Under argon DC glow plasma, the nitrogen removal from molten steel was studied. The experimental result showed that nitrogen mass percent could be reduced to 0000 8%. The change of polarity had no impact on nitrogen...Under argon DC glow plasma, the nitrogen removal from molten steel was studied. The experimental result showed that nitrogen mass percent could be reduced to 0000 8%. The change of polarity had no impact on nitrogen removal when the nitrogen mass percent was low. The mechanism of denitrogenation of molten steel under argon DC glow plasma was discussed.展开更多
The (DC-GDPAU) is a DC glow discharge plasma experiment that was designed, established, and operated in the Physics Department at Ain Shams University (Egypt). The aim of this experiment is to study and improve some p...The (DC-GDPAU) is a DC glow discharge plasma experiment that was designed, established, and operated in the Physics Department at Ain Shams University (Egypt). The aim of this experiment is to study and improve some properties of a printed circuit board (PCB) by exposing it to the plasma. The device consists of cylindrical discharge chamber with movable parallel circular copper electrodes (cathode and anode) fixed inside it. The distance between them is 12 cm. This plasma experiment works in a low-pressure range (0.15 - 0.70 Torr) for Ar gas with a maximum DC power supply of 200 W. The Paschen curves and electrical plasma parameters (current, volt, power, resistance) characterized to the plasma have been measured and calculated at each cm between the two electrodes. Besides, the electron temperature and ion density are obtained at different radial distances using a double Langmuir probe. The electron temperature (<em>KT<sub>e</sub></em>) was kept stable in range 6.58 to 10.44 eV;whereas the ion density (<em>ni</em>) was in range from 0.91 × 10<sup>10</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup> to 1.79 × 10<sup>10</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup>. A digital optical microscope (800×) was employed to draw a comparison between the pre-and after effect of exposure to plasma on the shaping of the circuit layout. The experimental results show that the electrical conductivity increased after plasma exposure, also an improvement in the adhesion force in the Cu foil surface. A significant increase in the conductivity can be directly related to the position of the sample surfaces as well as to the time of exposure. This shows the importance of the obtained results in developing the PCBs manufacturing that uses in different microelectronics devices like those onboard of space vehicles.展开更多
Using a combination of the Monte Carlo models of fast electrons,of molecular ions(N_2^++) and of atomic species (N^+,N_f),the influence of the discharge pressure (P) and voltage(V_c) on the energy distributions of fas...Using a combination of the Monte Carlo models of fast electrons,of molecular ions(N_2^++) and of atomic species (N^+,N_f),the influence of the discharge pressure (P) and voltage(V_c) on the energy distributions of fast atomic species (N^+,N_f) produced by e^--N_(2s) and N_2^+-N_(2s) dissociation reactions at the cathode in a nitrogen do glow discharge was investigated.Boththe angular distributions and the density distributions along the radius of the species (N^+,N_f)produced by the two dissociations at the cathode were calculated.The results show that:(1)there is an optimum discharge condition for P and V_c in order to obtain the species (N^+,N_f)at the cathode with high a density and energy,(2) when the voltage is above 800 V,the species(N^+,N_f) bombarding the cathode are mainly produced by the N_2^+-N_(2s) dissociation,whereas whenthe voltage is below 300 V,they are mainly produced by the e^--N_(2s) dissociation,and (3)at highvoltages the incident angles of a considerable number of N_f into the cathode are quite small.Thedensity of the species (N^+,N_f) at the cathode increases with the voltage,and when the pressuregoes up to about 133 Pa,it decreases with the increasing pressure.展开更多
DC plasma is a very promising technology for processing different materials, and is becoming especially interesting when low environmental impact and high-performance treatments are needed. Some of the intrinsic chara...DC plasma is a very promising technology for processing different materials, and is becoming especially interesting when low environmental impact and high-performance treatments are needed. Some of the intrinsic characteristics of DC plasma technology, which make it suitable for powder metallurgy (PM) and powder injection molding (PIM) parts production, are low- pressure processing and plasma environment high reactivity. Moreover it can be considered as a highly competitive green technology. In this work, an overview of some of the important DC plasma techniques applied to PM and PIM parts processing is presented. Emphasis is given to the descriptions of the main characteristics and the technique potentials of plasma-assisted nitriding, plasma-assisted thermal debinding, plasma-assisted sintering, and simultaneously plasma-assisted sintering and surface alloying. The aspects presented and discussed in this paper indicate that DC plasma processes are promising and competitive techniques for PM and PIM parts processing.展开更多
Optical emission spectroscopy is used to investigate the nitrogen-hydrogen with trace rare gas(4% Ar) plasma generated by 50 Hz pulsed DC discharges.The filling pressure varies from1 mbar to 5 mbar and the current den...Optical emission spectroscopy is used to investigate the nitrogen-hydrogen with trace rare gas(4% Ar) plasma generated by 50 Hz pulsed DC discharges.The filling pressure varies from1 mbar to 5 mbar and the current density ranges from 1 mA·cm-2to 4 mA·cm-2.The hydrogen concentration in the mixture plasma varies from 0% to 80%,with the objective of identifying the optimum pressure,current density and hydrogen concentration for active species([N] and [N2])generation.It is observed that in an N2-H2gas mixture,the concentration of N atom density decreases with filling pressure and increases with current density,with other parameters of the discharge kept unchanged.The maximum concentrations of active species were found for 40% H2in the mixture at 3 mbar pressure and current density of 4 mA·cm-2.展开更多
Nonlinear behavior of glow discharge plasmas is experimentally investigated.The glow is generated between a barrier semiconductor electrode,Chromium doped namely Gallium Arsenide(Ga As:Cr),as a cathode and an Indium–...Nonlinear behavior of glow discharge plasmas is experimentally investigated.The glow is generated between a barrier semiconductor electrode,Chromium doped namely Gallium Arsenide(Ga As:Cr),as a cathode and an Indium–Tin Oxide(ITO) coated glass electrode as an anode,in reverse bias.The planar nature of electrodes provides symmetry in spatial geometry.The discharge behaves oscillatory in the time domain,with single and sometimes multiperiodicities in plasma current and voltage characteristics.In this paper,harmonic frequency generation and transition to chaotic behavior is investigated.The observed current–voltage characteristics of the discharge are discussed in detail.展开更多
Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry(XRD), scanning...Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry(XRD), scanning electron microscopy(SEM), and atomic force microscopy(AFM) are used for the structural and morphological analysis of the nitrided layers. Vickers' microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar(1 bar = 105Pa). A considerable increase in surface microhardness(approximately by a factor of 2) is observed for longer duration(10 h) and 2-mbar pressure. Longer duration(10 h) and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.展开更多
A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equati...A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column).Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.展开更多
A different combined effects for helium gas discharge such as: magnetic field strength, breakdown voltage, applied power, applied pressure, cathode fall thickness, edge effect, distribution of the electron temperature...A different combined effects for helium gas discharge such as: magnetic field strength, breakdown voltage, applied power, applied pressure, cathode fall thickness, edge effect, distribution of the electron temperature and density, and finally exposure time for Staphylococcus aureus substrate over slides at the cathode edge, are discussed under the influence of cold, nonthermal plasmas, ultra low pressure, and presence of the magnetic field for disinfection of bacteria for short exposure times, compatible to International Commission on Non-Ionizing Radiation Protection, Health Phys (ICNIRP) for healing applications. Furthermore, analyses of the experimental data of initial and final densities of cells alive, using survival curves, showed an impressive inhibitory effect of plasma discharge to the remaining survival of bacterial ratio under the influence of the magnetic field.展开更多
文摘Under argon DC glow plasma, the nitrogen removal from molten steel was studied. The experimental result showed that nitrogen mass percent could be reduced to 0000 8%. The change of polarity had no impact on nitrogen removal when the nitrogen mass percent was low. The mechanism of denitrogenation of molten steel under argon DC glow plasma was discussed.
文摘The (DC-GDPAU) is a DC glow discharge plasma experiment that was designed, established, and operated in the Physics Department at Ain Shams University (Egypt). The aim of this experiment is to study and improve some properties of a printed circuit board (PCB) by exposing it to the plasma. The device consists of cylindrical discharge chamber with movable parallel circular copper electrodes (cathode and anode) fixed inside it. The distance between them is 12 cm. This plasma experiment works in a low-pressure range (0.15 - 0.70 Torr) for Ar gas with a maximum DC power supply of 200 W. The Paschen curves and electrical plasma parameters (current, volt, power, resistance) characterized to the plasma have been measured and calculated at each cm between the two electrodes. Besides, the electron temperature and ion density are obtained at different radial distances using a double Langmuir probe. The electron temperature (<em>KT<sub>e</sub></em>) was kept stable in range 6.58 to 10.44 eV;whereas the ion density (<em>ni</em>) was in range from 0.91 × 10<sup>10</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup> to 1.79 × 10<sup>10</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup>. A digital optical microscope (800×) was employed to draw a comparison between the pre-and after effect of exposure to plasma on the shaping of the circuit layout. The experimental results show that the electrical conductivity increased after plasma exposure, also an improvement in the adhesion force in the Cu foil surface. A significant increase in the conductivity can be directly related to the position of the sample surfaces as well as to the time of exposure. This shows the importance of the obtained results in developing the PCBs manufacturing that uses in different microelectronics devices like those onboard of space vehicles.
基金supported by the Natural Science Foundation of Hebei Province,China(No.A2006000123)
文摘Using a combination of the Monte Carlo models of fast electrons,of molecular ions(N_2^++) and of atomic species (N^+,N_f),the influence of the discharge pressure (P) and voltage(V_c) on the energy distributions of fast atomic species (N^+,N_f) produced by e^--N_(2s) and N_2^+-N_(2s) dissociation reactions at the cathode in a nitrogen do glow discharge was investigated.Boththe angular distributions and the density distributions along the radius of the species (N^+,N_f)produced by the two dissociations at the cathode were calculated.The results show that:(1)there is an optimum discharge condition for P and V_c in order to obtain the species (N^+,N_f)at the cathode with high a density and energy,(2) when the voltage is above 800 V,the species(N^+,N_f) bombarding the cathode are mainly produced by the N_2^+-N_(2s) dissociation,whereas whenthe voltage is below 300 V,they are mainly produced by the e^--N_(2s) dissociation,and (3)at highvoltages the incident angles of a considerable number of N_f into the cathode are quite small.Thedensity of the species (N^+,N_f) at the cathode increases with the voltage,and when the pressuregoes up to about 133 Pa,it decreases with the increasing pressure.
文摘DC plasma is a very promising technology for processing different materials, and is becoming especially interesting when low environmental impact and high-performance treatments are needed. Some of the intrinsic characteristics of DC plasma technology, which make it suitable for powder metallurgy (PM) and powder injection molding (PIM) parts production, are low- pressure processing and plasma environment high reactivity. Moreover it can be considered as a highly competitive green technology. In this work, an overview of some of the important DC plasma techniques applied to PM and PIM parts processing is presented. Emphasis is given to the descriptions of the main characteristics and the technique potentials of plasma-assisted nitriding, plasma-assisted thermal debinding, plasma-assisted sintering, and simultaneously plasma-assisted sintering and surface alloying. The aspects presented and discussed in this paper indicate that DC plasma processes are promising and competitive techniques for PM and PIM parts processing.
基金supported by QAU URF,Pakistan Science Foundation(PSF)Project No.PSF/RES/Phys(152),HEC project 20-2002(R&D) and HEC project for Gomal University Plasma Physics Laboratorythe financial support of HEC for their doctoral studies under the indigenous fellowship scheme
文摘Optical emission spectroscopy is used to investigate the nitrogen-hydrogen with trace rare gas(4% Ar) plasma generated by 50 Hz pulsed DC discharges.The filling pressure varies from1 mbar to 5 mbar and the current density ranges from 1 mA·cm-2to 4 mA·cm-2.The hydrogen concentration in the mixture plasma varies from 0% to 80%,with the objective of identifying the optimum pressure,current density and hydrogen concentration for active species([N] and [N2])generation.It is observed that in an N2-H2gas mixture,the concentration of N atom density decreases with filling pressure and increases with current density,with other parameters of the discharge kept unchanged.The maximum concentrations of active species were found for 40% H2in the mixture at 3 mbar pressure and current density of 4 mA·cm-2.
基金supported by the Scientific Research Project Fund of Middle East Technical University,under project # BAP-08-11-2016-044
文摘Nonlinear behavior of glow discharge plasmas is experimentally investigated.The glow is generated between a barrier semiconductor electrode,Chromium doped namely Gallium Arsenide(Ga As:Cr),as a cathode and an Indium–Tin Oxide(ITO) coated glass electrode as an anode,in reverse bias.The planar nature of electrodes provides symmetry in spatial geometry.The discharge behaves oscillatory in the time domain,with single and sometimes multiperiodicities in plasma current and voltage characteristics.In this paper,harmonic frequency generation and transition to chaotic behavior is investigated.The observed current–voltage characteristics of the discharge are discussed in detail.
基金supported by the Higher Education Commission (HEC) of Pakistan under a research project
文摘Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry(XRD), scanning electron microscopy(SEM), and atomic force microscopy(AFM) are used for the structural and morphological analysis of the nitrided layers. Vickers' microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar(1 bar = 105Pa). A considerable increase in surface microhardness(approximately by a factor of 2) is observed for longer duration(10 h) and 2-mbar pressure. Longer duration(10 h) and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.
基金The project supported by the National Nature Science Foundation of China (No. 10275010)
文摘A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column).Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.
文摘A different combined effects for helium gas discharge such as: magnetic field strength, breakdown voltage, applied power, applied pressure, cathode fall thickness, edge effect, distribution of the electron temperature and density, and finally exposure time for Staphylococcus aureus substrate over slides at the cathode edge, are discussed under the influence of cold, nonthermal plasmas, ultra low pressure, and presence of the magnetic field for disinfection of bacteria for short exposure times, compatible to International Commission on Non-Ionizing Radiation Protection, Health Phys (ICNIRP) for healing applications. Furthermore, analyses of the experimental data of initial and final densities of cells alive, using survival curves, showed an impressive inhibitory effect of plasma discharge to the remaining survival of bacterial ratio under the influence of the magnetic field.
