Ar Spectral Lines Research Articles

CF-LIBS quantification and depth profile analysis of Be coating mixed layers

• LIBS & SIMS depth profiles analysis of Be-based layers containing C, O, H, & D-fuel. • Deconvolution of D α and H α lines by Lorentz fitting for the quantification of D & H. • MESB plot and Stark broadening of H α line for the evaluation of T e and n e , resp. • Determination of the fuel content by CF-LIBS and comparison with TOF-ERDA and IBA. • Study of the variation of the elemental composition when changing T e and n e . A remote LIBS system is being considered as an analysis tool in ITER for monitoring the erosion and fuel retention in the first wall. This necessitates further investigation of the performance of LIBS for thick co-deposited layers consisting of ITER-relevant materials. The main goal of this work is determining the fuel content of the samples and D depth profile by LIBS and to compare the results with those obtained by other methods. The studied samples were Be-based mixed coatings on W substrates, containing D and in some cases C, O, or both. These impurities are relevant not only for ITER, but also for other fusion devices, such as JET-ILW. The laser ablation was performed at 10 mbar Ar pressure using a 5 ns pulse Nd:YAG laser at 1064 nm. Suitable Be and Ar spectral lines were employed for the evaluation of the electron temperature of the plasma using multi-elemental Saha-Boltzmann (MESB) plots. The electron density was obtained from the Stark broadening of the D α and H α spectral lines following deconvolution. The average elemental content of each coating was then obtained by calibration-free LIBS (CF-LIBS) and are in agreement with other techniques (TOF–ERDA, IBA).

Discharge characteristic of very high frequency capacitively coupled argon plasma* *Project supported by the National Natural Science Foundation of China (Grant No. 11665021) and the Natural Science Foundation of Gansu Province, China (Grant No. 20JR10RA078).

The discharge characteristics of capacitively coupled argon plasmas driven by very high frequency discharge are studied. The mean electron temperature and electron density are calculated by using the Ar spectral lines at different values of power (20 W–70 W) and four different frequencies (13.56 MHz, 40.68 MHz, 94.92 MHz, and 100 MHz). The mean electron temperature decreases with the increase of power at a fixed frequency. The mean electron temperature varies non-linearly with frequency increasing at constant power. At 40.68 MHz, the mean electron temperature is the largest. The electron density increases with the increase of power at a fixed frequency. In the cases of driving frequencies of 94.92 MHz and 100 MHz, the obtained electron temperatures are almost the same, so are the electron densities. Particle-in-cell/Monte-Carlo collision (PIC/MCC) method developed within the Vsim 8.0 simulation package is used to simulate the electron density, the potential distribution, and the electron energy probability function (EEPF) under the experimental condition. The sheath width increases with the power increasing. The EEPF of 13.56 MHz and 40.68 MHz are both bi-Maxwellian with a large population of low-energy electrons. The EEPF of 94.92 MHz and 100 MHz are almost the same and both are nearly Maxwellian.

Spectroscopic and Langmuir probe measurements of Ar-N2 mixture plasma in magnetic pole enhanced ICP source

Over the last decade, the plasma sources based on electromagnetic power absorption mechanisms have emerged for large scale semiconductor manufacturing. For this purpose inductively coupled plasmas (ICPs), helicons, electron cyclotron resonance (ECR) etc have been widely explored. Recently, new designs of ICPs have been proposed for the improvement of plasma processing reactors including ICPs enhanced by a ferromagnetic core and ICPs with multiple antennas for a uniform spread of plasma over a large processing area. Present paper deals with variation in plasma processing parameters of a low pressure Ar-N2 inductively coupled plasma source with magnetic pole enhancement (MaPE-ICP). Optical emission spectroscopy (OES) and an RF compensated Langmuir probe are employed to examine the trends of parameters including the electron density, electron temperature and electron energy probability functions (EEPFs). Moreover, Ar metastable fractions are also calculated from line ratio method using optical emission intensities of the Ar spectral lines. The variation in emission intensities of the selected lines and in metastable fractions can be related with electron densities in various parts of the EEPFs. Furthermore, at low RF powers the evolution in EEPFs from ‘bi-Maxwellian’ to ‘Maxwellian’ distribution with increasing Ar concentration in the mixture is also observed. The dissociation fraction of N2 determined by ‘advanced actinometry’ technique, based on Trace rare gas-actinometry (TRG-actinometry), is also reported. It is found that dissociation fraction increases with Ar concentration in the discharge as well as RF power and filling gas pressure.

HIGH-RESOLUTION FOURIER TRANSFORM SPECTROSCOPY OF Nb i IN THE NEAR-INFRARED

In this study, a Fourier Transform spectrum of Niobium (Nb) is investigated in the near-infrared spectral range from 6000 to 12,000 cm−1 (830–1660 nm). The Nb spectrum is produced using a hollow cathode discharge lamp in an argon atmosphere. Both Nb and Ar spectral lines are visible in the spectrum. A total of 110 spectral lines are assigned to the element Nb. Of these lines, 90 could be classified as transitions between known levels of atomic Nb. From these classified Nb i transitions, 27 have not been listed in literature previously. Additionally, 8 lines are classified for the first time.

Study on Start Burning Performance of Micro-ICP Using Stereo Spiral Coil

According to the problem of low energy utilization of plane spiral coil used in micro-ICP, a kind of micro stereo helical coil was designed. Made 24 different structural parameters of stereo spiral coil whose diameter range 3~10 mm. Using comprehensive experimental method tested different parameters’ coils inspire argon plasma. In 13.56MHz RF power, relationships between argon pressure, coil turns, coil diameter and combustion /maintaining power of micro-ICP excitation source were tested. From spectrometer observed 17 argon emission spectrum in 690~860 nm. Spectral lines intensity influenced by RF power and work pressure. Experiments proved that micro-ICP excitation source using stereo helical coil is feasible. It can form Ar plasma and inspire Ar spectral lines.

Investigation on plasma-quenching efficiency of various gases using the inductively coupled thermal plasma technique: effect of various gas injection on Ar thermal ICP

Application of the inductively coupled thermal plasma (ICTP) technique was proposed for investigating plasma-quenching efficiency of various gases including the arc-quenching medium of SF6. The ICTP enables us to study fundamentally the effect of gas injection on thermal plasma without any impurities because it has no electrode. Seven kinds of gases including CO2, SF6 and environmentally benign gases (N2, O2, air, He and H2) were injected into Ar ICTP. Spectroscopic observation was carried out in order to investigate a change in the excited state of Ar atoms due to addition of these gases. Radial distributions of the radiation intensity of Ar spectral lines and the temperature of Ar ICTP were estimated. It was found that 10% CO2 addition causes a remarkable decline of the radiation intensity and temperature at any radial position, similarly to 2% SF6 addition. Two-dimensional local thermal equilibrium modelling for Ar ICTP also revealed that CO2 causes temperature decay more than the other gases of N2, O2, air, He and H2 except SF6.

Measured, calculated and predicted Stark widths of the singly ionized C, N, O, F, Ne, Si, P, S, Cl and Ar spectral lines

In order to find reliable Stark width data, needed in plasma spectroscopy comparision between the existing measured, calculated and predicted Stark width values was performed for ten singly ionized emitters: C, N, O, F, Ne Si, P, S, Cl and Ar in the lower lying 3s - 3p, 3p - 3d and 4s - 4p transitions. These emitters are present in many cosmic light sources. On the basis of the agreement between mentioned values 17 spectral lines from six singly ionized spectra have been recommended, for the first time, for plasma spectroscopy as spectral lines with reliable Stark width data. Critical analysis of the existing Stark width data is also given.

The application of a double voltage modulation technique to a glow discharge source with a supplementary electrode

The Ar spectral lines are suppressed in glow discharge source atomic emission spectroscopy by a double voltage modulation technique with a supplementary electrode. The voltage is modulated between two levels, typically 350 and 700 V. At the lower voltage level mainly the Ar emission occurs where at the higher voltage level both the Ar and the metal atoms sputtered from the sample contribute to the emission. The power supply of the supplementary electrode is switched on when the glow discharge passes from operation at 700 V to 350 V. The intensity of argon gase lines is regulated by the current applied to the supplementary electrode at that period. Therefore, there is no need for electronical amplification and lower voltage adjustment of two operation modes. This modified DVM technique has been applied to the determination of Si and Cu in Al- samples. The suppression of Ar lines is possible, and the elements can be determined without Ar interferences.

High Voltage Plane Cathode -Comb Anode Discharge

Abstract Investigations on the characteristics of a plane cathode-comb anode discharge are presented. This discharge arrangement consists of a plane cathode with a series of anodes, resembling a comb, above it. A significant increase of the discharge voltage was obtained by increasing the number of comb-teeth. Voltage-current characteristics, the intensity and the spatial distribution of He, Al, and Ar spectral lines were investigated as functions of the number of comb-teeth, He pressure and discharge current. Due to the increase of discharge voltage, the spectral line intensities increased significantly in the negative glow region. In case of the Al-I 396.1 nm and the He-I 318.7 nm lines an intensity peak was observed also in the cathode glow region. This peak was pronounced in the case of high voltage anode arrangements and is attributed to excitation by positive ions.

Background suppression of Ar lines in glow discharge atomic emission spectrometry by a lock-in amplifier and Kalman filter deconvolution

The Ar spectral lines are suppressed in Grimm-type glow discharge lamp atomic emission spectrometry (GDL-AES) by a double voltage modulation technique. The GDL is modulated between two voltage levels, typically 400 and 700 V. At the lower voltage level mainly Ar emission contributes whereas at the higher voltage level both Ar and atoms sputtered from the cathode contribute to the emission. The Ar emission spectrum at the lower voltage level is multiplied by a constant factor to scale it up to the same level of Ar emission found at the higher voltage level. This signal is then subtracted from the signal obtained at the higher voltage level by a lock-in amplifier to obtain the net analyte signal. The digital Kalman filter technique is also applied to background suppression; it is known to be the optimum filter for deconvolution of mixtures in noisy environments. The detection limits are found to be improved by nearly a factor of 10 with both double voltage modulation and Kalman filter techniques.

Stark widths and shifts of neutral neon spectral lines.

The neon spectrum is of considerable laser-physics interest, yet few measurements of its spectral line broadening and shift parameters have been performed. In this investigation the Stark widths and shifts of twenty Ne lines originating from several multiplets were measured as functions of electron density and temperature in the ranges (0.15--1.40)\ifmmode\times\else\texttimes\fi{}${10}^{23}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$ and (1--2.5)\ifmmode\times\else\texttimes\fi{}${10}^{4}$ K, respectively. The light source was the plasma of an electromagnetically driven ``T tube'' operating in a mixture of neon and argon in the ratio 2:5 in order to avoid self-absorption. The electron density was measured by single-wavelength laser interferometry using the visible \ensuremath{\lambda}=632.8 nm transition of a He-Ne laser, and the electron temperature from the Boltzmann slope of several Ar spectral lines with estimated errors of \ifmmode\pm\else\textpm\fi{}7% and \ifmmode\pm\else\textpm\fi{}10%, respectively. The obtained measured Stark widths (w) and shifts (d) with estimated errors of \ifmmode\pm\else\textpm\fi{}15% are compared with the existing experimental and theoretical data. All together, Stark widths and shifts data are used to demonstrate the nature of Stark broadening and shift dependence on the upper-level ionization potential of the corresponding line in a transition array.

Temperature measurements of atmospheric Ar plasma freejets by means of the Moire-Schlieren and spectroscopic methods.

The atmospheric Ar plasma freejets, generated by an electric arc discharge, are visualized and measured by the Moire-Schlieren method to obtain the details of their high temperature fields. Electron temperatures and electron number densities are also deduced from a combined method of the absolute intensity measurements of Ar spectral lines and the collisional-radiative process theory. From the experiments performed under the conditions of arc currents of 100-200 A and nozzle diameters of 3-4 mm, the following are found : (i) The gas temperatures are 1000-5000 K and the electron temperatures are about 8500 K. (ii) The distributions of gas temperature for the conditions show a similar form. (iii) The freejets are thermally in nonequilibrium, though the plasmas are fairly dense.