MAGNETS FOR THE PROTON STORAGE RING AT LOS ALAMOS

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MAGNETS FOR THE PROTON STORAGE RING AT LOS ALAMOS

A. Harvey

To cite this version:

A. Harvey. MAGNETS FOR THE PROTON STORAGE RING AT LOS ALAMOS. Journal de Physique Colloques, 1984, 45 (C1), pp.C1-245-C1-248. �10.1051/jphyscol:1984149�. �jpa-00223705�

JOURNAL DE PHYSIQUE

Colloque C1, suppl6ment a u n o I , Tome 45, janvier 1984 page C l - 2 4 5

MAGNETS FOR T H E PROTON STORAGE R I N G A T L O S ALAMOS

A. Harvey

Los AZamos National ihboratory, Los AZamos, NM 87545, U.S.A.

Rgsum@ - L'anneau d ' a c c u m u l a t i o n de p r o t o n s de Los Alamos u t i l i s e r a des p r o t o n s venant de l l a c c @ l e r a t e u r LAMPF. Les aimants s o n t , pour l a p l u p a r t , a l i m e n t c s en c o u r a n t con- t i n u e t s o n t de bonne q u a l i t e . Les c a r a c t e r i s t i q u e s s p c c i a l e s s o n t des l a m i n a t i o n s p o u r un a i m a n t de 36" de courbe u t i l i s a n t une b a r r e d r o i t e ; des aimants septum avec i s o - l a t i o n de v e r r e " s o l - g e l " , e t un d i p o l e a g r a d i e n t e l e v e p o u r l a t r a n s f o r m a t i o n des p a r - t i c u l e s H- _{en HO} $ i n j e c t e r .

A b s t r a c t

-

The P r o t o n Storage R i n g (PSR)[l] now under c o n s t r u c t i o n a t Los Alamos, New Mexico, w i l l t a k e H- p a r t i c l e s a t 800 MeV f r o m t h e LAMPF a c c e l e r a t o r , and s t o r e them as p r o t o n s , i n e i t h e r one l o n g bunch p e r t u r n o r s i x s h o r t bunches p e r t u r n , b e f o r e t h e y a r e e x t r a c t e d t o a s p a l l a t i o n t a r g e t . The PSR i s 28 m i n diameter, c o m p r i s i n g t e n 1.2-T d i p o l e s and t w e n t y 180-mm-bore quadrupoles w i t h 4.5-T/m g r a d i e n t , i n a OOFO s t r u c t u r e .

The d i p o l e magnets were made o f 1.5-mm-thick low-carbon-steel l a m i n a t i o n s , t o achieve r e p r o d u c i b l e magnetic p r o p e r t i e s f r o m magnet t o magnet b y s h u f f l i n g l a m i n a t i o n s f r o m t h e v a r i o u s h e a t s r e q u i r e d t o produce t h e 150 t o n s o f s t e e l used. Because t h e mag- n e t s bend t h e p a r t i c l e s 36", t h e y a r e curved, and a s i g n i f i c a n t f a c t o r i n a c h i e v i n g t h e 0.05-mm t o l e r a n c e t o t h e s p e c i f i e d 4.058-111 r a d i u s o f t h e magnet was t h e use o f a s t r a i g h t s t a c k i n g b a r f o r t h e core. T h i s c l o s e t o l e r a n c e was r e q u i r e d because t h e p o l e f a c e s a r e shimmed t o achieve a f l a t f i e l d f r o m t h e minimum-sized magnet. M a t i n g w i t h t h e b a r i s a n o t c h i n t h e b o t t o m o f each l a m i n a t i o n , w i t h t h e l o c a t i o n o f t h e c e n t e r o f t h e n o t c h i n t h e n t h l a m i n a t i o n g i v e n b y

where

R i s t h e s t a c k e d c o r e r a d i u s (4.058 m),

L i s t h e o v e r a l l c o r e s t a c k l e n g t h (2.203 m), and

t i s t h e mean s t a c k l e n g t h p e r l a m i n a t i o n , measured under t h e f i n a l c o r e l o a d o f 75 t o n s .

The advantage o f t h i s i n n o v a t i v e scheme[2) i s , o f course, t h a t l a m i n a t i o n s do n o t move r e l a t i v e t o t h e i r n e i g h b o r s as t h e c o r e i s compressed. The n o t c h i s c u t i n t h e l a m i n a t i o n , u s i n g a d i g i t a l r e a d - o u t p o s i t i o n i n g t a b l e , a t a w o r k s t a t i o n a d j a c e n t t o t h e s t a c k i n g f i x t u r e . F i g u r e 1 shows t h e f i r s t d i p o l e , w i t h a measuring c o i l i n t h e a p e r t u r e . The two-dimensional f i e l d i s u n i f o r m t o 1 p a r t i n 104 o v e r 105-mm diam, i n e x c e l l e n t agreement w i t h MIRTr31 c a l c u l a t i o n s .

To measure these, and o t h e r , d i p o l e s , a t h r e e - a x i s p o i n t - b y - p o i n t mapping machine has been c o n s t r u c t e d ( F i g . 2). Capable o f c o v e r i n g a volume o f 0.5 m b y 0.5 m b y 2 m i n

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984149

C1-246 JOURNAL DE PHYSIQUE

F i g . 1. PSR main r i n g d i p o l e . F i g . 2. Three-axis measuring machine.

v a r i a b l e increments, t h e d e v i c e i s c o n t r o l l e d b y an LSI-11 microcomputer. The

" p o i n t " measurinq c o i l r 4 1 can b e o r i e n t e d t o r e a d t h e X, Y , o r Z component o f t h e magnetic f i e l d . A p a r t f r o m some t e m p e r a t u r e s e n s i t i v i t y i n t h e v - t o - f c o n v e r t o r [ 5 1 and i t s a s s o c i a t e d i n t e g r a t i n g c o u n t e r , t h i s d e v i c e i s o p e r a t i n g s a t i s f a c t o r i l y . The r i n g quadrupoles must be h i g h q u a l i t y , b u t a r e s h o r t ( a b o u t 0.5-m e f f e c t i v e l e n g t h ) . The p o l e - t i p d e s i g n was accomplished b y t r a n s f o r m i n g t h e quadrupole t o d i p o l e geometry, shimming t h e p o l e f a c e u s i n g MIRT, and t h e n t r a n s f o r m i n g back t o quadrupole. Duodecapole i s e l i m i n a t e d b y adding c y l i n d r i c a l shim s t a c k s a t t h e a p p r o p r i a t e [ 6 1 p l a c e s on t h e p o l e ends.

The i n j e c t i o n and e x t r a c t i o n beamlines a s s o c i a t e d w i t h t h e PSR have d i p o l e s and quadrupoles w i t h l e s s demanding f i e l d q u a l i t y . However, .we have found i t advanta- geous t o r e q u i r e harmonic a n a l y s i s o f t h e quadrupoles, w i t h a l i m i t on s e x t u p o l e o f 0.1% o f t h e quadrupole. T h i s n o t o n l y checks t h e symmetry o f t h e i r o n c o n s t r u c t i o n , b u t a l s o i d e n t i f i e s c o i l s w i t h e r r o r s i n t h e number o f t u r n s - - a problem w i t h some quadrupoles. I n F i g . 3 can be seen a beamline quadrupole, 155-mm b o r e ( w i t h v e r y

low s e x t u p o l e ! ) , and pole-end chamfers t o m i n i m i z e duodecapole.r71

Septum magnets i n t h e e x t r a c t i o n system have c u r r e n t d e n s i t i e s up t o 88 ~/mm~.r2]

I n s u l a t i o n systems b e i n g c o n s i d e r e d f o r t h e septum c o n d u c t o r s a r e p o r c e l a i n enamel (0.2-mm t h i c k ) and s o l - g e l glassT81 (0.05-mm t h i c k ) . The s o l - q e l t e c h n i q u e i s a t t r a c t i v e because o f t h e v e r y t h i n i n s u l a t i o n l a y e r p o s s i b l e . I t i s impermeable t o m o i s t u r e and has t h e r a d i a t i o n - r e s i s t a n c e o f glass, as w e l l as i t s h i g h t e m p e r a t u r e c a p a b i l i t y . The procedure f o r a p p l y i n g t h e c o a t i n g comprises o x i d i z i n g t h e copper s u r f a c e t o promote bonding, s p r a y i n q on t h e g l a s s i n a s o l v e n t base, d r y i n g t h e c o a t - i n g t o a g e l , and f i r i n g t h e c o n d u c t o r i n a i r . The model septum shown i n F i g . 4 i s used t o e v a l u a t e t e c h n i q u e s t o c o n t r o l leakage f i e l d s , such as c o i l e x t e n s i o n s , f e r - romagnetic s h i e l d s and compensation windings. [ 9 1

As p a r t o f t h e i n j e c t i o n system, t h e r e i s a h i g h - g r a d i e n t (200-T/m) d i p o l e of 10-mm a p e r t u r e t o s t r i p t h e H- i o n s t o HO,[lO1 f o r i n s e r t i o n i n t o t h e r i n g t h r o u g h a h o l e i n t h e r e t u r n yoke o f a r i n g d i p o l e . A l t h o u g h a r e s i s t i v e e l e c t r o m a g n e t i s f e a s i b l e , some c o n s i d e r a t i o n i s b e i n g g i v e n t o a samarium-cobalt permanent magnet f o r t h i s a p p l i c a t i o n .

F i g . 3. 155-mm beamline quadrupole. F i g . 4. Septum development model.

Most o f t h e magnet components o f PSR a r e manufactured b y i n d u s t r y ( t h e s e p t a a r e t h e e x c e p t i o n ) . Costs f o r t h e s e procurements are g i v e n i n Table I; t o o l i n g i s n o t

i n c l u d e d .

T a b l e I

Magnet 80-mm quadrupole

100-mm quadrupole 100-mm quadrupole 100-mm quadrupole 155-mm quadrupole 180-mm quadrupole 100-mm d i p o l e Main r i n g d i p o l e s

127-mm d i p o l e 127-mm d i p o l e

REFERENCES

Number 4 4 9 8 13 2 1 5 11 1 1

Weight (kg)

408 87 1 740 519 1584 1733 2475 14 851 9208 4703

Cost 9K p e r u n i t

6.5 8.5 9.1 7,2 10.5 12.7 16.0 89.0 34.6 25.0

[I] Lawrence, G. P., e t a l , Paper presented a t t h e X I t h I n t . Conf. on High Energy A c c e l e r a t o r s , CERN, Geneva, J u l y 1980, Los Alamos S c i e n t i f i c L a b o r a t o r y document LA-UR-80-1946.

[ 2 ] Glavish, H., and MacKinnon, B., P r i v a t e communication, GMW Consultants, Redwood C i t y , CA.

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r 3 1 MIRT i s p a r t o f a f a m i l y o f e l e c t r o - a ~ d m a q n e t o - s t a t i c d e s i g n codes m a i n t a i n e d b y t h e Los Alamos N a t i o n a l L a b o r a t o r y . The codes a r e a l l d e r i v e d f r o m o r i q i n a l work b y A l a n M. Winslow, J. Comp. Phys. 2, 149-172, 1967.

[4] Thomason, M. D., Los Alamos S c i e n t i f i c L a b o r a t o r y r e p o r t LA-5304-MS, June 1973.

r 5 1 Dynamic Measurements Corp., Winchester, MA, USA, model 7287.

r 6 1 Halbach, K., and Yourd, R., Lawrence R a d i a t i o n L a b o r a t o r y r e p o r t UCRL-18916, May 1969.

C71 Hassenzahl, W. V., MT-4, Conf-720908, Brookhaven N a t i o n a l L a b o r a t o r y , p. 469 (1972).

C83 ~ r i n k e r , C. J., and Mukherjee, S. P., J. o f May1 S c i .

2,

[9] K e i z e r , R. K., CERN 74-13, Geneva 1974.

[ l o ] Jason, A. J. e t a l , I E E E Trans. Nucl. S c i . 28, p. 2704 (June 1981).

[ill Harvey, A., MT-4, Conf-720908, Brookhaven ~ x i o n a l Laboratory, p. 456 (1972).