scholarly journals Diagnostics of dusty plasma properties in planar magnetron sputtering device

2019 ◽  
Vol 13 (26) ◽  
pp. 64-75
Author(s):  
Qusay A. Abbas
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Discharge Current ◽  
Plasma Potential ◽  
Dust Particles ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Radial Profiles ◽  
Planar Magnetron ◽  
Radial Axis

The effect of Al dust particles on glow discharge regions, dischargevoltage, discharge current, plasma potential, floating potential,electron density and electron temperature in planar magnetronsputtering device has been studied experimentally. Four cylindricalLangmuir probes were employed to measure plasma parameters atdifferent point on the radial axis of plasma column. The resultsshows the present of Al dust causes to increase the discharge voltageand reduce the discharge current. There are two electron groups inthe present and absent of Al dust particles. The radial profiles ofplasma parameters in the present of dust are non- uniform. Thefloating potential of probe becomes more negatively while theplasma potential becomes positive when the dust immersed intoplasma region. The electron density increases in the present of dustparticle which lead to decreases the electron temperature.

scholarly journals Effect of the gas puff location on the divertor plasma properties in COMPASS tokamak

2020 ◽  
Vol 1492 (1) ◽  
pp. 012003
Author(s):  
M Dimitrova ◽  
M Tomes ◽  
Tsv Popov ◽  
R Dejarnac ◽  
J Stockel ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Vacuum Chamber ◽  
Plasma Potential ◽  
Saturation Current ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Low Field ◽  
Saturation Current Density ◽  
Deuterium Gas

Abstract Langmuir probes are used to study the plasma parameters in the divertor during deuterium gas puff injection on the high- (HFS) or low-field sides (LFS). The probe data were processed to evaluate the plasma potential and the electron temperatures and densities. A difference was found in the plasma parameters depending on the gas puff location. In the case of a gas puff on the LFS, the plasma parameters changed vastly, mainly in the inner divertor – the plasma potential, the ion saturation-current density and the electron temperature dropped. After the gas puff, the electron temperature changed from 10-15 eV down to within the 5-9 eV range. As a result, the parallel heat-flux density decreased. At the same time, in the outer divertor the plasma parameters remained the same. We thus concluded that using a gas puff on the LFS will facilitate reaching a detachment regime by increasing the density of puffed neutrals. When the deuterium gas puff was on the HFS, the plasma parameters in the divertor region remained almost the same before and during the puff. The electron temperature decreased with just few eV as a result of the increased amount of gas in the vacuum chamber.

Study of moving striations in plasmas. I. Measurement of the phase between the variations of several plasma parameters

1968 ◽  
Vol 46 (16) ◽  
pp. 1787-1793 ◽  
Author(s):  
Michel G. Drouet ◽  
Miloš Šicha
Keyword(s):  
Light Intensity ◽  
Electric Field ◽  
Electron Temperature ◽  
Discharge Current ◽  
Plasma Potential ◽  
Plasma Parameters ◽  
Temperature Plasma ◽  
Continuous Waves ◽  
Slow Moving ◽  
Made In

The phases between the variations of electron density, electron temperature, plasma potential, electric field, and light intensity have been measured in slow-moving striations in a neon discharge for different values of the discharge current. The reported measurements were made in moving striations artificially excited in the form of both continuous waves and wave of stratification.

scholarly journals Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 148
Author(s):  
Vittorio Giannetti ◽  
Manuel Martín Saravia ◽  
Luca Leporini ◽  
Simone Camarri ◽  
Tommaso Andreussi
Keyword(s):  
Discharge Current ◽  
Fluid Model ◽  
Low Frequency ◽  
Hall Thruster ◽  
Hall Thrusters ◽  
Current Signal ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Breathing Mode ◽  
Spatio Temporal

One of the main oscillatory modes found ubiquitously in Hall thrusters is the so-called breathing mode. This is recognized as a relatively low-frequency (10–30 kHz), longitudinal oscillation of the discharge current and plasma parameters. In this paper, we present a synergic experimental and numerical investigation of the breathing mode in a 5 kW-class Hall thruster. To this aim, we propose the use of an informed 1D fully-fluid model to provide augmented data with respect to available experimental measurements. The experimental data consists of two datasets, i.e., the discharge current signal and the local near-plume plasma properties measured at high-frequency with a fast-diving triple Langmuir probe. The model is calibrated on the discharge current signal and its accuracy is assessed by comparing predictions against the available measurements of the near-plume plasma properties. It is shown that the model can be calibrated using the discharge current signal, which is easy to measure, and that, once calibrated, it can predict with reasonable accuracy the spatio-temporal distributions of the plasma properties, which would be difficult to measure or estimate otherwise. Finally, we describe how the augmented data obtained through the combination of experiments and calibrated model can provide insight into the breathing mode oscillations and the evolution of plasma properties.

scholarly journals COMPARISON BETWEEN 2D TURBULENCE MODEL ESEL AND EXPERIMENTAL DATA FROM AUG AND COMPASS TOKAMAKS

2015 ◽  
Vol 55 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Peter Ondac ◽  
Jan Horacek ◽  
Jakub Seidl ◽  
Petr Vondrácek ◽  
Hans Werner Müller ◽  
...  
Keyword(s):  
Turbulent Transport ◽  
Plasma Potential ◽  
Density Fluctuations ◽  
Tokamak Plasma ◽  
Plasma Parameters ◽  
Fluid Turbulence ◽  
Radial Profiles ◽  
Parallel Dynamics ◽  
Two Machines ◽  
Probe Measurements

<!-- p, li { white-space: pre-wrap; } --><p style="text-indent: 0px; margin: 0px;">In this article we have used the 2D fluid turbulence numerical model, ESEL, to simulate turbulent transport in edge tokamak plasma. Basic plasma parameters from the ASDEX Upgrade and COMPASS tokamaks are used as input for the model, and the output is compared with experimental observations obtained by reciprocating probe measurements from the two machines. Agreements were found in radial profiles of mean plasma potential and temperature, and in a level of density fluctuations. Disagreements, however, were found in the level of plasma potential and temperature fluctuations. This implicates a need for an extension of the ESEL model from 2D to 3D to fully resolve the parallel dynamics, and the coupling from the plasma to the sheath.</p>

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

Coatings ◽  
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.

scholarly journals The effect of electron bite-outs on artificial electron heating and the PMSE overshoot

2005 ◽  
Vol 23 (12) ◽  
pp. 3633-3643 ◽  
Author(s):  
M. Kassa ◽  
O. Havnes ◽  
E. Belova
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Electron Density Profile ◽  
Dust Particles ◽  
High Electron ◽  
Heating Effect ◽  
Ion Temperature ◽  
Degree Of Ionization ◽  
Electron Heating ◽  
Transmitter Power

Abstract. We have considered the effect that a local reduction in the electron density (an electron bite-out), caused by electron absorption on to dust particles, can have on the artificial electron heating in the height region between 80 to 90km, where noctilucent clouds (NLC) and the radar phenomenon PMSE (Polar Mesospheric Summer Echoes) are observed. With an electron density profile without bite-outs, the heated electron temperature Te,hot will generally decrease smoothly with height in the PMSE region or there may be no significant heating effect present. Within a bite-out Te,hot will decrease less rapidly and can even increase slightly with height if the bite-out is strong. We have looked at recent observations of PMSE which are affected by artificial electron heating, with a heater cycling producing the new overshoot effect. According to the theory for the PMSE overshoot the fractional increase in electron temperature Te,hot/Ti, where Ti is the unaffected ion temperature=neutral temperature, can be found from the reduction in PMSE intensity as the heater is switched on. We have looked at results from four days of observations with the EISCAT VHF radar (224 MHz), together with the EISCAT heating facility. We find support for the PMSE overshoot and heating model from a sequence of observations during one of the days where the heater transmitter power is varied from cycle to cycle and where the calculated Te,hot/Ti is found to vary in proportion to the transmitter power. We also looked for signatures of electron bite-outs by examining the variation of Te,hot/Ti with height for the three other days. We find that the height variation of Te,hot/Ti is very different on the three days. On one of the days we see typically that this ratio can increase with height, showing the presence of a bite-out, while on the next day the heating factor mainly decreases with height, indicating that the fractional amount of dust is low, so that the electron density is hardly affected by it. On the third day there is little heating effect on the PMSE layer. This is probably due to a sufficiently high electron density in the atmosphere below the PMSE layer, so that the transmitted heater power is absorbed in these lower layers. On this day the D-region, as given by the UHF (933MHz) observations, extends deeper down in the atmosphere than on the other two days, indicating that the degree of ionization in and below the PMSE layers is higher as well.

The Effection of Discharge Current on Hydrogen Plasma in the Cascaded Arc

2014 ◽  
Vol 1082 ◽  
pp. 85-89
Author(s):  
Jiang Long Li ◽  
Hong Lei Hao
Keyword(s):  
Electric Conductivity ◽  
Electron Density ◽  
Discharge Current ◽  
Symmetry Axis ◽  
Hydrogen Plasma ◽  
Plasma Temperature ◽  
Plasma Properties ◽  
Temperature Conductivity ◽  
Simulation Results

In this paper, we use PLASIMO to investigate the effect of discharge current on hydrogen plasma in the cascaded arc, the effects of discharge current on plasma properties were investigated. temperature, conductivity, and the distribution of electron density along the symmetry axis of hydrogen plasma is analyzed in the simulation area. The simulation results show that plasma temperature is 0.9503×104, 1.09862×104, 1.26675×104, 1.65102×104 K in the symmetry axis when the discharge current is 35, 50, 75 and 100A, meanwhile, electric conductivity is 1738.03, 2272.72, 2819.86, 3820.73 s/m.

Dust vortices in a direct current glow discharge plasma: a delicate balance between ion drag and Coulomb force

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
Sayak Bose ◽  
M. Kaur ◽  
P. K. Chattopadhyay ◽  
J. Ghosh ◽  
Edward Thomas ◽  
...  
Keyword(s):  
Glow Discharge ◽  
Discharge Current ◽  
Discharge Plasma ◽  
Coulomb Force ◽  
Plasma Potential ◽  
Glow Discharge Plasma ◽  
Dust Particles ◽  
Charged Dust ◽  
Surface Evolution

Dust vortices with a void at the centre are reported in this paper. The role of the spatial variation of the plasma potential in the rotation of dust particles is studied in a parallel plate glow discharge plasma. Probe measurements reveal the existence of a local potential minimum in the region of formation of the dust vortex. The minimum in the potential well attracts positively charged ions, while it repels the negatively charged dust particles. Dust rotation is caused by the interplay of the two oppositely directed ion drag and Coulomb forces. The balance between these two forces is found to play a major role in the radial confinement of the dust particles above the cathode surface. Evolution of the dust vortex is studied by increasing the discharge current from 15 to 20 mA. The local minimum of the potential profile is found to coincide with the location of the dust vortex for both values of discharge currents. Additionally, it is found that the size of the dust vortex as well as the void at the centre increases with the discharge current.

Characterization of the palladium plasma produced by nanosecond pulsed 532 nm and 1064 nm wavelength lasers

Laser Physics ◽  
2021 ◽  
Vol 32 (2) ◽  
pp. 026002
Author(s):  
M Asif ◽  
U Amin ◽  
Z U Rehman ◽  
R Ali ◽  
H Qayyum
Keyword(s):  
Kinetic Energy ◽  
Electron Temperature ◽  
Electron Density ◽  
Laser Plasma ◽  
Laser Fluence ◽  
Plasma Heating ◽  
Total Charge ◽  
Plasma Parameters ◽  
Wide Range ◽  
532 Nm

Abstract Palladium plasma produced by nanosecond pulsed 532 nm and 1064 nm wavelengths lasers is studied with the help of planer Langmuir probe. The experiment is conducted over a wide range of the laser fluence (1.6–40 J cm−2). The measured time of flight ions distributions are used to infer total charge, kinetic energy of the palladium ions and plasma parameters. Our results indicate that the ion charge produced by both laser wavelengths is an increasing function of the laser fluence. Initially, the ion charge produced by 1064 nm is lower than 532 nm, but it increases at much faster rate with the rise of laser fluence as the inverse bremsstrahlung plasma heating prevails at higher plasma densities. The most probable kinetic energy of the Pd ions produced by 1064 nm wavelength is also lower than that of 532 nm. The time varying plasma electron temperature and electron density are derived from the current–voltage plots of the two plasmas. For both wavelengths, the electron temperature and electron density rapidly climb to a maximum value and then gradually decline with time. However, in case of the 532 nm, the electron temperature and electron density remain consistently high throughout the laser plasma. The results are compared the available literature and discussed by considering surface reflectivity, ablation rate of the Pd target and laser plasma heating. The results presented in this work will provide more insight into the process of laser ablation and can be useful for the development of laser-plasma ion sources.

Plasma gradient effects on double-probe measurements in the magnetosphere

1995 ◽  
Vol 13 (2) ◽  
pp. 130-146 ◽  
Author(s):  
H. Laakso ◽  
T. L. Aggson ◽  
R. F. Pfaff
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Large Scale ◽  
Plasma Potential ◽  
Bias Current ◽  
Small Scale ◽  
Error Signal ◽  
Double Probe ◽  
Gradient Effects ◽  
Probe Measurements

Abstract. The effects on double-probe electric field measurements induced by electron density and temperature gradients are investigated. We show that on some occasions such gradients may lead to marked spurious electric fields if the probes are assumed to lie at the same probe potential with respect to the plasma. The use of a proper bias current will decrease the magnitude of such an error. When the probes are near the plasma potential, the magnitude of these error signals, ∆E, can vary as ∆E ~ Te(∆ne/ne)+0.5∆Te, where Te is the electron temperature, ∆ne/ne the relative electron density variation between the two sensors, and ∆Te the electron temperature difference between the two sensors. This not only implies that the error signals will increase linearly with the density variations but also that such signatures grow with Te, i.e., such effects are 10 times larger in a 10-eV plasma than in a 1-eV plasma. This type of error is independent of the probe separation distance provided the gradient scale length is much larger than this distance. The largest errors occur when the probes are near to the plasma potential. At larger positive probe potentials with respect to the plasma potential, the error becomes smaller if the probes are biased, as is usually the case with spherical double-probe experiments in the tenuous magnetospheric plasmas. The crossing of a plasma boundary (like the plasmapause or magnetopause) yields an error signal of a single peak. During the crossing of a small structure (e.g., a double layer) the error signal appears as a bipolar signature. Our analysis shows that errors in double-probe measurements caused by plasma gradients are not significant at large scale (»1 km) plasma boundaries, and may only be important in cases where small-scale (<1 km), internal gradient structures exist. Bias currents tailored for each plasma parameter regime (i.e., variable bias current) would o1q1improve the double-probe response to gradient effects considerably.

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