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Submitted on 1 Jan 1979
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ON THE INLFUENCE OF ELECTRODES ON THE PROPERTIES OF HIGH PRESSURE DISCHARGE
V. Peskov
To cite this version:
V. Peskov. ON THE INLFUENCE OF ELECTRODES ON THE PROPERTIES OF HIGH PRESSURE DISCHARGE. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-333-C7-334.
�10.1051/jphyscol:19797164�. �jpa-00219140�
JOURNAL DE PHYSIQUE CoZZoque C7, suppZ6ment au n07, Tome 40, JuiZZet 1979, page C7- 333
ON M E IFClUENCE OF ELECTRODES ON
M E
PROPERTIES OF HIGH PRESSURE DISCHARGEV.D. Peskov.
I n s t i t u t e for PhysicaZ ProbZems, Moscow, U.S. S.R.
It i s known, t h a t i n t h e nearelectrode regions of low pressure a r c s t h e r e occur a l o t of e x o t i c phenomena [I] . As f o r t h e high pressure discharges , t h e information about t h e e l e c t r o d e phenomena is very scanty because t h e i n t e n s i t y of v i s i b l e , emission i s u s u a l l y comparable t o t h e ra- d i a t i o n of nearelectrode regions.
Present work i s devoted t o compa;ison of v i s i b l e and V W s p e c t r a (500-10000A) of t h e
e l e c t r o d e l e s s (EL) [2J and electrode (E) HF discharges and d i r e c t c u r r e n t a r c (A) with W , Mo or Cu e l e c t r o d e s i n H2, D2 and r a r e gases a t t h e pressures up t o 30 atm with s i m i l a r dimensions, power, c u r r e n t and o t h e r c h a r a c t e r i s t i c s . Space d i s t r i b u t i o n of t h e luminosity of t h e v i s i b l e l i g h t was measu- r e d by s t e r e o s c o p i c a l system composed of two d i s s e c t o r s . I n t h e
ITUPand u l t r a s o f t X-ray regions we used t h e two-dimensional coordinate counters. I n t h e whole s p e c t r a l region (30-7000 i) space r e s o l u t i o n was about 0.1 mm.
I.
Exp- eriments a t p=l atm a ) Spectra i n
0
2000-10000
Aregion. The s p e c t r a of H2 and D2 discharges have H- continuum and Balmedlines. The diameter of H- emission region was a f e w
mml a r g e r compared t o l i n e emission zone. With i n c r e a s i n g of t h e discharge power from 0.5 t o 3 W t t h e plasma parameters v a r i e d i n such a way:
i n
A- Te from 0.8 t o 1.1 eV, ne - from
5-10 l5 t o loq7 cme3, i n E - Th from 0.7
t o 0.9 ev,
M e- from 2 loq5 t o loq6 cme3,
a q f m m 0.7 t o 1.2 eV,
Qe- from
3 . 1 0 ' ~ t o loq5 c i 3
(, ne -electron
temperature and d e n s i t g , respectively).
One may conclude t h a t i n EL n, i s of some o r d e r s l e s s e r , t h a n equilibrium
Mec a l c u l a t e d by Saha equation, whereas i n
Aand E t h i s disagreement does not exseed 2.
I n ELone observes a l s o t h e disagreement of about two o r d e r s with Boltzmann law f o r l e v e l population. Due t o low
d e n s i t y t h e e l e c t r o n energy d i s t r i b u t i o n f u n c t i o n has t h e "cut-tail" [3] so the impurity l i n e s in ELwith &
l b; , El -ioni- z a t i o n p o t e n t i a l of t h e main gas - were not
excited. But even i n t h e regims when e l e c t r o n d e n s i t i e s of a l l t h e types of discharges were equal, i n EL d i f f e r e n t t o
Aand E, l i n e s of i m p u r i t i e s were not
e x c i t e d
(Te of EL was l a r g e r than i n
A
and E). S i m i l a r r e s u l t s were obtained i n r a r e gases.
a Spectra i n t h e range 500-2000 i I n IT2
and D2 i n
Awith
Wand Mo e l e c t r o d e s t h e highest luminosity was observed on t h e cathode spot with dimensions about
0.'1mm.
The r a d i a t i o n from Cathode has pulse form with a time of -ps, moreover in some cases we succeeded t o observe by means of coordinate counters t h e pulse jets,flowing from t h e spots t o column (Fig.1) .Theref ore we o b t a i n i n W and Mo e l e c t r o d e s an "ex- plosive" mechanism of emission [I ] .
F i 1 Oscillograms of t h e s i g n a l s (see[41)
*two-dimensional counters observing t h e region of 0.5x0.5 mm a) t = O , b) t=1 ps,
c) t = 2 p s .
Electron concentration i n t h e nearcathode region measured by the coincidence of t h e s i g n a l s from spectrograph and coordinate counters was about loq8 so t h e s e j e t s c a r r y t h e e l e c t r o n s and i o n s i n t o t h e plasma column. Nearelectrode regions emit- t e d t h e i n t e n s e continuum s p e c t r a too.
Bdaximum energy Ed of t h e photons,
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797164