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
The effects of the ionic wind on the heat transfer rate from a heated vertical flat plate are described. The ionic wind is induced by three different types of discharge, corona discharge, dielectric barrier discharge ...The effects of the ionic wind on the heat transfer rate from a heated vertical flat plate are described. The ionic wind is induced by three different types of discharge, corona discharge, dielectric barrier discharge （DBD） and dc glow discharge. The heat transfer coefficients for the heated copperplate under free convection conditions with and without an ionic wind are obtained by measuring the temperature and the heating power of the copper plate. It has been proved that the convective heat transfer coefficients increase by several times with the help of the ionic wind. With the ionic wind induced by a uniform dc glow discharge, the heat transfer coefficient of the heated copper plate is highly enhanced compared with those induced by a corona discharge or DBD. With the use of DBD, the breakdown voltage is increased significantly, which is helpful in avoiding a breakdown when heat transfer is enhanced by the ionic wind. In addition, it makes the application of the ionic wind much safer.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
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＋） and of atomic species （N^＋, Nf）, the influence of the discharge pressure （P） and voltage （Vc） on the energy distributio...Using a combination of the Monte Carlo models of fast electrons, of molecular ions （N＋） and of atomic species （N^＋, Nf）, the influence of the discharge pressure （P） and voltage （Vc） on the energy distributions of fast atomic species （N^＋, Nf） produced by e^--N2s and N2^＋- N2s dissociation reactions at the cathode in a nitrogen dc glow discharge was investigated. Both the angular distributions and the density distributions along the radius of the species （N^＋, Nf） produced by the two dissociations at the cathode were calculated. The results show that： （1） there is an optimum discharge condition for P and Vc in order to obtain the species （N^＋, Nf） at the cathode with high a density and energy, （2） when the voltage is above 800 V, the species （N^＋, Nf） bombarding the cathode are mainly produced by the N^＋-N2s dissociation, whereas when the voltage is below 300 V, they are mainly produced by the e-N2s dissociation, and （3） at high Voltages the incident angles of a considerable number of Nf into the cathode are quite small. The density of the species （N^＋ Nf） at the cathode increases with the voltage, and when the pressure goes up to about 133 Pa, it decreases with the increasing pressure.展开更多
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.
文摘The effects of the ionic wind on the heat transfer rate from a heated vertical flat plate are described. The ionic wind is induced by three different types of discharge, corona discharge, dielectric barrier discharge （DBD） and dc glow discharge. The heat transfer coefficients for the heated copperplate under free convection conditions with and without an ionic wind are obtained by measuring the temperature and the heating power of the copper plate. It has been proved that the convective heat transfer coefficients increase by several times with the help of the ionic wind. With the ionic wind induced by a uniform dc glow discharge, the heat transfer coefficient of the heated copper plate is highly enhanced compared with those induced by a corona discharge or DBD. With the use of DBD, the breakdown voltage is increased significantly, which is helpful in avoiding a breakdown when heat transfer is enhanced by the ionic wind. In addition, it makes the application of the ionic wind much safer.
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.
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＋） and of atomic species （N^＋, Nf）, the influence of the discharge pressure （P） and voltage （Vc） on the energy distributions of fast atomic species （N^＋, Nf） produced by e^--N2s and N2^＋- N2s dissociation reactions at the cathode in a nitrogen dc glow discharge was investigated. Both the angular distributions and the density distributions along the radius of the species （N^＋, Nf） produced by the two dissociations at the cathode were calculated. The results show that： （1） there is an optimum discharge condition for P and Vc in order to obtain the species （N^＋, Nf） at the cathode with high a density and energy, （2） when the voltage is above 800 V, the species （N^＋, Nf） bombarding the cathode are mainly produced by the N^＋-N2s dissociation, whereas when the voltage is below 300 V, they are mainly produced by the e-N2s dissociation, and （3） at high Voltages the incident angles of a considerable number of Nf into the cathode are quite small. The density of the species （N^＋ Nf） at the cathode increases with the voltage, and when the pressure goes up to about 133 Pa, it decreases with the increasing pressure.
