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CONSTRUCTION AND TEST OF SUPERCONDUCTING QUADRUPOLE
PROTOTYPES FOR HERA
R. Auzolle, A. Patoux, J. Perot, J. Rifflet
To cite this version:
R. Auzolle, A. Patoux, J. Perot, J. Rifflet. CONSTRUCTION AND TEST OF SUPERCONDUCT-
ING QUADRUPOLE PROTOTYPES FOR HERA. Journal de Physique Colloques, 1984, 45 (C1),
pp.C1-263-C1-266. �10.1051/jphyscol:1984153�. �jpa-00223709�
Colioque CI, suppl6ment au no 1, Tome 45, janvier 1984 page C1-263
CONSTRUCTION AND TEST OF SUPERCONDUCTING QUADRUPOLE PROTOTYPES FOR HERA
R. A u z o l l e , A. P a t o u x , J . P e r o t and J . M . R i f f l e t
DPhPE S.
T.
I. P. E., C. E.N.
Sac lay, 91 291 Cif-sur-Yve tte, FrcnzceRBsume
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Q u a t r e q u a d r u p o l e s p r o t o t y p e s pour l a machine HERA 2 DESY (Hambourg) s o n t a c t u e l l e m e n t c o n s t r u i t s e t testes 1 S a c l a y . A c e j o u r , deux q u a d r u p o l e s o n t B t B t e s t d s a v e c s u c c 2 s ( p a s d e t r a i n i n g e t bonne q u a l i t Z d e champ).A b s t r a c t
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Four q u a d r u p o l e p r o t o t y p e s f o r t h e HERA machine a t DESY (Hamburg) a r e b e i n g c o n s t r u c t e d and t e s t e d a t S a c l a y . So f a r two q u a d r u p o l e s h a v e been c o n s t r u c t e d and s u c e s s f u l l y t e s t e d (no t r a i n i n g , good f i e l d homogeneity).GENERAL MAGNET DESCRIPTION
F i g u r e 1 i s a c r a s s - s e c t i o n a l view of t h e q u a d r u p o l e i n i t s c r y o s t a t . The c o i l s (1) c o n s i s t of two l a y e r s o f c o n d u c t o r s p r e c i s e l y h e l d i n p o s i t i o n by a system of c o l l a r s (2) made of s t a c k s of non-magnetic s t a i n l e s s s t e e l s h e e t s . T h e s e c o l l a r s c o n f i n e t h e e l e c t r o m a g n e t i c f o r c e s a c t i n g on t h e c o i l s . The c o i l s and t h e i r f r a m e a r e mounted
i n a t u b e ( 3 ) by means of k e y s ( 4 ) . T h i s e n s u r e s l o n g i - t u d i n a l r i g i d i t y w h i l e preven- t i n g a n y t w i s t i n g of t h e magnet a b o u t i t s c e n t r a l a x i s . The a n n u l a r s p a c e between t h e t u b e ( 3 ) and t h e p a r t i c l e beam chamber ( 5 ) i s f i l l e d
10 w i t h c i r c u l a t i n g h e l i u m
p r e s u r i z e d a t 2 t o 4 b a r . Tubes ( 6 ) c o n t a i n f l o w i n g
8
'
h e l i u m b o i l i n g a t ( 4 . 2 K ) . The h e a t o f v a p o r i - 1 b a r z a t i o n of t h e b o i l i n g h e l i u m2 p r o v i d e s c o o l i n g f o r t h e
3
,
p r e s s u r i z e d helium. A t h e r m a l9 s c r e e n ( 7 ) a t 50 K l i m i t s
r a d i a t e d h e a t i n p u t from t h e vacuum e n c l o s u r e ( 9 ) , which i s made of s o f t i r o n and c o n s t i t u t e s t h e f e r r o m a g n e t i c c i r c u i t . The components a t t h e t e m p e r a t u r e of l i q u i d h e l i u m and t h e s c r e e n s a r e h e l d r i g i d l y w i t h r e s p e c t t o
v v t h e room t e m p e r a t u r e p a r t by
t i t a n i u m t i e - r o d s ( 1 0 ) P i g . 1
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Magnet c r o s s s e c t i o n .Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984153
JOURNAL
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F a i n magnet p a r a m e t e r s...
- C e n t r a l nominal g r a d i e n t 88.86 ~ / m
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C e n t r a l g r a d i e n t d u e t o t h e i r o n yoke...
0.94 T/m- Nominal c u r r e n t
...
5582 A-
Focusing power...
171 T...
- K a g n e t i c l e n g t h 1. 924 m
- C o i l i n n e r d i a m e t e r
...
75 mm...
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S t o r e d energy 76 kJTHE CONDUCTOR
The c o n d u c t o r i s a "Keystoned" f l a t c a b l e of t h e R u t h e r f o r d t y p e c o n t a i n i n g 23 s t r a n d s . It i s i n s u l a t e d f i r s t by two l a y e r s of K a ~ t 0 n t a p e 10 mm wide and 25 11 t h i c k w i t h 80 % o v e r l a p and second by a 10 mm wide and 1 3 5 ~ t h i c k f i b e r g l a s s r i b o n w i t h a 4 mm gap between a d j a c e n t t u r n s . T h i s l a s t r i b b o n c o n t a i n s a R s t a g e epoxy r e s i n . Each s t r a n d i s 0.83 mm i n d i a m e t e r and c o n t a i n s a b o u t 2000 f i l a m e n t s of 13
v.
The copper t o s u p e r c o n d u c t i n g r a t i o i s 1 . 8 t o 1 and t h e t w i s t p i t c h 25 mm. The c a b l e h a s a dimen- s i o n of (1.33-
1.67) x 9.5 mm2 w i t h o u t i n s u l a t i o n . I t s c r i t i c a l c u r r e n t i s 6800 A a t 5.5 T and 4.2 K .COIL CONSTRTJCTION
The f i r s t c o i l l a y e r i s wound o n a c y l i n d r i c a l mandrel w i t h key provided f o r c o i l a n g l e s .
The completed h a l f c o i l i s t h e n p u t under h y d r a u l i c p r e s s u r e i n a f i r s t mold and c u r e d a t 160°C f o r 2 H , t h e maximum f o r c e a p p l i e d i s 500 t .
A f t e r c u r i n g , t h e l a y e r i s removed from t h e mold, and f i b e r g l a s s s p a c e r s a r , e p u t on t o p of i t t o p r o v i d e helium c h a n n e l s between t h e two l a y e r s . The second l a y e r i s t h e n wound on t h e f i r s t one and cured t h e same way i n a second mold.
A l l t h e t o o l i n g s u c h a s winding mandrel, c o i l keys, c u r i n g mold, a r e made of punched l a m i n a t i o n s s t a c k e d t o g e t h e r up t o t h e needed l e n g t h (2 m). Using punched l a m i n a t i o n g i v e s a v e r y good a c c u r a c y and a l l o w s t o d u p l i c a t e t h i s t o o l i n g for: mass p r o d u c t i o n w i t h s m a l l e x t r a c o s t .
Once molded, f o u r c o i l s a r e mounted around a n o t h e r c y l i n d r i c a l mandrel. T h i s l a s t mandrel i s n o t l a m i n a t e d b e c a u s e i t must s l i d e on t h e c o i l s u r f a c e i n o r d e r t o b e
removed a f t e r assembly.
Ground i n s u l a t i o n made of f o u r l a y e r s of 0.125 mrn t h i c k Kapton s h e e t i s provided a t t h e o u t e r d i a m e t e r of t h e c o i l s and t h e s t a i n l e s s s t e e l l a m i n a t e d c o l l a r s a r e s t a c k e d o v e r t h e c o i l s ( F i g . 2 ) .
F i g . 2
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C o i l s c o l l a r i n gc e n t r a l keys of t h e l a m i n a t i o n s . The c o l l a r e d magnet i s t h e n p u t i n a q u a d r u p o l a r p r e s s which a p p l i e s c o r r e c t p r e s t r e s s on t h e c o i l s by pushing t h e c o l l a r s i n f o u r p e r - p e n d i c u l a r r a d i a l d i r e c t i o n s .
With t h e p r e s s u r e s t i l l a p p l i e d , t h e l a m i n a t i o n s a r e f a s t e n e d t o g e t h e r by means o f keys s o t h a t t h e a p p l i e d p r e s t r e s s remains i n t h e c o i l s a f t e r t h e p r e s s i s removed.
A f t e r a l l t h e c o l l a r s have been p r e s s e d and f a s t e n e d t h e c e n t r a l mandrel i s removed w i t h a n h y d r a u l i c j a c k .
MAGNET TESTS
a )
G ~ i f
-c_u_rregt_ :So f a r two magnets have been made and t e s t e d . The working t e m p e r a t u r e of t h e quadru- p o l e is 4 . 6 K i n p r e s s u r i z e d helium, b u t t h e t e s t s t o o k p l a c e i n a v e r t i c a l c r y o s t a t i n b o i l i n g helium a t 4 . 2 K .
The c u r r e n t was r a i s e d t o t h e nominal c u r r e n t ( 5 5 8 2 A) w i t h o u t quench, t h e n r a i s e d up t o 6 3 3 5 A which i s t h e c r i t i c a l c u r r e n t a t 4 . 6 K . T h i s l a s t c u r r e n t r e p r e s e n t s 9 0
X
o f t h e c r i t i c a l c u r r e n t a t 4.2 K. No quench h a s been r e c o r d e d .
The e q u i v a l e n t of t h e c r i t i c a l c u r r e n t a t 4 . 6 K b e i n g r e a c h e d , no t r y was made t o quench t h e magnet above t h i s v a l u e . The second magnet behaved t h e same a s t h e f i r s t .
The m u l t i p o l e c o e f f i c i e n t s have been measured u s i n g r o t a t i n g pick-up c o i l s . One c o r r e c t i o n c o i l i s used t o c a n c e l t h e q u a d r u p o l e term and a n o t h e r one t o c a n c e l t h e d i p o l e term coming from a n o f f - c e n t e r i n g of t h e r o t a t i n g system. A l l t h e s e c o i l s extend a x i a l l y from t h e m i d d l e of t h e q u a d r u p o l e t o f a r beyond t h e end s o t h a t t h e h a l f f i e l d - i n t e g r a l i s measured.
The m u l t i p o l e f i e l d c o e f f i c i e n t s have t h e f o l l o w i n g d e f i n i t i o n :
a i s t h e i n n e r c o i l r a d i u s ,
Z i s any complex c o o r d i n a t e w i t h i n t h e u s e f u l a p e r t u r e .
On Table 11, t h e AB/B d u e t o each term i s g i v e n up t o n = 10 f o r a = 2 5 mm c o r r e s - ponding t o Z/a = 0 . 6 7 .
CONCLUSION
The two q u a d r u p o l e s which have been c o n s t r u c t e d r e a c h e d t h e i r c r i t i c a l c u r r e n t w i t h o u t any t r a i n i n g .
F i e l d homogeneity i s w i t h i n a few f o r most of t h e m u l t i p o l e s i n s i d e t h e u s e f u l a p e r t u r e .
T h e r e f o r e t h e d e s i g n and t h e c o n s t r u c t i o n t e c h n i q u e s used f o r t h e q u a d r u p o l e s can b e c o n s i d e r e d a d e q u a t e f o r mass p r o d u c t i o n . Complete t e s t s i n t h e i r f o r c e d f l o w c r y o s t a t remain t o b e made and c r y o g e n i c systems t o be checked, such a s t h e s u s p e n s i o n scheme.
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AB/B a t 25 mm (67 % of c o i l a p e r t u r e ) f o r nominal c u r r e n t ( i n u n i t s )
ACKNOWLEDGEMENTS
W e want t o e x p r e s s our thanks t o a l l t h e people who have c o n t r i b u t e d t o t h e d e s i g n , f a b r i c a t i o n and t e s t of t h e s e magnets, e s p e c i a l l y t o A. ABEILLERA, S. CLAUDET,
J. FARRR, M. HAMANG, J.?. HELLO, D. IANNONE, R. FARAND, D. EORIZE, H. MOUSSIKIAN,
Y. PABOT, J.C. TOUSSAINT.
We a r e a l s o g r a t e f u l t o t h e Permilab f o r t h e information k i n d l y provided on i t s c o n s t r u c t i o n technique.