A hydrodynamic model is used to investigate the characteristics of positive ions in the sheath region of a low-pressure magnetized electronegative discharge. Positive ions are modeled as a cold fluid, while the electr...A hydrodynamic model is used to investigate the characteristics of positive ions in the sheath region of a low-pressure magnetized electronegative discharge. Positive ions are modeled as a cold fluid, while the electron and negative ion density distributions obey the Boltzmann distribution with two different temperatures. By taking into account the ion-neutral collision effect in the sheath region and assuming that the momentum transfer cross section has a power law dependence on the velocity of positive ions, the sheath formation criterion （modified Bohm＇s criterion） is derived and it is shown that there are specified maximum and minimum limits for the ion Mach number M. Considering these two limits of M, the behaviors of electrostatic potential, charged particle density distributions and positive ion velocities in the sheath region are studied for different values of ion-neutral collision frequency.展开更多
A hydrodynamic model is used to investigate the properties of positive space-charge and net current density in the sheath region of magnetized, collisional plasmas with warm positive ions. It is shown that an increase...A hydrodynamic model is used to investigate the properties of positive space-charge and net current density in the sheath region of magnetized, collisional plasmas with warm positive ions. It is shown that an increase in the ion-neutral collision frequency, as well as the magnitude of the external magnetic field, leads to an increase in the net current density across the sheath region. The results also show that the accumulation of positive ions in the sheath region increases by increasing the ion-neutral collision frequency and the magnitude of the magnetic field. In addition, it is seen that an increase in the positive ion temperatures causes a decrease in the accumulation of positive ions and the net current density in the sheath region.展开更多
A hydrodynamic approach is used to investigate a three-component magnetized plasma sheath which consists of electrons and two species of positive ions. Assuming a phase space of one-dimensional spatial coordinate syst...A hydrodynamic approach is used to investigate a three-component magnetized plasma sheath which consists of electrons and two species of positive ions. Assuming a phase space of one-dimensional spatial coordinate system and three-dimensional velocity coordinate system, the effect of different concentrations of positive ion species on some characteristics of the plasma sheath such as the velocity and density distribution of positive ion species and the electrostatic potential of this region is investigated. The calculated results show that the increase in the density ratio of positive ion species causes a decrease in both the ion velocities and the electrostatic potential of the sheath region. Also, it is shown that in the sheath region of a magnetized plasma consisting of only one positive ion species the bumps of the net density of charged particles disappears much faster. In addition, three-dimensional velocity of each positive ion species in the sheath region is plotted for different concentrations of positive ion species.展开更多
文摘A hydrodynamic model is used to investigate the characteristics of positive ions in the sheath region of a low-pressure magnetized electronegative discharge. Positive ions are modeled as a cold fluid, while the electron and negative ion density distributions obey the Boltzmann distribution with two different temperatures. By taking into account the ion-neutral collision effect in the sheath region and assuming that the momentum transfer cross section has a power law dependence on the velocity of positive ions, the sheath formation criterion （modified Bohm＇s criterion） is derived and it is shown that there are specified maximum and minimum limits for the ion Mach number M. Considering these two limits of M, the behaviors of electrostatic potential, charged particle density distributions and positive ion velocities in the sheath region are studied for different values of ion-neutral collision frequency.
文摘A hydrodynamic model is used to investigate the properties of positive space-charge and net current density in the sheath region of magnetized, collisional plasmas with warm positive ions. It is shown that an increase in the ion-neutral collision frequency, as well as the magnitude of the external magnetic field, leads to an increase in the net current density across the sheath region. The results also show that the accumulation of positive ions in the sheath region increases by increasing the ion-neutral collision frequency and the magnitude of the magnetic field. In addition, it is seen that an increase in the positive ion temperatures causes a decrease in the accumulation of positive ions and the net current density in the sheath region.
基金supported by the Research Council of the Shahaid Beheshti University,G.C.of Iran
文摘A hydrodynamic approach is used to investigate a three-component magnetized plasma sheath which consists of electrons and two species of positive ions. Assuming a phase space of one-dimensional spatial coordinate system and three-dimensional velocity coordinate system, the effect of different concentrations of positive ion species on some characteristics of the plasma sheath such as the velocity and density distribution of positive ion species and the electrostatic potential of this region is investigated. The calculated results show that the increase in the density ratio of positive ion species causes a decrease in both the ion velocities and the electrostatic potential of the sheath region. Also, it is shown that in the sheath region of a magnetized plasma consisting of only one positive ion species the bumps of the net density of charged particles disappears much faster. In addition, three-dimensional velocity of each positive ion species in the sheath region is plotted for different concentrations of positive ion species.
