Seishiro Hashiguchi

Experimentally Determined Branching Ratios for Transitions in ArII

Values of 272 branching ratios are determined for 98 ArII levels which include 5s, 6s, 4p, 5p, 4d, 5d, 4f and 5f levels. Among them, 178 branching ratios are not given in the NBSs table. Spectral intensities of ArII lines were measured in the wavelength range from 500 nm to 200 nm using a hollow cathode glow discharge as a light source. Values of the branching ratio agree with those obtained by Danzmann and Kock within ±5%.

Investigation of discharge phenomena in a cell of color plasma display panel. I: One-dimensional model and numerical method

A numerical simulation method using a one-dimensional fluid model under the local field approximation is presented in order to understand pulsed-dc discharge in He?Xe gas mixture in a cell of a full-color plasma display panel. Spatiotemporal behaviors of the electric field and number densities of twelve independent particles, including electrons and four kinds of ions, were calculated self-consistently at a gas pressure of 200?Torr (27?kPa) and an electrode distance of 0.02?cm. The imprisonment of 147-nm-resonance radiation, the excitation source of phosphors, was also taken into account. Calculated results of the discharge current and voltage are consistent with those of experiment. The waveform of 147-nm-resonance radiation agreed well with experiment, although that of the discharge current showed some difference, probably due to the local field approximation.

Theory of the Hollow Cathode Glow Discharge

A theory of the hollow cathode glow discharge based on the two-temperature electron model is developed. The following two interdependent mechanisms are consistently taken into account: the creation of ions and excited atoms due to electron collisions in the discharge and the emission of secondary electrons on the cathode surface due to ions and ultraviolet photons. Trapped electrons in the hollow are also considered. Numerical calculations are made for helium gas in a cylindrical hollow cathode whose inner diameter and length are 10 and 32 mm, respectively, on the basis of a onedimensional steady state model. Voltage-current relations are obtained at gas pressures of 0.13, 0.27 and 0.40 kPa. Population densities of 64 excited atomic levels are determined as a function of the radial distance r as well as the densities of the ions and electrons.

Calculations for the Distribution Function of Energetic Electrons in a Helium Hollow Cathode Glow Discharge with the Monte Carlo Method

The distribution function of energetic electrons is calculated by tracing their trajectories with the Monte Carlo method. Electrons were made to have inelastic and elastic collisions with helium atoms in the ground state. Calculations were made for a cylindrical hollow cathode whose inner diameter is 1 cm. The electron density increased rapidly with decreasing energy near the lower limit of its energy. The number density of electrons whose energy equals the cathode-fall potential has a peak at the central axis. Their velocities are found to be directed along a collisionless trajectory. The broad angular distribution of the velocity was found in slower electrons. The peak of the number density at the central axis decreased with increasing pressure. The energetic electrons can hardly penetrate into the central region when the gas pressure is 1.3 kPa.

Numerical calculations for the electron energy distribution in a helium, hollow-cathode glow discharge

An electron energy distribution is determined with the Monte Carlo method in a helium, hollow-cathode glow discharge. Electron-electron collisions are taken into account, as well as electron collisions with atoms. In the negative glow, a plateau-like profile is obtained in the low-energy region; the profile approximates a Maxwellian distribution in this energy range. The energy distribution decreases rapidly at about the minimum excitation energy of the atom. In the center of the negative glow, the low-energy electrons are five orders of magnitude as many as the high-energy electrons, which have enough energy to excite or ionize atoms. >

Evaluation of improved efficiency with a diamond coating for a plasma display panel electrode

Application of diamond to electrode coating of a plasma display panel (PDP) is evaluated, since we expect diamond to emit much secondary electron due to the Auger neutralization induced by Xe ions. In a conventional magnesium oxide-xenon (MgO/Xe) system, the most abundant Xe+ produced in the discharge does not effectively cause the secondary electron emission, because the condition of the Auger neutralization is not satisfied. In order to increase the efficiency of ultraviolet (UV) radiation, being especially important for engineering, we should avoid such inefficiency. Under suitable conditions in diamond/Xe system the Auger neutralization can occur. Further, if the electron affinity χ is negative, i.e., negative electron affinity (NEA), the condition of the Auger neutralization in diamond/Xe system is sufficiently satisfied. First, we calculate the coefficients of the secondary electron emission on diamond of clean surface or of hydrogenated surface where the dangling bonds are terminated, on the basis ...

Numerical simulation of metal-halide lamp using a time-dependent two-dimensional model

Numerical simulation of a vertically held metal-halide lamp (Hg/Na/Sc system) is presented. The lamp was driven by an ac current of 60 Hz. The model took convection and diffusion of various species into account. A method for rapid calculation of optically thick radiation power was developed. Density of scandium ions and sodium ions has a minimum on the central axis due to radial ambipolar diffusion. Density of metallic atoms and ions and metal iodine molecules decreases with increasing axial distance from the bottom of the tube. This tendency was explained by convection and diffusion. The density of scandium ions depends on the direction of the current; the density was greater at upward current than at downward current.

Improvement of Efficiency of Ultraviolet Radiation in a Plasma Display Panel with a Complex Buffer Gas

Discharge in an opposed discharge-type ac plasma display panel cell was analyzed with a one-dimensional fluid model. The present study used helium, neon, argon and some combination of them as a buffer gas which was added to xenon gas. Calculation was performed for a sequence of pulses of sustaining voltage after applying a writing voltage. The composition of Ne/Ar buffer gas with Ne:Ar=1:3 gave the highest efficiency of Ultraviolet radiation. It was 1.6 times as large as the efficiency of simple neon buffer gas for 10%Xe. The efficiency increased with increasing fraction of xenon but the region of stable discharge decreased in size with increasing fraction of xenon.

Numerical Investigation of Vertical Mercury Arc Operating at Various Tube Radii

Vertically standing mercury-arc discharge was investigated with a fluid model which treated radiation power due to optically thick lines precisely. Transport coefficients were determined using on electron-mercury atom collision cross section which was recently measured by England and Elford. The radiation power which was expressed as a function of temperature agreed with experiment for a 400-W operation. Variations of temperature and axial velocity were studied as a function of tube radius. At the central region, it was found that the input power almost transferred to radiation power for large tube radii and that it was mainly consumed as heat conduction loss for small tube radii. Normalized axial velocity profile along the radial direction was almost independent of the tube radius, although its maximum value increased with increase in the tube radius.

Multi Electron-Temperature Models for a Hollow Cathode Glow Discharge

A numerical simulation is made of a cylindrical hollow cathode glow discharge in helium gas. Electrons are assumed to consist of two or three groups of different temperatures. Calculations are made for the following conditions: gas pressure of 0.24 kPa, cathode fall potential of 260 V and discharge current of 33 mA. Numerical results present number densities of electrons, ions and excited atoms of 64 excited levels as a function of the radial distance r. Experimentally determined population densities of excited atoms are also presented as a function of r. Agreement of calculation with experiment is good for densities at the center of the cathode. Calculated densities, however, have a larger peak near the edge of the negative glow than measured densities.