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Submitted on 1 Jan 1984
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SUPERCONDUCTING CORRECTION COILS FOR HERA
C. Daum, P. Schmüser
To cite this version:
C. Daum, P. Schmüser. SUPERCONDUCTING CORRECTION COILS FOR HERA. Journal de
Physique Colloques, 1984, 45 (C1), pp.C1-267-C1-270. �10.1051/jphyscol:1984154�. �jpa-00223710�
JOURNAL DE PHYSIQUE
Colloque C1, suppl6ment a u n o I, Tome 45, janvier 1984 page C1-267
SUPERCONDUCTING CORRECTION COILS FOR HERA
C .
Dam and P. ~chmiiser*
NIKHEE-H, Amsterdam 1009 AJ, The Netherlands
*II. I n s t i t u t fiir Eqerimentalphysik der U n i v e r s i t a t Hamburg, F. R. G.
R6sum6 - Les bobines de c o r r e c t i o n q u a d r u p o l a i r e s e t s e x t u p o l a i r e s de l ' a n n e a u de p r o t o n s HERA s e r o n t mont6es s u r l a chambre a' v i d e f r o i d e a' l ' i n t e r i e u r des aimants d i p o l a i r e s p r i n c i p a u x . Un p r o t o t y p e de b o b i n e d ' u n n 6 t r e de l o n g a 6 t 6 c o n s t r u i t e t t e s t 6 avec succ6s. Les c a r a c t g r i s - t i q u e s de c o n c e p t i o n des bobines de c o r r e c t i o n s u r 1 a chambre a' v i d e a i n s i que l e s r 6 s u l t a t s des t e s t s s o n t p r g s e n t g s .
A b s t r a c t - I t has been proposed t o mount t h e quadrupole and s e x t u p o l e c o r r e c t i o n c o i l s o f t h e HERA p r o t o n r i n g on t h e c o l d beam p i p e i n s i d e t h e main d i p o l e magnets. A one m e t e r l o n g p r o t o t y p e c o i l has been b u i l t and s u c c e s s f u l l y t e s t e d . Design c h a r a c t e r i s t i c s o f t h e beam p i p e c o r - r e c t i o n c o i l s and t e s t r e s u l t s a r e r e p o r t e d .
LAYOUT OF CORRECTION SYSTEM
The 820 GeV p r o t o n s t o r a g e r i n g o f t h e HERA ep c o l l i d e r i s equipped w i t h superconducting d i p o l e and quadrupole magnets w h i c h a r e e x c i t e d by t h e same c u r r e n t . The magnets a r e arranged i n 208 h a l f c e l l s each c o n s i s t i n g o f t h r e e 6 m l o n g d i p o l e s w i t h a nominal f i e l d o f 4.53 T and one 2 m l o n g quadrupole o f 90 T/m. The Q v a l u e o f t h e a c c e l e r a t o r can be v a r i e d by + 2 u n i t s by means o f quadrupole c o r r e c t i o n c o i l s w i t h a f i e l d i n t e g r a l o f 0.54 T m p e r h a l f c e l l , measured a t a r e f e r e n c e r a d i u s ro
=25 nm. C h r o m a t i c i t y c o r r e c t i o n and compensation o f p e r s i s t e n t c u r r e n t s e x t u p o l e s i s achieved b y s e x t u p o l e c o i l s w i t h a f i e l d i n t e g r a l o f 0.35 T m a t r o = 25 mm. These c o i l s w i l l be mounted on t h e c o l d beam p i p e i n s i d e two o f t h e t h r e e d i p o l e s o f a h a l f c e l l . Closed o r b i t c o r r e c t i o n r e q u i r e s i n a d d i t i o n c o r r e c t i o n d i p o l e s o f 0.68 T m p e r h a l f c e l l w h i c h w i l l be b u i l t as s e p a r a t e u n i t s .
A one meter l o n g p r o t o t y p e beam p i p e c o i l c o n s i s t i n g o f two l a y e r s has been b u i l t . The i n n e r l a y e r has a t w o f o l d symmetry and c o n t a i n s t h r e e independent s u b c o i l s t o produce any c o m b i n a t i o n o f d i p o l e and s e x t u p o l e f i e l d s . The o u t e r l a y e r has a f o u r f o l d symmetry and c o n t a i n s two s u b c o i l s which produce an a l m o s t p u r e quadrupole f i e l d . The l a y o u t o f a q u a r t e r o f t h e quadrupole l a y e r i s shown i n F i g . l.*
*A s i m p l i f i e d d e s i g n w i l l be used f o r t h e 6 m l o n g c o i l s : an i n n e r l a y e r w i t h a s i x f o l d symmetry and an o u t e r l a y e r w i t h a f o u r f o l d symmetry, each o f w h i c h have o n l y one s u b c o i l . F o r a d e t a i l e d d e s c r i p t i o n we r e f e r t o C.Daum, P.Schmiiser, DESY-HERA Note 83/01 (1983).
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984154
JOURNAL DE PHYSIQUE
A q u a r t e r o f t h e quadrupole l a y e r .
A l o n g i t u d i n a l c r o s s s e c t i o n showing t h e dimensions and m a t e r i a l s used i s g i v e n i n F i g . 2 . The c o i l s a r e mounted on a p i p e o f s t a i n l e s s s t e e l 1 . 4 5 4 1 w i t h 65 mm o u t e r d i a m e t e r and 2 . 5 mm w a l l t h i c k n e s s which i s i n s u l a t e d b y Kapton and g l a s s f i b r e . The c o i l s a r e wound f r o m a s i n g l e s t r a n d s u p e r c o n d u c t i n g w i r e made by MCA which has 0 . 7 mm diameter, 2050 Nb-Ti f i l a m e n t s o f 9 pm d i a m e t e r and a q u o t e d c r i t i c a l c u r r e n t o f 270 A a t 4 . 2 K and 4 . 5 T. The w i r e i s i n s u l a t e d by an o v e r l a p p i n g 25 vm Kapton wrapping and a f i b e r g l a s s i n s u l a t i o n . The sub- c o i l s a r e wound on a f l a t t a b l e , f i x e d t o a Kapton f o i l and t h e n g l u e d around t h e beam p i p e . A f t e r each c o i l f i v e l a y e r s o f t h e a r a ~ i d e f i b e r ARENKA 900 a r e wound around t h e p i p e w i t h h i g h t e n s i o n (900 N/mm ) . These compression wrappings p r o v i d e t h e main mechanical s t r e n g t h o f t h e package. The epoxy used i s S h e l l E p i k o t e 215 and V 140 i n a r a t i o o f 2 : 1 and a c u r i n g t e m p e r a t u r e of 1. 150" C .
Quadrupole Call
33 0
32.5 i 5
1
F i g . 2 - L o n g i t u d i n a l c r o s s s e c t i o n o f beam p i p e and c o r r e c t i o n c o i 1 package.
beam pipe
30.0
1
beam axls
0
1
MEASUREMENTS
The p r o t o t y p e c o i l was t e s t e d i n a v e r t i c a l b a t h c r y o s t a t u s i n g a I m l o n g super-
c o n d u c t i n g magnet w i t h 100 mm b o r e t o produce an e x t e r n a l d i p o l e f i e l d o f up
t o 5 . 1 5 T a t 4.6 K. A t t h e i r nominal c u r r e n t s ( < 100 A) none o f t h e s u b c o i l s
showed any quenches i n t h e h i g h e s t a c c e s s i b l e e x t e r n a l f i e l d . Systeiiiatic quench
t e s t s were performed w i t h quadrupole s u b c o i l 1. N o t a s i n g l e t r a i n i n g s t e p was
observed. R e v e r s i n g t h e p o l a r i t y y i e l d e d t h e same quench c u r r e n t . F i g . 3 shows
quench current In quodrupole cod 1 at460K
F i g . 3 - Measured quench c u r r e n t o f quadrupole s u b c o i l 1 as a f u n c t i o n o f t h e e x t e r n a l d i p o l e f i e l d .
external field Bo [Teslal
5 0 1 1 1
t h e measured quench c u r r e n t a t T
=4.60 K as a f u n c t i o n o f t h e e x t e r n a l f i e l d . The temperature dependence i n a f i x e d f i e l d o f 4.94 T i s p l o t t e d i n F i g . 4.
I n b o t h cases we observe a r a t h e r smooth, a l m o s t l i n e a r b e h a v i o u r . The c o i l s p r o b a b l y r e a c h t h e s h o r t sample c u r r e n t o f t h e c a b l e .
150
4.0 4.2 4.4 4.6 K
temperature 36116
I ' I ' I I I
- -
quench current ot B = 4.34 T
- -
quadr. coil 1
dipole cool 3
-\-
I , I , I , I
