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Submitted on 1 Jan 1979
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MODULATION OF SPECTRA OF DRIFT WAVES DUE TO THE HIGH-FREQUENCY FIELDS
F. Assadulin, G. Batanov, A. Veriaev, A. Sapozhnikov, K. Sarksian
To cite this version:
F. Assadulin, G. Batanov, A. Veriaev, A. Sapozhnikov, K. Sarksian. MODULATION OF SPECTRA
OF DRIFT WAVES DUE TO THE HIGH-FREQUENCY FIELDS. Journal de Physique Colloques,
1979, 40 (C7), pp.C7-653-C7-654. �10.1051/jphyscol:19797317�. �jpa-00219308�
JOURNAL DE PHYSIQUE
MOWLATION OF SPECTRA OF DRIFT WAVES DUE TO THE HIGH-FREQUENCY FIELDS
F.F. Assadulin, G.M. Batanov, A.A. Veriaev, A.V. Sapozhnikov and K.A. Sarksian.
P.
N.Lebedev PhysicaZ I n s t i t u t e Academy of Sciences, U . S. S. R.
I n d i f f e r fromb-4: we s h a l l d i s c u s s of t h e pump f i e l d E, . Figure 2 show
t h e i n f l u e n c e of lower-hybrid pump waves t h e i n c r e a s e o f frequency o f d r i f t waves d ) o = ( 3 i 5 ) q H , C i ~ ~ ~ = * / p i % ~ / m n t h e A 4 v e ~ s u s f i e l d E,. We a l s o measured
sound type (R/d>%;) d r i f t waves i n c o l l i - i:he .value of plasma n o i s e div ((sfi)'")~,
L 4 L -
j j d ( w ) d w , where dalZi; L O O C ~ S
a i o n a l plasma ,due t o d r i f t - d i s s i p a t i v e i n -
s t a b i l i t y , The experimental r e s u l t s given which had been recorded a t d i f f e r e n t below i n c l u d e t h e incomplete euppresion v a l u e s o f @o This de- and s p e c t r a modification of d r i f t o e c i l l a - pendence given in figure 3*The main ex- tiona.Meaaurements were c a r r i e d out a t low perimental as it may be
pump f i e l d s &42 %m ,when t h e r e is no pa- t h e c a p t u r e s a r e t h e following:
r a m e t r i c e x c i t a t i o n of a c o u s t i c waves and 1. There i e nonthreshold modification t h e r e a r e no changes i n macroscopic p l a s m of d r i f t waves and ma parameters (&(..,m ,z ).The parame- their i n c O m ~ l e t e with the inc- t e r s of plasma [ 53 a r e t h e following: t h e r e a s e of E o f a s t of a l l on t h e s i d e o f high- l e n g t h of c y l i n d r i c a l coulumn of plasma = t e r frequences.
I00 em, t h e diameter = 4 Cm,strength of 2. The o b s e w a b l e change i n picks i n s t a t i o n e r y megnetic f i e l d , a p p l i e d along t h e s p e c t r a i s t o t h e l a r g e r v a l u e s of t h e a x l a -- 400 Game, plasma d e n s i t y f r e q m c y without t h e change i n v a l u e s of b = l O 10 cmm3,~e=6 ev, Te/TielO;the p r e s s u r e wave v e c t o r s a t low f i e l d ( & , 4 3v/~rn)
of nonionized g a s ( ~ r )p&+3*4~P4t o r r , t h e s i z e and it is such t h a t
AW&=0.01-0.1.
of inhomogeneity x=(&% ( i . 1 ~ ~ ~ ; t h e f r e - 3. With t h e i n c r r a s e of E, t h e i n t e n - quencies of d r i f t wavea Ci&/2%4 I00 k f k . s i t y of d r i f t waves d e c r e a s e s with an High f requenoy f i e l d q p = 24 MHz have i n c r e a s e of pump wave frequency W2 .
been e x c i t e d by two s e m i c y l i n d r i c a l p l a t e s The problem of t h e e f f e c t of a high 45 cm i n length, There were [63 t h e T r i v e l - frequency f i e l d on t h e d r i f t i n s t a b i l i t e s piece-Gould(axisgmmetric modes 1 and d i s p e r - ( s e e ref.[8,9]) w i t h t h e e l e c t r i c f i e l d 8 i 0 n f o r Langmuir waves LJ,=@~/LJ~/ ,where perpendicular t o t h e magnetic f i e l d is
-"-+
B = / ~ , g/ .phe r e l a t i o n s between t h e ,.ha- c l o s e t o experimental c o n d i t i o n s of t h e r a c t e r i s t i c feequencies i n t h e experiment ~ r e s e b t work, but i n our c a s e t h e r e is a
i s c o l l i s i o n - - plasma. A s t h a t was d i s c u s s e d
a,; <. Wd < &<< w,,-~%-<Y<<%<+ ) i n ref.[71 from t h e hydrodynamic approach under t h e c o n d i t i o n s uo2d&, 1';5 ,
( && - t h e frequency of c o l l i s i o n s of Wd>q2 r t h e following d i s p e r s i o n equat-
e l e c t r o n s with n e u t r a 1 s ; t h e o t h e r nota-
i o n f o r t h e branch of d r i f t waves mentio- t i o n s a r e s t a n d a r t ) . The l a t t e r r e d u c e s
ned above h a s been s e t up t h e p o s s i b i l i t i es o f comparison w i th t h e e
r e t i c a l c ~ l c ~ l ~ t i o n s {?I, which d e s c r i b a uz=K'$2(~+i xY$Seff)-' K r eJo ( 2 )
2 2
the linear of t h e d e v e l o p m a t of whe5e &,,= d O + z i / ' / C
K jCJd/B2~,F,
d r i f t - d i s s i p a t i v e i n s t a b f l i t y i n t h e pre- .-
= /e/m,. .Equation ( 2 ) a t t h e experi- s e n c e , o l the f i e l d of a lower-bybrid pump mental conditions s K eo 1' K=
2~&2 and a t wave Figure show the s ~ e c t r o g r m of
s m a l l Eo l e s d e a t o t h e i n c r e a s e in t h e d r c f t waves , d e r i v e 4 from s e v e r a l v a l u e s
d r i f t wave frequency with E~ .
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797317
2 2
A &d/i& = M-k c 5 LAcJce
/~~/j/2,2&, $ ,
9-
When t h e working f i e l d s & a r e of t h e order of 1 v/cm t h i s i n c r e a s e i n frequency is a few p e r c e n t of &d what is moresthe c h a r a c t e r i s t i c f i e l d E* modifying s p e c t r a a t l a r g e v a l u e s of t h e d r i f t wave f r e q u - ency Ud i s s m a l l e r . The dependence of
LX from uo is l i n e a r , w h i c h is i n a good agreement w i t h t h e experiment.The compari- s o n of t h e o r e t i c a l calculations w i t h t h e experimental r e s u l t s may be only q u a l i t a - t i v e and may t a k e place only i n t h e r e g i o n of s m a l l EO.one can r e f e r ( a s i t was done i n o t h e r works r e f . l 2 , 4 1 ) t o t h e i n c r e a - s e i n Landau damping of d r i f t waves follow- i n g from t h e i n c r e a s i n g u d w i t h .& a s
t h i s mechanism a f f e c t t h e observable de- c r e a s e i n t h e amplitude of d r i f t waves.
Though t h i s conception seems t o be very r u t h f a l , i t i s n e c e s s a r y t o c a r r y out t h e t h e o r e t i c a l i n v e s t i g a t i o n of t h e develop- ment of d r i f t - d i s s i p a t i v e i n s t a b i l i t y i n t h e presence of H F f i e l d w i t h t h e simul- taneous study of Landau damping both a t t h e l i n e a r s t a g e and a t t h e s t a g e of a a t u - r a t i o n of u n s t a b l e d r i f t wavee,
Thus, e x p e r i m e n t a l l y observed modifi- c a t i o n of t h e s p e c t r a of i o n - a c o u s t i c ty- pe d r i f t waves and q u a l i t a t i v e accordance w i t h experimental d a t a shaw t h a t t h e H.F.
e l e c t r i c f i e l d component which i s perpen- d i c u l a r t o t h e e x t e r n a l magnetic f i e l d a f - f e c t s e s s e n t i a l l y t h e dynamic of d r i f t d i s s i p a t i v e i n s t a b i l i t y and can l e a d t o t h e euppreasion ( a t t h e process of lower-hyb- r i d h e a t i n g of plasma) of long wavelength p o t e n t i a l (e.i. dangerous f o r plasma con- finement i n tokamaka, s t e l l a r a t o r s e t c . ) i n s t a b i l i t i e s ,
O
