2004/ Feb./17-KEKB Review

Superconducting Magnet for Super-KEKB
Norihito Ohuchi(1) SC Magnets Design Constraints(2) Final Focus Quadrupole (QCS)(3) Compensation Solenoid (ES)(4) Superconducting Special Magnets (QC1)(5) Summary and Further Study for SC Magnets

(1) SC Magnets Design Constraints
Magnet-cryostat design was performed under the following spatial constraints;•••

Beam envelops (from the beam optics of X=30 mrad and βx=20cm by H. Koiso)
Synchrotron light envelops (from the estimation by Y. Funakoshi)
Boundary with Belle detector (same as the present system)
QC1R-cryostat-bore

QC1L-cryostat-bore

150

3800

2800
QCSR-cryostat-bore

100HER

QCSL-cryostat-bore
969.4

501163.30[mm]LER-50-100
central beam orbit
beam envelop
SOR from the beam at the IP or arc sides of each QCS
deviation of SOR from the central beam

(2) Final Focus Quadrupole (QCS)
QCSR & ESR (viewed from IP)

New Cross Section of QCSR & ESR
R 239

R 230

ESR
R 92

QCSR

R 90

QCS-R

R 65
50HER-100

100

LER

9.2-50

Corrector
Coils
R 69••••2 layer coilSC cable size : 1.1mm×10mm
Design current : 3650 A for G=36 T/mMagnetic center shift w.r.t. the Belle axis
QCSR = 0.0 mm, QCSL = 29.1mm••••

CompensationSolenoid

6 layer coilSC cable size : 1.1mm×4.1mm
Design current : 1134 A for G=36 T/mMagnetic center shift w.r.t. the Belle axis
QCSR = 9.2 mm, QCSL = 21.2mm

KEKB-QCS-cross-section

SC conductor size : 1.1mm × 7.0mm (KEKB-QCS)

1.1mm × 10.0mm(old design)
1.1mm × 4.1mm(new design)Parameters of New QCS Design
6 layer coils (3-double pane cake coils)
Inner radius : 90 mm
Cable size : 1.1mm(W), 4.1mm (H)Field gradient =36 T/m @1134A
Max. field in the coil = 3.74 T
Effective magnetic length•
QCSR = 0.333 m•
QCSL = 0.398 m
7. Inductance•
QCSR = 77.94 mH•
QCSL = 93.16 mH
8. Stored Energy @1134A•
QCSR = 50.09 kJ•
QCSL = 59.87 kJ
9. Iop/Ic = 68 % @ 4.7 K
10. Field quality (@ r=55mm)
b2=10000, b6=0.16, b10=0.61, b14=0.43

876

Magnetic field, T

1.
2.
3.
4.
5.
6.

Ic @ 4.2K
Ic @ 4.5K
Ic @ 4.7K
QCS, T
QCSR+ESR(3T)+Belle, T

5.9 T

5
3.622 T4

3.297 T

321134 A

100500

1000

1500

2000

2500

3000

SC cable current, A

QCS load line with ESR and Belle fields.
The plotted results are calculated by the twodimensional model.

LHe by-pass line

Effect of New Designed QCS
on the cryogenic system

Multi-layer
insulation
Radiation
shieldSC bus lines

Current Leads(Physically, the environments at LHe temp. and room temp.
connect by these current leads.)
KEKB-QCS current leads
GHeGHe (room temp.)

P. S. Room temp.

LHe temp. 4.5 K

LHe
LHe (4.5K)

LN2 returnline

LHe return line

2830A

H.E.

LHe lines andSC bus lines
LN2 flowline

LHe flow line

Heat load of the cryogenic system

Cooling capacity of QCS refrigerator
QCS-refrigerator.kdat

Refrigerating power, W

250
Operating point(Super-KEKB)

200

164 W
27.5 L/h

200 W
18.6 L/h(measured value)

150
129 W
35 L/h100

94 W
18.7 L/h(new)

50

94 W
35 L/h(old)92 W
27.5 L/hOperating point(KEKB)

0010203040

Liquefaction of LHe, L/h50

(3) Compensation Solenoid (ES)ES and QCS configuration (old design)
969.4

ESR

QCSL

QCSR

30.

17.00 °

00°

ESL

1163.3IP

1.4 10 5

Electromagnetic Force :– ESR 42288 N (4.3 tons)
KEKB-ESR : 7050.5 N (0.7 tons)– ESL -134820 N (13.8 tons)
KEKB-ESL : -23505 N (2.4 tons)

Serious problem on the mechanicaldesign of the cryostats

Electro-magnetic force in z direction, N

y = 43110 - 182.16x
R= 0.99792
y = 1.3628e+05 - 495.97x
R= 0.99606

1.2 10 5ESR, NESL, N

1 10 58 10 46 10 4

Target Level of EMF

4 10 42 10 40050100150200

Movement values of ESR and ESL to IP, mm

Electromagnetic force as a function of the ESR and ESL positions.

ESR, QCSR and cryostat

ESR-1
ESR-2

2.11 Tesla

2.98 Tesla

ESR Parameters
Central field w.o.
Belle field, T
Max. field w.o.
Belle field, T
Current Iop, A
Iop / Ic, %Coil
Inner radius, mm
Outer radius, mmLength, mm

ESR-1

ESR-2

2.98

2.113.00619512.45619
47

155
165.2
1050

77
87.2
150

Electro-magnetic force
4.2×104N—> 2.2×104N(0.7×104N for KEKB)Heat load via support rods in cryostat
3.4 W(KEKB) —> 3.5 W

ESL, QCSL and cryostat

ESL-2
3.72 Tesla

ESL-1
2.23 Tesla

ESL Parameters
Central field w.o.
Belle field, T
Max. field w.o.
Belle field, T
Current Iop, A
Iop / Ic, %Coil
Inner radius, mm
Outer radius, mm
Length, mm

ESL-1

ESL-2

2.23

3.72

2.59
615
48

4.14
615
63

185
194
519

7793.9175

Electro-magnetic force
13.5×104N—> 4.8×104N(2.4×104N for KEKB)Heat load via support rods in cryostat
3.2W(KEKB) —> 4.5W

Bz profile along the Belle axis
Bz.prof.KEKB.vs.SKEKB.kdat

21B z, T

0-1-2-3IP

Belle center-4
Super-KEKB.v2.1.1
KEKB-5-3-2-1

0Position, m1

23

Solenoid field distortion in the Belle detector
Contour plots: 1.2 T < Bz <1.7 T
Belle-solenoid

Super
KEKB
ESL-1

ESL-2

ESL-2

ESR-1

KEKB

ESLESR(4) Superconducting Special Magnets (QC1)
R 210

Parameters of QC1R and QC1LR 80

QC1RQC1L
Coil2-layer
1-layer
Coil inner radius, mm
80.0
31.0
Coil outer radius, mm84.0
33.0Yoke outer radius, mm
210200
Field gradient, T/m
34.0
42.9
Eff. mag. Length, m
0.266
0.232
Current Iop, A1319
1319
Max. field, T
3.28
1.62
Iop / Ic, %7359
Leak field on LER beam, Gauss < 20
< 1.5SC cable
1.1mm × 1.9mm(solid composite of rectangular cross section)

14

SC CoilIron Yoke

Cross sectionof QC1R
R 200.0

R 31.0SC CoilR 28.0

25.6

Iron YokeCross sectionof QC1L

(5) Summary and Further Study for SC Magnets■ Summary• QCS– New magnet cross section
 6 layer coil (3 double pancake coils)
 Magnet current 1134 A for G=36 T/m
 Estimated margin of refrigerator=105.6 W ( KEKB:72 W)
 Field quality by 2 dim. cross section @Rref=55mm
b2=10000, b6=0.16, b10=0.61, b14=0.43• ES– Compensation solenoid-> two solenoids for each side
 EMF
ESR=2.2 × 104N, ESL=4.8 × 104N
( KEKB: ESR=0.7 × 104N,
ESL=2.4 × 104N )• QC1– Rough calculation of the 2-D cross section
 G=34 T/m, Leff.=0.266 m, leak field on LER beam<20 Gauss for QC1R
 G=42.9 T/m, Leff.=0.232 m, leak field on LER beam<1.5 Gauss for QC1L■

Further study for the SC magnets

3-D magnetic field calculation for the all SC magnet






Field quality of the whole magnet with coil and magnet ends
Maximum magnetic field of each magnet under the combined operation ofall magnets
Electromagnetic force calculation between the magnets
Quench analysis

Design of the cryostats and vacuum chambers


Mechanical and thermal design of the cryostats
Interference between the cryostats and vacuum chambers