DEVELOPMENT AND STUDY OF THE UNK SUPERCONDUCTING DIPOLE MODELS

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DEVELOPMENT AND STUDY OF THE UNK SUPERCONDUCTING DIPOLE MODELS

N. Andreyev, V. Balbekov, E. Bulatov, Yu. Dmitrevskiy, V. Dolzhenkov, K.

Gertsev, V. Gridasov, K. Myznikov, V. Sytnik, N. Tarakanov, et al.

To cite this version:

N. Andreyev, V. Balbekov, E. Bulatov, Yu. Dmitrevskiy, V. Dolzhenkov, et al.. DEVELOPMENT

AND STUDY OF THE UNK SUPERCONDUCTING DIPOLE MODELS. Journal de Physique Col-

loques, 1984, 45 (C1), pp.C1-249-C1-253. �10.1051/jphyscol:1984150�. �jpa-00223706�

JOURNAL DE PHYSIQUE

Colloque C l , supplCment a u n o I , Tome 45, janvier 1984 ^page C1-249

DEVELOPMENT AND STUDY OF THE UNK SUPERCONDUCTING D I P O L E MODELS

N . I . Andreyev, V.I. Balbekov, E.A. B u l a t o v , Yu. P . D m i t r e v s k i y ,

V . I . Dolzhenkov, K.F. G e r t s e v , V . I . G r i d a s o v , K.P. Myznikov, V.V. S y t n i k , N.M. Tarakanov, L.M. V a s i l i e v , V.A. V a s i l i e v and V.V. Y e l i s t r a t o v

I n s t i t u t e f o r High Energy P h y s i c s , Serpukhov, Moscow Region, U.S.S.R.

RCsum6

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~ ' e x ~ 6 r i e n c e a c q u i s e l o r s d e l ' b t u d e d e modsles c o u r t s a permis d e r g a l i s e r e t d ' e s s a y e r deux d i p s l e s l o n g s d e 6 m. Les e s s a i s s e s o n t d 6 r o u l Q s dans l e c r y o s t a t 5 immersion s a n s f e r . La p r e m i s r e t r a n s i t i o n a r d v b l b un cou- r a n t d e l ' o r d r e d e 6 kA c e q u i c o r r e s p o n d au champ dans un aimant d e 5 T avec l e f e r . Le c o u r a n t maximum e s t de 6 , 5 kA. Les p e r t e s t o t a l e s pour l e c o u r a n t d e 6 kA e t 1 l a v i t e s s e d e l ' i n j e c t i o n d e 100 A/s s o n t d e 750 j l c . Les v a l e u r s a b s o l u e s d e s composantes harmoniques du champ d a n s l a p a r t i e c e n t r a l e d u - d i - p e l e c o r r e s p o n d e n t aux v a l e u r s t h z o r i q u e s e t s o n t p r o c h e s d e s v a l e u r s a d m i s s i - b l e s . E l l e s dbpendent peu du n i v e a u d u champ c e q u i prouve une bonne s t a b i l i t d mCcanique e t une f a i b l e dCformation d e l a bobine b l ' b c h e l l e 1 .

A b s t r a c t

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Two f u l l - s c a l e d i p o l e models, 6 m l o n g each, have been manufactured i n t h e s c o p e of t h e programme on development o f s u p e r c o n d u c t i n g & p o l e s f o r t h e UNK. R e s u l t s o f t h e i r t e s t s i n a b a t h c r y o s t a t a r e r e p o r t e d . A number of s h o r t models have been manufactured and t e s t e d w i t h view t o improve t h e i n t e g r a l cha- r a c t e r i s t i c s of t h e magnetic f i e l d , The r e s u l t s o f magnetic measurements of t h e c e n t r a l and edge f i e l d a r e p r e s e n t e d . Also r e p o r t e d a r e t h e r e s u l t s o f s t u d y o f t r a i n i n g and dynamic c h a r a c t e r i s t i c s of d i p o l e s .

IHEP c o n t i n u e s work on s i m u l a t i o n o f s u p e r c o n d u c t i n g d i p o l e magnets f o r t h e 3 TeV UNK / I / . P r o c e e d i n g from t h e c o n s t r u c t i o n o f t h e p r e v i o u s s e r i e s o f s h o r t models /2/, d e s i g n e d t o o b t a i n a 5 T b o r e f i e l d i n d u c t i o n t h e r e have been manufactured a few mo- d e l s o f a new s e r i e s from a s u p e r c o n d u c t i n g c a b l e w i t h improved c u r r e n t d e n s i t y and a d i a m e t e r o f f i l a m e n t s o f 3 0 p m . These models made i t p o s s i b l e t o o b t a i n t h e UNX working f i e l d i n t h e b o r e w i t h o u t t r a i n i n g and t o have a r e s e r v e i n t h e c r i t i c a l cur- r e n t n e c e s s a r y i n c a s e o f i n c r e a s e d h e a t r e l e a s e s i n t h e w i n d i n g d u e t o i r r a d i a t i o n . Based on t h e e x p e r i e n c e i n working o u t s h o r t models /3/, two 6-m f u l l - s c a l e models have been manufactured. T e s t s o f t h e f i r s t long models showed r e p r o d u c i b i l i t y of t h e r e s u l t s o b t a i n e d f o r s h o r t models.

FULL- SCALE MODELS

IHEP d i p o l e s a s t h o s e o f FNAL /4/ have a t w o - s h e l l winding w i t h some d i s t i n c t d e s i g n f e a t u r e s a l l o w i n g a n i n c r e a s e i n t h e b o r e f i e l d up t o 5 T. Due t o a h i g h f i e l d i n t e n - s i t y o f a p r o t o n beam a c c e l e r a t e d i n t h e UNK t h e y s h o u l d have a r e s e r v e i n t h e c r i t i - c a l c u r r e n t which could p r o v i d e a s t a b l e o p e r a t i o n of magnets w i t h p o s s i b l e p a r t i c l e l o s s e s .

The c r o s s - s e c t i o n a l view o f t h e d i p o l e s i s g i v e n i n f i g . I and t h e i r b a s i c c h a r a c t e - r i s t i c s a r e p r e s e n t e d i n T a b l e 1 .

For t h e s e models, t h e c a b l e h a s been manufactured from 0.85 mm i n d i a m e t e r s t r a n d s . Each s t r a n d c o n t a i n s 2970 Nb-Ti f i l a m e n t s , I O p m i n d i a m e t e r , embedded i n t o a copper m a t r i x w i t h a packing f a c t o r of 42%. The c a b l e was t r a n s p o s e d from 23 s t r a n d s , 1 2 of which were c o a t e d by Sn

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5 w t % Ag w i t h a 7 5 mm t r a n s p o s i t i o n p i t c h . The keystoned c a b l e was 10.55 mm i n h e i g h t , t h e o u t e r w i d t h was 1.68 mm and t h e i n n e r one was 1.34 mm ( w i t h o u t i n s u l a t i o n ) . The c a b l e was i n s u l a t e d by two l a y e r s o f a 2 0 h m l a v s a n t a p e and 100,Um t h i c k epoxy-impregnated f i b e r - g l a s s t a p e w i t h a 4 mm gap between t h e a d j a c e n t t u r n s .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984150

C1-250 _JOURNAL DE PHYSIQUE

T a b l e 1 THE BASIC CHARACTERISTICS OF A DIPOLE I n n e r r a d i u s of t h e 1st s h e l l mm 45.16 Angle of t h e 1st s h e l l d , d e g 72.425 Angle o f t h e 2nd s h e l l d.2 deg 36.532 Number o f t u r n s i n t h e 1 s t s h e l l 2 x 39 Number of t u r n s i n t h e 2nd s h e l l 2 x 24 T o t a l l e n g t h o f s h e l l s mm 5925

R a t i o B/I w i t h i r o n T/kA 0.880

R a t i o B/I w i t h o u t i r o n T/kA 0.753

F i g . 1

-

Magnet c r o s s - s e c t i o n : i n n e r c o i l s h e l l ( I ) , o u t e r s h e l l ( 2 ) , h e l i w n f l o w chan- n e l s ( 3 ) , s p a c e r s ( 4 ) , i n s u l a t i n g s p a c e r s ( 5 ) , bandage ( 6 ) .

F i g . 2

-

The t r a i n i n g c u r v e s f o r f u l l - s c a l e models: I

-

model DD-I, 2

-

model DD-2.

The models have been t e s t e d w i t h o u t an i r o n yoke i n a b a t h c r y o s t a t w i t h p o o l - b o i l i n g helium. The t r a i n i n g c u r v e s f o r t h e two models a r e shown i n f i g . 2. F o r t h e f i r s t model, t h e maximum f i e l d was a t t a i n e d a f t e r t h e 36 quench. I t exceeded by o n l y 3%

t h e f i e l d a t t a i n e d a t t h e 1 s t quench.

The maximum v a l u e o f t h e a t t a i n e d c u r r e n t c o i n c i d e s w i t h t h a t of a s h o r t sample t o an a c c u r a c y o f 2.5%.

The magnet h a s r e p e a t e d l y been t e s - t e d w i t h i n e v e r y two months a f t e r warmlng up t o t h e ambient tempera- t u r e . Each t i m e , t h e c u r r e n t a t t a i - ned i t s maximum v a l u e a l r e a d y a t t h e

1 s t quench and i t s v a l u e was r e p r o - duced t o an a c c u r a c y o f 10 A . A s e - cond magnet model h a s been manufac- t u r e d from a s u p e r c o n d u c t i n g m a t e r i a l w i t h an improved c u r r e n t d e n s i t y . D u r i n g j u s t t h e 1 s t quench i t s c u r -

r e n t was 6 kA. At h i g h e r c u r r e n t s , t h e r e was a long-term t r a i n i n g o b s e r - ved. A f t e r 26 quenches t h e a t t a i n a b l e c u r r e n t was 6 . 6 kA, c o r r e s p o n d i n g a b o r e f i e l d o f 5 T w i t h o u t an i r o n s h i e l d .

A d e t a i l e d s t u d y of harmonics o f c e n t r a l f i e l d n o n l i n e a r i t y h a s been made f o r b o t h magnets. I n a c c u r a c y o f measuring t h e r e l a t i v e v a l u e s o f f i e l d harmonics d i d n o t exceed 5 . 1 0 - ~ f o r n o n l i n e a r i t i e s lower t h a n t h e 5 t h o r d e r and f o r h i g h e r - o r d e r n o n l i n e a r i t i e s /5/. F i g s . 3 and 4 show even and odd n o n l i n e a r i t i e s * )

,

r e s p e c t i v e l y , a t a d i s t a n c e o f 35 mm from t h e c e n t r e v e r s u s t h e magnet c u r r e n t . The a n a l y s i s shows t h a t w i t h i n t h e 70 mm b o r e d i a m e t e r t h e f i e l d n o n l i n e a r i t i e s a r e c l o s e t o t h o s e c a l c u l a t e d f o r b o t h f u l l - s c a l e magnets and keep. t h e i r v a l u e s un- changed w i t h i n t o l e r a n c e s i n a work- i n g f i e l d r a n g e from 0.67 T t o 5 T.

The dynamic l o s s e s measured i n t h e t r a p e z o i d a l c y c l e s c u r r e n t changes f o r t h e 700 A/sec ramp r a t e and 6kA a m p l i t u d e ( t h e r e a l c y c l e o f t h e UNK) were 750 J, 550 J b e i n g h y s t e r e s i s l o s s e s .

The f u l l - s c a l e d i p o l e models a r e t a k e n a s t h e b a s i s f o r f u r t h e r deve- lopment. One of t h e models i s assemb- l e d now i n a f o r c e - c i r c u l a t i n g c r y o s - t a t w i t h a magnet s h i e l d ( f i g . 5) and i s r e a d y t o b e t e s t e d a t a f o r c e - c i r c u l a t i n g c r y o g e n i c t e s t f a c i l i t y .

he

c o e f f i c i e n t Cn c o r r e s p o n d i n g t o t h e n o n l i . n e a r i t y o f t h e o r d e r of n-1.

F i g . 3

-

Normal even n o n l i n e a r i t i e s F i g . 4 - Normal odd n o n l i n e a r i t i e s v e r - v e r s u s magnet c u r r e n t . s u s magnet c u r r e n t .

F i g . 5

-

^A f u l l - s c a l e d i p o l e model i n a f o r c e - c i r c u l a t i n g c r y o s t a t

6: T STUDY OF SHORT MODELS

6.0

55

50

0

S t u d y o f s h o r t models i s g o i n g on. A few models w i t h a n improved c u r r e n t

. d e n s i t y o f t h e c a b l e have been manufac-

t u r e d . Being t e s t e d i n a b a t h c r y o s t a t a t a t e m p e r a t u r e of 4 . 2 5 K t h e s e models w i t h an i r o n s h i e l d p r o v i d e b o r e f i e l d of a b o u t 5 . 5 T a f t e r t h e 1 s t quench.

F i g . 6 shows t h e t r a i n i n g c u r v e s f o r

- t h r e e magnets o f t h i s s e r i e s . As s e e n ,

t a f t e r some t r a i n i n g t h e maximum f i e l d

a t t a i n e d was 6 . 2 T. With a t e m p e r a t u r e of t h e helium b a t h down f i r s t t o 3.9 K and t h e n t o 3.65 K t h e maximum f i e l d a t t a i n e d was 6.55 T and 6.7 T, r e s p e c -

- t i v e l y , a f t e r a s h o r t - t e r m t r a i n i n g a t

e a c h l e v e l (3-4 q u e n c h e s ) . The harmonic

" " " " " " " ~ ' ~ " ~ " ~ ' t ' " ' t a n a l y s i s has b e e n done f o r e a c h f i e l d

'

O

'

^{2* 25 3o}

'

l e v e l . B e s i d e s , w i t h t h e h e l p o f r e s i s - F i g . 6

-

The t r a i n i n g c u r v e s f o r new s h o r t t o r - t y p e s t r a i n gauges t h e dependence

d i p o l e models. of r a d i a l bandage movement d u e t o pon-

Cl-252 JOURNAL DE PHYSIQUE

d e r o m o t i v e f o r c e s h a s been measu- r e d . As shown by t h e s e measure- ments, t h e r e l a t i v e v a l u e s o f h a r - monics d e v i a t e from t h o s e t o l e r a b - l e by 1 . a t a f i e l d e x c e e d i n g 6 T, which i s accompanied by a bandage d e f o r m a t i o n by above 100,um. So, t h e developed c o n s t - r u c t i o n h a s a good m e c h a n i c a l s t a - b i l i t y a t t h e UNK working f i e l d and a l s o a n e c e s s a r y r e s e r v e i n t h e c r i t i c a l c u r r e n t .

UNX f u l l - s c a l e d i p o l e s t o b e manu- f a c t u r e d a r e supposed t o b e r e c t i - l i n e a r . I n t h i s c a s e s t r i n g e n t r e - q u i r e m e n t s a r e imposed on t h e edge f i e l d q u a l i t y . The r e l a t i v e v a l u e s o f harmonics C3 and C5 s h o u l d s a - t i s f y t h e c o n d i t i o n s

I

S c 3 d s

( <

3 , 5 . 1 0 - ~ m and F i g . 7

-

A h a l f - c o i l o f a s h o r t model; t h e l a y -

Id ^I

o u t o f t u r n s on t h e e d g e s i s s e e n .

l L c 5 d s

1

< ~ . I o - ~ m ,

%o

cJ%

^{where A s i s} t h e end l e n d t h . To

meet t h e s e r e q u i r e m e n t s , t h e t u r n s a t t h e e d g e s were l a i d i n s u c h a way t h a t t h e i n t e g r a l v a l u e s o f harmonics C3 and C5 i n t h e edge f i e l d b e c l o s e t o z e r o /6/. F i g . 7

0.5.5 shows t h e p i c t u r e of t h e s e win-

d i n g s . The end p a r t o f t h e winding of t h e i n n e r s h e l l h a s a 11.2 mm wide f i b e r g l a s s s p a c e r a f t e r t h e 4 t h t u r n and a 47.2 mm wide o n e a f t e r t h e 30-th t u r n . The o u t e r l a y e r h a s n o t s u c h s p a c e r s . F i g . 8 shows t h e d e s i g n and measured de-

-2 pendences o f d i p o l e and s e x t u p o l e

.--3 components o f t h e edge f i e l d on

. - I t h e l o n g i t u d i n a l c o o r d i n a t e measu-

r e d from t h e m i d d l e o f t h e d i p o l e . The c a l c u l a t e d and e x p e r i m e n t a l d a t a a r e i n a s a t i s f a c t o r y a g r e e - ment. The way o f l a y i n g o u t t u r n s a t t h e winding e d g e s made it a l s o p o s s i b l e t o improve t h e i n t e g r a l F i g . 8 - T h e d i p o l e and s e x t u p o l e components o f c h a r a c t e r i s t i c s o f t h e d i p o l e t h e edge magnetic f i e l d . The dashed l i n e i s f o r f i e l d . The c o n t r i b u t i o n s from t h e t h e c a l c u l a t i o n , t h e p o i n t s a r e f o r t h e e x p e r i - edge f i e l d i n t o lower-order non- m e n t a l v a l u e s . l i n e a r i t i e s a r e w i t h i n t o l e r a n c e s

f o r t h e c a s e o f a f u l l - s c a l e d i - p o l e .

Dynamic c h a r a c t e r i s t i c s o f d i p o l e s h a v e been measured. F i g . 9 shows a d e - pendence of t h e c r i t i c a l c u r r e n t on t h e ramp r a t e t y p i c a l f o r t h e d i p o l e s o f t h i s s e r i e s . As s e e n i n t h e t h e whole r a n g e o f r a t e s up t o 250 A/sec t h e quench c u r r e n t remains unchanged.

P r e s e n t l y t h e work on d i p o l e s t u d y c o n t i n u e s . A s a n e x t s t e p , a s t u d y w i l l b e made o f t h e i r o p e r a t i o n a l pe- c u l i a r i t i e s i n f o r c e - c i r c u l a t i n g c o o l - i n g mode.

6000

1

0 100 ZOO SO0 400 500

=

F i g . 9

-

The c r i t i c a l c u r r e n t o f a s h o r t model v e r s u s ramp r a t e .

REFERENCES

/1/ RALBEKOV V. I .

,

DMITREVSKIY Yu .P.

,

DUNAITSM A. F . e t a l , h he IHEP A c c e l e r a t i n g and S t o r a g e Complex (UNK). S t a t u s ~ e ~ o r t " , R e p o r t a t XI1 I n t e r n a t i o n a l Confe- r e n c e on High Energy A c c e l e r a t o r s , FNAL, 1983.

/2/ RALBEKOV V . I . , BULATOV E.A., DEMYANCHUK V.I. e t a l , IEEE T r a n s a c t i o n s on Magne- t i c s , v . MAG-17,

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(1981) 1886.

/3/ NREYEV N . I . , BALBEKOV V . I . , BULATOV E.A. e t a l . P r e p r i n t IHEP 82-31, Serpukhov, 1982.

/4/ A P r o g r e s s Report on t h e Energy D o u b l e r , S a v e r , C o l l i d e r P r o j e c t , FNAL Design R e p o r t , 1976.

/5/ BALBEKOV V.I., GERTSEV K.F., SMIRNOV N.L. e t a l . P r e p r i n t IHEP 82-134, Serpuk- hov, 1982.

/6/ BALBEKOV V . I . , TKACHENKO L.M. P r e p r i n t IHEP 82-167, Serpukhov, 1982.