Estimation of electron-impact line widths for singly-, doubly- and triply-charged vanadium ions

Serbian Astronomical Journal ◽

10.2298/saj9857109p ◽

1998 ◽

pp. 109-114

Author(s):

L.C. Popovic ◽

M.S. Dimitrijevic

Keyword(s):

Electron Temperature ◽

Electron Impact ◽

Electron Density ◽

Semiempirical Method ◽

Line Widths ◽

Vanadium Ions

In this paper we present the electron-impact widths for 28 transitions of singly-, doubly-, and triply- ionized vanadium estimated by using the modified semiempirical method. The electron-impact widths have been estimated for the electron density of 1023m?3 and presented as a function of electron temperature.

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Hybrid simulation of instabilities in capacitively coupled RF CF4/Ar plasmas

Plasma Sources Science and Technology ◽

10.1088/1361-6595/ac47e4 ◽

2022 ◽

Author(s):

Wan Dong ◽

Yi Fan Zhang ◽

ZhongLing Dai ◽

Julian Schulze ◽

Yuan-Hong Song ◽

...

Keyword(s):

Electric Field ◽

Electron Temperature ◽

Electron Impact ◽

Electron Density ◽

Etching Rate ◽

Reaction Rates ◽

High Energy ◽

Density Fluctuations ◽

Negative Ion ◽

Capacitively Coupled

Abstract Radio frequency capacitively coupled plasmas (RF CCPs) sustained in fluorocarbon gases or their mixtures with argon are widely used in plasma-enhanced etching. In this work, we conduct studies on instabilities in a capacitive CF4/Ar (1:9) plasma driven at 13.56 MHz at a pressure of 150 mTorr, by using a one-dimensional fluid/Monte-Carlo (MC) hybrid model. Fluctuations are observed in densities and fluxes of charged particles, electric field, as well as electron impact reaction rates, especially in the bulk. As the gap distance between the electrodes increases from 2.8 cm to 3.8 cm, the fluctuation amplitudes become smaller gradually and the instability period gets longer, as the driving power density ranges from 250 to 300 W/m2. The instabilities are on a time scale of 16-20 RF periods, much shorter than those millisecond periodic instabilities observed experimentally owing to attachment/detachment in electronegative plasmas. At smaller electrode gap, a positive feedback to the instability generation is induced by the enhanced bulk electric field in the highly electronegative mode, by which the electron temperature keeps strongly oscillating. Electrons at high energy are mostly consumed by ionization rather than attachment process, making the electron density increase and overshoot to a much higher value. And then, the discharge becomes weakly electronegative and the bulk electric field becomes weak gradually, resulting in the continuous decrease of the electron density as the electron temperature keeps at a much lower mean value. Until the electron density attains its minimum value again, the instability cycle is formed. The ionization of Ar metastables and dissociative attachment of CF4 are noticed to play minor roles compared with the Ar ionization and excitation at this stage in this mixture discharge. The variations of electron outflow from and negative ion inflow to the discharge center need to be taken into account in the electron density fluctuations, apart from the corresponding electron impact reaction rates. We also notice more than 20% change of the Ar+ ion flux to the powered electrode and about 16% difference in the etching rate due to the instabilities in the case of 2.8 cm gap distance, which is worthy of more attention for improvement of etching technology.

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Comparison of the measured and modelled electron densities and temperatures in the ionosphere and plasmasphere during 20-30 January, 1993

Annales Geophysicae ◽

10.1007/s00585-000-1257-6 ◽

2000 ◽

Vol 18 (10) ◽

pp. 1257-1262 ◽

Cited By ~ 1

Author(s):

A. V. Pavlov ◽

T. Abe ◽

K.-I. Oyama

Keyword(s):

Magnetic Field ◽

Heat Flux ◽

Electron Temperature ◽

Field Line ◽

Electron Density ◽

Magnetic Field Line ◽

New Approach ◽

Additional Heating ◽

Vibrational Levels ◽

The Magnetic Field

Abstract. We present a comparison of the electron density and temperature behaviour in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite with numerical model calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere during the geomagnetically quiet and storm period on 20–30 January, 1993. We have evaluated the value of the additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the daytime plasmasphere region above 5000 km along the magnetic field line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite within the Millstone Hill magnetic field flux tube in the Northern Hemisphere. The additional heating brings the measured and modelled electron temperatures into agreement in the plasmasphere and into very large disagreement in the ionosphere if the classical electron heat flux along magnetic field line is used in the model. A new approach, based on a new effective electron thermal conductivity coefficient along the magnetic field line, is presented to model the electron temperature in the ionosphere and plasmasphere. This new approach leads to a heat flux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasmasphere found for the first time here allow the model to accurately reproduce the electron temperatures observed by the instruments on board the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The effects of the daytime additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modified electron heat flux is used. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at the first vibrational levels of N2 and O2 and the second level of O2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The resulting effect of N2(v > 0) and O2(v > 0) on NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 1.5. The modelled electron temperature is very sensitive to the electron density, and this decrease in electron density results in the increase of the calculated daytime electron temperature up to about 580 K at the F2 peak altitude giving closer agreement between the measured and modelled electron temperatures. Both the daytime and night-time densities are not reproduced by the model without N2(v > 0) and O2(v > 0), and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement.Key words: Ionosphere (ionospheric disturbances; ionosphere-magnetosphere interactions; plasma temperature and density)

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Machine Learning Prediction of Electron Density and Temperature from Optical Emission Spectroscopy in Nitrogen Plasma

Coatings ◽

10.3390/coatings11101221 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1221

Author(s):

Jun-Hyoung Park ◽

Ji-Ho Cho ◽

Jung-Sik Yoon ◽

Jung-Ho Song

Keyword(s):

Machine Learning ◽

Electron Temperature ◽

Real Time ◽

Electron Density ◽

Emission Spectroscopy ◽

Optical Emission Spectroscopy ◽

Optical Emission ◽

Plasma Parameters ◽

Plasma Nitridation

We present a non-invasive approach for monitoring plasma parameters such as the electron temperature and density inside a radio-frequency (RF) plasma nitridation device using optical emission spectroscopy (OES) in conjunction with multivariate data analysis. Instead of relying on a theoretical model of the plasma emission to extract plasma parameters from the OES, an empirical correlation was established on the basis of simultaneous OES and other diagnostics. Additionally, we developed a machine learning (ML)-based virtual metrology model for real-time Te and ne monitoring in plasma nitridation processes using an in situ OES sensor. The results showed that the prediction accuracy of electron density was 97% and that of electron temperature was 90%. This method is especially useful in plasma processing because it provides in-situ and real-time analysis without disturbing the plasma or interfering with the process.

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Diagnostics of low-pressure capacitively coupled RF discharge argon plasma

Iraqi Journal of Physics (IJP) ◽

10.30723/ijp.v13i27.266 ◽

2019 ◽

Vol 13 (27) ◽

pp. 76-82

Author(s):

Kadhim A. Aadim

Keyword(s):

Electron Temperature ◽

Electron Density ◽

Langmuir Probe ◽

Gas Flow ◽

Low Pressure ◽

Gas Pressure ◽

Rf Discharge ◽

Electrode Gap ◽

Probe Characteristic ◽

Capacitively Coupled

Low-pressure capacitively coupled RF discharge Ar plasma has been studied using Langmuir probe. The electron temperature, electron density and Debay length were calculated under different pressures and electrode gap. In this work the RF Langmuir probe is designed using 4MHz filter as compensation circuit and I-V probe characteristic have been investigated. The pressure varied from 0.07 mbar to 0.1 mbar while electrode gap varied from 2-5 cm. The plasma was generated using power supply at 4MHz frequency with power 300 W. The flowmeter is used to control Argon gas flow in the range of 600 standard cubic centimeters per minute (sccm). The electron temperature drops slowly with pressure and it's gradually decreased when expanding the electrode gap. As the gas pressure increases, the plasma density rises slightly at low gas pressure while it drops little at higher gas pressure. The electron density decreases rapidly with expand distances between electrodes.

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Measurement of plasma electron temperature and density by using different applied voltages and working pressures in a magnetron sputtering system

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.9459 ◽

2018 ◽

Vol 7 (3) ◽

pp. 1177 ◽

Cited By ~ 2

Author(s):

Sabah N. Mazhir ◽

Mohammed K. Khalaf ◽

Sarah K. Taha ◽

Hussein K . Mohsin

Keyword(s):

Magnetron Sputtering ◽

Electron Temperature ◽

Electron Density ◽

Applied Voltage ◽

Low Cost ◽

Plasma Electron ◽

Spectral Lines ◽

Glow Discharge Plasma ◽

Working Pressure ◽

Sputtering System

This paper discusses applying different voltages and pressure in the presence of silver target and argon gas to produce plasma. Home-made dc magnetron sputtering system was used to produce glow discharge plasma. The distance between two electrodes is 4 cm. Gas used to produce plasma is argon that flows inside the chamber with flow rate 40 sccm. Intensity of spectral lines, electron temperature and electron density were studied. The results show that the intensity of spectral lines increases with the increase of the working pressure and applied voltage. Electron temperature increases by the increase of applied voltage but decreases with the increase of working pressure, while electron density decreases with the increase of applied voltage and increases with the increase of working pressure. This research demonstrates a new low cost approach to start producing high corrosion resistance materials.

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