Vacuum ultraviolet assessment of ionization temperature by space-resolved emission spectroscopy

2013 ◽  
Vol 91 (9) ◽  
pp. 733-736 ◽  
Author(s):  
Mohamed A. Khater
Keyword(s):  
Emission Spectroscopy ◽  
Vacuum Ultraviolet ◽  
Target Surface ◽  
Laser Pulses ◽  
Ionic Species ◽  
Operating Conditions ◽  
Spectral Lines ◽  
Local Thermal Equilibrium ◽  
Axial Distance ◽  
Ionization Temperature

In this article, the electron ionization temperature in plasmas generated by 1064 nm laser pulses in the vacuum ultraviolet spectral range is evaluated as a function of the axial distance from a steel target surface using emission spectroscopy. The temperature was determined using the relative line intensities ratio of C II 90.41 nm and C III 97.7 nm spectral lines, applied to the Saha–Boltzmann equation. Ionization temperatures determined in this way changed from 33 900 K at the target surface to 26 800 K (2.92–2.31 eV) at 4.0 mm away from it. Large differences between the measured excitation and ionization temperatures suggest nonthermal equilibrium conditions between electrons and heavier ionic species. Based upon the results obtained from this and a previous study under the same operating conditions, the validity of the local thermal equilibrium condition in the plasmas investigated is presented and discussed.

scholarly journals Observation of Argon Lines at Normal Pressure in the Vacuum Ultraviolet

1972 ◽  
Vol 14 ◽  
pp. 563-564
Author(s):  
D. Müller ◽  
Ć. Vadla ◽  
V. Vujnović
Keyword(s):  
Vacuum Ultraviolet ◽  
Normal Pressure ◽  
Spectral Lines ◽  
Local Thermal Equilibrium ◽  
Ultraviolet Region ◽  
Pumping System ◽  
Hot Plasma ◽  
Differential Pumping ◽  
Inhomogeneous Gas ◽  
Vacuum Monochromator

A normal pressure arc having local thermal equilibrium, is a useful source for measurements of atomic parameters in the vacuum ultraviolet region (Boldt, 1970). However, it imposes severe difficulties if the spectral lines ending on low-lying levels should be observed. The reason is the absorption effective in cold and inhomogeneous gas layers intervening in the optical path between the homogeneous hot plasma column and the vacuum monochromator. Here a version of a cascade arc with a differential pumping system is described which makes possible the observation of argon resonance lines at 1067 and 1048 Å, considerably free of absorption. For this purpose it was found necessary to use a bored anode as a pumping port.

Optimization of the Emission Characteristics of Laser-Produced Steel Plasmas in the Vacuum Ultraviolet: Significant Improvements in Carbon Detection Limits

2002 ◽  
Vol 56 (8) ◽  
pp. 970-983 ◽  
Author(s):  
Mohamed A. Khater ◽  
John T. Costello ◽  
Eugene T. Kennedy
Keyword(s):  
Vacuum Ultraviolet ◽  
Limit Of Detection ◽  
Laser System ◽  
Normal Incidence ◽  
Laser Pulses ◽  
Laser Wavelength ◽  
Visible Spectral Range ◽  
Spectral Lines ◽  
Array Detector ◽  
Emission Characteristics

A detailed optimization study for laser-produced steel plasmas using time-integrated, spatially resolved emission spectroscopy in the vacuum ultraviolet (VUV) (40–160 nm) is presented. The influences of the laser focusing lens type, laser power density, laser wavelength, laser pulse energy, ambient atmospheres, and pressure, as well as spatial distribution of emitting species, on the emission characteristics of the steel plasmas are investigated. The aim of the work is to improve the detection power of the technique for the quantitative determination of carbon in solid steel alloys. In most of the work, Q-switched Nd:YAG (1064 nm, 820 mJ max. energy) laser pulses were used to create the steel plasmas. For the laser harmonics investigations, a second Q-switched Nd:YAG laser system that generated radiation at the second, third, and fourth harmonics as well as at the fundamental was employed. Air, argon, and helium were used as the surrounding atmospheres, and the pressure was varied from 0.005 mbar to 5.0 mbar depending on the gas composition. A 1 m normal incidence vacuum spectrometer, equipped with a 1200 grooves/mm concave reflective grating, was used to disperse the VUV radiation. The radiation was detected by a back-illuminated, anti-reflection coated, charge-coupled device (CCD) array detector. In general, the emission characteristics of the VUV spectral lines studied are similar to those previously investigated in the UV-visible spectral range. An unprecedented limit of detection for carbon in steels of 1.2 ± 0.2 μg/g was measured in this work.

scholarly journals Analytical capability of the plasma induced by IR TEA CO2 laser pulses on copper based alloys

2015 ◽  
Vol 80 (12) ◽  
pp. 1505-1513 ◽  
Author(s):  
Milos Momcilovic ◽  
Jovan Ciganovic ◽  
Dragan Rankovic ◽  
Uros Jovanovic ◽  
Milovan Stoiljkovic ◽  
...  
Keyword(s):  
Co2 Laser ◽  
Pulse Length ◽  
Target Surface ◽  
Laser Pulses ◽  
Spectral Lines ◽  
Tea Co2 Laser ◽  
Plasma Spectroscopy ◽  
Plasma Region ◽  
Co2 Laser Radiation ◽  
Good Signal

The applicability of nanosecond infrared (IR) transversely excited atmospheric (TEA) CO2 laser, operating at 10.6 ?m and 100 ns pulse length (initial spike), induced plasma under reduced air pressure for spectrochemical analysis of bronze and brass samples was investigated. The plasma consisted of two clearly distinguished and spatially separated regions and expanded to a distance of about 10 mm from the surface. Elemental composition of the samples was determined using a time-integrated space-resolved laser-induced plasma spectroscopy (TISR-LIPS) technique. Sharp and well resolved spectral lines mostly atomic, and negligibly low background emission, were obtained from a plasma region 7 mm from the target surface. Good signal to background and signal to noise ratios were obtained. Estimated detection limits for trace elements Mg, Fe, Al and Ca were in the order of 10 ppm in bronze and around 50 ppm in brass. Damage on the investigated samples induced by TEA CO2 laser radiation was negligible.

Near‐infrared‐to‐vacuum‐ultraviolet high‐harmonic Raman and plasma emission spectroscopy with ultrashort mid‐infrared laser pulses

2021 ◽  
Author(s):  
Alexander V. Mitrofanov ◽  
Mikhail V. Rozhko ◽  
Dmitry A. Sidorov‐Biryukov ◽  
Alexander A. Voronin ◽  
Andrei B. Fedotov ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Near Infrared ◽  
Vacuum Ultraviolet ◽  
High Harmonic ◽  
Laser Pulses ◽  
Infrared Laser ◽  
Plasma Emission ◽  
Mid Infrared ◽  
Plasma Emission Spectroscopy

Infrared Emission Spectroscopy as a Reliability Tool

1999 ◽  
Author(s):  
Q. Kim ◽  
S. Kayali
Keyword(s):  
Spatial Resolution ◽  
Emission Spectroscopy ◽  
Hot Spot ◽  
Cost Effective ◽  
Infrared Emission ◽  
Test System ◽  
Operating Conditions ◽  
Yield Enhancement ◽  
Infrared Emission Spectroscopy ◽  
Channel Temperature

Abstract In this paper, we report on a non-destructive technique, based on IR emission spectroscopy, for measuring the temperature of a hot spot in the gate channel of a GaAs metal/semiconductor field effect transistor (MESFET). A submicron-size He-Ne laser provides the local excitation of the gate channel and the emitted photons are collected by a spectrophotometer. Given the state of our experimental test system, we estimate a spectral resolution of approximately 0.1 Angstroms and a spatial resolution of approximately 0.9 μm, which is up to 100 times finer spatial resolution than can be obtained using the best available passive IR systems. The temperature resolution (<0.02 K/μm in our case) is dependent upon the spectrometer used and can be further improved. This novel technique can be used to estimate device lifetimes for critical applications and measure the channel temperature of devices under actual operating conditions. Another potential use is cost-effective prescreening for determining the 'hot spot' channel temperature of devices under normal operating conditions, which can further improve device design, yield enhancement, and reliable operation. Results are shown for both a powered and unpowered MESFET, demonstrating the strength of our infrared emission spectroscopy technique as a reliability tool.

Numerical Analysis of the Heat and Mass Transfer Characteristics in an Autothermal Methane Reformer

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Joonguen Park ◽  
Shinku Lee ◽  
Sunyoung Kim ◽  
Joongmyeon Bae
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Heat And Mass Transfer ◽  
Steam Reforming ◽  
Space Velocity ◽  
Reaction Model ◽  
Operating Conditions ◽  
Local Thermal Equilibrium ◽  
Inlet Temperature ◽  
Transfer Characteristics

This paper discusses a numerical analysis of the heat and mass transfer characteristics in an autothermal methane reformer. Assuming local thermal equilibrium between the bulk gas and the surface of the catalyst, a one-medium approach for the porous medium analysis was incorporated. Also, the mass transfer between the bulk gas and the catalyst’s surface was neglected due to the relatively low gas velocity. For the catalytic surface reaction, the Langmuir–Hinshelwood model was incorporated in which methane (CH4) is reformed to hydrogen-rich gases by the autothermal reforming (ATR) reaction. Full combustion, steam reforming, water-gas shift, and direct steam reforming reactions were included in the chemical reaction model. Mass, momentum, energy, and species balance equations were simultaneously calculated with the chemical reactions for the multiphysics analysis. By varying the four operating conditions (inlet temperature, oxygen to carbon ratio (OCR), steam to carbon ratio, and gas hourly space velocity (GHSV)), the performance of the ATR reactor was estimated by the numerical calculations. The SR reaction rate was improved by an increased inlet temperature. The reforming efficiency and the fuel conversion reached their maximum values at an OCR of 0.7. When the GHSV was increased, the reforming efficiency increased but the large pressure drop may decrease the system efficiency. From these results, we can estimate the optimal operating conditions for the production of large amounts of hydrogen from methane.

Measurement of the spatial characteristics of an erosive silicon laser plasma using small-sized high-resolution spectrometers

2021 ◽  
pp. 38-42
Author(s):  
Boris A. Lapshinov ◽  
Nikolay I. Timchenko
Keyword(s):  
Laser Plasma ◽  
Emission Spectra ◽  
Target Surface ◽  
Spectral Lines ◽  
Slit Diaphragm ◽  
Plasma Radiation ◽  
Atmospheric Conditions ◽  
Spatial Characteristics ◽  
Silicon Target ◽  
Oriented Parallel

The spatial characteristics of the erosion laser plasma are investigated. The application of small-sized spectrometers of the visible and ultraviolet ranges for recording the spectrum of plasma radiation is considered. Erosive laser plasma is formed on the surface of a silicon target under the action of pulsed laser radiation with a wavelength of 1064 nm under normal atmospheric conditions. The laser plasma torch was scanned using a movable slit diaphragm oriented parallel to the target surface. The emission of erosion laser plasma was recorded using small-size spectrometers. Based on the obtained plasma emission spectra, the dependences of the intensity of the spectral lines of silicon on the geometric position of the slit diaphragm are revealed. A comparison is made of the intensities of the spectral lines of silicon on the polished and grinded sides of the target.

scholarly journals Synthesis of Nanotips Through Femtosecond Laser Ablation of Glass with Assisted Gas

2021 ◽  
Author(s):  
Nikunj Patel
Keyword(s):  
Femtosecond Laser ◽  
Building Materials ◽  
High Vacuum ◽  
Synthesis Method ◽  
Femtosecond Laser Ablation ◽  
Target Surface ◽  
Laser Pulses ◽  
Single Step ◽  
Femtosecond Laser Irradiation ◽  
Ambient Conditions

Nanotips are the key nanostructures for many applications. Until now, the nanotips of only the crystalline materials have been produced via various deposition methods which require sophisticated equipment, high vacuum, and clean room operations. This thesis proposes a single step, rapid synthesis method using femtosecond laser irradiation at megahertz frequency with background flow of nitrogen gas at ambient conditions. Amorphous nanotips are obtained without the use of catalyst. The nanotips grow from highly energetic plasma generated when target is irradiated with laser pulses. The vapor condensates, nanoparticles and droplets from the plasma get deposited back on to the hot target surface where they experience force imbalance due to which the stems for the nanotips growth are initiated. Once the stems are generated, the continuous deposition of vapor condensates [sic] provides building materials to the stems to complete the growth of nanotips. Further study found that the growth of the nanotips is influenced by laser parameters and gas conditions.

scholarly journals Accounting for Interelement Interferences in Atomic Emission Spectroscopy: A Nonlinear Theory

2021 ◽  
Vol 11 (23) ◽  
pp. 11237
Author(s):  
Anna N. Popova ◽  
Vladimir S. Sukhomlinov ◽  
Aleksandr S. Mustafaev
Keyword(s):  
Nonlinear Theory ◽  
Emission Spectroscopy ◽  
High Speed ◽  
Atomic Emission ◽  
Carbon Steels ◽  
Atomic Emission Spectroscopy ◽  
Spectral Lines ◽  
Analytical Line ◽  
Simulation Problem ◽  
Heat Resistant Steels

The article describes a nonlinear theory of how the presence of third elements affects the results of analyzing the elemental composition of substances by means of atomic emission spectroscopy. The theory is based on the assumption that there is an arbitrary relationship between the intensity of the analytical line of the analyte and the concentration of impurities and alloying elements. The theory has been tested on a simulation problem using commercially available equipment (the SPAS-05 spark spectrometer). By comparing the proposed algorithm with the traditional one, which assumes that there is a linear relationship between the intensity of the analytical line of the analyte and the intensities of the spectral lines (or concentrations) in the substance, it was revealed that there is a severalfold decrease in the deviations of nominal impurity concentrations from the measured ones. The results of this study allow for reducing the number of analytical procedures used in analyzing materials that have different compositions and the same matrix element. For instance, it becomes possible to determine the composition of iron-based alloys (low-alloy and carbon steels; high-speed steels; high-alloy, and heat-resistant steels) using one calibration curve within the framework of a universal analytical method.

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