PROPAGATION OF CONDENSATION IN CORONAL PLASMA

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PROPAGATION OF CONDENSATION IN CORONAL PLASMA

S. Poberaj

To cite this version:

S. Poberaj. PROPAGATION OF CONDENSATION IN CORONAL PLASMA. Journal de Physique

Colloques, 1979, 40 (C7), pp.C7-711-C7-712. �10.1051/jphyscol:19797344�. �jpa-00219338�

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JOURNAL DE PHYSIQUE CoZZoque C7, suppZdment au n07, Tome 40, JuiZZet 1979, page C7- 711

PROPAGATION (X CONDENSATION M CORONAL PLASMA

S. Poberaj.

University of LjubZjana, Faculty for EZeetrieaZ Engineering and J. Stefan I n s t i t u t e , L jubZ,jana, YugosZavia.

The a p p e a r a n c e o f t h e luminous m a t t e r i n t h e s o 1 . a ~ c o r o n a i s i n many c a s e s due t o t h e c o n d e n s a t i o n o f t h e c o r o n a l p l a s - ma. T h i s r e l a t i v e l y c o o l and d e n s e m a t t e r a p p e a r s a s prominences i n s i d e a v e r y h o t and r a r i f i e d plasma. We c o n s i d e r h e r e t h e a p p a r e n t motion o f t h e c o n d e n s a t i o n s a l o n g t h e m a g n e t i c f i e l d .

L e t u s suppose t h a t t h e t e m p e r a t u r e d r o p s i n some r e g i o n o f a h o t plasma i n t h e m a g n e t i c f i e l d . F o r t h e c o n d e n s a t i o n p r o c e s s t h e number o f t h e r e c o m b i n a t i o n s h i g h l y i n c r e a s e d and s o d o e s t h e e n e r g y r a d i a t e d i n t o s u r r o u n d i n g s p a c e . The tem- p e r a t u r e may d r o p from a b o u t l o 6 K t o

t h e w i d t h o f t h e zone i n which t h e c o o l - i n g o f t h e plasma i s t a k i n g p l a c e . A z i s a p p r o x i m a t e l y t h e d i s t a n c e on which t h e t e m p e r a t u r e d r o p s from T1 t o

T2

where T1 i s t h e t e m p e r a t u r e of t h e h o t plasma and T2 i s t h e t e m p e r a t u r e i n t h e c o n d e n s a t i - on. The t i m e

zE

i n which t h e t e m p e r a t u r e d r o p s from T7 t o T i s a p p r o x i m a t e l y equ-

L 2

a1 t o t h e e n e r g y r e l a x a t i o n t i m e f o r t h e e! e c t v o n s f l o w i n g a:.ong t h e m a g n e t i c f i eld i n t o t h e c o n d e n s a t i o n from t h e h o t r e y i on.

Simi1.erl.y a s i n t h e problme of an infl.am- mabi e 1 i q u i d we g e t

4 whe.?e

IJ,,"

i s t h e t e m p e r a t l ~ r e c o n d u c t i v i -

2

.

10 K o r l e s s . S i n c e t h e p! asma i s i n

t y of t h e e l e c t r o n s a l o n g t h e m a g n e t i c t h e m a g n e t i c f i e l d t h e h e a t f l o w a c r o s s

f i e l d . 'The thermal. c o n d u c t i v i t y i s g i v e n t h e m a g n e t i c f i e l d i s s t r o l z g l y r e d u c e d ,

b y tk r e : z t i o n (2) b e c a u s e X ,

/

) ~ , , 4 1 . , where %A and x , a r e

thermal c o n d u c t i v i t i e s i n t h e d i r e c t i o n s e e K), =

-

p e r p e n d i c u l a r and p a r a l l e l t o t h e magne- e 2

-

^Cll

t i c f i e l d . I f t h e inward e n e r g y f l o w i s ^c^;⁾^: i s t h e e l e c t r i . c a l c o n d u c t i v i t y ; , a r a l - low enough t h e c o o l r e g i o n w i l l s p r e a d le7 t o t h e f i e l d . Y r s a t i n g t h e e l e c t r o n a l o n g t h e m a g n e t i c f i e l d i n t o t h e h o t one. g a s a s a n i d e a l one we g e t

T h i s problem we t r e a t s i m i l a r l y a s it i s _{k T e}

= - -

t r e a t e d t h e problem o f t h e p r o p a g a t i o n o f _{5 z2ne}

-

^G,"

flame above an inflammable l i q u i d i n a

, ~ .

Taking f o r t h e Q," t h e e x p r e s s i o n

We assume t h a t t h e m a g n e t i c f i e l d i s we g e t o r i e n t e d a l o n g t h e z a x i s . . L e t A z be

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797344

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R e f e r e n c e s :

where t. e i s t h e mean c o l ' l i s i o n t i m e f o r t h e e l e c t r o n s , From t h e Eqs. (1) and ( 3 ) we g e t f o r t h e a p p a r e n t v e l o c i t y o f t h e p r o p a g a t i o n o f a c o n d e n s a t i o n a l o n g t h e m a g n e t i c f i e l d

Let u s u s e t h i s e q u a t i o n t o c a l c u l a t e t h e v e l o c i t y v a i n a prominence i n t h e s o l a r

corona. F o r Te we t a k e a t y p i c a l v a l u e Te = 2

.

¹⁰4 ^K. The e n e r g y r e l a x a t i o n ti- me

r E

i s much l o n g e r t h a n t h e mean c o t -

- .

,i:.iion t i m e

ze.

We c a n t a k e f o r t h e hy- d r o g e n plasma

Te/z

⁼ F o r va we g e t va ⁼

45

h / s . V e l o c i t i e s of s i m i l a r

( 3 )

magnitude have r e a l l y b e e n measured

.

If va = 0 it d o e s n o t mean t h a t t h e mat- t e r i s f l o w i n g a l o n g t h e f i e l d l i n e s . T h i s i s t h e v e l o c i t y of t h e r e g i o n o f t h e en- hanced r a d i a t i o n . I n m a j o r i t y of t h e mo- v i n g prominences t h e m a t t e r r e a l l y moves a l o n g t h e m a g n e t i c f i e l d .

I ) Landau, L.D., and L i f s h i t z , E.M.,F?uid Mechanics, Pergamon P r e s s I n c . , New York, 1963.

2 ) S h k a r o f s k y , I . , B e y n s t e i n , I. a z d Robinson B., Phys. o f F l u i d s

6 ,

40

(1965).

3) Kaplan, S.A., P i k e l n e r , S.B., Tsyto- vFch V-.N., Plasma P h y s i c s o f S o l a r Atmosphere, ( i n Russian:, flauka, Moscow 1977.