ELECTRON-IMPACT BROADENING OF Cu IV LINES FOR THE DIAGNOSTIC OF THE ARC PLASMA OF ELECTRODYNAMIC MACRO-PARTICLE ACCELERATOR

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ELECTRON-IMPACT BROADENING OF Cu IV LINES FOR THE DIAGNOSTIC OF THE ARC

PLASMA OF ELECTRODYNAMIC MACRO-PARTICLE ACCELERATOR

M. Dimitrijevic, Z. Juric, A. Mihajlov

To cite this version:

M. Dimitrijevic, Z. Juric, A. Mihajlov. ELECTRON-IMPACT BROADENING OF Cu IV LINES FOR THE DIAGNOSTIC OF THE ARC PLASMA OF ELECTRODYNAMIC MACRO- PARTICLE ACCELERATOR. Journal de Physique Colloques, 1989, 50 (C1), pp.C1-623-C1-626.

�10.1051/jphyscol:1989169�. �jpa-00229369�

JOURNAL DE PHYSIQUE

Colloque C1, suppl6ment au nol, Tome 50, janvier 1989

ELECTRON-IMPACT BROADENING OF Cu IV LINES FOR THE DIAGNOSTIC OF THE ARC PLASMA OF ELECTRODYNAMIC MACRO-PARTICLE ACCELERATOR

M.S. DIMITR~JEVIC?, Z .D. J U R I ~ and A.A. MIHAJLOV'

Astronomical Observatory, Volgina 7 , YU-11050 Beograd. Yugoslavia

* ~ n s t i t u t e of Physics, PO Box 57, YU-11001 Beograd, Yugoslavia

RESUME E n utilisant une m e t h o d e m o d e l e pour la s i m u l a t i o n des pertes sur les surfaces l i m i t e s , on a c a l c u l k la temperature e t la c o m p o s i t i o n d u p l a s m a de l'arc dans l*aac414rateur dldctrodynamique des m a c r o p a r t i c u l e s , i n i t i O p a r 1 ' 6 v a p o r a t i o n d'une plaque d u c u i v r e . L a largeur s t a r k diagnostique de p l a s m a de l'arc, on OtO calculbes e n utilisant la m 6 t h o d e s e m i e m p i r i q u e m o d i f i6e.

ABSTRACT U s i n g a m o d e l m e t h o d of loss e n e r c y s i m u l a t i o n on the b o u n d a r y surfaces, t e m p e r a t u r e and c o m p o s i t i o n of an electrodynamic m a c r o p a r t i c l e accelerator arc p l a s m a created b y t h e e v a p o r a t i o n of a C u foil, have been c a l c u l a t e d . S t a r k w i d t h s f o r C u IV lines of interest f o r t h e arc p l a s m a diagnostic h a v e b e e n c a l c u l a t e d also, b y u s i n g t h e m o d i f i e d s e m i e m p i rical m e t h o d .

1.INTRODUCTION

I n v e s t i g a t i o n of t h e e l e c t r o n - i m p a c t broadening of a t o m i c and ionic lines is i m p o r t a n t f o r a n u m b e r of p h y s i c a l and a s t r o p h y s i c a l p r o b l e m s . H e r e , w e p r e s e n t t h e C u I V S t a r k line w i d t h calculations f o r t h e e l e c t r o d y n a m i c accelerator of m a c r o p a r t i c l e s , arc p l a s m a diagnostics. S u c h p l a s m a is e s p e c i a l l y interestin(; since this is a n e x a m p l e of v e r y dense p+ma a t r e l a t i v e l y l o w temperatures. M o r e o v e r , u p t o now t h e diagnostic of such a plasma is v e r y difficult. O u r results are suitable f o r t h e far arc-tail p l a s m a diagnostics.

2.ELECTRODYNAMIC MACROPARTICLE ACCELERATOR ARC PLASMA

T h e electrodynamic accelerators of m a c r o p a r t i c l e s e n a b l e t h e creation of e x t r e m e l y dense p l a s m a s at r e l a t i v e l y low t e m p e r a t u r e s . An e x a m p l e of s u c h a p p a r a t u r s < b a s e d on t h e conductor acceleration i n t h e circuit's m a g n e t i c field) consists of

an

electrical power source and two parallel metal rails between w h i c h t h e m a c r o p a r t i c l e m o v e /I/. T h e circuit is closed b y t h e electrical a ~ c created b e t w e e n t h e rails. T h e arc plasma < f o ~ m e d b y t h e e v a p o r a t e d m e t a l foil throwh w h i c h t h e discharge is

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1989169

C1-624 JOURNAL DE PHYSIQUE

initiated) is accelerated by t h e magnetic field, and its hydrodynamic p r e s s u r e accelerates t h e macroparticle- projectile.

U s i n ( ; a model method A/ of l o s s enerby simulation on t h e boundary surfaces, w e calculated a r c plasma c h a r a c t e r i s t i c s Ctemperature, composition> f o r rect-ular geometry. I t is assumed, like in Ref.1, t h a t t h e a r c plasma is created by t h e evaporation of a Cu foil. Results obtained are presented i n Table I. Our r e s u l t s show t h a t in t h e a r c plasma electron density is 10~'m-' in t h e a r c t a i l and increase monotonically in t h e main aFc p a r t . The electron temperature vary from 25000K t o 70000K.

Table I. Plasma composition on t h e axis of arc. x is t h e position on t h e axis CxrO is t h e front). N is t h e ground state density f o r ions in t h e respective ionization s t a g e and

Ne is t h e electron density Cin units of 1 0 ~ ~ r n - ~ > .

x TCK> Ne NII NIII NIV

The a r c plasma contains mainly Cu I11 ions. However, Cu IV :ions also p r e s e n t and t h e i r lines are more convenient f o r diagnostic purposes due t o t h e less influence of selfabsorption.

For such a reason, w e performed also t h e calculation of electron-impact broadening parameters f o r selected Cu IV lines.

$.STARK BROADENING

For t h e calculation, t h e modified semiempirical approach /3/ has been used. Electron-impact full haifwidth WsEM can be calculated from t h e following expression:

Here, i and f designate initial and final energy levels, n is t h e effective principal quantum number, 2-1 is t h e ionic charge, @ t h e Bates and Damgaard f a c t o r <see e.g. Ref.3) and E = 3kT/2. Atomic energy level data are taken from Ref.4.

Electron-impact full halfwidths f o r s i x Cu I V multiplets a r e given i n Table 2. The r e s u l t s are presented f o r t h e standard electron density 10"cm-' < f a r a r c plasma t a i l condition) but f o r higher densities across t h e a r c plasma axis electron-impact width w i l l be l a ~ g e .

Table 2. Electron-impact full halfwidths <Wsru> in A q s t r 6 m s f o r Cu IV lines f o r different temperatures CT) and a t electron concentration i ~ ~ ~ c r n - ~ .

Ion Transition

A C ~ >

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REFERENCES

/I/ POWELL, J.D., BATTEH, J.H., J.Appl.Phys. 52 <1981> 2717

/2/ D J U R I ~ , Z.,MIHAJLOV, A.A., t o be p u b l i s h e d in C o n t . P l . P h y s . C1988>

/3/ DIMTTRIJEWO, M.S., KoNJEVI~, N., JQSRT,

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<1980> 457 /4/ SCHRtlDER, J.F., VAN KLEEF, TH.A.M., P h y s i c a ,

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