Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge

Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge

This work focuses on diagnosing the plasma in an electric arc discharge in an argon flow using optical emission spectroscopy. The method employed for determining the population of energy levels and the concentration of metal atoms based on the absolute values of emission intensity is described and v...

Повний опис

Збережено в:
Бібліографічні деталі
Опубліковано в: :Problems of Atomic Science and Technology
Дата:2023
Автор: Murmantsev, A.
Формат: Стаття
Мова:English
Опубліковано: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2023
Теми:
Gas discharge, plasma-beam discharge and their applications
Онлайн доступ:https://nasplib.isofts.kiev.ua/handle/123456789/196192
Теги: Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Цитувати:Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge / A. Murmantsev // Problems of Atomic Science and Technology. — 2023. — № 4. — С. 139-146. — Бібліогр.: 16 назв. — англ.

Репозитарії

Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-196192
record_format dspace
spelling Murmantsev, A.
2023-12-11T12:36:44Z
2023-12-11T12:36:44Z
2023
Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge / A. Murmantsev // Problems of Atomic Science and Technology. — 2023. — № 4. — С. 139-146. — Бібліогр.: 16 назв. — англ.
1562-6016
PACS: 52.70.-m, 52.80.Mg
DOI: https://doi.org/10.46813/2023-146-139
https://nasplib.isofts.kiev.ua/handle/123456789/196192
This work focuses on diagnosing the plasma in an electric arc discharge in an argon flow using optical emission spectroscopy. The method employed for determining the population of energy levels and the concentration of metal atoms based on the absolute values of emission intensity is described and validated. The experimental setup includes a spectrograph and an RGB CMOS matrix as the emission registration device. By obtaining the absolute values of the spectral radiances of Cu I lines and considering the axial symmetry of the electric arc discharge, the local radiation intensity of these lines is determined. Radial distributions of copper atom concentrations are then calculated using the absolute values of emission intensities and the radial distribution of the excitation temperature, which is determined using the Boltzmann plots technique. Two methods are employed for calculating the atom concentra ions. The first method involves Boltzmann plots based on four spectral lines of Cu I and the corresponding excitation temperature. The second method determines the concentrations directly from the population of copper’s energy levels, which are derived from the absolute values of emission intensity of the Cu I spectral lines. The results obtained from these two methods exhibit a coincidence of within 20%, supporting the recommendation of this technique for plasma diagnostics in electric arc discharges.
Робота присвячена діагностиці плазми електродугового розряду в потоці аргону методами оптичної емісійної спектроскопії. Описано та апробовано метод визначення заселеності енергетичних рівнів та концентрації атомів металу із абсолютних значень інтенсивності випромінювання спектральних ліній. Дослідження проводили з використанням спектрографа та RGB CMOS матриці як пристрою реєстрації випромінювання. Отримано абсолютні значення спектральної яскравості ліній Cu I, та з урахуванням осьової симетрії електродугового розряду визначено їх локальну інтенсивність випромінювання. Із залученням абсолютних значень інтенсивності випромінювання та радіального розподілу температури заселення, визначеної методом діаграм Больцмана, отримано радіальні розподіли концентрацій атомів міді. Розглянуто два методи розрахунку концентрації атомів. А саме, розрахунок із діаграми Больцмана на основі чотирьох спектральних ліній Cu I та визначеної температури заселення. З іншого боку, концентрацію отримано із заселення енергетичних рівнів міді, визначених безпосередньо із абсолютних значень інтенсивності випромінювання цих спектральних ліній Cu I. Результати, отримані цими двома методами, збігаються в межах 20%, що дає підстави рекомендувати дану методику для діагностики плазми електродугових розрядів.
This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement 101052200-EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. Moreover, the author considers it an honour to express his gratitude to Prof. A. Veklich for supervising and reviewing the work, to V. Boretskij, M. Kleshych, S. Fesenko, and V. Telega for assistance in conducting the experiment and obtaining the results.
en
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
Problems of Atomic Science and Technology
Gas discharge, plasma-beam discharge and their applications
Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
Дослідження просторового розподілу домішок парів металів у плазмі електродугового розряду
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
spellingShingle Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
Murmantsev, A.
Gas discharge, plasma-beam discharge and their applications
title_short Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
title_full Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
title_fullStr Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
title_full_unstemmed Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
title_sort investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge
author Murmantsev, A.
author_facet Murmantsev, A.
topic Gas discharge, plasma-beam discharge and their applications
topic_facet Gas discharge, plasma-beam discharge and their applications
publishDate 2023
language English
container_title Problems of Atomic Science and Technology
publisher Національний науковий центр «Харківський фізико-технічний інститут» НАН України
format Article
title_alt Дослідження просторового розподілу домішок парів металів у плазмі електродугового розряду
description This work focuses on diagnosing the plasma in an electric arc discharge in an argon flow using optical emission spectroscopy. The method employed for determining the population of energy levels and the concentration of metal atoms based on the absolute values of emission intensity is described and validated. The experimental setup includes a spectrograph and an RGB CMOS matrix as the emission registration device. By obtaining the absolute values of the spectral radiances of Cu I lines and considering the axial symmetry of the electric arc discharge, the local radiation intensity of these lines is determined. Radial distributions of copper atom concentrations are then calculated using the absolute values of emission intensities and the radial distribution of the excitation temperature, which is determined using the Boltzmann plots technique. Two methods are employed for calculating the atom concentra ions. The first method involves Boltzmann plots based on four spectral lines of Cu I and the corresponding excitation temperature. The second method determines the concentrations directly from the population of copper’s energy levels, which are derived from the absolute values of emission intensity of the Cu I spectral lines. The results obtained from these two methods exhibit a coincidence of within 20%, supporting the recommendation of this technique for plasma diagnostics in electric arc discharges. Робота присвячена діагностиці плазми електродугового розряду в потоці аргону методами оптичної емісійної спектроскопії. Описано та апробовано метод визначення заселеності енергетичних рівнів та концентрації атомів металу із абсолютних значень інтенсивності випромінювання спектральних ліній. Дослідження проводили з використанням спектрографа та RGB CMOS матриці як пристрою реєстрації випромінювання. Отримано абсолютні значення спектральної яскравості ліній Cu I, та з урахуванням осьової симетрії електродугового розряду визначено їх локальну інтенсивність випромінювання. Із залученням абсолютних значень інтенсивності випромінювання та радіального розподілу температури заселення, визначеної методом діаграм Больцмана, отримано радіальні розподіли концентрацій атомів міді. Розглянуто два методи розрахунку концентрації атомів. А саме, розрахунок із діаграми Больцмана на основі чотирьох спектральних ліній Cu I та визначеної температури заселення. З іншого боку, концентрацію отримано із заселення енергетичних рівнів міді, визначених безпосередньо із абсолютних значень інтенсивності випромінювання цих спектральних ліній Cu I. Результати, отримані цими двома методами, збігаються в межах 20%, що дає підстави рекомендувати дану методику для діагностики плазми електродугових розрядів.
issn 1562-6016
url https://nasplib.isofts.kiev.ua/handle/123456789/196192
citation_txt Investigation of spatial distribution of metal vapours admixtures in the plasma of an electric arc discharge / A. Murmantsev // Problems of Atomic Science and Technology. — 2023. — № 4. — С. 139-146. — Бібліогр.: 16 назв. — англ.
work_keys_str_mv AT murmantseva investigationofspatialdistributionofmetalvapoursadmixturesintheplasmaofanelectricarcdischarge
AT murmantseva doslídžennâprostorovogorozpodíludomíšokparívmetalívuplazmíelektrodugovogorozrâdu
first_indexed 2025-11-25T21:31:28Z
last_indexed 2025-11-25T21:31:28Z
_version_ 1850558388435419136
fulltext ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 139 https://doi.org/10.46813/2023-146-139 INVESTIGATION OF SPATIAL DISTRIBUTION OF METAL VAPOURS ADMIXTURES IN THE PLASMA OF AN ELECTRIC ARC DISCHARGE A. Murmantsev Faculty of Radiophysics, Electronics and Computer Systems of Taras Shevchenko National University of Kyiv, Kyiv, Ukraine E-mail: murmantsev.aleksandr@gmail.com This work focuses on diagnosing the plasma in an electric arc discharge in an argon flow using optical emission spectroscopy. The method employed for determining the population of energy levels and the concentration of metal atoms based on the absolute values of emission intensity is described and validated. The experimental setup includes a spectrograph and an RGB CMOS matrix as the emission registration device. By obtaining the absolute values of the spectral radiances of Cu I lines and considering the axial symmetry of the electric arc discharge, the local radia- tion intensity of these lines is determined. Radial distributions of copper atom concentrations are then calculated using the absolute values of emission intensities and the radial distribution of the excitation temperature, which is determined using the Boltzmann plots technique. Two methods are employed for calculating the atom concentra- tions. The first method involves Boltzmann plots based on four spectral lines of Cu I and the corresponding excita- tion temperature. The second method determines the concentrations directly from the population of copper's energy levels, which are derived from the absolute values of emission intensity of the Cu I spectral lines. The results ob- tained from these two methods exhibit a coincidence of within 20%, supporting the recommendation of this tech- nique for plasma diagnostics in electric arc discharges. PACS: 52.70.-m, 52.80.Mg INTRODUCTION The study of electric arc discharge plasma with metal vapour admixtures is of great interest to researchers due to its scientific significance and numerous practical appli- cations. Processes such as electric arc welding and cutting [1 - 3], plasma surface treatment [4 - 7], and current switching in electrical devices [8] involve the evapoura- tion of materials from switching contacts and electrodes. To address the challenges posed by these applications, the development of diagnostic methods for electric arc dis- charge plasma with metal vapour admixtures is crucial. During the switching of an electric circuit, arc dis- charge occurs, leading to contact erosion [8] and reduc- ing the service life of switches and contacts. Therefore, investigating the physical processes that occur in plasma media during switching and on contact surfaces is of great importance. The study of electric arc discharge plasma with metal vapour admixtures from electrode materials can contribute to reducing electrode erosion by optimizing material composition and developing new manufacturing technologies. Traditionally, the erosion intensity of electrode mate- rials caused by the thermal effect of electric arc discharge plasma is indirectly determined by calculating the content of metal vapours in the positive plasma column based on its equilibrium composition [9, 10]. This method requires experimental determination of plasma parameters such as temperature and electron density. The most common ap- proach for obtaining electron density is direct calculation from the full width at half-maximum (FWHM) of the spectral line contours [11]. However, this approach has limitations in practical diagnostics. It relies on high- resolution spectral devices to accurately observe emission spectral line contours, especially in low-current electric arc discharges. Moreover, the width of spectral line con- tours in such plasma sources can be comparable to the instrumental function of spectral devices. The main objective of this work is to propose an al- ternative parameter to electron density for calculating the equilibrium plasma composition and to develop a method for its determination. Specifically, the method focuses on measuring the concentration of metal vapour admixtures in the discharge gap using the absolute val- ues of emission intensity. 1. DETERMINATION OF THE ATOMS' CONCENTRATION BY THE METHOD OF ABSOLUTE INTENSITIES OF SPECTRAL LINES The emission intensity (or emissivity) of a spectral line should be considered as the energy emitted in 1 s in 1 m 3 within the contour of the spectral line [12]. Then the total emissivity of the spectral line εL can be ex- pressed by eq. (1): , 4 L L ki k Line hc d A n      , (1) where ελ,L is the spectral distribution of the emissivity of the spectral line; h is the Planck constant; c is the speed of light; λ is the wavelength in the centre of the spectral line; Aki is the probability of the electron transition from the k th to the i th energy level (the Einstein coefficient for spontaneous emission); nk is the concentration of emit- ting particles or the population of the k th level. Since the absolute values of the total emissivity of the spectral line were determined, it is possible to calcu- late the population of the k th energy level by eq. (2): 4 k L ki n hcA   . (2) According to the Boltzmann law: k B E k Tk k a g n ne    , (3) where gk is the statistical weight of the k th energy level; Σa is the partition function of atoms of the emitting ma- mailto:murmantsev.aleksandr@gmail.com 140 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) terial; Ek is the energy of the k th level; kB is the Boltz- mann constant, and T is the excitation temperature. Tak- ing into account eq. (3) in (1), the intensity dependence on the temperature and on the concentration of atoms of the emitting element n is defined by eq. (4): 4 k B E k Tki k L a A ghc ne     . (4) In case of a known oscillator strength fik, the transi- tion probability Aki can be determined by eq. (5): 2 2 2 8 i ki ik ke ge A f gm c    . (5) The linearization of (4) leads to equation (6) of a slope-intercept form y ax b  : ln ln 4 kL ki k B a E hc n A g k T                  , (6) where ln L ki k y A g         ; kx E ; 1 B a k T   ; ln 4 a hc n b         . Using the Boltzmann plot technique based on the in- tensities of at least two spectral lines, the excitation temperature T can be determined by eq. (7): 1 B T k a   . (7) Obtaining the temperature parameter allows deter- mining the partition function of atoms using eq. (8) due to the latter dependence on the former: m B E k T a m m g e     . (8) Based on this, it is possible to calculate the concen- tration of particles of the emitting element according to eq. (9): 4b ae n hc   . (9) Thus, it is enough to determine the absolute values of the spectral lines intensity to obtain the population of energy levels and the atoms' concentration of an emit- ting element. 2. DETERMINATION OF ABSOLUTE VALUES OF THE EMISSION INTENSITY OF SPECTRAL LINES The intensity εL can be determined from the radiance of spectral lines, which is obtained experimentally. The radiance should be understood as the energy that passes through a unit of area per unit of time within a unit solid angle perpendicular to the selected plane. For an isotropic, optically thin and homogeneous plasma, the emissivity of the spectral line ελ,L depends on its radiance IL as L LI d  , where d is the width of the emitting layer [12]. In the case of optically thin and inhomogeneous plasma, but which is characterized by cylindrical sym- metry (e.g. the plasma of the electric arc discharge), the dependence takes the form:       0 1 2 2 2 1 r r I x dx r x r       , (10) where ε(r) is the emission intensity at a distance r from the axis of symmetry of the radiation source (radial dis- tribution of the emissivity); r0 is the emission boundary; I(x) is the radiance integrated along the line-of-sight at a distance x from the centre of the radiation source (spa- tial distribution of the radiance). An integral equation of the type (10) is known as the Abel integral. Its numeri- cal solution was proposed by Bockasten [13], which makes it possible to determine the values of the emis- sion intensity (local values) of spectral lines at known values of their radiance (observed values). Thus, to determine the absolute values of the intensi- ty of spectral lines in the plasma of electric arc dis- charges with cylindrical symmetry, it is necessary to determine the absolute values of the radiance of these spectral lines. The observed radiance values obsI , obtained using the spectral device, differ from the radiance values *I of the emission that falls on the sensor (for example, a CMOS matrix), as follows: * * obsI I t     , (11) where t is the registration time (exposure of the CMOS matrix), and *  is the spectral sensitivity of the sensor. Fig. 1. Optical scheme of the experimental setup for studying emission with spatial resolution The issue of determining the absolute values of emission intensity is reduced to determining the spectral sensitivity of the used spectral device, which is calibrat- ed in energy units (W∙m 2 /nm according to spectral radi- ance units). In order to solve this issue, a spectrograph based on a diffraction grating with a period of 600 l/mm has been used (Fig. 1). The lens O 1 was installed between the radiation source S and the horizontally oriented entrance slit ES of the spectrograph (slit height 20 μm) at a dou- ble focus distance (F1 = 200 mm) from each. Thus, an image was formed at the ES without magnification, and the fulfillment of the Abbe sine condition [12] ensured the equality of the emission intensity value directly from the source and its image (radiation losses depend only on the transmittance of the O1). In turn, the ES is located in the focus F2 of the O2 collimator. A parallel beam of light formed by the lens O2 and directed through the glass window G1 is reflect- ed from the mirror M and enters the diffraction grating D. The radiation that passes through the window G2 is focused by the lens O3 to obtain an image S∗ on the sur- face of the detector. In this work, the CMOS matrix ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 141 (RGB Sensor) of the Nikon D7000 camera was used as a light-sensitive element. If the spectral radiance of the radiation source is de- noted as Iλ, then with this configuration of the optical scheme, the spectral radiance that gets to the sensor can be expressed as: *I I   , (12) where Ω is the solid angle at which the dispersing ele- ment D is seen from the entrance slit ES; τ is the total transmittance of the optical scheme, which includes the transmittances of the lenses O1 and O3, the windows G1 and G2, the collimator O2 and all other possible losses. Then, taking into account eq. (12) in (11), the equation (13) can be obtained: * obsI I t      , (13) where χλ is the spectral sensitivity of the proposed spec- tral device: * obsI I t         . (14) The spectral radiance Iλ can be calculated theoreti- cally and registered using a reference source of emis- sion. A tungsten band-lamp of the СИ-8-300 [14] type with an incandescent band has been used as a source of reference emission. Taking into account the temperature of tungsten, the spectral radiance emitted by band of such a lamp, can be calculated as: , , ,T T TI I B       , (15) where τλ is the transmittance of the lamp window, ελ,T is the emissivity of tungsten as a real “gray body” at tem- perature T, Bλ,T is the spectral radiance of a blackbody at a true temperature T. According to Planck's law: 1 2 , 2 5 2 1B hc k T T W hc B e m nm                 . (16) Since the tungsten incandescent band is not a black- body, the calibration of the reference lamp (usually by the method of optical pyrometry) is carried out accord- ing to its brightness temperature Tbr. The brightness temperature of the body corresponds to the temperature of the blackbody, at which its spectral radiance at a wavelength of 650 nm is equal to the radiance of a body with a true temperature at the same wavelength. The true temperature T is related to the brightness tempera- ture Tbr by eq. (17):  0ln br B br T hcT T k T hc    (17) or   1 4 0 0, 1 1.041 10 lg T br T T            . (18) In eq. (17) and (18) τ0 is the transmittance of the lamp window at a wavelength of 650 nm, and ε0,T is the emissivity of tungsten at the temperature T at the same wavelength. The calibration curve of the reference tungsten band- lamp (the dependence of Tbr on the incandescent cur- rent I) is shown in Fig. 2. In this work, the current was 21.7 A, which corresponds to the brightness temperature of 2175 K. The temperature of tungsten, calculated from eq. (18), is 2400 K. The spectral distributions of the transmittance and emissivity of tungsten at a tempera- ture of 2400 K are shown in Figs. 3 and 4, respectively. 8 10 12 14 16 18 20 22 24 1000 1200 1400 1600 1800 2000 2200 2400 T e m p e ra tu re , K I, A Tbr, K Fig. 2. Calibration curve of a reference tungsten lamp with an incandescent band 300 400 500 600 700 800 900 1000 1100 0.0 0.2 0.4 0.6 0.8 1.0 B % (2) B , nm , a.u. Fig. 3. Spectral distribution of the transmittance of glass [14] 0 500 1000 1500 2000 2500 3000 3500 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 1 2 0 0 , nm ,T, a.u. Fig. 4. Emissivity of tungsten at a temperature of 2400 K [15] Since an image sensor of the digital camera is used as a detector, the obtained images of emission spectra require additional processing. Namely, images obtained in *. NEF format (without compression and digital pro- cessing) with a resolution of 6036×4020 pixels and a colour depth of 12 bits were linearized from the distri- bution of tetrads of colour filters array (Bayer's filters) to the distribution of pixels with RGB components. 142 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) Then the RGB images were converted to grayscale for their subsequent calibration both in wavelength and in spatial coordinates. The plasma emission spectrum of the electric arc discharge between single-component copper and nickel electrodes has been obtained and applied to calibrate the spectral coordinate of the registration device (Fig. 5). The choice of electrodes is due to the fact that the spec- trum of copper is well studied, and the spectrum of nickel contains a large number of spectral lines that can be used as reference points for wavelength calibration. Wavelength data for Cu I and Ni I spectral lines were taken from the NIST database [16]. 0 1000 2000 3000 4000 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 C u I 5 1 5 .3 n m C u I 5 2 1 .8 n m Pixel number Іobs, a.u. C u I 5 1 0 .5 n m Fig. 5. Observed emission spectrum of arc discharge plasma between Cu and Ni electrodes according to pixel number At the first iteration of the calibration of the spectral dependence, the lines of copper Cu I 510.5, 515.3, and 521.8 nm have been identified and linear interpolation of wavelength values has been performed. The depend- ence of the wavelength on the pixel number obtained in this way is not sufficiently accurate, since the dispersion of the diffraction grating is non-linear. Therefore, in the next iteration, the positions of all reference wavelengths have been determined, the values of which were taken from the NIST database (see Fig. 6). The calibration curve has been obtained by interpolating the wave- lengths by a second degree polynomial (see Fig. 7). 350 400 450 500 550 600 650 700 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 D X , nm Registered spectrum Іobs  , a.u. 0 1000 2000 3000 4000 NIST data for Cu I 0 2000 4000 6000 8000 NIST data for Ni I Fig. 6. Emission spectrum of arc discharge plasma be- tween Cu and Ni electrodes with calibrated wavelength 0 1000 2000 3000 4000 300 350 400 450 500 550 600 650 700 750 Real wavelength Calibration curve W a v e le n g th , n m Pixel number , nm Fig. 7. Resulting calibration curve of the spectral registration device 300 350 400 450 500 550 600 650 700 750 0 20 40 60 80 100 120 140 160 180 b (λ , T ) , nm Radiance of BB radiation Radiance of tungsten radiation I, , W/m2nm Fig. 8. Emission spectrum of blackbody and tungsten band of the reference lamp at a temperature of 2400 K Fig. 9. RGB image of the tungsten band emission of the reference lamp at a temperature of 2400 K (exposure time 100 ms) Fig. 10. Observed emission spectrum with spatial resolution (radial coordinate is presented in pixel numbers) ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 143 The obtained values of the wavelength for each pixel and the real radiation temperature were used to calculate the spectral distribution of the radiance of the blackbody emission Bλ,T and tungsten Iλ from eq. (16) and (15), respectively (Fig. 8). The RGB image of the tungsten band emission at a temperature of 2400 K registered with an exposure of 100 ms is shown in Fig. 9. The ob- served emission spectrum in grayscale with spatial reso- lution is shown in Fig. 10. The observed spectrum in the centre of the tungsten band is shown in Fig. 11. In order to eliminate the noise caused by the fluctuations of the CMOS matrix due to heating, the emission spectrum was additionally smoothed as shown in Fig. 11. 300 350 400 450 500 550 600 650 700 750 0 5000 10000 15000 20000 25000 30000 35000 B , nm Registered spectrum Smoothing curve I, a.u. Fig. 11. Emission spectrum observed in the centre of the tungsten incandescent band 300 350 400 450 500 550 600 650 700 750 0 5000 10000 15000 20000 25000 χ (λ ) , nm , m2nm/W Fig. 12. Spectral sensitivity of the registration device The spectral sensitivity of the proposed spectral de- vice obtained according to eq. (14) is shown in Fig. 12. It can be seen from the behavior of the spectral sen- sitivity, that the use of this spectral device is correct in the wavelength range of 430…650 nm. Since the spec- tral sensitivity goes to zero outside this range, its use in these regions of the spectrum is inexpedient. 3. DETERMINATION OF RADIAL DISTRIBUTIONS OF TEMPERATURE AND ATOMS' CONCENTRATION An electric arc discharge burning in an argon flow between single-component copper electrodes was used to validate the method of determining the energy levels population and the concentration of atoms in the plasma of arc discharge from the absolute values of the emis- sion intensity. The discharge was operated at an arc cur- rent of 3.5 A, a discharge gap of 8 mm, an argon flow rate of 7 LPM, an electrode diameter of 5 mm. Fig. 13. RGB image of the plasma emission (exposure time 2 ms) Fig. 14. Space-resolved emission spectrum of plasma (the spectral sensitivity of the device is taken into account) The plasma emission of such a discharge was regis- tered by the optical scheme shown in Fig. 1. The regis- tered RGB image of the spectral emission of plasma with copper vapours admixtures is shown in Fig. 13. This image has been converted in the grayscale and the spectral sensitivity (see Fig. 12) has been taken into account. The space-resolved emission spectrum of the plasma obtained in such a way is shown in Fig. 14. The boundaries of emission of spectral lines r0 were determined according to the spatial coordinate for each registered copper spectral line, namely 510.5, 515.3, 521.8, and 578.2 nm. The obtained space intervals were separated into 9 equidistant segments. Thus, 10 spatial points, each of which contained the spectral distribution of radiance, was used for the further calculations. An approximation of contours of the spectral lines by the Gaussian function was used as it shown in Fig. 15 to determine the radiance of the corresponding lines. Spa- tial distributions of the radiance I(x) (Fig. 16) have been obtained by repeating the procedure for each spatial point and each Cu I spectral line. These distributions were approximated by the Gaussian function to obtain a smooth function, which was used to calculate the radial distributions of the emission intensity of spectral lines ε(r) according to eq. (10) by the Bockasten method [13] (Fig. 17). 144 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 510.0 510.5 511.0 0 50 100 150 200 250 300 350 S p e c tr a l ra d ia n c e , W /m 2 /n m Experimental dots at r = 0 mm Approximation by Gaussian , nm I, W/m2/nm Model Gauss Equation y=y0 + (A/(w*sqrt(pi/2)))*exp(-2*((x-x c)/w)^2) Plot 3.96 y0 0 ± 0 xc 510.4903 ± 0.00227 w 0.13372 ± 0.00641 A 0.83272 ± 0.02706 Reduced Chi-Sqr 0.01922 R-Square (COD) 0.99278 Adj. R-Square 0.99117 Fig. 15. Typical approximation of the Cu I 510.5 nm spectral line registered at the axis of the discharge channel 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 10 20 30 40 50 R a d ia n c e , W /m 2 Cu I 510.5 nm Cu I 515.3 nm Cu I 521.8 nm Cu I 578.2 nm x, mm I(x), W/m2 Fig. 16. Spatial distributions of radiance of copper spectral lines and their approximation by Gaussian function (dash lines) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 2000 4000 6000 8000 10000 12000 In te n s it y , W /m 2 /n m Cu I 510.5 nm Cu I 515.3 nm Cu I 521.8 nm Cu I 578.2 nm r, mm (r), W/m3 Fig. 17. Radial distributions of emission intensity of copper spectral lines The obtained values of the emission intensity of each spectral line were used to determine the radial dis- tributions of population of the upper energy levels n(r) corresponding to wavelength of the transition (Fig. 18) by eq. (2). 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 1E13 1E14 1E15 1E16 1E17 1E18 1E19 1E20 r, mm 3d104p (Cu I 510.5 nm) 3d104d (Cu I 515.3 nm) 3d104d (Cu I 521.8 nm) 3d104p (Cu I 578.2 nm) n(r), m-3 Fig. 18. Radial distributions of energy levels population of copper atoms 3.5 4.0 4.5 5.0 5.5 6.0 6.5 24 26 28 30 32 510.5 515.3 521.8 578.2 ln(r3/gf) r = 0 mm r = 1.5 mm r = 3.4 mm 0 E, eV Fig. 19. Typical Boltzmann plots for different radial points on the basis of the absolute intensities of copper spectral lines 0.0 0.5 1.0 1.5 2.0 2.5 3.0 4000 4500 5000 5500 6000 4 lines T e m p e ra tu re , K r, mm T(r), K Fig. 20. Radial distribution of excitation temperature The Boltzmann plot technique on the basis of the ob- tained absolute values of emission intensity of spectral lines has been applied according to eq. (6). The typical Boltzmann plot based on Cu I 510.5, 515.3, 521.8, and 578.2 nm spectral lines, constructed for different radial points of plasma emission are shown in Fig. 19. Thus, the radial distribution of the excitation temperature (Fig. 20) has been obtained by eq. (7). In turn, the con- centration of copper atoms was determined by eq. (9) ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 145 using partition function obtained according to eq. (8) on the basis of known radial distribution of the tempera- ture. Additionally, the radial distributions of concentra- tions were obtained on the basis of populations of cop- per energy levels (see Fig. 18) by eq. (3). The radial distributions of the concentrations ob- tained in different ways are shown in Fig. 21. As one can see, the distributions obtained from the population of energy levels differ insignificantly from that one ob- tained by Boltzmann plot technique. The error bars for the last one were constructed assuming that the accuracy of the method is not less than 80%. One can see that such an assuming is correct for a distance from the axis of the arc up to 2 mm. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 1E20 1E21 C o n c e n tr a ti o n s , m -3 r, mm Cu I 510.5 nm Cu I 515.3 nm Cu I 521.8 nm Cu I 578.2 nm Boltzmann plot n(r), m-3 Fig. 21. Radial distributions of concentrations obtained by Boltzmann plot technique (shown with error bars) and from energy levels population of copper atoms CONCLUSIONS The alternative parameter to electron density for fur- ther calculation of the equilibrium plasma composition and the technique for its measuring have been proposed and described. Namely, the method for determining the atoms' concentration of metal vapours admixtures in the discharge gap from the absolute values of emission in- tensities has been considered. Additionally, a spectral device based on a spectrograph with a diffraction grat- ing and a RGB CMOS matrix as a registration device has been applied to realize such a technique. The copper atoms' concentration has been determined in the plasma of electric arc discharge between single-component copper electrodes in the argon flow by Boltzmann plots technique based on the four spectral lines of Cu I and the determined excitation temperature. Moreover, the concentrations have been calculated from the population of copper's energy levels, determined directly from the absolute values of the emission intensity of these Cu I spectral lines. The results obtained by these two meth- ods coincide within 20%, which gives grounds for rec- ommending such a technique for plasma diagnostics of electric arc discharges. ACKNOWLEDGEMENT This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Pro- gramme (Grant Agreement 101052200-EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. Moreover, the author considers it an honour to ex- press his gratitude to Prof. A. Veklich for supervising and reviewing the work, to V. Boretskij, M. Kleshych, S. Fesenko, and V. Telega for assistance in conducting the experiment and obtaining the results. REFERENCES 1. A.B. Murphy. A Perspective on Arc Welding Re- search: The Importance of the Arc, Unresolved Questions and Future Directions // Plasma Chemis- try and Plasma Processing. 2015, v. 35, p. 471-489. https://doi.org/10.1007/s11090-015-9620-2. 2. A.B. Murphy. The effects of metal vapour in arc welding // Journal of Physics D: Applied Physics. 2010, v. 43(43), p. 43401. https://doi.org/10.1088/0022-3727/43/43/434001. 3. B. Heider, M. Oechsner, U. Reisgen, J. Ellermeier, T. Engler, G. Andersohn, R. Sharma, E. Gonzalez Olivares, E. Zokoll. Corrosion Resistance and Mi- crostructure of Welded Duplex Stainless Steel Sur- face Layers on Gray Cast Iron // Journal of Thermal Spray Technology. 2020, v. 29, p. 825-842. https://doi.org/10.1007/s11666-020-01003-y. 4. M. Yan. Micro-beam plasma-arc surface processing for ferrous and nonferrous metals // Journal of Ma- terials Science. 2003, v. 38, p. 3219-3222. https://doi.org/ 10.1023/A:1025169517526. 5. F. Darvish, N.M. Sarkari, M. Khani, E. Eslami, B. Shokri, M. Mohseni, M. Ebrahimi, M. Alizadehg, Ch. Fu Dee. Direct Plasma Treatment Approach Based on Non-Thermal Gliding Arc for Surface Modification of Biaxially-Oriented Polypropylene with Post-Exposure Hydrophilicity Improvement and Minus Aging Effects // Applied Surface Science. 2020, v. 509, p. 144815. https://doi.org/10.1016/j.apsusc.2019.144815. 6. S. Zeng, M. Xiao, X. Liu, Y. Wu, K. Li, Zh. Qiu, D. Zeng. Effects of Process Parameters on Morphol- ogies of Titanium Carbide Powder by Thermal Plasma Treatment // Materials Research Express. 2020, v. 6(12), p. 1265h5. https://doi.org/10.1088/2053-1591/ab5ddb. 7. S. Samal. Thermal Plasma Technology: The Pro- spective Future in Material Processing // Journal of Cleaner Production. 2017, v. 142(4), p. 3131-3150. https://doi.org/10.1016/j.jclepro.2016.10.154. 8. P.G. Slade. Electrical contacts, principles and appli- cations [Second edition]. CRC Press. 2014, 1312 p. 9. O.O. Murmantsev, A.M. Veklich, V.F. Boretskij, M.M. Kleshych, S.O. Fesenko, G.I. Levada1. Spec- troscopy of Thermal Plasma of Electric Arc Dis- charge Between Melting Electrodes // Bulletin of Shevchenko National University of Kyiv. Physics and Mathematics. 2018, v. 2, p. 83-88. 10. A. Murmantsev, A. Veklich, V. Boretskij, M. Bartlová, L. Dostál, J. Píška, D. Šimek, A. Gajdos, O. Tolochyn. Composite Cu-Cr materials https://doi.org/10.1007/s11090-015-9620-2 https://doi.org/10.1088/0022-3727/43/43/434001 https://doi.org/10.1007/s11666-020-01003-y https://doi.org/%2010.1023/A:1025169517526 https://doi.org/10.1016/j.apsusc.2019.144815 https://doi.org/10.1088/2053-1591/ab5ddb https://doi.org/10.1016/j.jclepro.2016.10.154 146 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) under thermal action of electric arc discharge plasma // Problems of Atomic Science and Technology. 2021, № 1(131), p. 98-101. https://doi.org/10.46813/2021-131-098. 11. R. Konjevic, N. Konjevic. Stark broadening and shift of neutral copper spectral lines // Physica. 1986, v. 18(4), p. 327-335. 12. W. Lochte-Holtgreven. Plasma Diagnostics. Am- sterdam: North-Holland Publishing Company. 1968, 928 p. 13. K. Bockasten. Transformation of Observed Radianc- es into Radial Distribution of the Emission of a Plasma // Journal of the Optical Society of America. 1961, v. 51(9), p. 943-947. 14. T. Tmenova, A. Veklich, V. Boretskij. Calibration of spectral response of the SDH-IV spectrometer // Bul- letin of the Taras Shevchenko National University of Kyiv. Radiophysics and Electronics. 2016, v. 24(1), p. 54-60. 15. J.C. De Vos. A new determination of the emissivity of tungsten ribbon // Physica. 1954, v. 20(7-12), p. 690-712. https://doi.org/10.1016/S0031-8914(54)80182-0. 16. A. Kramida. NIST Atomic Spectra Database (ver. 5.8) [Online]. Ralchenko Yu, Reader J and NIST ASD Team // National Institute of Standards and Technology. 2021. Available: https://physics.nist.gov/asd. Article received 15.07.2023 ДОСЛІДЖЕННЯ ПРОСТОРОВОГО РОЗПОДІЛУ ДОМІШОК ПАРІВ МЕТАЛІВ У ПЛАЗМІ ЕЛЕКТРОДУГОВОГО РОЗРЯДУ О. Мурманцев Робота присвячена діагностиці плазми електродугового розряду в потоці аргону методами оптичної емі- сійної спектроскопії. Описано та апробовано метод визначення заселеності енергетичних рівнів та концент- рації атомів металу із абсолютних значень інтенсивності випромінювання спектральних ліній. Дослідження проводили з використанням спектрографа та RGB CMOS матриці як пристрою реєстрації випромінювання. Отримано абсолютні значення спектральної яскравості ліній Cu I, та з урахуванням осьової симетрії елект- родугового розряду визначено їх локальну інтенсивність випромінювання. Із залученням абсолютних зна- чень інтенсивності випромінювання та радіального розподілу температури заселення, визначеної методом діаграм Больцмана, отримано радіальні розподіли концентрацій атомів міді. Розглянуто два методи розраху- нку концентрації атомів. А саме, розрахунок із діаграми Больцмана на основі чотирьох спектральних ліній Cu I та визначеної температури заселення. З іншого боку, концентрацію отримано із заселення енергетичних рівнів міді, визначених безпосередньо із абсолютних значень інтенсивності випромінювання цих спектраль- них ліній Cu I. Результати, отримані цими двома методами, збігаються в межах 20%, що дає підстави реко- мендувати дану методику для діагностики плазми електродугових розрядів. https://doi.org/10.46813/2021-131-098 https://doi.org/10.1016/S0031-8914(54)80182-0 https://physics.nist.gov/asd.

Схожі ресурси