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50 12 2015 599

KEKB

*1,† *1 *1 *1 *1 *2 *2

Cryogenic System in the KEKB Beam Interaction Region and Operation Experience

Masanori KAWAI*1,†, Norihito OHUCHI*1, Yoshinari KONDO*1, Yasuhiro MAKIDA*1,

Kiyosumi TSUCHIYA*1, Tomonari ENDO*2 and Takayuki KANEKIYO*2

Synopsis: Two types of superconducting magnets were installed in the beam interaction region of the KEKB accelerator. One was a QCS superconducting magnets for final focusing of the e- and e+ beams, and the other was a huge superconducting solenoid for the particle detector, Belle. While the two magnets had completely different cold masses, two refrigerators of the same cooling power were used during the long-term 12-year operation for the KEKB physics experiment. This paper briefly describes these two cryogenic systems, and reports the operational problems and development of the cryogenic systems for SuperKEKB.

Keywords: KEKB, beam interaction region, superconducting magnets, helium refrigerator, long term operation (Some figures in this article may appear in colour only in the electric version)

KEKB Belle B

1,2)

KEKB Belle 1999 102010 6 122

KEKB

QCSQCS 2

4 2 6

3) Belle1.8 m 3.91 m 4)

QCS BelleTRISTAN QCS

1989 4 5) 2KEKB

2 3 QCSBelle 12

4 SuperKEKB

Fig. 1 Fig. 2 QCS BelleTable 1 QCS Belle

CE

2 Claude Cycle 1

250 W 4.4 K

*1

Received October 5, 2015

305-0801 1-1 High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan

*2

744-0002 794

Hitachi Plant Mechanics Co., Ltd., 794 Higashitoyoi, Kudamatsu, Yamaguchi 744-0002, Japan

E-mail: [email protected] DOI : 10.2221/jcsj.50.599

600 TEION KOGAKU J. Cryo. Super. Soc. Jpn. Vol. 50 No. 12 2015

Table 1 Main specifications of the He refrigeration systems for QCS and Belle QCS System Belle Solenoid System

Cold box: Type Claude cycle Claude cycle

Cooling power @ 4.4 K 250 W (using LN2) 250 W (using LN2)

Compressor: Type Screw compressor Screw compressor

Flow rate 1,250 Nm3/h 1,250 Nm3/h

Oil and impurity separators #1, #2, #3 and #3b, #4 #1, #2, #3, #4, #5 and #6

Sub-cooler: Heat exchanger Cu tube with fin, L=32 m ID/OD=18 mm/20.9 mm Cu tube with fin, L=32m ID/OD=18mm/20.9mm

LHe vessel volume 100 L 160 L

He gas tank: 2.06 MPa, V=20 m3 1 unit (400 Nm3) 2.06 MPa, V=20 m3 2 units (800 Nm3)

Additional component: Recovery GHe tank at quench (0.395 MPa, V=5 m3) LHe vessel for cooling current leads at quench (200L)

LN2 storage tank: 9800 L 10000L

Magnet: Type 2 quadrupoles, 2 solenoids, 6 correctors Solenoid

Cold mass of magnets 400 kg (QCSL) + 440 kg (QCSR) 8000 kg

Cooling method Subcooled LHe forced flow cooling Conduction cooling with forced flow subcooled LHe

Heat load at 4.5 K 75 W + 29 L/h (current lead) 84 W + 26 L/h (current lead)

Stored energy 0.52 MJ in total 34 MJ

Cool down time (RT 4K) 35 hrs 150 ~ 160 hrs

Fig. 1 Flow diagram of the QCS cryogenic system.

Fig. 2 Flow diagram of the Belle solenoid cryogenic system.

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Table 2 Separator configuration in the He compressors

#1 #2 #3 #3b #4 #5 #6

QCS D GF GF GF AC + MS

Belle D GF GF AC MS + CB GF

D: Demister, GF: Glass fiber filter, AC: Activated charcoal (QCS=150 kg, Belle=202 kg), MS: Molecular sieve (QCS=40 kg, Belle=272 kg), CB: Ceramic ball (Belle=70 kg)

1.67 MPa1250 Nm3/h

970 Nm3/h TRISTAN28,000

6) TRISTAN

7) KEKBQCS

#1 #4 #3#3b Belle #5#4 #4 #5 #4 #5

#6

Table 2 QCS #450 wt. ppb

Table 1Belle QCS

104 K 4 K

Fig. 3 Fig. 4

QCS 1.5 Belle 6 7QCS 2 Belle 4

Belle QCS49 A

QCS 75 W + 29 L/h Belle 84 W + 26 L/hQCS

156 W + 29 L/h Belle 186 W + 26 L/hQCS 81 W Belle

102 W

4.4 K 0.157 MPa

QCS

Fig. 3 Cool-down characteristics of the QCS magnets and Belle solenoid.

Fig. 4 Warm-up characteristics of the QCS magnets and Belle solenoid.

110 g/s

QCS 214.2 W 13.8 W

12.1 W 10.2 W0.157 MPa

4.65 K 4.60 K QCS8) Belle

10 g/s

21 1.7

g/s31.8 W Belle

40

200

QCS BelleEX9 Table 3


Fig. 5 Control system for the QCS and Belle cryogenic systems.

Table 3 Input/Output signals of QCS and Belle systems

QCS Belle

AI 209 (T=92, P=30, F=9, O=78 ) 95 (T=40, P=31, F=4, O=20 )

AO 38 (V=37, H=1) 33 (V=31, H=2)

DI 56 (CS=21, QS=13, O=22) 37 (CS=29, QS=1, O=7)

DO 48 42

T: Temperature, P: Pressure, F: Mass flow, V: Control valve, H: Heater, CS: Cryogenic system status, QS: Quench status, O: Others

QCS Belle Fig. 5

CPU MLC Multi-Loop-Controller QCSBelle

MLC

1 km6.5 kW

10) KEKB

QCS Belle 19972010 7

QCS 74,123 Belle 75,985Fig. 6 1997 1998

KEKB Belle3000 KEKB

1999 2008

Fig. 6 Operating hours of the QCS and Belle cryogenic systems during the year.

QCS 6473 269.7Belle 6657 277.42008 KEKB Belle

20082010 7 12 KEKB

Fig. 7 Fig. 8 QCS Belle

2 12QCS 175 Belle 128 Table 4 QCS

BelleBelle

QCS KEKB1999 2000

KEKB

4

50 12 2015 603

Table 4 Number of problems arising during 12-year-operation

QCS Belle Cold box 46 22 Compressor 16 23 Computer controller 8 27 Air compressor 10 4 Vacuum pump 7 6 Cooling water 22 29 Voltage drop or power failure due to lightning

10 7

Quench 58 10

22 7 7

52001 6

QCS12.4 Belle 16.1

92 Fig. 9Fig 10 Table 4 KEKB

Fig. 7 Number of problems with the QCS system.

Fig. 8 Number of problems with the Belle system.

Fig. 9 KEKB operation downtime caused by the QCS system in a year.

Fig. 10 Belle operation downtime caused by the Belle solenoid system. Belle

QCS 253.4 Belle 294.21999 2010

0.36 0.40

QCS Belle2

2004 1 QCS

2 QCS Belle1989

QCSFig. 11 Fig. 12 QCS

2


Fig. 11 He compressor for the QCS cryogenic system.

Fig. 12 Rust bank at the strainer due to corrosion on the inner surface of the cooling pipe.

2005 Belle 2

KEKB 96.3

Fig. 13

Fig. 13 Two turbines of the Belle solenoid cryogenic system (upper), heat exchanger for the #2 turbine (middle) and water leak point (shown by the red arrow) for the #1 turbine (lower).

PH 9.6JAR-

GL1

QCS Belle

QCS

50 12 2015 605

He

QCS Belle 1 79 12

120 Nm3/h1.57 MPa

Fig. 1490

TRISTAN QCS

1 ppmKEKB

QCS 90 0.1 ppm10 60 96

0.03 ppm Belle10 96 0.03 ppm 40108 BelleQCS 2

#5

Fig. 14 Change in the helium gas dew point during purification.

5 #4 #5

70 2.6 ppm

#4 120 Belle #5 150#4

O120

KEKB 2010 SuperKEKB

11) KEKB 2 843 Belle4 55 2

Fig. 15 QCS1

76.4 W + 28.4 L/h 1 2

TRISTAN QCS1

KEKB20

1

QCSKEKB 351 765 KEKB

QCS


Fig. 15 QCS cryogenic system of SuperKEKB beam interaction region.

100 200

2.06 MPa 20 m3 1 2 TRISTAN

Belle

QCSEX

KEKB22

14

QCSBelle

SuperKEKBQCS

KEKB

SuperKEKB 2017KEKB

Belle

1) KEKB B-Factory Design Report, KEK Report 95-7, August 1995. 2) Belle Technical Design Report, KEK Report 95-1, April 1995. 3) K. Kanazawa, H. Nakayama, T. Ogitsu, N. Ohuchi, T. Ozaki, K.

Satoh, R. Sugahara, M. Tawada, N. Toge, K. Tsuchiya, Y. Yamada, M. Yoshida and M. Yoshioka: “The interaction region of KEKB,” Nucl. Instr. Meth. Phys. Res. A 499 (2003) 75-99

4) Y. Makida, H. Yamaoka, Y. Doi, J. Haba, F. Takasaki and A. Yamamoto: “Development of a superconducting solenoid magnet system for the B-Factory detector (BELLE),” Adv. Cryo. Eng. 43A (1998) 221-228

5) K. Tsuchiya, N. Ohuchi, Y. Morita, R. Sugahara, A. Kabe, K. Endo, S. Kawamura and K. Matsumoto: “Helium cryogenic systems for the superconducting insertion quadrupole magnets of the TRISTAN storage ring,” Adv. Cryo. Eng. 37A (1992) 667-674

6) K. Tsuchiya, N. Ohuchi, Y. Morita, A. Kabe, R. Sugahara and T. Ogitsu: “Operational experience and reliability of the cryogenic systems for the TRISTAN insertion quadrupole magnets,” Adv. Cryo. Eng. 41A (1996) 719-726

7)

4pp4-7

8) N. Ohuchi, T. Ogitsu, K. Tsuchiya and S. Nakamura: “Cryostat for the KEKB IR superconducting magnets,” Adv. Cryo. Eng. 45A (2000) 787-794

9) EX is the process control computer by Hitachi High-Tech Solutions Corporation

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10) H. Nakai, Y. Kojima, K. Nakanishi, K. Hara, K. Hosoyama, T. Honma, Y. Morita and T. Kanekiyo: “Large-scale helium refrigeration system for KEKB/TRISTAN superconducting cavities – operation experience for 27 years and next operation –,” TEION KOGAKU 50 (2015) 549-556 (in Japanese)

KEKB/TRISTAN27

50 (2015) 549-556 11) N. Ohuchi, Y. Arimoto, N. Higashi, H. Koiso, A. Morita, Y.

Ohnishi, K. Oide, H. Sugimoto, M. Tawada, K. Tsuchiya, H. Yamaoka, Z. Zong, M. Anerella, J. Escallier, A. Jain, A. Marone, B. Parker and P. Wanderer: “Design of the superconducting magnet system for the SuperKEKB interaction region,” Proceedings of NA-PAC (2013) 759-761

1966 7 25 1985

1993

Belle CERN ATLAS

1958 6 19 1982

1987

1962 8 2 19851987

1987

2007 J-PARC

1961 7 23 19834

1947 11 23 1972

19741974

19871996

2011 2011 2012~2014

1973 4 27 19921995

1995

2011

1962 7 21 19811981

1984JT-60

1988

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