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GANIL ECRIS STATUS AND DEVELOPMENT
P. Sortais, P. Attal, L. Bex, M. Bisch, M. Bourgarel, Y. Bourgoin, P.
Leherissier, J. Pacquet
To cite this version:
JOURNAL DE PHYSIQUE
Colloque Cl, supplement au n o l , Tome 50, janvier 1989
GANIL ECRIS STATUS AND DEVELOPMENT
P. SORTAIS, P. ATTAL, L. BEX, M. BISCH, M.P. BOURGAREL, Y. BOURGOIN,
P. LEHERISSIER and J.Y. PACQUET
GANIL, BP 5027, F-14021 Caen Cedex, France
GANIL possede actuellement 2 sources ECR op6rationnelles : ECRl (Minimafios) et ECR2 (Ferromafios) et est en train d l e n construire 2 autres : ECR3 (Caprice 2B 10 GHZ) et ECR4
(NBomafios 14.5 GHz). wce
ECRl est opBrationnelle sur l'acc616rateur depuis 1985 et a fourni des faisceaux d'ions mgtalliques (10% de stabilitd) pour des "runs" de longue d u d e en Ca, Ni, MO et Ta. L'optimisation de ces faisceaux se fait sur le banc de test de GANIL sur lequel la source Ferromafios est installee.
L10p6ration "0.A.E" (Op6ration Augmentation dlEnergie) consiste 2 augmenter prochainement 1'6nergie finale des particules, d'un facteur 2 pour les ions plus lourds que le x6non.
Cette modification de l'acc616rateur implique une augmentation des courants d'ions pour les forts Btats de charge des 616ments lourds : ~ r ' ~ + , xe17+
,
uz4+
(avec I > 30 pA).Les faisceaux de Kr et Xe seront produits par la source Caprice ( 2B ,,,ce
,
10GHz) actuellement en construction et qui sera op6rationnelle sur l'injection axiale actuelle (20 kV) pour mi-89, pour la nouvelle version de la machine. De manisre 5 produire de forts courants d'ions m6talliques fortement charges une nouvelle source est en cours de dBveloppement : NEOMAFIOS 14.5 GHz.C'est une source, dont la structure magnetique est partiellement faite B partir
d'aimants permanents au FeNdB (60%) et de bobines 6lectromagn6tiques classlques.
Ce prototype a 6t6 6tudi6 pour minimiser la consommation 6lectrique pour une structure magngtique & fort confinement (B > 2B wee, 14.5 GHz
=
10400 G) et devrait Btre install6e sur la nouvelle plate-forme haute tension (100 kV), 6quip6e de sa nouvelle ligne d'injection axiale, pour la mi-1990, sur le 28me injecteur de Ganil.Abstract
GANIL is using presently two operational ECRIS : ECRl (Minimafios) and ECR2 (Ferromafios) and is building two others : ECR3 (Caprice) and ECR4 (Neomafios 14.5 GHz). ECR2 is in operation on the accelerator since 1985 andhasdelivered stable metallic ion beams ( = 10% of stability) during long rungs (t > 100 h) for Ca, Ni, MO and Ta. Optimization of such beams is done on the GANIL test bench on which Ferromafios is installed.
The next modification of GANIL named 0.A.E consists increasing the final energy of the particles by a factor of two, for ions heavier than Xe.
This modification of the accelerator involves the increase of the beam intensi+ty for high charge states in the case of the heavy elements : Kr13+, xe17+, ~ a " + ,
uZ4
(withI
> 3 0 pA). Beams of Kr and Xe will be produced by the source Caprice (2B, 10 GHz) (ECR3), presently under construction and expected to be operational by the middle of 1989 on the actual axial injection (20 kV). In order to produce higher currents for the high charge states of metallic ions a new ion source is being developped : NEOMAFIOS 14.5 GHz.This source has an axial magnetic structure made partially with FeNdB permanents magnet (60%) and classical coils.
This prototype has been designed for minimizing the electrical power needed for a high confinement magnetic structure (B > 2B wee, 14.5 GHz
=
10400G).It will be installed on
a
high voltage platform (100 kV) and a new axial injection line, by the middle of 1990, on the second injector cyclotron.JOURNAL DE PHYSIQUE
Introduction
D i f f e r e n t s t e p s o f development of Ganil a r e i n t i m a t e l y bound t o t h e development o f . t h e
CR i o n s o u r c e s . Minimafios (ECR1) and i t s legendary r e l i a b i l i t y a l l o w s t o f o r g e t a l l d i f f i c u l t i e s o f t h e P I G s o u r c e . Ferromafios (ECR2) i n s t a l l e d on t h e t e s t bench o f GANIL, h a s been designed f o r t h e development o f t h e " m e t a l l i c n i o n s . I t is a l r e a d y p o s s i b l e t o work f o r very long r u n s ( t > l 0 0 h ) o f " m e t a l l i c " beams on t h e machine. The "0.A.E" p r o j e c t a s s o c i a t e d with t h e very optimized 10 GIiz s o u r c e Caprice 2 B w e e (ECR3) w i l l g i v e a f a c t o r o f two o r t h r e e f o r t h e f i n a l energy o f t h e h e a v i e s t element beams. And now with t h e "0.A.I" p r o j e c t ( l 0 0 kV H . V p l a t f o r m ) a s s o c i a t e d with a high frequency ECRIS (ECR4) u s i n g t h e up-to-date technology o f t h e FeNdB permanent magnet, we c a n hope t o g a i n a f a c t o r o f t e n o r more on t h e c u r r e n t s t o be d e l i v e r e d t o t h e p h y c i c i s t s . We a r e going t o d e s c r i b e t h e s t a t e o f f u n c t i o n n i n g o r development o f t h e d i f f e r e n t G a n i l ' s ECRIS.
1 ) Minimafios
Minimafios r o u t i n e l y has d e l i v e r e d "gazeous" beams f o r t h e p a s t t h r e e y e a r s . Multicharged heavy i o n beams o f m e t a l l i c elements a r e today a major r e q u e s t f o r Ganil. An i m p o r t a n t r u n h a s been performed i n o c t o b e r 1987 i n o r d e r t o produce Ca i o n beams ( F i g .
1 ) .
We have used a mixture of " ~ a 0 and A 1 (provided by Dubna p h y c i c i s t s ) i n a s m a l l Tantalum c r u c i b l e
( 6
5mm) d i r e c t l y heated with t h e plasma. The beam i n t e n s i t y e x t r a c t e d from E C R l was 10 p A o f Ca 6 ++
' ' ~ a S++
0*+
and 150 - 250 nA have been a c c e l e r a t e d by t h e machine f o r a consumption of 1 . 8 mg/h.A long r u n had been performed with N i 7 + i o n s . The samples were made o f N i O powder compacted and heated a t high temperature under vacuum. The machine r u n s d u r i n g one week with s m a l l r o d s o f 4 mm i n diameter and 5 c e n t i m e t e r s i n l e n g t h .
A machine s t u d y f o r "0.A.E" p r o j e c t , has a l s o been performed with ~ a " + ( 5 d ~ ( s o u r c e ) ) d u r i n g 3 days with an e x c e l l e n t s t a b i l i t y .
/Element ( X (Charge J ~ o u r c e J ~ n e r ~ J ~ n t e n s l t y on target l
I I I I H V l I I I l 1 s o t o p e l S t a t e s I l I I I I I I ( k v ) IMeV/u lpps X 10" l nAe I I I I I I I I I C 12 ( 1 ) l 100 1 2/6 1 6 . 7 1 40 1 10.4 1 1000 I /C 12 1 - 1 2/6 111.3 1 70 1 10.4 1 1000 I IC 1 2 ( l ) l 100 1 2 1 6 . 7 1 3.61 10.4 1 1000 I [C 1 3 1 1 0 0 1 2 / 6 1 9 . 1 1 5 0 1 6.2 / 600 1 10 16 / 100 1 2 / 8 111.1 1 5 0 1 10.7 1 1200 1 10 16 1 - I 3.8 112.8 1 94 1 11.7 1 1500 1 10 1 7 1 50 1 3/8 112.5 1 84 1 5.46 1 700 1 10 l 8 I l 0 0 I 3/8 115.5 1 65 1 15.6 1 2000 1 1eiem I i o o ~ n / g 117.3 1 4 0 1 4.9 1 700 l jNe 20 1 - 1 3 / 9 1 9 . 4 1 5 9 1 2.8 1 400 1 I N e 2 0 1 1 0 0 1 3 / 9 1 1 0 . 8 1 6 0 1 1.8 1 230 1 INe 22 1 100 / 3/9 1 9 . 2 1 45 1 4.2 1 600 1 I N e 2 2 1 - 1 3 / 9 112.0 1 6 0 1 3.5 1 500 1 I A r 36 1 1 0 0 1 5 / 1 7 1 1 5 . 9 1 85 1 3.5 1 1000 I IAr 40 ( 1 ) 1 100 1 6 117.6 1 7.51 10.4 1 1000 I Ar 40 1 - / 4 / 1 4 / 7 . 9 1 2 7 1 1.4 1 300 1 IAr 40 1 - 1 4/15 111.3 ! 41 1 5.1 1 1200 I jAr 40 1 - 1 4 / 1 6 1 1 2 . 1 1 4 4 1 3.9 1 1000 I jAr 40 / - 1 5/16 112.9 1 60 1 3 . 1 5 3.4 I A r 40 / - / 5/17 114.1 1 65 1 1.8 I A ~ 40 l 100 1 6/16 110.0 1 56.81 0.6 1 120 1 {Ca 48 ) 70 1 6/18 112.0 1 55 1 0.87 1 250 l ICa 40 l 100 1 4/17 (13.6 / 50.61 1.4 1 300 1 I K r 84 1 90 1 9/25 1 7.3 1 27 ( 0.07 0.1 1 30-40 1 IN1 58 1 67 1 7/24 114.2 1 65.01 0.7 1 250 1 /K= 84 I - 1 7/26 111.5 1 34 1 0.35 1 150 1 I ~ r 8 4 1 - 1 8 / 2 9 1 1 3 . 1 1 45 1 .3 1 150 1 / K = 84 / 90 1 7/26 111.5 1 31.51 I 1 I K r 86 ( 1 ) l 100 1 12 118.9 1 7.51 1.0 1 200 1 I K r 8 6 1 - / 8 / 2 9 1 1 2 . 8 1 4 3 1 . 3 1 150 1 / X e 129 ( 1 ) l 70 1 17 1 6.51 .26 1 70 1 jxe 129 1 - 1 10/35 1 1 27 1 .09 1 50 1 ITa 181 ( 1 ) l 100 1 20 1 / 15.01 0.7 1 230 1 I I I I I I I I ( 1 ) SSCl o n l y
2) ECR2 and t h e Ganil t e s t bench
2.1. The Ferromafios i o n s o u r c e
The Ferromafios source evolved from t h e f i r s t model CAPRICE was b u i l t ( i n Grenoble) e s s e n t i a l l y t o produce beams of m e t a l l i c elements. Ferromafios i s very s i m i l a r t o Minimafios except f o r t h e magnetic s t r u c t u r e which i s made with an i r o n yoke, reducing t h e e l e c t r i c a l consumption from 100 t o 40 kW.
This s o u r c e i s p r e s e n t l y i n s t a l l e d on t h e Ganil t e s t bench ( F i g . 2 ) .
This bench i n c l u d e s a s o l e n o i d and two d i a g n o s t i c s boxes, p l a c e d b e f o r e and a f t e r t h e bending magnet. Each box i s equiped with s l i t s , p r o f i l e probes and Faraday cup. We s t a r t e d t o p u t them i n o p e r a t i o n i n o r d e r t o s t u d y t h e o p t i c a l c h a r a c t e r i s t i c s o f t h e beams.
,,,"
h e x a p o l e
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2.2. Production of beams of metallic elements
Important beams for Ganil are
' ' l
" Ca 6 + 5 8 ~ i 7 + , 6 3 ~ ~ 7 + and l o o ~0~'. Except for Ca which is easy to produce with metallic sample dir).ectly placed in the plasma (for * ~ a see $11, the three other elements are relatively more difficult because the vapor pressure is too low, just near the melting point. So we decided to work with compacted and heated NiO and Cu, 0powder.
It seems that it,is a good technique to obtain very stable beams during long runs.
I
I
I
I
I
-I
qI
i(
timeI
I
I
I
I
(pA)1
(h)I
(mg/h)l
We must only replace the sample by another one, through an air-lock, every thirty to fifty hours. We will use this technique to produce beams of "'MO (a very expensive isotope of Molybdenum) which can be found only as a powder (Fig. 3, 4a, 4b, 5).
p r o f l l e s p r o b e
1 - 1
U I U
Figure 4a : Energies expected at
ejection of SSC2 as a function of the charge state at the source (stripping ratio 2.5)
Figure 4b : Energies computed (solids lines) and obtained (dots) as a function of the charge state at the source (stripping ratio 3.5)
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3) The "0.A.E" project and the ECR3 ion source (Caprice 2&,)
3.1. The "0.A.E" project
Ganil has been designed to accelerate beams of heavy ions produced by a PIG source in an energy range extending from 95 MeV per nucleon for Carbon to 8 MeV per nucleon for Uranium. It now appears that ECR sources can compete in .intensity with the PIG sources for gaseous ions, and particulary for beams of "solid" ions up to Uranium.
A modification of GANIL is necessary in order to take full advantage of the higher charge states available with the ECR.
A new stripping ratio, namely 2.5, shall be substituted to the present one of 3.5, but other modifications are also necessary (new injection radius for SSC2, coupling of the injection to SSC1, modification of the injector, etc
...
) .The so-called "project 0.A.E" will result in an augmentation of the energy of medium heavy ions by the factor 2 and very heavy ions by the factor 3
.
Figure (4a) corresponds to a stripping ratio of 2.5. It shows the energy of the beam accelerated by SSC2 as a function of the ionisation state at the ion soyrce, for different elements. Each individual curve is limited to the point where the most abundant charge after stripping can no longer be used. The corresponding state of ionisation is 23 for the heaviest ions, 17 for Xenon, 13 for Krypton and 7 for Argon. Figure (4b) displays the same curves in the present case of stripping 3.5. It can be seen that the energy gain in the new configuration is important for atomic numbers higher than 40.
In order to work with higher current for ions of heavy elements Ganil has decided to build a new ECR ion source (ECR3), which is a Caprice source initially developped by B. Jacquot and
R.
Geller, at Grenoble. Its good results for beams of "gazeous" ions will permit an easy tuning of the machine for K r 1 3 + and xel'+.ECR3 parameters (Caprice)
l~agnetic field
I
I
I
l~agnet power : 35 kW
I~exa. field at wall : 0.75 T
I
I~ag-field on axis : 0.3-
0.8 Tt
[Microwave powerl
I
~ U H F injection : CO-axial
I
l
UHF power : 2.5 KW (10 GHz)I
I
l~lasma chamber length : 16 cmI
I
Ij
" diam. : 7 cmI
i
3.2. The source ECR3 (Caprice 2 Bwce)
The Caprice ion source is a compact 10 GHz source with an electrical consumption of 35 KW for coils in an iron yoke (Fig. 6).
The hexapole has an hybrid structure.
It is made of an iron yoke, S m Cos permanent magnets with flux concentration magnetic structure (similar to the magnets of the Pauthenet's hexapole of 0.8 T, built for the Minimafios 16.6 GHz source) and classical rectangular magnets a,t the ends.
The UHF injection is made with a CO-axial line, which is tuned with a small piston under vacuum, in order to optimize the power in the CO-axial line.
The principal gas is injected inside the central part of the CO-axial line and the support gas is injected directly in the CO-axial line.
The grounded electrode is very similar to the Minimafios electrode, but the best result is obtained when the electrode and its support are made of iron.
We can see (Fig. 7a
-
b) the magnetic topology ( [ B (r, z ) ( for 0 < R < 3 4 mm, - 85 mm < z <l r o n
hexapo
l
ehexapo l e I f l u x c o n c e n t r o t . l on l
level
7200 G ,
level
7200
G-
10 GHz <
l B
I <*
GHzFigure 7 : Source ECR3 (Caprice 2B)
I B
(r, 2 )I
for B W c ez = - 85 mm, r = 0.34 m m W ce
(N hexapolar face) (a)
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JOURNAL DE PHYSIQUE
The s o l e n o i d a l magnetic s t r u c t u r e h a s been c a l c u l a t e d with t h e POISSON program o f CERN
(2D) and t h e hexapole s t r u c t u r e has been c a l c u l a t e d with t h e simple model o f t h e uniformly charged p l a t e s ( 3 ~ ) ~ . The g l o b a l s t r u c t u r e i s a l i n e a r s u p e r p o s i t i o n o f t h e two r e s u l t s .
The f i g u r e s 7a
-
b show t h e magnetic f i e l d s topology without i r o n e l e c t r o d e and f o r v a l u e s o f magnetic f i e l d between (3600 G)(wce 1 0 GHz) and 7200 G ( 2 *wee.
1 0 GHz).We can s e e t h a t t h e magnetic f i e l d e x h i b i t s a very s t r o n g g r a d i e n t i n t h e r e g i o n between t h e f i r s t and t h e second s t a g e . The r e l a t i v e minimum v a l u e o f t h e magnetic f i e l d i s n e a r t h e e x t r a c t i o n .
Abnormalities o f f t h e a x i s , a r e due t o t h e f r i n g e f i e l d magnetic f i e l d o f t h e hexapole and t h e r a d i a l component o f t h e s o l e n o i d a l f i e l d induced by t h e v e r y s t r o n g g r a d i e n t n e a r t h e i r o n p i e c e o f t h e f i r s t s t a g e ( F i g . 6 ) .
The s o u r c e i s now under c o n s t r u c t i o n and i s expected t o be t e s t e d by t h e end o f 1988 on t h e t e s t benc'h o f Ganil. I t w i l l be o p e r a t i o n n a l by t h e middle o f 1989 and p u t i n p l a c e o f Minimafios on t h e 20 KV p l a t e f o r m by t h e end of t h e "0.A.E" p r o j e c t .
4) The "0.A.I" p r o j e c t and t h e ECR4 i o n s o u r c e
4.1. The "0.A.I" p r o j e c t
Ganil r o u t i n e l y a c c e l e r a t e s up t o microamperes o f i o n s a t e n e r g i e s r a n g i n g from 25 t o 95 MeV/A. Already a t t h e s e l e v e l s space charge problems d r a s t i c a l l y a f f e c t t h e bunching e f f i c i e n c y between t h e ECR s o u r c e and t h e CO compact i n j e c t o r .
The g a i n given by t h e bunching system d e c r e a s e s very r a p i d l y (from 6 t o 1) when t h e i n j e c t e d i n t e n s i t y i n c r e a s e from 10 t o 100 p A . I n t h e "0.A.E" v e r s i o n o f G a n i l , we n o t only aim t o widen t h e energy and i o n r a n g e s o f Ganil, b u t a l s o we e x p e c t t o i n c r e a s e t h e i n t e n s i t i e s by a f a c t o r 10 o r more i f p o s s i b l e , a t l e a s t f o r some i o n s l i k e A r and K r .
C a l c u l a t i o n s have shown t h a t i n o r d e r t o improve t h e bunching e f f i c i e n c y , t h e ECR i o n s o u r c e h a s t o be a t t h e h i g h e s t p o t e n t i a l p o s s i b l e .
Consequently, t h e r e i s a n e c e s s i t y f o r Ganil t o own a very e f f i c i e n t i o n s o u r c e , a b l e t o
-
be p l a c e d on a high v o l t a g e p l a t f o r m (low e l e c t r i c a l consumption),-
g i v e high c u r r e n t s o f "gaseous" i o n s ,- g i v e h i g h c u r r e n t s o f m e t a l l i c i o n s u s e f u l f o r t h e "0.A.E" v e r s i o n o f Ganil ( t y p i c a l l y q
=
22 f o r m > 1 5 0 ) .These requirements have r e s u l t e d i n t h e d e c i s i o n t o s t u d y a new 1 4 . 5 GHz ECRIS. This new s o u r c e i n under developement and i t s name i s Neomafios 1 4 . 5 GHz (ECR4).
4.2. ECR4 - Neomafios i o n s o u r c e
We can s e e ( F i g . 8) t h e comparative r e s u l t s f o r Minimafios 10 GHz ( a ) , Caprice (2Bwce10 GHz ( b ) and Minimafios 16.6 GHz ( c ) f o r Xenon i o n s ? The b e s t r e s u l t s on each i o n beam a r e shown
.
We can s e e t h e g a i n given t o t h e c u r r e n t s , by t h e change o f t h e magnetic s t r u c t u r e ( c u r v e s a and b ) and by t h e change o f t h e frequency ( c u r v e s a and c ) .With t h e change o f t h e magnetic s t r u c t u r e , we d o n ' t observe t h e i n c r e a s e o f t h e average q of e x t r a c t e d beams, b u t only t h e i n c r e a s e o f t h e e x t r a c t e d c u r r e n t s . We can e x p l a i n i t j u s t a s an o p t i m i z a t i o n o f t h e plasma d e n s i t y n e a r t h e e x t r a c t i o n r e g i o n . ,
On t h e o t h e r hand, with t h e change o f t h e frequency, we observe a g l o b a l s h i f t o f t h e spectrum toward high charge s t a t e s ( 1 7 t o 24 f o r Xenon) a s s o c i a t e d with t h e i n c r e a s e o f t h e t o t a l e x t r a c t e d c u r r e n t . We can understand it a s an i n c r e a s e o f t h e average d e n s i t y o f t h e
3
plasma p r o p o r t i o n n a l t o t h e s q u a r e o f frequency r a t i o .
For Tantalum s p e c t r a ( F i g . g ) , we d o n ' t observe fundamental d i f f e r e n c e between Minimafios and Caprice. I t i s probably due t o t h e f a c t t h a t with d i r e c t e v a p o r a t i o n of metal i n s i d e t h e magnetic s t r u c t u r e , we d i s t u r b i t s o p t i m i z a t i o n . So, we c a n ' t observe t h e e f f e c t due t o a good magnetic s t r u c t u r e . On t h e o t h e r hand, with t h e high frequency i o n s o u r c e , we s t i l l observe t h e s h i f t o f t h e spectrum towards t h e high charge s t a t e s , because t h i s e f f e c t i s on:Ly depending on t h e frequency.
So, Neomafios 14.6 GHz w i l l be a source with a high confinement magnetic s t r u c t u r e (Bmi, 5200 G and B,,,<10400 G = 2
*
B w c e 1 4 . 5 GHz) very s i m i l a r t o t h e magnetic s t r u c t u r e o f Caprice 2 B w c e . We can s e e ( F i g . 1 0 , 11) t h e magnetic topology i n s i d e t h e second s t a g e f o r 5200 G <[ B / <1.0400 G.
Figure 8 : Xenon performances f o r d i f f e r e n t ECRIS
a ) Minimafios 10 GHz b) Caprice 2 B 10 GHz
c ) Minimafios 16.6 GHz
d) High confinement, high frequency ion source (supposition)
Figure 9 : Tantalum performances f o r d i f f e r e n t ECRIS a ) Minirnafios 10 GHz b ) Caprice 2 B 10 GHz c ) Minimafios 16.6 GHZ pulsed regime) d ) (continuous regime)
Figure 10 : Source ECR4 (Neomafios 14.5 GHz
I B
( r . z ) l f o rB w e
< I B I <2*Boce z = 100 mm, r = 0,34 mmJOURNAL
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13CR4 parameters
Magnetic parameters :
I
Permanent magnet t y p e : FeNdB (VAC 370)
I
Axial magnet weight : 156 Kgl
Hexa. l, : 20 KgI
I
Hexa. f i e l g a t w a l l : 1 T Mag-field on a x i s : 0 . 4 T-
1.1 TI
Elec. power : 0 KW (10 GHz)I
I
0 - 60 KW ( 1 4 . 5 GHz)I
l
Microwawe parameters :i
l
~ U H F i n j e c t i o n : a x i a lI
" : 2 . 5 KW (10 GHz) 2.0 KW (14.5 GHz)I
IL.
o f plasma chamber : 1 8 cm I ~ i a m . t t 9 I : 7 cmI n o r d e r t o minimize t h e e l e c t r i c a l consumption and work with a s m a l l plasma chamber (compact s o u r c e ) well adapted t o t h e UHF power, t h e a x i a l f i e l d i s p a r t i a l l y made with FeNdB permanent magnet i n a s t r u c t u r e s i m i l a r t o t h e Neomafios 10 GHz o f Grenoble. The a x i a l
4
s t r u c t u r e i s o b t a i n e d w i t h an uniformly a x i a l l y magnetized r i n g ( F i g . 1 2 , 1 3 ) d i v i d e d i n 6 b l o c k s , l i k e t h e Grenoble s o u r c e . The a x i a l system u s e a l s o a s m a l l r i n g i n t h e median p l a n e i n o r d e r t o c o n t r o l t h e m i r r o r r a t i o and r a d i a l l y magnetized magnets p l a c e d on a i r o n box i n o r d e r t o i n c r e a s e t h e maximum f i e l d o f t h e magnetic m i r r o r ( f l u x c o n c e n t r a t i o n geometry)
( F i g . l . 4 ) .
C o i l s p l a c e d on t h e magnets a r e used f o r t u n i n g t h e magnetic f i e l d f o r valuesbetween 6500 G and 10500 G. The plasma chamber i s reduced t o one mechanical p a r t , l i k e t h e Grenoble s o u r c e and s u p p o r t s t h e UHF and g a s i n j e c t i o n . The s o u r c e i s under development and we hope t o f i n i s h t h e assembly by middle o f 1989 and t h e t e s t by t h e middle of 1990.
UHF .gas ; r c m
m
FeNdB ( h e x a . l m F e N d B [ a x l e 1 l e F e N d B (radial 1Figure 13 : Schematic diagram of the ECR4 Ganil source (Neomafios 14.5 GHz)
Figure 14 : vAcoDYn 370 Bp. 12.41 KG H C J - -19.1 KOs Hob* -11.2 KO. EH,,,- 3 4 . 8 noo~ -13.B -7.88
Backward curve of the VACODYM 370 magnets
f ssd
JOURNAL DE PHYSIQUE
References :
1) J. FERME e t A 1 - " P r o j e c t "0.A.E" a t G a n i l "
1 1 t h . I n t . Conf. on c y c l o t r o n s and t h e i r A p p l i c a t i o n s , Tokyo, Oct. 1986
2 ) B. JACQUOT e t A 1
-
"Source d ' i o n s l o u r d s C a p r i c e 1 0 GHz, 2wce",
N I M , A269, ( 1 9 8 8 ) , 1
-
63 ) R . GELLER e t A 1 - "The Grenoble ECRIS s t a t u s 1 9 8 7 and p r o p o s a l s f o r ECRIS s c a l i n g s " I n t . Conf. on ECR I o n S o u r c e s and t h e i r A p p l i c a t i o n s , NSCL Rep, NSUCP-47, 1987
4 ) P. SORTAIS e t A 1
-
"Study o f a magnetic s t r u c t u r e f o r an ECRIS b u i l t e x c l u s i v e l y w i t h permanent magnet".
I n t . c o n f . o n ECR I o n S o u r c e s and a p p l i c a t i o n s , NSCL Rep. NSUCP-
47, 19875 ) R . PAUTHENET - "New permanent magnet d e v i c e " , J d e Phys. C l , 4 5 f198d)
