PETROZAVODSK STATE UNIVERSITY

PETROZAVODSK STATE UNIVERSITYResearch and Educational Center "Plasma"

Optical diagnostics of heterogeneous plasma

Optical diagnostics of Optical diagnostics of heterogeneous heterogeneous

low temperature plasmalow temperature plasmaEkimov Konstantin, Ermakov Michail , Jiganov Eugeny, Khakhaev Anatoly, Kobylin Vladimir , Luizova Lidia, Podryadchicov Sergey, Prichodchenko Roman, Scherbina Alexandr, Solovyev Alexey, and students:Anisimov Alexey, Bulba Artem, Kravchenko Alexandr, Prichodchenko Anna, Schtykov Alexey, Troshkova Anna, Rudakov Denis.



Aim :Development of spectral and other optical methods of control and diagnostics of plasma media both for some basic problem solutions and for perfection of plasma devices and processes of an applied importance.

Tools: - For data acquisition and control of experiment- automated hard- and software complexes on the basis of standardized and uniform technical and software modules, including self-constructed modules, designed according to current standards- For data processing- rational algorithms and corresponding software, which allow to decrease the processing time as well as the noise influence to results.

Though these methods and experimental equipment are almost universal, this year they will applied to the following plasma devices:



1. Metal-halid lamp. Alternative current arc discharge in mercury vapors with addition of thallium. Suitable test object for development of heterogeneous plasma spectroscopy. Have been studied by many authors. But even now the physical conception of this discharge are discrepant.

Hashiguchi S et al. Journ. of Appl. Phys.-2002.-V.92, -P. 45-54. Karabourmiotis D. Journ. of Appl. Phys.-2002.-V.92, -P. 25-31.



2. The transformer coupled induction toroidal discharge.New very effective and long -lived light source developed by Prof. Ulanov and his team in Novosibirsk.

We are beginning the team- work with this source.



3. The micro plasmotron for biological application, developed in our Center by Prof. Gostev. The spectral analysis of plasma composition and condition will allow to determine what plasma components are responsible for biological activity and increase this activity.



4. Dusty ordered structure in direct current glow discharge.

Dusty plasma is investigated by several teams for last ten years , but we were first who have found the correlation between plasma spectral characteristics and ordered structure properties.



This year innovation in experimental equipment and software

The complex for local spectroscopy of cylindrically symmetric non-stationary plasma which runs under the control of the IBM-compatible computer with software developed in Labview environment, was supplemented by new modules:

1. Module automated spatially and spectral scanning in the given spectral and spatial intervals and time phase. It allows to collect large two-dimensional arrays of samples F(i,xj) corresponding to spectral surface radiance b(i,xj)in the given spectral (i) and spatial (xj) points at the chosen time moment.



2. Module of data loading for subsequent analysis. It allows -to look through the result of experiment in detail and to derive various information from a spectrum by Labview tools for graphic processing (scaling and cursor positioning ). - to transform digital read-out array to array of a source surface brightness.- to realize in Labview environment the rational algorithm of data array processing.



The rational algorithm of data array processing was for the first time applied to real plasma source.

Reconstruction of (i, rj) by "combined" processing

(), r=0

"Individual"processing:

- deconvolution for each x- radial transform for each

"Combined"processing:

- radial transform for all f- deconvolution for projections

measured data



Systems of automation of experiment with dusty plasma based on LabPC board and LabView graphical environment, providing the simultaneous control of optical and electrical parameters of the plasma, synchronized with the moment of particles injection and structure image registration by digital photos and video cameras was supplemented by new software and experimental equipment.

1. Laser complex with tunable dye laser was adapted to measurement of metastable density in plasma by laser fluorescence method.The increasing of method sensitivity is now in process.



2. Correlator purchased with funds provided by REC allows to begin measurement of dusty particle diffusion coefficient- the very important parameters in the theory of interparticle and plasma- particle interactions.

PhotoCor photon counter The example of measured and calculatedcorrelation function



3. Powerful laser purchased with funds provided by REC gives the opportunity to receive good 2D structure images in laser sheet

4. The software for 2D structure image processing allows to determine the total number of particles in the structure, the average distance between the nearest particles and to build the analog of binary correlation function - the main characteristic of ordered structure.



5. For the first time was developed software for reconstruction of 3D particle distribution by means of computer tomography. There are some difficulties in tomography application to dusty structures , connected with high resolution of imaging system and movement of particles. Our estimations and first experiment show that dusty plasma tomography is possible.

Program window after real 3D structure reconstruction. White spots are the measured projection patterns, the red - calculated ones from reconstructed particle positions.


Optical diagnostics of heterogeneous plasmaNew results and perspective

In the metal-halid lamp radial distribution of mercury atoms density in the maximum current phase as well as electron density distribution in maximum and minimum current phases were determined and this results are in agreement with early experiments of our and other teams.

But anomalous broadening of several mercury spectral lines was noticed for the first time. For explanation of this effect the investigation of metal-halid lamps have to be continued.

Tl and Hg line profiles for the center of discharge



In the transformer coupled induction toroidal discharge the integral spectral line intensity and their radial distribution are received in the preliminary experiment. The investigation of spectral line profiles for measurement of atom temperature and (perhaps) atom and electron densities is planned to be carried out by our automated high resolution spectroscopic set up with Fabry-Perot interferometer.

Radial distribution of intensity forseveral supply power.



Preliminary experiments with helium micro plasmotron allows to estimate by spectral lines broadening the helium atom density in the first excited states 21P, 23P as 4*1012 cm-3 , so we can suppose that it is one of the important biological active plasma component.

The investigation of micro plasmotron is going on. Helium spectral line (21S-41P)

profile. Points-experiment, red line -calculation for N= 4*1012 cm-3



New earlier unknown regularities in forming of ordered dusty structures and correlation of plasma medium characteristics with parameters of "plasma crystal" have been found.( all results received with particles Al2O3 up to 60 microns in neon glow discharge in a range of currents 0.4-3 mA and pressures of 0.26-1.5 Torr.)

It is shown that mean distance between particles R and the size of structure as a rule increases with the discharge current.

P=0.4 Torr , a-1.5 mA, b -1.7 mA, c-2.0 mA,



It is shown that the structure parameters (total number of particles in the structure and the average distance between the nearest particles R ) depends on number of injection N. ( new injection in each 5 minutes).



It is shown that the intensity of spectral lines depends on discharge burning time and on particle presence.

We are going to measure the particle diffusion coefficient in this condition by correlation spectroscopy to receive more information for explanation of structure growth and saturation of this process.



We hope to use tunable lasers not only for excited atom density measurement but also for measurement of electric fields in plasma. ( We have established contacts with leaders of this field of spectroscopy professors V.P. Gavrilenko and V. N. Ochkin)

Finally, our automated spectral complexes are very suitable for Raman spectroscopy; we have just purchased with funds provided by REC the powerful Ar laser and we are going to begin such investigations of plasma modification of carbon materials for finding there fullerens and nanotubes.


Contribution into education

APPLICATIONS OF OPTICSTO PLASMA DIAGNOSTICS

Training in basic courses when studying plasma diagnostics

Optics (basic physics)1. geometrical optics2. Diffraction3. optical resolution4. photo effect, photometry5. dispersion theory6. interference, holography7. Polarization8. light scattering Quantum physics9. atomic and molecular spectroscopy10. perturbation theory11. atoms in external fields12. superposition of states13. photon statistics

Laser physics (14) Correlation spectroscopy (13,14)

Plasma tomography (1-3,6,14)Emission and absorption

spectroscopy (1,2,3,4,9,13)Diagnostics by refraction index

(2,6,7,14)

Diagnostics by line shapes (3,10,11)"Pure" and dusty plasma diagnostics

by light scattering (2,4,7,8,14)Spectroscopic measurements

of electric fields (9,12,14)Laser fluorescence (14)

Intradoppler spectroscopy (12,14)



Laboratory programs used in education of plasma diagnostics are performed with use of new information technologie, automated spectral complexes, virtual instruments , remote access to information resourses.

Laboratory program on

diagnostics by spectral line

profiles carried out on the automated high resolution spectroscopic

set up with Fabry- Perot

interferometer



Our educational programs are known in the world

We was presented at ETOP conferences at 1991,1995,2001,2003



Thanks for attention!

PETROZAVODSK STATE UNIVERSITY

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