M

JHa

b

c

d

e

h

���

a

ARR2AA

KICJS

1

[bmtrtt

0h

Fusion Engineering and Design 88 (2013) 1461– 1464

Contents lists available at ScienceDirect

Fusion Engineering and Design

journa l h om epa ge: www.elsev ier .com/ locat e/ fusengdes

anufacture of ITER feeder sample conductors

inggang Qina,∗, Yu Wua, Min Yua, Bo Liua, Huajun Liua,∗∗, Klaus-Peter Weissb, Laifeng Li c,ongwei Lid, Erwu Niud, Pierluigi Bruzzonee

Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, PR ChinaInstitute for Technical Physics, Karlsruhe Institute of Technology, Karlsruhe D-76344, GermanyKey Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, PR ChinaChina International Nuclear Fusion Energy Program Execution Center, Beijing 100862, PR ChinaEPFL-CRPP, Fusion Technology, 5232 Villigen, Switzerland

i g h l i g h t s

Develop the technique of MB conductor.Develop the technique of CB conductor.Sultan test results show that MB and CB samples have good performance.

r t i c l e i n f o

rticle history:eceived 7 September 2012eceived in revised form9 November 2012ccepted 7 January 2013vailable online 31 January 2013

eywords:TER Feeder conductor

a b s t r a c t

The ITER feeders are the components that connect the ITER magnet systems located inside the maincryostat to the cryogenics, power-supply and control system interfaces outside the cryostat. The feederbusbars rely on the Cable-In-Conduit Conductor (CICC) design concept as all the conductors for the ITERmagnet systems. There are two types of busbars for the feeder systems. One is the Main Busbar (MB) forthe TF, CS and PF feeders, and the other is the Corrector Busbar (CB) for the CC feeders. The busbar cable iswound from multiple stage sub-cables made with Cu and superconducting strands. The superconductingmaterial is NbTi for the busbar strands of all feeder systems. All Feeder conductors are provided by China.The R&D programs are needed to acquire knowledge on the behavior of such conductors.

ablingacketample

Since the conductors are new, some full size copper dummy conductors have been produced for thetesting of the cabling parameters, definition of automatic TIG welding of seamless jacket section, elabo-ration of cable insertion and compaction. Then, two short qualification conductor samples (MB and CB)are prepared in ASIPP, and NbTi advanced strands are produced by Western Superconductor Technology(WST).

The details of manufacturing procedures for Feeder conductor samples will be described in this paper.

. Introduction

ITER is a joint international research and development project1,2] that aims to demonstrate the scientific and technical feasi-ility of fusion power. The ITER magnet system is made up of fourain sub-systems: the 18 Toroidal Field coils, referred to as TF coils;

he Central Solenoid, referred to as CS; the 6 Poloidal Field coils,eferred to as PF coils; and the Correction Coils, referred to as CCs.

he Main Busbar for the TF, CS and PF feeders, referred to as MB [3];he Corrector Busbar for the CC feeders, referred to as CB [3]. All

∗ Corresponding author. Tel.: +86 15856984206.∗∗ Corresponding author.

E-mail addresses: qinjg@163.com (J. Qin), liuhj@ipp.ac.cn (H. Liu).

920-3796/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.fusengdes.2013.01.008

© 2013 Elsevier B.V. All rights reserved.

coils with different dimensions used Cable-In-Conduit Conductors(referred to as CICC).

The CICC (MB and CB) for the Feeder system rely on twisted, mul-tifilament, NbTi based, Ni-plated, composite strands. The strands inMB and CB conductor are assembled in a multi-stage cable around acopper rope (MB) or an open central spiral (CB). The cable is insertedinside a stainless steel jacket.

China needs to provide MB and CB conductors for the ITERFeeder system. The conductors are manufactured in superconduc-tor center, institute of plasma physics Chinese academy of sciences(ASIPP).

The R&D program has been launched since 2010 to qualify the

cabling, jacketing and conductor compaction. Several conductorswere fabricated, including dummy and superconducting conduc-tors. The Sultan samples were tested in CRPP. In this paper, themanufactures of MB and CB sample conductor were descried,

1462 J. Qin et al. / Fusion Engineering and Design 88 (2013) 1461– 1464

Table 1Main parameters of strand.

Item Parameter

Ni-plated strand diameter 0.73 mmFilament diameter 6–7 �mTwist pitch 15 mmTwist direction Right handCopper/non-copper ratio 2.25–2.45RRR (293 K/20 K) 157Ic @ 5 T, 4.2 K 360 An-Value, 5 T 35

its

2

r

3

csasId

Fig. 1. Cross section of NbTi strand used for MB and CB conductor.

ncluding superconducting strand, cabling, jacket properties, inser-ion and companion. The test results of Sultan samples were givenimply.

. Superconducting strand characteristics

Strands used for cable comes from WST. Main characteristics areeported in Table 1 cross section is shown in Fig. 1.

. Cabling

ITER Feeder cables (MB and CB) are multi-stage. The ITER MBable is a 5-stage, which is similar to TF cable, and has a largeub-cable (stage 4), a copper core in the last-but-one (LBO) cables,

copper rope made of copper wire(∅2.0 mm, RRR: 131) which ishown in Fig. 2, and wide wrap. The total number of strands is 1422.n order to get the perfect superconducting cable, several full sizeummy conductors made of copper strands were manufactured

Fig. 2. Copper rope of MB cable(left)

Fig. 3. MB final cable (top) and CB final cable (bottom) before wrapping.

to qualify the production process. For all dummy cables, thespecifications are as same as superconducting cable. The cable ismanufactured in Baosheng Company, China.

The ITER CB cable is also a 5-stage cable, but the layout is differ-ent from MB. The final cable is wrapped with wide wrap, and onespiral is in the cable, shown in Fig. 2. The cable is manufactured inChangtong company, China.

The pictures of final MB and CB cable before wrapping are shownin Fig. 3. The cable parameters are shown in Table 2.

Before cabling, the CORD model [4] was used to compute thecabling tension and die dimension in order to avoid the strand dam-ages or kinks during manufacture. The computed cross sections areshown in Fig. 4. The cabling tension was tested many times duringcabling. The final MB and CB cable need compaction, which couldcause strand damages. There was one copper dummy trial to adjustthe roller position before superconducting cable manufacture.

4. Jacketing

The cables are all inserted into 316 L SS tubes. All tubes areproduced by extrusion and drawing, and all jacket sections are butt-welded together. Before welding, all tubes are examined, mainlyincluding dimensions, Non destructive examination, and chemical

and metallographic analysis, mechanical tests [5]. Before mechan-ical testing, the cold work (compaction) was performed on thejacket. The elongation caused by cold work is about 3% for MB,

and spiral of CB cable (right).

J. Qin et al. / Fusion Engineering and Design 88 (2013) 1461– 1464 1463

Table 2MB and CB cable parameters.

Item MB CB

Layout ((2Sc + 1Cu) ×3 ×5 × 5 + Core) × 6 + Cu rope (2Sc + 1Cu) × 3 ×3 × 3 ×4 + spiralTwist pitch 45:85:145:250:450 mm 42:70:122:182:250 mmCable diameter 41.3 + 0.2/−0.3 mm 18.4 + 0.1/−0.1 mmCopper rope 18.5 ± 0.5 mm (1 + 6 +12 + 18 + 24) Not applicableWrap overlap 30–40% 30–40%

Fig. 4. Cross section of numerical MB (left) and CB (right) cable before compaction (magetriplet). (For interpretation of the references to color in this figure legend, the reader is re

Table 3Mechanical properties of MB and CB jacket at 4.2 K.

Item MB (min, max) CB (min, max)

Yield strength (MPa) 710, 773 700, 882Ultimate tensile strength (MPa) 1500, 1520 1285, 1359Young’s modulus (GPa) 205, 207 202, 212Elongation at failure (%) 36, 37 33.3, 37.2

aF

T

SULTAN test facility located at CRPP, Switzerland from July 25 to

Fig. 5. Fracture surface of MB tensile samples.

nd 5% for CB. The mechanical properties are shown in Table 3 and

igs. 5 and 6.

The cable lengths for MB and CB conductor sample are all 20 m.he cable insertions are drawn by electric motor, and the maximum

Fig. 6. Fracture surface of CB tensile sampl

nta represents the copper core, other colors show the layout of cable especially forferred to the web version of the article.)

pulling forces of MB and CB are about 200 kgf and 150 kgf, respec-tively.

Compaction was performed after insertion, which needs rollers.Different compaction machines were used for MB and CB conductorbecause of different conductor dimensions. The cross sections offinal conductors are shown in Fig. 7. From the CB cross section, wecan find that there is a large excentricity of the spiral in the CBconductor. The CB final cable has 4 sub-cables (stage 4), and thesub-cable has smaller diameter. It is difficult to make the spiral inthe center during cabling. Many trails have been made to reducethe excentricity, and the results look good.

5. Sample analysis

The MB and CB Sultan sample were manufactured in ASIPP, andtested in CRPP. The Tcs requirement of Feeder conductors is shownin Table 4.

Chinese first MB Conductor sample (MBCN1) was tested at the

August 3, 2011. The sample exhibited the performance with a cur-rent sharing temperature (Tcs) of the order of 6.6 K for right legat 57 kA and background field of 2.75 T before cyclic loading with

es (left: full size and right: sub-size).

1464 J. Qin et al. / Fusion Engineering and Design 88 (2013) 1461– 1464

Fig. 7. Cross section of MB and CB conductor (left: MB and right: CB).

Fig. 8. Tcs result of MB (left) and C

Table 4Tcs requirement of Feeder conductor.

hAir

Aa(Tt

6

Ab

[

[

[

[4] J. Qin, Y. Wu, L.L. Warnet, A. Nijhuis, A novel numerical mechanical model for

Item MB CB

Tcs requirement 6.7 K@3.9 T, 45.5 kA 7 K@2.9 T, 20 kA

eating w/out steps and the order of 6.72 K with heating in steps.fter 1250 cyclic loading, the Tcs was 6.92 K for right leg with heat-

ng w/out steps. After 2000 cyclic loading, the Tcs was 6.98 K foright leg with heating w/out steps. The Tcs result is shown in Fig. 8.

The Tcs of PA requirement for CB conductor is 7 K@2.9 T, 20 kA.ccording to SULTAN test result, the Tcs of CBCN1 conductor isbout 7.6 K before cycling and after cycling at SULTAN field 2.63 T2.9 T peak field) and 10 kA current. The Tcs is about 7.23 K at SUL-AN field 2.63 T (3.15 T peak field) and 20 kA. The test result is betterhan PA requirement. The Tcs result is shown in Fig. 8.

. Conclusions

The MB and CB samples have been successfully manufactured bySIPP in China. The successful tests in SULTAN confirmed the relia-ility of the conductor design and Chinese conductor manufacture

[

B (right) conductor sample.

procedure. The fabrication of these prototypes has shown that theprocess developed in last years is well assessed and that the avail-able tools and procedures allow an industrial manufacture.

Acknowledgements

The author is very grateful to ITER IO for their help on mechan-ical test of jacket. This work was partly supported by the NationalNatural Sciences Foundation of China (Grant No. 51207157).

References

1] ITER Structural Design Criteria for Magnet Components (SDC-MC), N11 FDR5001-07-05 R 0.1, NAKA, Japan, 2001.

2] ITER Final Design Report, IAEA Vienna and ITER IT Team Design DescriptionDocument 1.1 Update, January 2004.

3] A. Devred, M. Calvi, P. Bruzzone, F. Cau, C. Marinucci, D. Bessette, P. Bauce, M.Jewell, A. Vostner, Feeder busbar conductor design, Presented at ITER FeederConductor FDR, Hefei, China, 2009.

the stress–strain distribution in superconducting cable-in-conduit conductors,Superconductor Science and Technology 24 (2011) 065012.

5] Standardization of CC & Feeder Conductor Jacket Mechanical Testing Proceduresv0.1, ITER Internal Document, 2011.