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Submitted on 1 Jan 1979
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OPTICAL INTERFEROMETRY OF PULSED MICRO-DISCHARGES
V. Klimkin, V. Pickalov
To cite this version:
V. Klimkin, V. Pickalov. OPTICAL INTERFEROMETRY OF PULSED MICRO-DISCHARGES.
Journal de Physique Colloques, 1979, 40 (C7), pp.C7-329-C7-330. �10.1051/jphyscol:19797162�. �jpa- 00219138�
JOUIiNAL DE PHYSIQUE CoZZoque C7, suppZdment a u n "7, Tome 40, JuiZZet 1979, page C7- 329
OPTICAL INTERFEROMETRY OF: PULSED MICRO-DISCHARGES
V.F. Klimkin and V.V. Pickalov.
I n s t i t u t e for Pw?e & Applied Mechanics S i b e r i a n D i v i s i o n , Academy o f Science U.S.S.R., Novosibirsk 630090.
Abstract.The investigations of discharge The real experaent was simulated by in- phenoaena in continuous medium are c o m e - troducing of random normal errors 3-10%
cted with the study of the objects of relative to maximum of function into erp- high density gradients, high speeds of propriate values of 4 <%). The Pig. 1
5 7
movement -10 -10 cm/s, m a l l characteris- ahows the m s u l t s of restoration of the tic length8 ~ l ~ " ~ - l ~ - ~ c r n . This work is function (2) with 5% noise level (A).
devoted to the analysio of special fer- One can see that the retrieval error of tures of microdisturbances interferomet- di~lcontunuity value is about 4% while ry. The ob;jects of 10-~crn sizes with the radius ira dividiug into 10 s m e s (*I
stepwise density discontinuity are inves- and not more than 1% while it's dividing tigated [l 1. into 1 5 zones ( 0 ) .
Por axial symmetry inhomogeneity the The numerous series of model cslcu- chbmgee of refraction index connected lations for smooth functions show the with the shift of interferometric frin- high accuracy of the reconstruction.
gesr !&(%)by the Abel iategrerl equation The poseribilitiee of the methods sp- (the refraction e f f e ~ t s being axegleetad):
- Q
The method of atatistical mgu1aril;artion was It usled to solve this equtrtioa
C
2,3I
.' 8 need to note the high influence of
data errors on the accuracy of restora- tion. It ia a first attempt of retrieval for such alaaar of problemst,
Therefore the rel.iability of the ap- proximate methods of the Abel equation solution wan checked up by numerical ex- periments on model function with stepwise discontinuity on the object '8 boundary
plied to aicroobjecta with the stepwise distribution of denrsity were determined on special Bet up including the ?&a&
Zehnder iaterferorneter and He-Ne laeer ae a source of light. The object m a a cylinder of melted quarts with tho dia- meter (0.5i2)- 10-~cm put into cell with
C q
.
It was poaaible te regulate the value of refraction index changing A n == n - ?I' by temperature variation of the
&
liquid. An average refmotion index of the melted quarz n and the temperature
9-
dependence of ref'mction index of CI% we- 4 re determined by refraetometer for the wavelength of =R32.8nm (the accuracy
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797162
of the measurement being -10'~) , the accuracy of thennoregulation being-0.IoC.
Fringe shifts were measured by the multiplication of photography (1 00 or 200 timiss) with the help of comparator. One can see (fig.2) the results of the recon- struction of the stepwise refraction in- dex profile ( R =1,05*10~~cm, avl=1,95.
lo'*) by the method of statistical re- B-
gularization. It is Been that the error of the shock reconstruction is about 7%.
The displacement from the relation A
= C O ~ L S ~ may be connected with the fine structure of microsamples. However an average of refraction index changing (-
-1 is in good agreement with measured one (----I.
As a result we come to conclusion about the sufficient reliability of the above method appliedin interferometric study of microdisturbances appearing at the initial stages of the electric dischar- ges in liquid dielectrics, In these ex- pireaents the ruby laser with the pulse duration of 5 *lo" was used,
The analyses of the possible errors show that the main deviations of the shifts values obtained, In the Big.3 one can see results of theAn(~)reconsructi-
namic relations.
In the Pig.4 we can see the results of thean(s)reconstruction for dlstur- bances in ether ( a 4). The reconatruc- tion of pressure profile for similar disturbances allows to appreciate its va- lue on the boundary of initial ionized channel in liquid ( ----I, whisk ia very
important for underatanding of physical processes connected with discharge,
RGFERENCES
I. H. C.Richrdson, A, J.Alcock, Appl. Phyrs*
Lett., 1971, 18 , 357.
2. V, F. Turchin, V. P. Kozlov, M, S.Malke- vich.Uepekhi fiz, nauk, 1970, 102 ,
345.
3. V.F,Klimkin, V.V,Pickalov. In: Abel inversion'and its generalisation. No- vosibirsk, 1978, 252,
4. V.P,Klimkin, A. G. Ponomarenko. Prep- rint ITW([ N4. Novosibirsk, 1978.
1
0.5 a - 2 Fig* 2.
on beyond the spherical shockwave front, arising as the result of local explosion on the surfase of positive electrode in
distilled water. Inveetigations of the 2 shock waves dyllQlmic allowed to estimerte 70-a
the value of maximum pressure and energy 70-2
4 I 1
density in the region of local discharge R c 5 7 ~ . [4] with the help of approximate gaedy- o - R = , 7 0 -
0.5 # / R
