Shogo Kajita

Influence of the dissociation process of oxygen on the electron swarm parameters in oxygen

Previous theoretical studies assumed that the energy loss of a colliding electron has a discrete value for dissociative excitation of molecular oxygen. In the calculation of the rate coefficients for oxygen atom yields using the Boltzmann equation, the previous reports have used discrete energy loss values of 6.1 eV for A3Σ+u and 8.4 eV for B3Σ−u. In this paper, we take account of the fact that the excitation to B3Σ−u has a continuum energy loss spectrum and describe the effects on calculated swarm parameters that are important in the simulation of ozonizer discharges. It can be seen that the use of a continuum electron energy‐loss spectrum as opposed to a discrete electron energy loss associated with excitation to the B3Σ−u state makes no significant difference in the calculated values of electron swarm parameters in oxygen. We also calculate the ozone yield as a function of E/N obtained from the analysis of the energy balance equation. In this case, the partial cross section for dissociation via B3Σ−u a...

Electron swarms in NF3-rare gas and NF3-N2 mixtures

The swarm parameter has been calculated as a function of the amount of NF3 in Ar, He and N2 using the two-term Boltzmann equation. In particular, the attachment coefficient and attachment rate coefficient in NF3 are compared with the experimental values measured by Lakdawala et al. The large discrepancies between the measured and calculated values of the attachment rate coefficient for NF3 mixture in Ar, which were pointed out by Lakdawala et al., are discussed.

Ozone production in corona discharges in air in a multi-needle to plane configuration

The authors present the experimental results of ozone production per unit power (OPPU) obtained with a multi-needle-to-plane discharge electrode configuration stressed with negative polarity. Results are reported for different needle separations and different values of the applied voltage. The OPPU increased as the needle separation increased. Measurements showed a significant decrease in the value of the OPPU with the transition to the pulseless discharge mode.<<ETX>>

Current density distribution on the plane electrode in a multineedle to plane configuration

The authors present the experimental results obtained with multineedle discharge electrodes, for use in electrostatic separators, stressed with positive and negative DC voltage. The aim was to determine the effect of gap height and needle spacing on the current density pattern and its value on the plane electrode. Profiles of ion density on the plane electrode were measured precisely. Results of measurements are reported for different needle separations and gap height. The interaction between the needles and its effect on the corona current and onset voltage are discussed.<<ETX>>

Ion Transport Analysis by Extended Wannier Theory: Effect of Ion Density Gradient.

In this paper, Wanniers integral-differential equations derived from the Boltzmann equation in the cases of cold gas or high-electric-field model with a uniform ion density distribution were extended to cases having density gradients toward the field direction. Velocity distributions of ion swarm were obtained by solving these equations using numerical calculations. The mobilities and diffusion coefficients obtained from these velocity distributions agreed with ones obtained previously through Monte Carlo simulation.

Velocity distribution of H+ ions under runaway conditions in helium

The velocity distribution of H+ ions in helium has been obtained using the Monte Carlo method for ratios of the electric field to gas number density E/N from 5.65-56.6 Td. The discrepancies in the velocity distributions between runaway conditions and non-runaway conditions are considered. In the case of the runaway conditions, the velocity distribution has elongated tails in all directions and the tail in the direction of the electric field is especially elongated.