Argon Flow Rate Research Articles

Characterization of solar fuels obtained from beech wood solar pyrolysis

Solar pyrolysis of biomass is a smart way to upgrade biomass and, thus, store intermittent solar energy as solar fuels (gas, bio-char and bio-oil). Distribution and energy content of gas, char and oil depend on experimental conditions. In order to determine these characteristics, experiments have been performed at temperatures of 600, 900, 1200 and 2000°C, heating rate of 50°C/s and argon flow rate of 6NL/min. The gas product was analyzed by micro-GC. The char product was characterized by CHNS, whereas the oil product was subjected to CHNS, Karl-Fischer titration and GC–MS analysis. The LHVs (lower heating values) for gas, char and oil were determined from empirical equations. The gas product yield and LHV significantly increase with temperature, which is mainly due to more H2 and CO formation by the enhanced secondary tar reactions. The char and oil characteristics highly depend on the temperature. Their high energy contents show that the obtained char and oil can be utilized as valuable solid and liquid fuels. The biomass energy upgrading due to solar processing is discussed. At optimum temperature 900°C, it ranges from 38% to 53% accounting for the uncertainty of bio-oil water content.

Facile Synthesis of Nb3Sn Via a Hydrogen Reduction Process

A controllable and facile process for the preparation of Nb3Sn intermetallic compound nanopowders using NbCl5 and SnCl2 vapors reduced by hydrogen has been developed. The vaporizing rates of the two chlorides are controlled by measuring their mass loss as a function of carrier gas (argon) flow rate at certain vaporization temperatures, respectively. X-ray diffraction (XRD) patterns indicate that hydrogenous Nb3Sn products are obtained under the vaporizing rate of 0.155 g min−1 for NbCl5 and 0.036 g min−1 for SnCl2 with the hydrogen flow rate of 2100 ml min−1 at 1273 K (1000 °C). Results of semi-quantitative analysis by X-ray fluorescence (XRF) demonstrate that the atomic ratio of Nb to Sn in the as-synthesized products is 3.48:1, and the content of (Nb + Sn) is taken up to 89.61 wt pct from the total weight of the products. The products can be purified by vacuum heat treatment. Images of transmission electron microscopy (TEM) show that the products are homogenous particles with a mean diameter of 31 nm. In addition, the reaction ratio of the chlorides and the powder yield are controllable by hydrogen flow rate.

Response surface regression analysis on FeCrBSi particle in-flight properties by plasma spray

This work discusses the interactive effects between every two of argon flow rate, voltage, and spray distance on in-flight particles by plasma spray and constructs models that can be used in predicting and analyzing average velocity and temperature. Results of the response surface methodology show that the interactive effects between voltage and spray distance on particle inflight properties are significant. For a given argon flow rate, particle velocity and temperature response surface are obviously bending, and a saddle point exists. With an increase in spray distance, the interactive effects between voltage and argon flow rate on particle in-flight properties appear gradually and then weaken. With an increase in voltage, the interactive effects between spray distance and argon flow rate on particle in-flight properties change from appearing to strengthening and then to weakening.

Process Engineering of Dimensional Fused Silica Etching

The process of dimensional fused silica etching was offered. The production process of molycoat by magnetron sputtering of molybdenum target in inert gas (Argon) on vacuum distillation unit (NIKA-2012 TN) was examined. The coat quality (delamination, discontinuity) was analyzed; the influence of the first kind internal strains on the type of the observed defects was determined. The research was conducted by means of microscopic and X-ray diffraction analysis. It has been established that the internal strain value in the coat depends on the sputtering gas (Argon) flow rate, and, consequently, its pressure in the magnetron system for molybdenum sputtering. Zero stresses are registered under Argon's flow rate, which is 7.5 L/h. Influence of internal stresses level in the barrier coating on the quality of etching dimple.

Studies on Nanostructure Aluminium Thin Film Coatings Deposited using DC magnetron Sputtering Process

Nanostructured thin film metallic coatings has become an area of intense research particularly in applications related solar, sensor technologies and many other optical applications such as laser windows, mirrors and reflectors. Thin film metallic coatings were deposited using DC magnetron sputtering process. The deposition rate was varied to study its influence on optical behavior of Aluminum thin films at a different argon flow rate. Studies on the optical response of these nanostructure thin film coatings were characterized using UV-VIS-NIR spectrophotometer with integrating sphere in the wavelength range of (250-2500nm) and Surface morphology were carried out using atomic force microscope with roughness ranging from 2 to 20nm and thickness was measured using Dektak measuring instrument. The reflection behavior of aluminium coatings on polycarbonate substrates has been evaluated. UV-VIS-NIR Spectrophotometer analysis indicates higher reflectance of 96% for all the films in the wavelength range of 250 nm to 2500 nm. Nano indentation study revealed that there was a considerable change in hardness values of the films prepared at different conditions.

Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

Effect of Argon Gas Flow Rate on the Optical and Mechanical Properties of Sputtered Tungsten Thin Film Coatings

Tungsten thin film coatings were deposited on SS304 substrates by DC magnetron sputtering process. Optical and mechanical properties changes have been studied as a function of varying argon gas flow rate during magnetron sputtering process. The effect of argon flow rate on depositionrate, mechanical and optical properties of the tungsten films prepared at Different power rate was investigated by surface profilometer, nanoindenter, FESEM and UV Vis NIR spectrometer. With increasing argon gas flow rate increases deposition rate and hence higher IR reflectance in IR region and at lower argon gas flow rate the absorptance is higher. The optimized results allows us to select the deposition condition for solar absorptance and thermal emittance for solar thermal applications. The XRD analysis shows that the deposited tungsten thin film coatings were in polycrystalline in nature and surface roughness increases with increase in argon gas flow rate. Nanoindentation test result yields that hardness of DC magnetronsputtered tungsten thin film increases with argon gas flow rate from 200sccm to 500sccm.

Metal Injection Moulding of Titanium Medical Components

The metal injection moulding technique is already established for serial production of complex parts, mostly from various stainless steels. However, for other materials, especially for titanium parts there is still the need for superior purity and enhanced surface quality. Facing the challenge of obtaining suitable medical titanium MIM parts, advances have been made at Fraunhofer IFAM over the last few years.One strategy to overcome the high risk of carbon up-take was to adjust the sintering program. Very low Argon flow rates, 50 mbar pressure and two hours dwell time at 1350°C were found to be optimal parameters. A cleaning cycle prior to the actual sintering at 1450°C under hydrogen was also found to enhance the results.Another strategy involved the choice of binder components. Stearic acid, which is often used to improve wettability of binder to powder particle, and high polymer content affect the oxygen content of the titanium parts. Low amounts of both are beneficial for high purity parts.Other investigations were performed concerning the surface quality. It was found that the surface roughness of the mould has an effect on the surface roughness of the sintered parts. Although sintered titanium surfaces as such exhibit quite rough surfaces of about 2-3 µm (Ra value) the influence of the surface finish of the mould was detectable. Using very fine powders of only 15 µm mean particle size and a polished mould a very low surface roughness of less than 1.2 µm on the sintered part was obtainable.

Flow pattern control in continuous slab casting moulds: physical modelling and plant trials

Full-scale water modelling studies combined with nail-dipping industrial trials at Shougang Jingtang (SGJT) Works were carried out in order to investigate the parameters that influence flow patterns in the continuous slab casting mould. The effects of casting speed/mould width combinations, argon bubbling flow rates, submerged entry nozzle (SEN) immersion depths and SEN geometries (port angle and bottom shape) on the flow patterns were examined. A CMI factor defined as casting speed/mould width ratio index is put forward to describe the combined effect of these parameters on the fluid flow patterns in the mould. The results show that the CMI and argon injection rates are the dominant factors that determine the flow pattern. On the basis of the results from this study, critical argon flow rates for different casting combinations have been evaluated. These findings provide operating guidelines for generating optimal flow patterns based on double roll flow with appropriate surface velocities in continuous slab casting moulds. On the basis of these considerations, slab quality at SGJT Works was substantially improved and the percentage of flow pattern-related sliver defects in cold rolled products was decreased from 4.5 to 2.3%.

An Assessment of Chemical Vapor Deposition Synthesis of SnO<sub>2</sub> Nanowires by Statistical Design

This paper studies the chemical vapor deposition (CVD) synthesis conditions for tin oxide (SnO2) nanowires (NWs) by using statistical design of experiment (DOE). The influences of synthesis parameters (growth temperature, deposition time and flow rate of argon) on SnO2 NWs diameter were studied. From perturbation analysis with DOE, it was found that temperature gave the most significant effect to the diameter of SnO2 NWs via CVD method followed by flowrate of argon and deposition time. Furthermore, based on the cube graph, the smallest SnO2 NWs (~18 nm) can be obtained at temperature of 850 °C with argon flow rate of 100 sccm using a deposition time of 60 min. On the other hand, the largest SnO2 NWs (~248 nm) can be produced at 900 °C.

Effect of oxygen on fracture toughness of Zr(N,O) hard coatings

Abstract The objectives of this study were to measure the fracture toughness (G c ) of Zr(N,O) hard coatings using internal energy induced cracking (IEIC) method, and to investigate the effect of oxygen on the fracture toughness of the Zr(N,O) coatings. Zr(N,O) coatings were deposited by unbalanced magnetron sputtering with different oxygen flow rates while maintaining constant nitrogen and argon flow rates. The elastic constants of the Zr(N,O) coatings were determined by nanoindentation, residual stress was measured by laser curvature method and the coating thickness was measured from cross-sectional images by scanning electron microscopy (SEM). Using the data of elastic constants, residual stress and coating thickness, G c could be obtained. The results showed that G c was texture dependent; for ZrN coatings with (111) texture G c was 26.7 ± 2.1 J/m 2 while that for coatings with (200) texture was 9.0 ± 0.9 J/m 2 . The fracture toughness of Zr(N,O) coatings containing small amount of zirconium oxynitride remained nearly the same as that of ZrN with (200) texture ranging from 8.7 ± 0.9 to 8.9 ± 0.6 J/m 2 . Both oxygen flow and oxygen contents were found to affect the structure and the accompanying properties of the Zr(N,O) coatings. Oxygen flow may interfere the migration of Zr adatoms and the subsequent film formation; consequently, the texture of Zr(N,O) coatings switched from (111) to (200). The oxygen contents of the Zr(N,O) coatings increased, but not substantially, with increasing oxygen flow rate. Since lower energy processing parameters were used in this study, the formation of oxide or oxynitride phases was not as distinct as that in our previous studies. The fractography showed that the main crack propagated stepwise. The crack initiation may occur due to the edge stress acting at local defects ahead of the edge inside the film. The stress distribution due to free edge effect could move with the crack front and consequently drove the main crack propagating stepwise.

Microstructure-controlled deposition of yttria-stabilized zirconia electrolyte for low temperature solid oxide fuel cell performance stability enhancement

Yttria-stabilized zirconia thin films were deposited with a controlled argon flow rate via DC reactive magnetron sputtering processes. Typically, thin film electrolytes fabricated by physical vapor deposition onto nano-porous substrates generate pinholes due to their columnar grain structure. The grain boundaries between these columnar grains can be considered as structural defects and can cause voltage drops due to electrical shorting when used as thin film electrolytes in energy conversion systems. By controlling the argon flow rate of the reactive sputtering method, YSZ thin films with dense and restrained columnar grains were fabricated. Scanning electron microscopy inspection was conducted to analyze the surface morphologies, grain structures, and nano-defects in the interior of YSZ thin films. X-ray photoelectron spectroscopy revealed that the composition of the YSZ electrolyte is determined by the flow rate of the oxygen-reactive gas. In addition, X-ray diffractometry was conducted to verify the crystalline phase of the YSZ films; it was determined that a lower argon flow rate produces a better crystalline phase. The films also showed high ionic conductivity compared to the reference data, and the restrained columnar structure had higher conductivity due to a reduction in the ion transport blockage. Furthermore, the fuel cell with the YSZ electrolyte fabricated under a low argon flow rate, which had restrained columnar grains, showed a higher peak power density and superior open circuit voltage performance compared to the fuel cell with a higher argon flow rate.

Characteristics of Single Cathode Cascaded Bias Voltage Arc Plasma**supported by the International Thermonuclear Experimental Reactor (ITER) Program Special of Ministry of Science and Technology (No. 2013GB114003), and National Natural Science Foundation of China (Nos. 11275135, 11475122)

A single cathode with a cascaded bias voltage arc plasma source has been developed with a new quartz cathode chamber, instead of the previous copper chambers, to provide better diagnostic observation and access to the plasma optical emission. The cathode chamber cooling scheme is also modified to be naturally cooled only by light emission without cooling water to improve the optical thin performance in the optical path. A single-parameter physical model has been developed to describe the power dissipated in the cascaded bias voltage arc discharge argon plasmas, which have been investigated by utilizing optical emission spectroscopy (OES) and Langmuir probe. In the experiments, discharge currents from 50 A to 100 A, argon flow rates from 800 sccm to 2000 sccm and magnetic fields of 0.1 T and 0.2 T were chosen. The results show: (a) the relationship between the averaged resistivity and the averaged current density exhibits an empirical scaling law as and the power dissipated in the arc has a strong relation with the filling factor; (b) through the quartz, the argon ions optical emission lines have been easily observed and are dominating with wavelengths between 340 nm and 520 nm, which are the emissions of Ar+−434.81 nm and Ar+−442.60 nm line, and the intensities are increasing with the arc current and decreasing with the inlet argon flow rate; and (c) the electron density and temperature can reach 2.0 × 1019 m−3 and 0.48 eV, respectively, under the conditions of an arc current of 90 A and a magnetic field of 0.2 T. The half-width of the ne radial profile is approximatively equal to a few Larmor radii of electrons and can be regarded as the diameter of the plasma jet in the experiments.

직류 마이크로 할로우 음극 방전을 이용한 이단 마이크로 플라즈마 추력기의 배기 플룸의 형상 특성

이단 마이크로 할로우 음극 방전(MHCD) 플라즈마를 사용하는 마이크로 플라즈마 추력기(<TEX>${\mu}PT$</TEX>)에 대한 실험 연구가 수행되었다. 40 sccm의 아르곤 유량과 10 W 미만의 전력으로 보다 더 직진성 있고 긴 침투 길이를 가진 배기 플룸을 만드는 정전기적 가속이 이단 MHCD에 의해 발생되었다. 전압-전류 특성에서는 이단 운전 시 두 번째 단의 가속 전압이 일정하게 되는 최적 영역이 있음을 보였다. 추정된 배기 플룸의 길이가 가속 전압으로 추산된 이론적 배출 속도와 비슷한 증가 경향을 보였다. 다중 채널을 가진 마이크로 플라즈마 추력기는 동일한 총 전력량에 대하여 단일 채널 추력기와 비슷한 특성을 보여, 이는 채널 당 허용 전력량을 낮춰 전체 전력량을 높일 수 있음을 의미한다. 아르곤 원자 분광선의 볼츠만 그래프에서 배기 플룸의 평균 전자 여기 온도는 약 2.6 eV(=약 30,170 K)임이 확인되었다. Micro plasma thruster (<TEX>${\mu}PT$</TEX>) was studied experimentally with a dual-stage micro-hollow cathode discharge (MHCD) plasma. Electrostatic-like acceleration exhibiting more directional and elongated exhaust plume was achieved by a dual layer MHCD at the total input power less than 10 W with argon flow rate of 40 sccm. V-I characteristic indicated that there was an optimal regime for dual-stage operation where the acceleration voltage across the second stage remained constant. Estimated exhaust plume length showed a similar trend to the analytic estimate of exhaust velocity which scales with an acceleration voltage. <TEX>${\mu}PT$</TEX> with multiple holes exhibited similar performance with single-hole thruster indicating that higher power loading is possible owing to decreased power through each hole. Boltzmann plot of atomic argon spectral lines showed average electron excitation temperature of about 2.6 eV (~30,170 K) in the exhaust plume.

Determination of cadmium in water samples by fast pyrolysis–chemical vapor generation atomic fluorescence spectrometry

A pyrolysis-vapor generation procedure to determine cadmium by atomic fluorescence spectrometry has been established. Under fast pyrolysis, cadmium ion can be reduced to volatile cadmium species by sodium formate. The presence of thiourea enhanced the efficiency of cadmium vapor generation and eliminated the interference of copper. The possible mechanism of vapor generation of cadmium was discussed. The optimization of the parameters for pyrolysis–chemical vapor generation, including pyrolysis temperature, amount of sodium formate, concentration of hydrochloric acid, and carrier argon flow rate were carried out. Under the optimized conditions, the absolute and concentration detection limits were 0.38ng and 2.2ngml−1, respectively, assuming that 0.17ml of sample was injected. The generation efficiency of was 28–37%. The method was successfully applied to determine trace amounts of cadmium in two certified reference materials of Environmental Water (GSB07-1185-2000 and GSBZ 50009-88). The results were in good agreement with the certified reference values.

Dust formation in the arc heating of zinc-plated steel

Dust formation in the plasma-arc heating of zinc-plated steel in argon is studied, when the current is 170–190 A, the argon flow rate is 0.06 m3/h, and the pressure in the furnace chamber is 0.1 MPa. Zinc evaporates practically completely in the first 30 s of heating. The structure of the trapped zinc-bearing dust is heterogeneous: the particles are of different shape (spherical, acicular, or membranous particles), different size, and different composition. The composition of individual dust particles is analyzed on an iCAP 6300 spectrometer (Thermo Electron, United States). On that basis, their oxide composition is estimated by means of Terra software. The dust includes particles consisting of ZnO, Fe2O4, carbon, and pure iron. The results indicate that, in the plasma heating of zinc-plated steel, the zinc-bearing dust may be captured separately from the other dust in the initial smelting period.

Gas-assisted dispersive liquid-phase microextraction using ionic liquid as extracting solvent for spectrophotometric speciation of copper

Gas-assisted dispersive liquid-phase microextraction (GA-DLPME) has been developed for preconcentration and spectrophotometric determination of copper ion in different water samples. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate and argon gas, respectively, were used as the extracting solvent and disperser. The procedure was based on direct reduction of Cu(II) to Cu(I) by hydroxylamine hydrochloride, followed by extracting Cu(I) into ionic liquid phase by using neocuproine as the chelating agent. Several experimental variables that affected the GA-DLPME efficiency were investigated and optimized. Under the optimum experimental conditions (IL volume, 50µL; pH, 6.0; acetate buffer, 1.5molL−1; reducing agent concentration, 0.2molL−1; NC concentration, 120µgmL−1; Ar gas bubbling time, 6min; argon flow rate, 1Lmin−1; NaCl concentration, 6% w/w; and centrifugation time, 3min), the calibration graph was linear over the concentration range of 0.30–2.00µgmL−1 copper ion with a limit of detection of 0.07µgmL−1. Relative standard deviation for five replicate determinations of 1.0µgmL−1 copper ion was found to be 3.9%. The developed method was successfully applied to determination of both Cu(I) and Cu(II) species in water samples.

Rapid Thermal Annealing in MgO Sensing EIS Membrane for Bio-Sensor Applications

We tried to find an alternative dielectric film to own the high quality sensitive properties, so that, magnesium oxide (MgO) has been selected as a pH sensitive dielectric for the EIS operation, and is known as an alternative gate dielectric as CMOS technology has aggressively scaled down.The high-k MgO as sensing membrane on EIS structure and to investigated the characteristics of the different rapid thermal annealing(RTA) temperature in oxygen ambient. Furthermore, we studied the sensing performance of the MgO EIS structure tested in different ion (H+,Na+, K+, Urea, Glucose) solution. The electrolyte-insulator-semiconductor (EIS) structures with MgO sensing membranes were fabricated on 4-inch n-type (100) Si wafer, which have a resistivity of 5–10 Ω-cm. Before deposition of the MgO film, the wafers were cleaned by using HF-dip (HF: H2O = 1:100) to remove the native oxide. Then, a 50-nm MgO was deposited by radio frequency (RF) reactive sputtering on n-type silicon wafer. During RF sputtering, Mg oxide-target was used with 25 sccm argon flow rate (Ar: O2=25:0). The (RF) power and pressure are 150Watt and 20mTorr, respectively. Next, Samples was annealed at different temperatures (600oC, 700oC, 800oC) by rapid thermal annealing (RTA) in O2 ambient for 30 sec. The back-side contact of the Si wafer was deposited by Al film with 300nm-thick. Then, sensing area was defined by standard photolithography process using a photosensitive epoxy, SU8-2005 of MicroChem Inc. Finally, the samples were fabricated on the copper lines of printed circuit board (PCB) by silver gel. Epoxy package was used to separate the EIS structure and the copper line. In this study, we report an electrolyte–insulator–semiconductor (EIS) sensor with a high-k magnesium oxide (MgO) as sensing material. The effect of rapid thermal annealing (RTA) on the deposited sensing membrane has been studied in terms of structural and sensing characteristics. We used X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) to investigate the structural and morphological characteristics of deposited films. Furthermore, we studied the sensing performance of the MgO EIS structure in different ion solutions such as Urea and Glucose solutions. EIS device with MgO as sensing membrane that has been subjected to 800 ºC RTA treatment exhibits better sensing characteristics such as sensitivity of 61.64 mV/pH, hysteresis voltage of 5.03mV and 1.55mV/hr drift rate.

Determination of rare earth and concomitant elements in magnesium alloys by inductively coupled plasma optical emission spectrometry

An Inductively Coupled Plasma Optical Emission Spectrometry method for simultaneous determination of Al, Ca, Cu, Fe, In, Mn, Ni, Si, Sr, Y, Zn, Zr and rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in magnesium alloys, including the new rare earth elements-alloyed magnesium, has been developed. Robust conditions have been established as nebulizer argon flow rate of 0.5mLmin−1 and RF incident power of 1500W, in which matrix effects were significantly reduced around 10%. Three acid digestion procedures were performed at 110°C in closed PFA vessels heated in an oven, in closed TFM vessels heated in a microwave furnace, and in open polypropylene tubes with reflux caps heated in a graphite block. The three digestion procedures are suitable to put into solution the magnesium alloys samples. From the most sensitive lines, one analytical line with lack or low spectral interferences has been selected for each element. Mg, Rh and Sc have been studied as internal standards. Among them, Rh was selected as the best one by using Rh I 343.488nm and Rh II 249.078nm lines as a function of the analytical lines. The trueness and precision have been established by using the Certified Reference Material BCS 316, as well as by means of recovery studies. Quantification limits were between 0.1 and 9mgkg−1 for Lu and Pr, respectively, in a 2gL−1 magnesium matrix solution. The method developed has been applied to the commercial alloys AM60, AZ80, ZK30, AJ62, WE54 and AE44.

Two modes of a plasma jet excited by a direct current voltage

A plasma jet excited by a direct current voltage is developed to generate a diffuse plasma plume by blowing atmospheric pressure argon. Results show that the plume discharge operates in a single-pulsed mode or a continuous one depending on the applied voltage. For the single-pulsed mode, the discharge frequency increases with increasing the applied voltage or the air concentration, while it keeps almost constant with increasing the argon flow rate. The discharge dynamics at the breakdown stage indicate that the light emission propagates along the gas flow at a velocity in the order of 104 m s−1. The spatially resolved emission intensity at the afterglow stage of the pulsed discharge manifests a stratification into dark and bright luminous regions along the gas flow. For the continuous mode, however, the emission intensity gradually decreases along the gas flow. It is found that the continuous discharge is in a Townsend discharge regime judged from both the positive slope of the voltage–current curve and the small current density on the cathode surface. Based on optical emission spectroscopy, excited electron temperature and gas temperature of the plasma plume are obtained by a Boltzmann plot and fitting the spectra of OH radicals, respectively.