QCS IR magnets
N. Ohuchi
On behalf of the SuperKEKB IR group2018/03/15

SuperKEKB Review 2018

1

Contents
1. IR magnets
2. Construction status of QCS system
3. Magnetic field measurement results
4. Some results from the cold tests
5. Summary

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SuperKEKB Review 20182

Overview of IR magnets
QCS-R Cryostat

QCS-L Cryostat

Helium Vessel

Helium Vessel
QC2LP
4 correctors(a1,b1,a2,b4)

ESR1 Solenoid

ESL solenoid

4 correctors

QC1LP
4 correctors

Leak field(a1,b1,a2,a3)

b3 corrector

cancel coils(b3,b4,b5,b6)

QC2RE

IP
(a1,b1,a2,b4)

QC1LE
4 correctors(a1,b1,a2,b4)

ESR2

QC1RE

(a1,b1,a2,b4)

QC2LE
4 correctors

Helium Vessel

4 correctors(a1,b1,a2,a3)

83 mradLeak fieldcancel coils(b3,b4,b5,b6)

QC1RP
5 correctors

b3 corrector(a1,b1,a2,a3,b4)

QC2RP
4 correctors

HER(a1,b1,a2,a3)

ESR3

Helium Vessel
4 SC main quadrupole magnets: 1 collared magnet, 3 yoked magnets
16 SC correctors: a1, b1, a2, b4
4 SC leak field cancel magnets: b3, b4, b5, b6
1 compensation solenoid
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LER

4 SC main quadrupole magnets: 1 collared magnet, 3 yoked magnets
19 SC correctors: a1, b1, a2, a3, b3, b4
4 SC leak field cancel magnets: b3, b4, b5, b6
3 compensation solenoid

SuperKEKB Review 20183

IR magnets• Main quadrupoles [QC1, QC2]

− Forming final beam focusing system with quadrupole doublets.

• Correctors [a1, b1, a2, a3, b3, b4]− a1, b1, a2: magnetic alignment of the magnetic center and the mid-plane phaseangle of main quadruple.
− a3, b3: correction of sextupoles induced by magnet construction errors.
− b4:increasing the dynamic transverse aperture (increasing the Touschek life time).

• Compensation solenoid[ESR, ESL]− Canceling the integral solenoid field by the particle detector (Belle II).
− By tuning the Bz profile, the beam vertical emittance can be minimized.
− The compensation solenoids are designed to be overlaid on the main quadrupoles
and correctors.
− ESR consists of three solenoid magnets of ESR1, ESR2 and ESR3.

• Leak field cancel coils [b3, b4 , b5, b6]− Canceling the leak field on the electron beam line from QC1P (collared magnet).

•

Total number of the SC devices in two cryostats = 55
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IR magnets• Cross section design of main quadrupoles [QC1, QC2]
– The quadrupole magnets are designed with the two layer coils (double pane cake design).
– In the early design, the smaller young modulus of the SC cable than the real cable were applied.
• As the result, 10 units sextupole field by the assembly error of the magnet was induced.
• All magnet cross sections were redesigned, and a3 and b3 correctors have been installed in theright cryostat.

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IR magnets• Main quadrupoles [QC1, QC2]
– QC1L(R)P, QC2L(R)P for the left (right) side cryostat to IP and for the positron beam line.
– QC1L(R)E, QC2L(R)E for the left (right) side cryostat to IP and for the electron beam line.
ESR-add
QC2LP

ESL

ESR

QC1LP

QC2RE

QC1RE

QC1RP

QC2LE

QC1LE

QC2RP

IRON

Integral field gradient, (T/m)・m

Magnet type

Z pos. from IP, mm

θ, mrad∆X, mm

∆Y, mm

QC2RE

13.58 [32.41 T/m × 0.419m]

Iron Yoke

2925

0

-0.7

0

QC2RP

11.56 [26.28 × 0.410]

Permendur Yoke

1925

-2.114

0

-1.0

QC1RE

26.45 [70.89×0.373]

Permendur Yoke

1410

0

-0.7

0

QC1RP

22.98 [68.89×0.334]

No Yoke

935

7.204

0

-1.0

QC1LP

22.97 [68.94×0.334]

No Yoke-935-13.65

0

-1.5

QC1LE

26.94 [72.21×0.373]

Permendur Yoke

-1410

0

+0.7

0

QC2LP

11.50 [28.05 × 0.410]

Permendur Yoke

-1925

-3.725

0

-1.5

QC2LE

15.27 [28.44×0.537]

Iron Yoke

-2700

0

+0.7

0

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IR magnets• Correctors– The SC correctors were designed and directly wound on the support bobbin (helium inner vessel) by BNL

under the US-Japan research collaboration• Direct winding method• Multi-layer coil [maximum layer=4 by limiting with the gap distance between the main quadrupole
magnet and the helium inner vessel]• Some correctors were assembled on the outer surface of the main quadrupole magnets.
– Each corrector magnet is excited by the individual bipolar power supply.
QCSL- Main Quadrupole

Corrector

QCSR-Main Quadrupole

Corrector

QC1LP

a1, b1, a2, b4

QC1RP

a1, b1, a2, b4, a3→b3

QC2LP

a1, b1, a2, b4

QC2RP

a1, b1, a2, a3

QC1LE

a1, b1, a2, b4

QC1RE

a1, b1, a2, a3

QC2LE

a1, b1, a2, b4

QC2RE

a1, b1, a2, a3

Between QC1RP and QC2RP

b3

Between QC1RE and QC2RE

b3

a1 corrector winding for QC1LP @BNL

2018/03/15

Assembly of QC2LE
SuperKEKB Review 2018
and correctors

7

IR magnets• Compensation solenoids [ESL, ESR1, ESR2-3]
ESR2-3 compensation solenoid

ESL compensation solenoid

ESR1 compensation solenoid

Magnet length= 914 mm
Maximum field at 403 A= 3.53 T
Stored Energy= 118 kJ
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SuperKEKB Review 2018

Magnet length= 1575 mm
Maximum field at 450 A=3.19 T
Stored Energy= 244 kJ
Cold diode quench protection system
8IR magnets• QC1P leak field cancel magnets
−
−
−
−
−

QC1P for the e+ beam line is non-iron magnet and the e- beam line is very close to QC1P. The leak fields from
QC1P go through the e- beam line.
B3, B4, B5 and B6 components of the leak fields are designed to be canceled with the SC cancel magnets.
By rolling QC1P in design and lower level of the QC1P axis than HER beam line, skew field components are
induced. The cancel magnets are rotated to cancel the skew components in design.
B1 and B2 components are not canceled, and they are included in the optics calculation.
B2 component is used for focusing and defocusing the e- beam.

QC1P
Leak field

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Construction status of IR magnets• Construction and tests of QCS system on the SuperKEKB
beam lines– August 1st, 2016: Setting the QCSL cryostat on the beam lines in the SuperKEKB IR– September 1st, 2016 ~ October 20th, 2016: Construction of the cryogenic system for QCSL
– November 7th, 2016 ~ December 22nd, 2016: Cool down test of the QCSL cryogenic system and the
–
–
–
–
–
–
–
–

excitation tests of the SC magnets
November 1st, 2016: During the final construction stage of ESR1, electrical insulation faults wasfound. The positions and the cause of the trouble were specified at Nov. 5th, 2016.
January 16th, 2017: In the final electrical tests of the QCSR magnet-cryostat, the electrical insulation
fault was detected at the cold diode for the quench protection of ESR1. The fault was repaired at
January 17th, 2017.
January 31st, 2017: The final electrical tests of the QCSR magnet-cryostat were passed in Mitsubishi.
February 13th, 2017: Setting the QCSR cryostat on the beam lines in the SuperKEKB IR
March, 2017: Construction of the cryogenic system for QCSR
April 11th, 2017: Moving the Belle-II detector at the beam interaction point
May ~ August, 2017: Commissioning the QCSL/QCSR systems, excitation tests and magnetic fieldmeasurements of all magnets
September ~ December, 2017: Final preparation of the system for the beam operation• Exchange of the cryostat inner pipe of the cryostat with the real beam pipes• Modification of the current lead ends for a safety operation of the SC magnets• Repairing the cold valve of the cold box for the QCSR system to recover the cooling power

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Installation and alignment of QCSL/R cryostats Using the references on the cryostats, we aligned the cryostats to the HER/LER

beam lines, which are defined by the normal conducting magnets andmonuments on the tunnel walls/floor.
 The cryostats were in their final positions, but without BELLE II detector.
 The RMS of the best fits to the target coordinates are 0.2-0.3 mm.

• Target position coordinates for QCSL are given by the QCS group. They are obtained
from the SSW measurements carried out on the measurement bench.
• The design coordinates from the cryostat drawing are used for aligning the QCSR
cryostat, as they did not have time for SSW measurement on the measurement bench
before installation.
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Misalignment concernsBeam line floor deformation (mainly sinking) after BELLE II roll-in is seen.
QCSL cryostat was disassembled for the QCS beam pipe installation after the SSW
measurements at the beam line. A very quick survey with limited view (not many
data points) suggests that the front and back parts of the cryostat are twisted bya couple of hundred mrad. No SSW after reassembling. Not confirmed.

Ring outside
Beam line floor sinks
towards the IP. QCS “nose”
probably hangs more as it iscantilevered.

Back

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SuperKEKB Review 2018

Front

Front and back parts may be
twisted when reassembled.
12

QCS System in Tsukuba Exper. Hall
• Construction of final focus magnet system in SuperKEKB IR wascompleted in March, 2017.

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Completed QCS systems

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Magnetic field measurements• Single Stretched Wire measurement (SSW)− Measurements of magnetic field centers and angles of the quadrupole field of QC1and QC2• Harmonic coil measurement− Magnetic field quality measurements of the SC magnets− Higher order multipole field profile measurements− Magnetic field strength measurements as the function of the transport magnet
current• 6 harmonic coils were prepared for the integral field measurements and thefield scan measurements (L=20 mm).

•

3 axis-hall probe measurement− Solenoid field profile measurements along the beam lines• Tuning the field profiles along the beam lines to complete the cancelation of
the integral Belle solenoid field.

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15

SSW measurement
SSW measurement system in the IR•••

Two magnet-cryostats of QCSL/R were aligned to the beam lines with the targets of the cryostats.
A BeCu single wire of φ 0.1 mm, which was aligned to the design beam line, was stretched through QCSR and QCSL
cryostat bores.
The measurements were performed with operating the Belle SC solenoid at 1.5 T, and ESL and ESR1 solenoids.
− The measured data include the displacement by the electro-magnetic forces between solenoids andmagnetic components in the cryostats.

QCSL magnetcryostat
QCSR magnetcryostat

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SSW measurement•

The quadrupole field centers and angles of 8 SC quadrupole magnets in the
QCSL/R magnet-cryostats from June 19, 2017 to June 30, 2017.

−−−

The FNAL research collaborator, Mr. Joseph DiMarco, was invited to complete the measurements .
The measurements were successfully completed, and the measured results were shown in the graph below.
In order to exclude the solenoid field effect on the measurements, the transport currents to the magnets in theoperation mode were AC 9 A.

Horizontal direction

Vertical direction

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SSW measurement•

Measured magnetic center shifts to the design values and field angles to thehorizontal planes of the 8 main quadrupoles as follows:
QC1LP

QC2LP

QC1RP

QC2RP

∆x, mm

0.014-0.335

0.684

0.486

∆y, mm

-0.211-0.692-0.2960.042∆θ, mrad-15.32 (-13.65)-7.77 (-3.725)

9.22 (7.204)-3.84 (-2.114)

QC1LE

QC2LE

QC1RE

QC2RE

∆x, mm

-0.212

0.129

0.245

0.079

∆y, mm-0.286-0.535-0.373-0.581∆θ, mrad-1.60 (0.0)-1.54 (0.0)-0.14 (0.0)-0.73 (0.0)

The magnetic field measurements were performed under the conditions of operating
the Belle solenoid and ESL/ESR solenoids.
− Electro-magnetic forces acting on the cryostats:• QCSL = 52.6 kN, QCSR=35.7 kN (calculation)

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Harmonic coil measurements• Measurements of harmonic coils in SuperKEKB IR (in July, 2017)̶̶̶

One unit of measurement system has two harmonic coils.
The harmonic coils are moved by the mover, the movement is measured by the digital scaler.
Two sets of the mover system were prepared for shortening the measurement period.
For QC1P and QC1E
L=600 mm and 20 mm, R=12 mm
For QC2P
L=700 mm and 20 mm, R=25 mm
For QC2E
L=800 mm and 20 mm, R=33 mm

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Integral field quality of the QC1 and QC2 magnets(measured under solenoid fields)

The strengths of the multipole field components are normalized with the B2 field strength.
QC1LP

at R=10mm, I=1.71 kA

QC1RP

at R=10mm, I=1.71kA

QC2LP

at R=30mm, I=0.91kA

QC2RP

at R=30mm, I=0.91kA

n

an

bn

an

bn

an

bn

an

bn

1

790.2

232.9

1265.4-140.25

399.7

13.8

-70.01

40.84

2

0.

10000.

0.

10000.

0.

-10000.

0.

-10000.

3

-0.07

1.69

0.65

-0.91

-1.03

2.61

2.58

-0.09

4

0.52

0.01

-0.94

-0.66

0.20

-0.20

-1.48

-0.22

5

0.01

-0.38

-0.35

0.35

0.92

0.32

-0.21

-0.07

6

-0.28

-0.10

0.37

-0.06

0.31

-3.58

0.62

-4.69

7

0.04

0.05

0.01

-0.06

-0.04

0.04

-0.21

0.00

8

0.07

-0.03

-0.04

-0.04

0.07

0.03

-0.07

0.07

9

0.10

-0.06

-0.01

0.05

-0.48

0.03

-0.12

-0.20

10

-0.03

-0.18

0.04

-0.18

0.21

0.86

0.34

1.77

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Integral field quality of the QC1 and QC2 magnets(measured under solenoid fields)

QC1LE

at R=15mm, I=1.71kA

QC1RE

at R=15mm, I=1.71kA

QC2LE

at R=35mm, I=1.11kA

QC2RE

at R=35mm, I=1.11kA

n

an

bn

an

bn

an

bn

an

bn

1

191.7

-313.2131.2-145.4-12.8

170.6415.4 (38.9)

114.0 (106.5)

20.

10000.

0.

10000.

0.

-10000.

0.

-10000.

3

-0.59

0.72

0.97

-0.47

-1.44

-1.25

-18.9 (-4.79)

2.84 (-2.90)

4

0.21

-0.24

-0.05

-0.18

-1.88

-0.29

8.09 (0.60)-0.66 (0.04)

5

-0.20

-0.28

0.02

0.03

-0.63

0.16

-0.42 (0.40)-0.21 (-0.10)

6

0.01

1.04

-0.07

0.92

0.18

-4.66

-0.22 (-0.19)-1.60 (-1.95)

7

0.02

0.05

0.10

-0.02

-0.01

0.02

-0.11 (-0.05)

0.20 (0.14)

8

-0.09

-0.10

0.02

-0.01

-0.22

0.06

-0.06 (0.05)

0.16 (0.11)

9

-0.22

0.57

0.08

0.17

-0.20

-0.17

0.02 (-0.03)-0.25 (-0.17)

10

-0.09

-0.08

-0.02

-0.60

0.08

2.22

0.06 (0.05)

1.80 (1.80)

Without excitation of solenoids
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Operation currents of the QC1/2 magnets
Current dependence of the magnetic field of QC1RE

Transfer function = G/I

The magnet excitation parameters aredefined by the 5th polynomial fitting withthe data during up-ramping.
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Magnetic field profile of the QC1/2 magnets
Measured results:QC1LE magnetic field profile along the HER beam line

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Magnetic field profile of the QC1/2 magnets
Measured results:QC2RE magnetic field profile along the HER beam line

A1 , B 1

A2 , B 2

A3, B3A4 , B 4

A5 , B 5

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A6 , B 6

24

Magnetic field profiles of the cancel magnets
QCSL: From the measurement results of the harmonic coil and SSW (-1.6 mrad) for QC1LE, the scandata by the short harmonic coil were corrected.

LcanB4=-25.797A

LcanB3=-39.948A

QC1LP=1625A
LcanB4=-25.797A

QC1LP=1625A
LcanB3=-39.948A
QC1LP Iop＝1601.6 A, ƩB3=0：

2018/03/15––

B3: operating current＝-40.3787 A
ƩA3＝3.86×10-4 Tm @ R=10mm

QC1LP Iop＝1601.6 A, ƩB4=0：

SuperKEKB Review 2018––

B4: operating current ＝-25.5742 A
ƩA4＝1.14×10-4 Tm @ R=10mm 25

Magnetic field profiles of the cancel magnets
QCSL

LcanB6=13.494 A
LcanB5=-17.011 A

QC1LP=1625A
LcanB6=13.494 A

QC1LP=1625A
LcanB5=-17.011 A

QC1LP Iop＝1601.6 A, ƩB5=0：––
2018/03/15

QC1LP Iop＝1601.6 A, ƩB6=0：

B5 : operating current＝ -17.602 A
ƩA5＝1.456×10-5 Tm @ R=10mm

SuperKEKB Review 2018––

B6 : operating current＝ 14.442 A
ƩA6＝-8.018×10-6 Tm @ R=10mm

26

Magnetic field profiles of the cancel magnets
QCSR: From the measurement results of the harmonic coil and SSW (-0.14 mrad) for QC1RE, the scandata by the short harmonic coil were corrected.

RcanB3=40.098 A
RcanB4=26.002 A

QC1RP=1625A
RcanB3=40.098 A

QC1RP Iop＝1602.2 A、ƩB3=0：––
2018/03/15

QC1RP=1625 A
RcanB4=26.002 A

QC1RP Iop＝1602.2 A、ƩB4=0：

B3 : operating current＝40.4403 A
ƩA3＝4.098×10-6 Tm @ R=10mm
SuperKEKB Review 2018––

B4 : operating current＝27.6702 A
ƩA4＝1.62×10-4 Tm @ R=10mm 27

Magnetic field profiles of the cancel magnets
QCSR

RcanB5=17.198 A
RcanB6=13.499 A

QC1RP=1625A
RcanB5=17.198 A

QC1RP=1625A
RcanB6=13.499 A
QC1RP Iop＝1602.2 A, ƩB5=0：

2018/03/15––

B5 : operating current ＝21.0970 A
ƩA5＝1.6076×10-5 Tm @ R=10mm

QC1RP Iop＝1602.2 A, ƩB6=0：

SuperKEKB Review 2018––

B6 : operating current ＝13.5785 A
ƩA6＝-1.5246×10-5 Tm @ R=10mm
28

Magnetic field measurements of the correctors

QC1LP

QC2LP

QC1LE

QC2LE
2018/03/15

Corrector

Specific requirement

Measurements at 60 A
(on the beam line)

Allowablealignment at ±60 A

a1

0.016 Tm @ R=10mm

0.0177 Tm± 0.73 mm

b1

0.016 Tm

0.0146 Tm± 0.63 mm

a20.64 T

0.801 T± 17.4 mradb4

60 T/m2

295 T/m2

̶

a1

0.03 Tm @ R=30mm

0.0350 Tm± 1.18 mm

b1

0.03 Tm

0.0409 Tm± 2.33 mm

a20.31 T

0.640 T± 27.9 mradb4

60 T/m2

107.7 T/m2

̶a1

0.027 Tm @ R=15mm

0.0323 Tm± 0.92 mm

b1

0.046 Tm

0.0551 Tm± 0.93 mm

a20.75 T

0.932 T± 17.3 mradb4

60 T/m2

730 T/m2

̶

a1

0.015 Tm @ R=35mm

0.0400 Tm± 2.52 mm

b1

0.015 Tm

0.0442 Tm± 2.89 mm

a2

0.37 T

0.753 T± 24.7 mradb4

60 T/m2

142.9 T/m2

̶SuperKEKB Review 201829

Magnetic field measurements of the correctors

QC1RP

QC2RP

QC1RE

2018/03/15

Corrector

Optics requirement

Measurements at 60 A
(on the beam line)

Allowablealignment at ±60 A

a1

0.016 Tm

0.0174 Tm± 0.57mm

b1

0.016 Tm

0.0159 Tm± 0.53 mm

a20.64 T

0.798 T± 17.4 mrada3-> b3

5.1 T/m

9.57 T/m̶b4

60 T/m2

268 T/m2

̶

a1

0.03 Tm

0.0578 Tm± 3.99 mm

b1

0.03 Tm

0.0362 Tm± 1.28 mm

a20.31 T

0.630 T± 27.3 mrad

a30.905 T/m

1.087 T/m2

̶a1

0.027 Tm

0.0313 Tm± 0.96 mm

b1

0.046 Tm

0.0550 Tm± 0.92 mm

a20.75 T

0.889 T± 16.8 mrada3

4.55 T/m

22.85 T/m̶

SuperKEKB Review 201830

Magnetic field measurements of the correctors
Corrector

Optics requirement

measurements at 60 A
(on beam lines)

Allowablealignment at ±60 A

a1

0.015 Tm

0.0310 Tm± 2.25 mm

b1

0.015 Tm

0.0353 Tm± 2.71 mm

a2

0.37 T

0.602 T± 23.1 mrada3

1.05 T/m

6.51 T/m

̶

QC1-2REb3

18.2 T/m

55.5 T/m

QC1-2RPb3

11.48 T/m

28.3 T/m

QC2RE

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̶
̶

31

Hall probe field measurements along the beam lines
Required precision of the magnetic field in the SuperKEKB IR• Field error for accelerator beam operation < 10 Gauss̶ Magnetic field mapping of the beam lines by 3-axis Hall probe• Field error for particle analysis < 15 Gauss– Magnetic field measurements inside the Belle director with the field mapper of 3axial Hall probes and the fixed 3-axial Hall probes (by DESY group under the Belle II
collaboration)

Measured magnetic field data are used for improving the 3D
magnetic field calculation model which produces the precise
field map in the SuperKEKB IR.
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Hall probe field measurements along the beam lines
Mapping the magnetic field along the beam lines••

The measurement system consisted of the commercial Hall probe and thescanning mover.
The hall probe
position was definedwith the Belle end
yokes.
3 Axis-Hall-probe

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Hall probe field measurements along the beam lines
Calculation by ANSYS

Measured field profile
along HER beam line

Belle Gp (DESY)
field mapping

QCSR

QCSL

Building the field profile with measurement and calculation

From the field measurements, the transport current of ESL was changed from 404 A to 390 A.
The currents of ESR1 and ESR2-3 are 450 A and 151 A.
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Hall probe field measurements along the beam lines
SuperKEKB IR magnetic field calculation model by OPERA-3D• All SC magnets and magnetic components are included.

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Some results from the cold tests
1. Quenches of the quadrupole magnets from thesuperconducting cables at the bottom of the current
leads
2. Movement of the LHe vessels which have the SC
magnets by the electro-magnetic forces from the Bellesolenoid field at 1.5 T
3. Cold valve trouble of the He refrigerator for QCSR

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Some results from the cold tests
1.

Quenches of the magnets from the superconducting cables at the bottom of
the current leads
All quenches happened−−−

Dec. 6th, 2016: QC1LE quench at 1752 A during up-ramping to 2000 A
Dec. 9th, 2016: QC2LP quench at 1240 A during up-ramping to 1250 A
Jun. 13th, 2017: QC1LE quench at 1090 A during up-ramping to 1577 A
Quench onset

at the SC cable between
the magnet and current
lead

V1L-V5 (Voltage between the bottom of
positive power lead and the magnet)

Current lead voltage taps

Quadrupole magnet and voltage taps
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Some results from the cold tests
Estimation of temperature at the end ofcurrent leads

Configuration ofcurrent lead
From PS

Lead conditions at quench:
SC cables from magnet wereconnected to the bottom terminals of
the current leads with solder• Superconducting cable(NbTi)–––

Terminal at room
temperature
Heat exchanger(conductor)

5T @ 4.22 K 307A
6T @ 4.22 K 247A
NbTi: Jc=5500 A/mm2 at 0 T & 4 K
•
•

•

–
–
–


To magnet

Top surface of the QCSR service
cryostat (30 pairs + 1 current leads)

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SuperKEKB Review 2018

Tcs=Tb + [ Tc (B) – Tb ][1- (Iop/Ic)]
Tc (0) = 9.2 K, Tb = 4.2 K
Tcs= 7.52 K
IC=5500 A/mm2, Iop=1848 A/mm2(corresponds to 1800 A of operating
current)

Improvement：
Two SC cables are added to thebottom terminal by soldering–

Bottom terminal of
current lead at 4K

Strand wire: O.D.=0.5mm (Cu ratio=1)
Strand number in cable=10
Performance of strand

Tcs= 8.64 K by reducing the current
density of the SC cables by one third38

Some results from the cold tests
20 current leads of the main quadrupole magnets, ESL and ESR1 were improvedby adding the additional SC cables to the bottom terminals from October toNovember, 2017.

Soldered two
cables to theterminal

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Some results from the cold tests
2. Movement of the LHe vessels which have the SC magnets by theelectro-magnetic forces from the Belle solenoid field at 1.5 T
QCSL helium vessel

The vessel is supported by the eight Ti alloy rods from thevacuum vessel.

Rear rod

Front rod

Measured stress in the QCSL
support rods
Under excitation of Belle solenoid

Belle solenoid + ESL
excitation
EMF=52.6 kN

Belle solenoid
excitation
EMF=57.3 kN

Rough estimation of the vessel movement• Front rod for 600 MPa: movement =1.8 mm• Rear rod for 600 MPa: movement=2.7 mm
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SuperKEKB Review 2018∆=600 MPa
Rear rods

Front rods∆=650 MPa40

Some results from the cold tests• The magnetic center was measured by the quadrupole field profile
Field profile of QC1LP

Summation of the measured B2

Position of the magnetic
center is defined.

Distance of the quadrupole center from IP, mm
QC1LP
QC1LE
QC2LE
QC1RP

QC1RE

With excitation of solenoids

939.501416.102695.10938.461413.28

Without excitation of solenoids

937.021414.362695.18

937.521412.41∆ (with-without)

2.48

1.74

0.08*

0.94

0.87

* EMF on QC2LE is small.
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Some results from the cold tests
3. Cryogenic valve trouble of the He refrigerator for QCSR
The cryogenic valve, which connected to the final stage heatexchanger, did not close the helium gas line.
••

By leaking the cold helium gas, the refrigerator lost thecooling power of 26.5 W at 4.4 K.
The cryogenic valve was repaired in January 26th, 2018, therefrigerator recovers the cooling power as same as the QCSL
refrigerator.

H.X.

The cold valve
was leaked during
operation

H.X.
H.X.
Cold helium tothe magnet

QCSR He refrigerator
250 W @ 4.4 K
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Refrigerator power (W)

H.X.

250

2013: QCS-L
ColdBox+Subcooler

200

2016/11: QCS-L
ColdBox+Subcooler

150
2018/02: QCS-R
ColdBox+Subcooler

115W@02/2018

100

88.5W@05/2017
Increased power ofheater: 26.5 W ColdBox+Subcooler+QCS-R cryostat

50
0

0

10

SuperKEKB Review 2018

20

30
40
50
Liquefaction (L/hour)

60

70

80
42

Some results from the cold tests
Cool-down of QCSR from room temperature to 4 K
May 2017

February 2018

The cool-down of QCSR was not completed in 70
hours in May 2017.
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The cool-down of QCSR was completed in 55
hours in February 2018.

SuperKEKB Review 201843

Summary• The final focus system, QCS, has been completed and it
is now ready to have beams.
• Data of the magnetic field measurements on the beamlines are still being studied.
– Magnetic field profiles of the SC magnets will be included in the optics
calculation.
– Calibration of the Hall probe is now planed with research collaboration withFNAL to understand the solenoid field profiles along the beam lines.
– With the field measurement data, the precise 3D field calculation model
will be constructed for the Phase-3 operation.

• Concerning for the quadrupole magnet vibration, we
started the development of the measurement systemwith BNL.
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Back-up files

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Major troubles of QCSR in company
QCSR magnet cryostat
1. ESR1 electrical insulation fault at 1st Nov. 2016.
–

The electrical insulation fault was detected at the withstanding voltage test after
assembling the ESR1 to the helium vessel.
»»

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For the ESR1 quench test with the KEK vertical test stand , film heaters were attached on
the surface of ESR1.
After the quench tests, the heaters were removed from the solenoid surface. Some pinholes were built there. The reason of the insulation faults were these holes.

SuperKEKB Review 201846

Major troubles of QCSR in company
Identifying the fault place in ESR1
It took two weeks for detection:

–
•

•

•

The fault was detected after welding the pipe tothe helium vessel. Inspection was centrally
performed on the cables assembled in the pipe.
As the result, it turned out that the fault existed
in the helium vessel, and then the helium vessel
was cut along the welding line.
The ESR1 solenoid was pulled out from thevessel, and the electrical tests were performedon the surfaces of ESR1. One fault was detected.

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Major troubles of QCSR in company
Repair of the ESR1 electrical insulation damage
Process for repair–

Additional electrical insulation on the ESR1 solenoid surface by Kapton tape
Wrapping glass tape with impregnating epoxy resin on the Kapton tape
Assembling Tungsten radiation shields around ESR1
After setting the ESR1 with the shields in the helium vessel, the electrical tests were performed in
the air. Test results were good.
After welding the vessel, the electrical tests in helium gas were performed. Test results were good.
[22nd Nov. 2016]

•
•
•
•
•

Glass tapes on the surfaceof ESR1

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Impregnating epoxy
resin and drying
Tungsten radiation
SuperKEKB Review 2018
resin process
shieldSetting helium
vessel48

Major troubles of QCSR in company
2. The second electrical insulation fault of ESR1•

12th Jan. 2017：The final electrical tests of QCSR cryostat in Mitsubishi––•

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Detecting the electrical insulation damage in the ESR1 electrical line»
Electrical discharge happened at AC1000 V against the test voltage of AC1800V.
Another 29 magnets showed good electrical performances.

Fault place: the cable to the cold diode for the quench protection of
ESR1 in the service cryostat

12th Jan. 2017

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Major troubles of QCSR in company
Cold diode for the ESR1 quench protection•

Stored energy of ESR1= ~800 kJ––

2018/03/15

When we apply the same protection system to QCSR1 as the ESL system, the temperatureof the 10 coil sections reach over 300 K. ERS1 consists of 15 coil sections.
For ESR1, 15 sections are divided into 6 groups. Each group is connected to the individual
cold diode.
»
Temperatures of all coil sections ＜150K»
The operation of the cold diode was confirmed in the cold test with the KEK vertical
test stand.

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Major troubles of QCSR in company
Electrical tests after repair of the cold diode cable••

17th Jan. 2017: After detecting the fault in the cable of the cold diode andrepairing the electrical insulation of the cable, ESR1 passed the electricaltests in the air.
24th Jan. 2017: The electrical tests for the magnets in the cryostat were
performed in air and in helium gas.
»

All magnets showed good electrical performances.

• 31st Jan. 2017：Success in the final electrical tests
31st Jan. 2017
QCSR cryostat wasdelivered to KEK at 13th
Feb. 2017.
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Vibration measurement system
Vibration measurements at BNL (Dec. 18 – 19, 2017)

KEK probe coil (2000 turns)

BNL Laser
vibrometer

Active vibration
dumping table

The test room and the granite table wereprepared by BNL.
Vibration
dumping
supportKEK vibration meters(acceleration meter)
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Vibration measurement system

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