Spectroscopic Diagnosis of the CdO:CoO Plasma Produced by Nd:YAG Laser

In this paper, the optical emission spectrum (OES) technique was used to analyze the spectrum resulting from the (CdO:CoO) plasma in air, produced by Nd:YAG laser with λ=1064 nm, τ=10 ns, a focal length of 10 cm, and a range of energy of 200-500 mJ. We identified laser-induced plasma parameters such as electron temperature (Te) using Boltzmann plot method, density of electron (ne), length of Debye (λD), frequency of plasma (fp), and number of Debye (ND), using two-Line-Ratio method. At a mixing ratio of X= 0.5, the (CdO:CoO) plasma spectrum was recorded for different energies. The results of plasma parameters caused by laser showed that, with the increase in laser energy, the values of Te, ne and fp were increased, while the value of λD was decreased. The calculated electron temperature value was in the range of 0.449-0.619 eV at ratio X=0.5

Spectroscopic evaluation of vibrational temperature and electron density in reduced pressure radio frequency nitrogen plasma

The optical emission spectroscopy technique is used to determine the vibrational temperature of the second positive band system,$$ N_{2} (C,\upsilon^{^{\prime}} - B,\upsilon^{^{\prime\prime}}$$ N 2 ( C , υ ′ - B , υ ″ ) in the wavelength range 367.1–380.5 nm by using the line-ratio and Boltzmann plot methods. The electron temperature is evaluated from the intensity ratio of the selected molecular bands corresponding to $$N_{2}^{ + } (B,\upsilon - X, \upsilon^{^{\prime}} , $$ N 2 + ( B , υ - X , υ ′ , 391.44 nm), and, $$N_{2} (C,\upsilon^{^{\prime}} - B,\upsilon^{^{\prime\prime}}$$ N 2 ( C , υ ′ - B , υ ″ , 375.4 nm) transitions, respectively. The selected bands have a different threshold of excitation energies and thus serve as a sensitive indicator of the electron energy distribution function (EEDF). The electron density has been determined from the intensity ratio of the molecular transitions corresponding to $$N_{2}^{ + } (B,\upsilon - X, \upsilon^{^{\prime}} , $$ N 2 + ( B , υ - X , υ ′ , 391.44 nm), and, $$ N_{2} (C,\upsilon^{^{\prime}} - B,\upsilon^{^{\prime\prime}}$$ N 2 ( C , υ ′ - B , υ ″ , 380.5 nm) for different levels of pressure and radio frequency power. The results show that the vibrational temperature decreases with increasing nitrogen fill pressure and radio frequency power. However, the electron temperature increases with radio frequency power and reduces with fill pressure. The electron density increases both with nitrogen fill pressure and radio frequency power that attributes to the effective collisional transfer of energy producing electron impact ionization. Plasma parameters show a significant dependence on discharge conditions and can be fine-tuned for specific surface treatments. Article Highlights Spectrum analysis of RF-driven nitrogen plasma for varying discharge conditions Evaluation of vibrational temperature using line-ratio and Boltzmann plot methods Comparison of vibrational temperatures for line-ratio and Boltzmann plot methods Evaluation of electron temperature and density using the intensity-ratio of bands Correlation of temperature and density with varying fill pressure and RF power

Tungsten plasma density and temperature time analysis using 1.064 $$\upmu $$m nanosecond dual-pulse laser

The information about time evolution of plasma electron temperature and density plays a fundamental role in numerous physics-related sciences. For CF DP-LIBS (calibration-free double-pulse laser-induced breakdown spectroscopy), not only may it serve to minimize the impact on the investigated sample, but also to optimize the laser and spectral parameters, or even to pave the way for real-time chemical analysis of the sample. To evaluate this impact and describe the plasma time behavior, electron temperature and density are calculated for plasma induced by double-pulse Nd:YAG laser with various (0–500 ns) inter-pulse delays. The parameters are calculated using various methods, such as Stark broadening, Boltzmann plot and Saha equation to provide complementary calculations for comparison. To ensure validity of the results, calibration of the measurement setup was performed. In the work, tungsten samples are investigated, because the W is chosen as the preferred material for plasma-facing components in future fusion devices such as ITER. Since LIBS method will be used to monitor tritium retention in ITER, the results may be utilized to improve the diagnostics.

EXPRESS: Feasibility of Using Boltzmann Plots to Evaluate the Stark Broadening Parameters of Cu(I) Lines

A linear Boltzmann plot was constructed using Cu I-lines of well-known atomic parameters. Aligning other spectral lines to the plot was adopted as a viable way to estimate the most probable values of Stark broadening parameters of Cu I-lines at 330.79, 359.91, and 360.2 nm. Plasma was generated by focusing of Nd: YAG laser radiation at wavelength 532 nm on a pure copper target in open air. Plasma emission was recorded at delay times of 3, 4, 5, 7, and 10 μs. The in situ optically thin H_α-line was used to determine the plasma reference electron density over the entire experiment. Following this method, the missing values of the Stark broadening parameters of the three Cu-I lines turn out to be about 0.15 ± 0.05 à (for 330.79 nm transition) and 0.17 ± 0.05 à (for 359.91, and 360.20 nm transition) at reference electron density of (1 ± 0.09)×10¹⁷ cm^-3 and temperature of 10800 ± 630 K. The apparent variation in plasma parameters at different delay times was found to scale with electron density and temperature as <i>~ n_e.T_e^0.166</i>.

Spectroscopic Characterization of Laser Ablated Germanium Plasma

In the present study, the germanium (Ge) sample has been studied by laser induced breakdown spectroscopy which leads to the formation of plasma plume in the air. This research work comprises on pure Ge sample, and it has been studied using laser irradiance 1.831011 watt.cm-2 and Q-Switched Nd:YAG laser pulse (λ ~ 1064 nm wavelength and  ~ 5 ns pulse width). The spatially resolved plasma plume parameters are investigated, such as variation of electron temperature Te and electron number density ne as a function of detector position. These parameters show variation in the plasma plume and yield electron temperature Te from 12340 to 7640 ± 1200 K. Whereas electron number density ne varies from 3.61017 to 1.601017 cm-3 with the change in detector position is moving away from plasma plume from 0 to 3 mm. The results show that electron temperature Te and electron number density ne are estimated from the Boltzmann plot method and by using Lorentzian function at spectral line using FWHM full width at half maximum at 265.11 nm (4p5s 3 p2 → 4p 2 3 p2) wavelength of Ge (I) line, respectively.

Investigation of Temperature Fluctuation of Diode-Rectified Multiphase AC Arc by High-Speed Visualization

An innovative multiphase AC arc was drastically improved by diode-rectification technique with bipolar electrode. Temperature fields and arc behaviour of the diode-rectified multiphase AC was successfully visualized on the basis of the high-speed camera technique with appropriate band-pass filter optics. Arc temperature was measured by Boltzmann plot method with two line emissions from atomic argon at 675.2834 nm and 794.8176 nm. Arc temperature fluctuates in the range from 7,000 to 13,000 K. The arc temperature near the cathode was higher than 13,000 K, while that near the anode was about 10,000 K. Arc temperature in the centre region in the furnace was about 7,000–9,000 K, which is sufficiently high to melt and evaporate the refractory metals or ceramics. Obtained results suggested the diode-rectified multiphase AC arc is a promising thermal plasma source for material processing at high productivity.

Gold Nanoparticle-Enhanced Laser-Induced Breakdown Spectroscopy and Three-Dimensional Contour Imaging of an Aluminum Alloy

In the present work, nanoparticle-enhanced laser-induced breakdown spectroscopy was used to analyze an aluminum alloy. Although LIBS has numerous advantages, it suffers from low sensitivity and low detection limits compared to other spectrochemical analytical methods. However, using gold nanoparticles helps to overcome such drawbacks and enhances the LIBS sensitivity in analyzing aluminum alloy in the current work. Aluminum was the major element in the analyzed samples (99.9%), while magnesium (Mg) was the minor element (0.1%). The spread of gold nanoparticles onto the Al alloy and using a laser with different pulse energies were exploited to enhance the Al alloy spectral lines. The results showed that Au NPs successfully improved the alloy spectral lines intensity by eight times, which could be useful for detecting many trace elements in higher matrix alloys. Under the assumption of local thermodynamic equilibrium, the Boltzmann plot was used to calculate the plasma temperature. Besides, the electron density was calculated using Mg and H lines at Mg(I) at 285.2 nm and Hα(I) at 656.2 nm, respectively. Three-dimensional contour mapping and color fill images contributed to understanding the behavior of the involved effects.

Plasma diagnostic of gliding arc discharge at atmospheric pressure

A gliding arc discharge (GAD) with a water spray system was constructed. A non-thermal plasma, generated between two V shaped electrodes in an ambient argon driven by 100 Hz AC voltage, was investigated using optical emission spectroscopy (OES) with different gas flow rates (0.5, 1, 1.5, 2 , 2.5 , 3 1/min). Boltzmann plot method was used to calculate electron temperature (Te) and electron density (ne). The electrodes design was spectrally recognized and its Te value was about 0.588-0.863 eV, while the ne value of 6.875×1017-10.938×1017 cm-3. The results of the plasma diagnostics generated by gliding arc showed that increasing gas flow rates was associated with decreased electron temperature (Te), Debye length, and Debye Number, along with decreased electron density (ne) and plasma frequency.