IR Magnets
SuperKEKB
N. Ohuchi
KEK(on behalf of KEK SC magnet group, IR group and BNL SC magnet group)

2013/03/04

SuperKEKB MAC 20131

Contents
1. Progress from the last MAC
2. IR Magnets Overview and specification
3. Design of S.C. magnets and cryostat
4. Test results of proto-type magnets
5. Construction status
6. Schedule
2013/03/04

SuperKEKB MAC 2013

2

Progress from the last MAC
1. IR magnet and cryostat design––––Improvement of the cross section design of all magnets from the prototype test results.
Permendur was chosen as the yoke material for QC1E and QC2P.
Heavy metal components are installed into the cryostats against the beam background noise.
The 3D designs of QC1/2 in the IR have started by OPERA under the research collaborationwith BNL.

2. R&D––

QC1P and QC1E proto-type magnets were constructed and tested in LHe.
Vibration study with the KEKB magnet cryostat

3. Construction–––

The company for construction of QCSL magnet cryostat was decided as Mitsubishi ElectricCorporation.
The three real corrector coils for QC1LP have been completed, and measured at room
temperature by BNL.
The cryogenic system in the left side has been completed in the 4th floor in Tsukuba
experimental hall and cold tested.

2013/03/04

SuperKEKB MAC 20133

IR magnets overview
Magnet-cryostat in the left
QCSL

Magnet-cryostat in the right
QCSR

QC1RP + QC1RE +QC2RP + Correctors +Cancel coils + Solenoid

QC1LP + QC1LE +QC2LP + Correctors +cancel coils + Solenoid

HER

LER

IP
QC2LE+correctors

2013/03/04

Heavy metal

QC2RE+ correctors
Two solenoids

Heavy metal

SuperKEKB MAC 2013

4

S.C. magnets in SuperKEKB IRDesign changes in the magnets: introducing Permendur yokes to QC1E and QC2P and Permendur
magnetic shields on the beam pipes
ESR-add
QC2LP

ESL

QC2RE

ESR

QC1LP

QC1RE

QC1RP

QC2LE

QC1LE

QC2RP

IRON

Integral field gradient, (T/m)・m
Solenoid field, T

Position fromIP, mm

Magnet type

Corrector

QC2RE

13.58 [32.41 T/m  0.4190m]

2925

S.C. + Iron Yoke and mag. shielda 1, b 1 , a 2, b 4

QC2RP

11.56 [26.28  0.4099]

1925

S.C. + Permendur Yoke and mag. shielda 1, b 1 , a 2, b 4

QC1RE

26.45 [70.890.3731]

1410

S.C. + Permendur Yoke and mag. shielda 1, b 1 , a 2, b 4

QC1RP

22.98 [68.890.3336]

935

S.C.

a 1, b 1 , a 2, b 4

b 3, b 4 , b 5, b 6

QC1LP

22.97 [68.940.3336]

-935

S.C.

a 1, b 1 , a 2, b 4

b 3, b 4 , b 5, b 6

QC1LE

26.94 [72.210.3731]-1410

S.C. + Permendur Yoke and mag. shielda 1, b 1 , a 2, b 4

QC2LP

11.50 [28.05  0.4099]-1925

S.C. + Permendur Yoke and mag. shielda 1, b 1 , a 2, b 4

QC2LE

15.27 [28.440.5370]-2700

S.C. + Iron Yokea 1, b 1 , a 2, b 4

ESR

4.3 T (max. field)

ESR-add

0.3 TESL

4.7 T (max. field)

2013/03/04

Leak fieldcancel coil

S.C. Solenoid
Each beam

S.C. Solenoid + Iron Yoke
S.C. Solenoid
SuperKEKB MAC 2013

5

Magnet design: Permendur yoke
QC1E magnetic design (4s operation) : presented in 2012-KEKB-MAC

2013/03/04

SuperKEKB MAC 2013

6

Magnet design: Permendur yoke
• Choice of Permendur for QC1E and QC2P Yoke.
1. Space between LER and HER beam lines along the QC1E isinsufficient not to have leak field of QC1E in the LER beamarea.
2. Compensation of Belle solenoid field by the accelerator
solenoid is not perfect in the local position.
̶The remanent solenoid field easily goes into the Yokes and themagnetic field in the yokes is enhanced.

3. 12 GeV accelerator operation is the severer magnetic
condition for the magnets than 4S (nominal) operation.

Permendur Yoke and Magnetic Shield
2013/03/04

SuperKEKB MAC 2013

7Magnet design: Permendur yoke
QC1E magnet and e+ beam line

Yoke

Position beam line (helium vessel) breaks
into the QC1E YOKE.
2013/03/04

SuperKEKB MAC 2013

Cross section of magnet-cryostat
8Magnet design: Permendur yoke
SuperKEKB
OperationalEnergy

4.364 GeV@860A
Maximum of thepower supply for LER

For 12 GeV operation:
QC1E and QC2E current = 1.25 × current @4s
QC1P and QC2P current = 1.09 × current @4s
2013/03/04

SuperKEKB MAC 2013

9

Magnet design: Permendur yoke
Field profile in the iron components (3D ANSYS)
Optimized condition (magnetic field in the iron: -0.5 T < B < 0.5 T)

Increasing Belle solenoid current by 1 % (magnetic field in the iron: -0.5 T < B < 1 T)

Increasing acc. solenoid current by 1 % (magnetic field in the iron: -0.1 T < B < 1 T)

2013/03/04

SuperKEKB MAC 2013

10

Magnet design: Permendur yoke
2D field calculation of QC1E (4s) : Yoke material= Iron
With 0T bias field

2.724 T0T0 Gauss

20 Gauss

In the nominal operation of 4s:
Magnet current = 1577 A
G = 72.21 T/mMax. field in the magnet = 2.724 T
Leak field in the e+ beam line center = 5 Gauss
2013/03/04

SuperKEKB MAC 2013

11

Magnet design: Permendur yoke
2D field calculation of QC1E (4s) : Yoke material= Iron
With 0.5 T field in the Iron Yoke

0 Gauss

With 1 T field in the Iron Yoke

20 Gauss

Leak field at the e+ beam center = 6 Gauss

2013/03/04

0 Gauss

400 Gauss

Leak field at the e+ beam center = 100 Gauss

SuperKEKB MAC 2013

12

Magnet design: Permendur yoke
B-H curves of Iron and Permendur

Permendur:Fe=49.2%, Co=49 %, V=1.8%
= 8.3 g/cm3
Bs > 2.35 T

2013/03/04

SuperKEKB MAC 2013

13

Magnet design: Permendur yokeComparison between Iron and Permendur
With 0.5 T field in the Yoke (4s)Permendur

Iron0 Gauss

20 Gauss

Leak field at e+ center = 6 Gauss

0 Gauss

5 Gauss

Leak field at e+ center <1 Gauss

With 1 T field in the Yoke (4s)

Iron0 Gauss
2013/03/04

400 Gauss

Leak field at the e+ center = 100 Gauss

0 Gauss

SuperKEKB MAC 201310 Gauss

Leak field at e+ center = 6 Gauss

14

Magnet design: Permendur yokeComparison between Iron and Permendur
With 1 T field in the Yoke (12 GeV)

Permendur

Iron0 Gauss

2013/03/04

1000 Gauss

0 Gauss

SuperKEKB MAC 2013

100 Gauss15

Cryostat mechanical design• 3D Magnetic field calculation (Yamaoka-san)– Model with the Belle II solenoid + acc. solenoids + iron components– Calculation of the magnetic field and force• Beam background noise study (Nakayama-san)– Installing the heavy metal components into the cryostats for theradiation shield

Mechanical calculation of the cryostat components by ANSYS

2013/03/04

SuperKEKB MAC 201316

Cryostat mechanical design• Magnetic field profile in the Belle II
Belle II Iron Yoke
Belle II Solenoid
QCSL

2013/03/04

QCSR

SuperKEKB MAC 201317

Cryostat mechanical design• Magnetic field profiles along the beam lines

2013/03/04

SuperKEKB MAC 201318

Cryostat mechanical design• Electro-magnetic forces on the iron components and solenoids
R-sideL-side

2

1(+)

3
4

Electro-magnetic force, kN
QCSL

QCSR

1

Solenoid

2

3Solenoid

4Acc. Solenoid ON

-0.81

48.3

-0.05

-1.89

-39.7

8.4

Acc. Solenoid OFF-60.9

0-0.15

6.01

015.3

The largest EMF for the one He vessel2013/03/04

SuperKEKB MAC 201319

Cryostat mechanical design• Heavy metal components in the cryostats– Material: W alloy [ W>95%, =18 g/cm3], nonmagnetic
W shield

QCSL

W front cap

W alloy components = 480 kg
Total weight (cold mass) = 1400 kg

W outer shield

W inner shield

QCSR

W front cap
2013/03/04

SuperKEKB MAC 2013

W alloy components = 800 kg
Total weight (cold mass) = 1700 kg
20

Cryostat mechanical design• Model for mechanical calculation by ANSYS
Support Rod (Ti alloy)

Vacuum vessel : 1142 kg

Fixed surface

EMF=7 tons

2013/03/04

Total weight of the QCSL cryostat and magnets = 2510 kg
Cold mass = 1400 kg
SuperKEKB MAC 201321

Cryostat mechanical design• Model for mechanical calculation by ANSYS

Helium vessel

Support rod

Support rod design
Most careful design: buckling in the support rods
Front rod: diameter=15 mm, length=80 mm, buckling stress of the rods=4550 MPa
Calculated stress in the rod = 224 MPa < 4550 Mpa
Rear rod: diameter=15 mm, length=132 mm, buckling stress of the rods=1670 MPa
Calculated stress in the rod = 124 MPa < 1670 Mpa
2013/03/04SuperKEKB MAC 201322

QC1 proto-type construction
1. Prototypes of QC1E and QC1P were constructed.
̶QC1P has the smallest inner radius (R=25mm) in the four types magnets. Mostdifficult magnet to get the sufficient field quality.
QC1E has the second-smallest radius (R=33mm) and has the magnetic yoke.
̶

2. QC1E Prototype––

Magnet construction : May 28 – June 28
Cold test : July 7 – July 13

3. QC1P Prototype––

Magnet construction : August 6 – September 7
Cold test : September 11 – September 20.

2013/03/04

SuperKEKB MAC 201323

Proto-type QC1E coil production
Coil winding on the mandrel
The coil was baked at 130 C and pressed.

The wound coil was set in theforming block.
2013/03/04

SuperKEKB MAC 201324

QC1E Prototype Magnet
430 mm

2nd layer coil
330 mm

1st layer coil
The coil length is 46 mm longer than QC1P.
The length of the coil straight section is 330 mm.

Four double layer coils

2013/03/04

SuperKEKB MAC 201325

Collaring and yoking processes
Assembled fourcoils on thesupport bobbin

Oil hydraulic press

Collaring press
2013/03/04

SS316LN collars(Yoking process is same as the collaring process)SuperKEKB MAC 201326

Yoked QC1E proto-type

2013/03/04

SuperKEKB MAC 201327

QC1E excitation test
QC1E magnet was excited up to 2157 A without quench.
Nominal operating current for 4S = 1558.5 A
The current of 2157 A is the limitation of the power supply.

•On the load line of QC1E,–––•For the operation at 12 GeV,–––

2013/03/04

Ic at 4.7 K = 2480 A
Iop/Ic = 1558.5/2480 = 0.628
I2157A/Ic = 0.870

SuperKEKB MAC 2013

The maximum HER energy is assumed
to be 8.75875 GeV.
QC1E current: I 8.75875 = 1950.1 A
I 8.75875 / Ic = 0.786

28QC1E integral field measurements
Integral quadrupole field•

Iop = 1558.5 A for 4S––

2013/03/04

Optics requirement of the quadrupole field = 26.938 T
Measured quadrupole field = 26.660 T• The assembled magnet produces 1% less quadrupole field than the design.
SuperKEKB MAC 2013

29

QC1E integral field measurements
Error field (Multipole field comp.)
R=9.54 mm at I=1561.7 A

R=15.0 mm at I=1561.7 Ananbn

anbn

3

1.14

5.50

1.78

8.59

40.18

-0.28

0.44

-0.68

50.06

-0.48

0.23

-1.83

6-0.06

-0.31

-0.39

-1.85

7-0.01

0.01

-0.09

0.10

80.05

-0.00

0.69

-0.02

90.02

-0.00

0.51

-0.09

10

-0.00

-0.02

-0.10

-0.62

Reference radius= 9.54 mm
an = An/B2  10000
bn= Bn/B2  100002013/03/04

SuperKEKB MAC 201330

QC1E field profile measurements
Quadrupole field profile
Field profile measurements were performed at I=1560.6 A.
The 40 mm HC was moved with a distance of 10 mm in the coil ends, and 20 mm in coil straight section.

Measured gradient = 70.07 T/m(Design = 70.63 T/m)

The measured field gradient along the coil straight section was 0.86 % less than the design value.
2013/03/04

SuperKEKB MAC 201331

QC1E field profile measurements
Sextupole field profile(a3, b3)

Coil straight section

Reference radius= 15 mm
an = An/B2@magnet-center  10000
bn= Bn/B2@magnet-center  100002013/03/04

SuperKEKB MAC 201332

QC1P prototype magnet
384 mm

2nd layer coil

1st layer coil
The designs of the coil ends are optimized
as to the integral magnetic length anderror field components.

Four double layer coils

2013/03/04

SuperKEKB MAC 201333

QC1P prototype magnet
Completed QC1P prototype magnet (collared magnet without yoke)

2013/03/04

SuperKEKB MAC 201334

QC1P excitation test
QC1P magnet was excited up to 2100 A without quench.
Nominal operating current for 4S = 1625 A•The SC cable performance was much better
than the specification.
–•

On the load line of QC1P,––•

SC cable supplier: Furukawa Electric. CO LTD
Ic at 4.7 K = 2770 A
Iop/Ic = 1625/2770 = 0.58

For the operation at 12 GeV,–––The maximum LER energy is assumed to be
4.364 GeV.
QC1P current: I 4.1171 = 1773 A
I 4.1171 / Ic = 0.64

QC1P Load Line with Solenoid Field
2013/03/04

SuperKEKB MAC 201335

QC1P integral field measurements
Integral quadrupole field•

Iop = 1624.93 A for 4S––

2013/03/04

Optics requirement of the quadrupole field = 22.966 T
Measured quadrupole field = 23.217 T• The assembled magnet produces 1% higher quadrupole field than the design.
SuperKEKB MAC 201336

QC1P integral field measurements
Error field (Multipole field comp.)
nanbn

2-0.000

10000

32.82

3.66

42.08

0.24

50.35

0.23

60.03

-0.59

70.07

0.13

80.03

0.01

9-0.080.05

100.020.01

n : Multipole number–

2013/03/04

Reference radius= 9.54 mm
an = An/B2  10000
bn= Bn/B2  10000
An : skew field of the n-th
Bn : normal field of the n-th
B1 : normal dipole,
B2 : normal quadrupole.

n = 2 : quadrupole field

SuperKEKB MAC 201337

QC1P field profile measurements
Quadrupole field profile
Field profile measurements were performed at I=1626 A.
The 40 mm HC was moved with a distance of 5 mm in the coil ends, and 20 mm in coil straight section.

Measured gradient = 68.384 T/m(Design = 68.844T/m)

The measured field gradient along the coil straight section was 1 % less than the design value.
2013/03/04

SuperKEKB MAC 201338

QC1P field profile measurements
Sextupole field profile(a3, b3)

Coil straight section

Reference radius= 10 mm
an = An/B2@magnet-center  10000
bn= Bn/B2@magnet-center  100002013/03/04

SuperKEKB MAC 201339

a3 and b3 error field• Sextupoles are produced by the dipole deformationof four coils•  r = 50 μm
 r= coil displacementin radial direction

b3 = 13.62  10-4
a3 = 0b4 = 0a4 = 0b5 = -1.63  10-4
a5 = 0•  r = 20 μm– b3 = 5.45  10-4
– a3 = 0– b4 = 0– a4 = 0– b5 = -0.65  10-4
– a5 = 0b3 = 10  10-4 corresponds to r = 36 μm.
QC1E: G=72.2 T/m@ R=15 mm : b3 = 14.75 Gauss (50 μm)、5.9 Gauss (20 μm)
2013/03/04

SuperKEKB MAC 201340

Improper design in Quadrupoles• a3 and b3 at 0.1% in the magnet straight section– The calculated displacement of the quadrant coil = 36 m• 0.1 % smaller produced magnetic field than the design– rin of the QC1E coil : 280 m larger than design– rin of the QC1P coil : 250 m larger than design• During the collaring process of the four coils, the coils weresqueezed on the support bobbin which had correctly the designradius.
– There existed the gap of ~300 m between the support bobbin and thecoil inner surfaces.

The mechanical parameters of SC cables were checked in themagnet cross section.
2013/03/04

SuperKEKB MAC 201341

Improper design in Quadrupoles• In the design of the magnet cross section– “EMF in the magnet + thermal contraction from room temp. to 4 K” is considered.
– Under the conditions at 4 K, the inner stress in the coils should be left so that thecables do not move by the EMF.
– In the magnet design, the inner stress at room temperature was designed at 30MPa.
– The magnet cross sections were designed with the cables at the compressed sizewith the stress.

• The improper mechanical parameter: Young modulus– Initial design: 648 MPa– Cable measurement: 8 GPa (In KEKB quadrupole, 6.86 GPa)
– In the produced coils after collaring, the inner radius was larger than the design.

• The designs of the cross sections and the coil ends in all magnets weremodified with the proper Young modulus.

2013/03/04

SuperKEKB MAC 201342

Improper design in Quadrupoles• QC1E coil end
Original shapes are circle

2013/03/04

SuperKEKB MAC 201343

Construction status1. QCSL QC1/2 SC quadrupoles at Mitsubishi• Technical transfers of QC1LP, QC1LE, QC2LP and QC2LE magnet drawings,
and all jig drawings have been almost completed.
• Tooling jigs, machines for QC1P/E and the SC cables were transported toMitsubishi in December 2012.
• The winding machines were set in the factory of Mitsubishi.
• The first test winding of QC1P proto-type coil were performed in January
2013 by the technicians of Mitsubishi for their training.
– The test winding has been completed with the same coil components and the QC1Pcable four times up to now.
– The final test winding with the actual coil end spacers is planed in April.

1st layer

2nd layer
2013/03/04

SuperKEKB MAC 201344

Construction status
2. SC corrector coils at BNL• The corrector coils (a1, b1 and a2) for QC1LP were completed by BNL andmeasured at room temperature. The correctors and bobbins will betransported to KEK in April, and they will be cold tested in KEK.
• The corrector coils (a1, b1, a2 and b4) for QC1LE are now wound on thesecond winding machine.
Test winding of leak field cancel coil

Field measurement at room temp. in BNL

Tilt sensor foraligning the coils
and the bobbin
QC1LPcorrectors andbobbin

2013/03/04

SuperKEKB MAC 201345

Construction status
Field quality of the correctors for QC1LP
a1 coila2 coil

nbn

an

bnan

bn

an

1

0.0

10000.0

10000.0

0.0

0.0

0.0

2

3.6

-9.9

10.5

-4.9

0.0

10000.0

3

-2.1

6.4

-6.6

4.0

0.4

-1.5

4

-0.5

-5.2

-1.3

6.3

-0.1

-1.6

5

0.1

-1.0

-1.6

-0.2

-1.5

0.0

6

0.00.6-0.1

0.9

-0.6

1.4

7-0.2

0.0

-0.9

-0.3

-0.1

0.1

8

0.2

-0.2

0.1

1.6

-0.1

-0.2

90.1

0.4

-1.1

-0.1

-0.1

-0.1

10-0.4

0.0

-0.1

0.3

0.0

0.1

0.0212T・m

0.0175T・m

Field strength@70A

2013/03/04

b1 coilSuperKEKB MAC 2013

0.982T

46

Construction status
3. Cryogenic system for QCSL
The LHe refrigerator Cold Box for QCSL
and subcooler were
installed in the 4thfloor undergroundand cold tested in thelast month.
Cryogenictransfer line

Cryostat-L

Cryostat-RBelle

2013/03/04

SuperKEKB MAC 201347

Construction status

Cold box and subcooler unit
2013/03/04

SuperKEKB MAC 201348

Construction status• Performance test cold box– The cold box showed the cooling power as same as the power in 20 years ago.
– Measured cooling power is 250 W at 4.3 K.
Feb. 27, 2013

Feb. 29, 2013
Feb. 29, 20132013/03/04

SuperKEKB MAC 201349

Construction schedule2013 JFY
Apr.-Jun.

Jul.-Sep.

Oct.-Dec.

2014 JFK
Jan.-Mar.

Apr.-Jun.

Jul.-Sep.

Oct.-Dec.

2015 JFK
Jan.-Mar.

Apr.-Sep.

Oct.-Mar.

QCSL: Magnetcryostat
Installing QCSL
on the beam line
Connection bet.
cryostat and cryo.
QCSL test andfield meas. On
the beam line
Accelerator
operationwithout QCS
QCSR: Magnetcryostat
Installing QCSR
on the beam line
Connection bet.
cryostat and cryo.
QCSL/R tests on
the beam lines
2013/03/04

SuperKEKB MAC 201350

Summary• Magnet and IR design– Permendur yoke for QC1E and QC2P.
– Redesign of all QC1/2 magnets.

• SC correctors and leak field cancel coils– Production of correctors has been started by BNL.
– The completed coils showed good field quality at room temperature, andthe final test at 4.2 K will be performed at April in KEK.
– All coils for QCSL will be completed in December 2013.

• Prototype QC1E/P magnets– Prototypes showed good excitation results.
– From the field measurement results, the improper parameter, Youngmodulus, in design was found. The correct parameter is already includedin the all magnet designs.

• Completion of QCSL on the beam line in May 2014 is now very
difficult, but our group will not give up.
2013/03/04

SuperKEKB MAC 201351