A THIN SUPERCONDUCTING SOLENOID WOUND WITH THE INTERNAL WINDING METHOD FOR COLLIDING BEAM EXPERIMENTS

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A THIN SUPERCONDUCTING SOLENOID WOUND WITH THE INTERNAL WINDING METHOD FOR

COLLIDING BEAM EXPERIMENTS

A. Yamamoto, H. Inoue, H. Hirabayashi

To cite this version:

A. Yamamoto, H. Inoue, H. Hirabayashi. A THIN SUPERCONDUCTING SOLENOID WOUND

WITH THE INTERNAL WINDING METHOD FOR COLLIDING BEAM EXPERIMENTS. Journal

de Physique Colloques, 1984, 45 (C1), pp.C1-337-C1-340. �10.1051/jphyscol:1984169�. �jpa-00223725�

JOURNAL DE PHYSIQUE

Colloque C1, suppl6ment a u no 1, Tome 45, janvier 1984 page c1-337

A THIN SUPERCONDUCTING SOLENOID WOUND WITH THE INTERNAL WI.NDING METHOD FOR COLLIDING BEAM EXPERIMENTS

A .

Yamamoto,

Inoue and

Hirabayashi

KEK,

NationaZ Laboratory for High Energy Physics, 0ho-mehi, Tsukuba-gun, Ibaraki-ken,

Japan

R6sume -

p r e s e n t e une nouvelle methode de f a b r i c a t i o n d'un grand s o l e - no'ide mince. Ce sol4no'ide u t i l i s e un supraconducteur ~bTi/Cu/Al bobin4 s u r l a f a c e i n t e r n e d'un c y l i n d r e d'aluminium. La f a b r i c a t i o n du soleno'ide p a r c e t t e methode e s t en cours.

Abstract - A new f a b r i c a t i o n method of a t h i n and l a r g e s o l e n o i d s is presented. The s o l e n o i d is wound with NbTi/Cu/Al superconductor, which is wound on t h e inner s u r f a c e of an aluminum c y l i n d e r . The f a b r i c a t i o n o f t h e solenoid i s i n progress with t h i s method.

I - INTRODUCTION

A

t h i n superconducting s o l e n o i d w i t h t h e s i z e of 2.9 m t x 5.1 m and with t h e f i e l d o f 1.2 Tesla w i l l be used i n t h e c o l l i d i n g beam d e t e c t o r ItTOPAZW f o r TRISTAN p r o j e c t a t KEK (Fig.

new technique has been developed i n r e a l i z i n g t h e l a r g e t h i n solenoid.

c a l l e d

I n conventional way /2,3,4/, a c o i l is wound on t h e s u r f a c e of c y l i n d r i c a l bobbin w i t h s u f f i c i e n t t e n s i o n . The bobbin i s very u s e f u l t o wind t h e c o i l , but does very l i t t l e t o r e i n f o r c e t h e c o i l a g a i n s t t h e electromagnetic f o r c e which a c t s outward. Thus a banding on t h e o u t e r s u r f a c e of t h e c o i l is necessary t o withstand t h i s s t r o n g f o r c e . The new i n t e r n a l winding method enables u s t o wind a c o i l d i r e c t l y on t h e i n n e r s u r f a c e o f and o u t e r c y l i n d e r and e l i m i n a t e s t h e bobbin and banding. An a d d i t i o n a l advantage is t h e increased c a p a b i l i t y of cooling due t o t h e b e t t e r thermal c o n t a c t of t h e c o i l t o o u t e r c y l i n d e r on which a helium cooling tube is welded before c o i l winding.

The method has been developed s i n c e a year ago. S e v e r a l t e s t uinding have been made i n order t o e s t a b l i s h t h e winding technique. The winding o f t h e main solenoid i s going t o complete t h i s autumn.

m w ra m

%xo

F i g .

I Cross sections o f t h e TOPAZ detector

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984169

JOURNAL DE PHYSIQUE

- - - ^pp-- .

F

^-

^_

. . . -- . - - . . - LHe COOLING PIPE

INNER VESSEL

I I

Fig. 2 Cross s e c t i o n a t t h e end of t h e TOPAZ s o l e n o i d

I1 - THE TOPAZ SOLENOID

A schematic cross section at the end of the TOPAZ solenoid is shown in Fig. 2. The pure-aluminum stabilized superconductor is wound on the inner surface of the outer cylinder made of high strength aluminum alloy (A2219-T85). The electrical

insulation thickness between the coil and cylinder is expected to be less than

by using the internal winding method.

The design parameters of the TOPAZ solenoid are shown in Table 1. In the design process, the safety condition was carefully considered in order to protect the solenoid from quenching and burning out when it occurs and releasing the stored energy of 19 MJ. The safety condition we have considered are as follows:

1)

The maximum operating current is chosen to be the half of the critical current at Bz2.4 Tesla and Tz4.Z.

2) The coil temperature should be less than 5 K at normal operation.

3) The temperature of the coil

4) The voltage across the coil should be less than 500 V , when the power supply is switched off because of a quench.

After the parameters were optimized each other, the total radiation thickness including the cryostat was estimated to be 0.71 Xo.

T a b l e 1 Main parameters o f t h e TOPAZ s o l e n o i d

Inner diameter

Length 5100

m

M a g n e t i c F i e l d ( w i t h r e t u r n y o k e ) 1 . 2 T e s l a m a x . Total r a d i a t i o n Thickness 0.71 Xo Current

Number of Turns Inductance Stored Energy Conductor

Material Ratio RRR (Al) Length

Number of j o i n t s

3630 A - 1340 Turns 3 H 19 MJ

111 - ^INTERNAL

AND MODEL COILS

Figure 3 shows a schematic l a y o u t o f t h e i n t e r n a l winding process f o r t h e TOPAZ solenoid.

A t f i r s t t h e conductor i n s u l a t e d with B s t a g e epoxy g l a s s type i s wound on t h e o u t e r s u r f a c e of a temporary mandrel and then preformed s o a s t o have almost same

curvature than t h a t of t h e o u t e r c y l i n d e r . The temporary winding is put i n t o t h e o u t e r c y l i n d e r . Then t h e winding on t h e inner s u r f a c e o f t h e c y l i n d e r is done by p u t t i n g compression s t r e s s along t h e conductor ( c ~ d i r e c t i o n ) s o t h a t t h e c o i l is pressed onto t h e s u r f a c e . Axial and r a d i a l compression f o r c e a r e a l s o a p p l i e d simultaneously t o t h e c o i l . To e l i m i n a t e l o c a l v o i d s and

g e t r e l i a b l e thermal c o n t a c t , wet epoxy r e s i n is s l i g h t l y painted on t h e i n n e r s u r f a c e o f t h e o u t e r c y l i n d e r which is i n s u l a t e d w i t h t h e lamination o f GFRP and KAPTON s h e e t s . F i n a l l y , t h e c o i l is cured with t h e a x i a l and r a d i a l compression a t t h e temperature of 150°C.

I n o r d e r t o e s t a b l i s h t h e winding technique a f u l l - s i z e \ m o d e l (2.9 m+

5 m) c o i l was wound with t h e dummy conductor where Nb-Ti/Cu matrix was replaced with Fe wire.

I n t e s t winding process, many parameters such a s compression s t r e s s , winding speed, q u a n t i t y of t h e wet epoxy and e t c . Figure 4 shows t h e view of t h e c o i l wound with 'the i n t e r n a l winding method.

A f t e r t h e c u r i n g process, t h e t e s t c o i l was c u t and observed. Figure 5 shows c r o s s s e c t i o n s of t h e f u l l s i z e t e s t c o i l . The void f r a c t i o n a t t h e l a y e r of epoxy r e s i n between t h e c o i l and o u t e r c y l i n d e r is n e g l i g i b l e and t h e averaged t h i c k n e s s o f t h e ground-insulation (epoxy r e s i n and GFRP-KAPTON lamination) was about 1 mm.

Mechanical p r o p e r t i e s a t t h e boundary between t h e c o i l and ground-insulation were a l s o measured a f t e r thermal c y c l e s betw2en room temperature and LN2 temperature.

The s h a r i n g s t r e n g t h was above 2 kgf/mm . It is enough a c c e p t a b l e from t h e view p o i n t s of s u p p o r t i n g f o r electromagnetic f o r c e and thermal s t r e s s .

A

small s i z e model s o l e n o i d was a l s o wound with t h e same superconductor t h a n t h a t of t h e main solenoid. The d i f f e r e n c e s of t h e parameters from t h a t o f t h e main solenoid a r e l i s t e d up i n Table

It was cooled down below 4.8 K and was e x c i t e d up t o 5530 A which corresponds t o 1.57 Tesla with o u t i r o n yoke. Detailed r e s u l t s of t h e t e s t f o r t h e small model c o i l w i l l be r e p o r t e d elsewhere.

Fig. 4 A view o f t h e coil winding.

i &-4 ^{Fig. 3} Layout o f the lnternal coil-winding.

C1-340 JOURNAL DE

Fig. 5 Cross sections of the f u l l s i z e model coil Table 2 Differences of the parameters of the small s i z e

model solenoid from t h a t of the main solenoid

Outer diameter 2.9 m 0.58 m

Length 5.1 m 0.9 m

OUTER CYLINDER

Thickness 9 mm 8 mm

COOLING TUBE

Pitch between u450 mm %600 mn parallel paths

Inner diameter 1 8 mrn 15 mm

I V - CONCLUSION

The i n t e r n a l winding technique f o r t h i n s o l e n o i d s has been e s t a b l i s h e d . Advantages of t h e i n t e r n a l winding are: ( i ) t o be adequate method from t h e view p o i n t o f s u p p o r t i n g t h e electromagnetic f o r c e and ( i i ) t o enable u s t o g e t r e l i a b l e thermal and mechanical c o n t a c t a t t h e boundary between t h e c o i l and o u t e r c y l i n d e r , because of l e s s epoxy r e s i n l a y e r and well c o n t r o l l e d compression s t r e s s and ( i i i ) t o have r e l i a b l e f a b r i c a t i o n process w i t h no c r i t i c a l paths.

The i n t e r n a l winding method i s adequate f o r l a r g e r t h i n s o l e n o i d s . It may be s u r e t h a t t h e i n t e r n a l winding is more adequate and r e l i a b l e method than o t h e r s a t l a r g e r t h i n solenoids.

The a u t h o r s would l i k e t o thank Professors S. Ozaki and K. Takahashi f o r t h e i r continuous encouragement and h e l p f u l d i s c u s s i o n s . The a u t h o r s deeply a p p r e c i a t e Furukawa E l e c t r i c Company Ltd. f o r valuable cooperations d u r i n g t h i s word. Thank a r e a l s o due t o F u j i E l e c t r i c Company Ltd. and Ishikawajima-Harima Heavy I n d u s t r y Company Ltd. f o r t h e i r e x p e r t cooperations.

REFERENCES

[lI,TRISTAN proposal, TRISTAN-EXP-002, TOPAZ c o l l a b o r a t i o n (1983).

[21

Deportes (H) e t a l . , Advances i n Cryogenic Engineering, Vol. 25, Plenum P r e s s , New York (19801, P.175.

L31 Green (M.A.) e t a l . , Advances i n Cryogenic Engineering, Vol. 25, Plenum P r e s s , New York (1980), P.194.

l41 Andrews (D) e t a l . , Advances i n Cryogenic Engineering, Vol. 27, Plenum P r e s s ,

New York (19811, P.143.