads coil under test SC bus-bars
460
500 A current leads
coil under test
SC bus-bars
Al-clad NbTi SC cable from Mu2e TS
λ-plate for subcooled LHe operation
300
Single coil test stand
(later 6-pole …)

16. Single Coil Sample Holdery x z

17. Purpose(s) of the test
To test a coil in “realistic” conditions to identify major faults in the design/assembly
A magnetic plate creates between iron and the coil an attractive force along the normal of the coil plane. In this way, the e.m. force pattern is more resembling to that experienced by a coil during its operation inside the magnet.
Fx (normal to the coil plane, half coil) 2.9 kN @ Iop, here reached at about 300 A
Fy (normal to long axis, half coil) kN @ Iop, “ A
Fz (normal to long axis, half coil) kN @ Iop, “ A
Test both at 4.2 K and 2 K
Single Coil short sample limit K K
Sextupole Iop K (or 40% on the load line)
2) To commission the “small” magnet test station, to be used to test sextupole, octupole and decapole

18. Test results First test at 4.2 K Test at subcooled LHe
Current increased by steps at 0.3 A/s. Quench induced with heaters at 90, 160, 200 and 220 A. Ramp up to 260 A (no quench induced at this current value by choice).
No spontaneous quench occurred.
Test at subcooled LHe
Significant heat load in the bath prevents from reaching a temperature lower than 2.5 K. Main reason is the thermal shield, whose temperature decreases very slowly: Tshield 194 K (early morning Apr 15), 134 K (night between Apr 16 and 17).
Current ramp up to quench.
Four training quenches occurred at
295 A (2.56±0.04 K) or 80% of the s.s. at this T
318 A (2.60±0.04 K) or 87% “
329 A (2.72±0.05 K) or 91% “
325 A (2.85±0.06 K) or 91% “
Training at 4.2 K
Current ramp up to quench at 0.3 A/s
First quench at 280 A, then repeated increasing the ramp rate up to 5.7 A/s (limited by power supply in this configuration). In total 14 quenches at 280 A (or 95% of the s.s. limit).

19. Final Comments & Conclusions
The 2D and 3D design studies shown here on some examples, have been performed on all the five magnet typology, from quadrupole to dodecapole. This work has produced 9 conceptual specifications (normal and skew magnets are considered separately), stored in EDMS. My statement is that this fulfils D1.1a and D1.1b (2D and 3D preliminary design). The sextupole design has been subjected to an informal review, that has not found any inconsistency or potential showstopper. A lot of efforts for the development of a suitable technique for coil winding and impregnation. The successful single coil test (initially not foreseen) has validated the choices. We have hired an experienced physicist and engineer (i.e. one person with both qualifications!) with cryo and SC experience to start on Sep 1st to collaborate to the corrector design, manufacture and test. This is expected to add a significant momentum to the project development.
Giovanni Volpini CERN, 30 June 2015

20. Giovanni Volpini CERN, 30 June 2015
Next steps
2015 Sextupole winding and impregnation tooling/mould manufactured Winding & Impregnation of six coils mid September (considering seasonal effects) Order to Company for sextupole components manufacture mid July Note: critical materials already procured Components manufactured mid September Sextupole mechanical assembly mid October Sextupole LHe cold tested at LASA mid November 2016 Octupole and Decapole built May
Giovanni Volpini CERN, 30 June 2015

21. The End