In Cheol Song

The Effects of Electrode Structures on the Luminous Efficacy of Micro Dielectric Barrier Discharges

A high-efficacy alternating-current plasma display panel utilizing various electrode structures is simulated using a 3-D fluid code for the investigation of the effects of cell structures on the discharge characteristics of micro dielectric barrier discharges. For the modification of the conventional coplanar electrode structure, three suggested electrode structures were simulated, namely, a patterned bus electrode, a multilayer bus electrode, and a two-electrode facial discharge structure. The time evolutions of infrared radiation images for the three structures compare well with the experimental results of test panels. The ultraviolet and visible-light emission profiles, as well as the time evolution of wall charge profiles, are analyzed in order to explain the role of the electrode structure for the improvement of luminous efficacy.

The effect of electrode tilt angle on the characteristics of coplanar dielectric barrier discharges with Xe-Ne mixtures

The results of a two-dimensional fluid simulation of a plasma display panel (PDP) cell show that the discharge characteristics of a coplanar dielectric barrier discharge can be controlled by the electrode tilt angle rather than by the gas mixture ratio or gap distance. The change in the tilt angle results in a significant change in the wall charge distribution and the discharge duration for each pulse. Therefore, the breakdown voltage, plasma density, light brightness, and luminous efficacy can be controlled by the tilt angle. A concave electrode structure allows large wall charge accumulation near the outer edge of two coplanar electrodes, and it results in a long-duration discharge, high luminance, and high luminous efficacy. On the other hand, a convex electrode structure allows high wall charge accumulation near the gap between two coplanar electrodes, and it results in a short-duration discharge with a decreased breakdown voltage.

Simulation of Low-Pressure Capacitively Coupled Plasmas Combining a Parallelized Particle-in-Cell Simulation and Direct Simulation of Monte Carlo

A parallelized particle-in-cell (PIC) simulation and direct simulation of Monte Carlo (DSMC) are combined to simulate low-pressure discharges. A two-dimensional (2-D) PIC simulation parallelized with graphics processing units is used to examine the discharge characteristics of a capacitively coupled plasma device at pressures <; 10 mTorr, whereas a DSMC method is used to calculate the neutral distribution instead of a fluid model. The neutral distribution profile is transferred to the PIC simulation as the initial condition. At low gas pressures, the neutral density profile shows nonuniform properties, which also changes the simulation results of plasma uniformity. Overall, the inclusion of an accurate neutral density profile is essential for obtaining exact simulation results that are comparable with the experimental results.

Ray-Trace Calculation of Visible Lights Emitted From a Display Device Utilizing Ultraviolet Lights From Gaseous Discharges

A ray-trace model has been developed for the visible lights coming out from phosphors excited by vacuum ultraviolet (UV) lights in gaseous discharges. The spatial and angular light distributions are calculated numerically by considering multiple reflections of the visible lights within a plasma-display-panel (PDP) cell. Luminance of the emitting visible lights is illustrated for two different electrode shapes of an ac-type PDP cell. This calculation can be used for the improvement of optical properties of display devices utilizing phosphors and UV lights from plasma discharges, such as flat fluorescent lamps as well as PDP.

A two-dimensional hybrid simulation for micro dielectric barrier discharges operated in atmospheric pressure

A plasma display panel cell is one example of micro dielectric barrier discharges operated in near atmospheric pressure. It is difficult to measure the phenomena experimentally in such a small discharge at atmospheric pressure. In most cases, atmospheric pressure discharges are simulated with a fluid model using drift-diffusion approximation and local field approximation. However, it was proved in our research that the drift-diffusion approximation is not applicable to heavy ions even at a high pressure. Especially, Xe ion motion is overestimated in the fluid code. In order to investigate the discharge characteristics and analyze the effects of cell size and Xe-content of more than 10%, a hybrid model has been developed which adopts a fluid model for electrons and a particle-in-cell (PIC) model for ions. Using the hybrid code, the discharge characteristics are investigated with the diagnostics for the electric field intensity, charged and excited particles distributions, energy and angle distributions of the ions at the boundary. Conventional diagnostics for a light device are also included such as luminance, power consumption, and luminous efficacy .We compared the result with experiment to confirm adequacy of the simulation.

P-92: Three-Dimensional Fluid Simulation of an ITO-less PDP Cell

In a plasma display panel (PDP), it is demanded to reduce the manufacturing cost as well as to improve luminous efficacy. Thus, high efficient ITO-less PDPs are necessary. In this work a three-dimensional fluid simulation is adopted to analyze the discharge phenomena of various ITO-less structures in neon-xenon gas mixture. The density of Xe 3P1 is investigated for the variation of electrode shapes and UV distributions on the phosphor surfaces are calculated for the 147 nm and the 173 nm. In order to investigate time and space resolved discharge physics, four structures of bus electrodes are proposed. The highest luminance efficacy was obtained with Pi structure among the proposed ITO-less structures.

Simulation of low-pressure capacitively coupled plasmas using a parallelized particle-in-cell simulation and a direct simulation of Monte Carlo for neutrals

Summary form only given. There are increasing demands for nano-scale plasma processing such as nano-particle generation, oxide etching, and high quality thin film deposition as the microelectronics industry grows rapidly. Under very low-pressure condition (up to a few mTorr), it is difficult to generate and maintain plasmas, and therefore it is important to understand the properties of neutral gas flow together. In this study, a two-dimensional axisymmetric particle-in-cell (PIC) simulation parallelized with graphic processing units (GPUs) was utilized for the investigation of discharge characteristics of a capacitively coupled plasma (CCP) device. Direct simulation Monte-Carlo (DSMC) method was used for the calculation of neutral distribution instead of fluid model for low-pressure regime. In order to increase plasma generation under very low-pressure condition, several methods can be applied such as external magnetic field, electron beam injection [1], and resonance heating [2], of which effects are investigated in this study.

51.3: Highly Reliable Modeling of AC Plasma Display Panels with a Three‐ Dimensional Hybrid Simulation

Discharge characteristics of a PDP cell have been investigated using a three-dimensional hybrid model with an electron-fluid and ion-particle model, which shows improvement of simulation results proved by the comparison with the experimental infrared light emission. The hybrid model represents experimental results very well compared with the conventional two-fluid model adopting drift-diffusion approximation for both the electrons and the ions.

The effects of electrode angle for micro dielectric barrier discharges

An AC Plasma display panel (PDP) is a display which uses glow gas discharge at a pressure range of 400-500 Torr. It is also one example of micro dielectric barrier discharge operated in near-atmospheric pressure. Simulation is useful in order to investigate the discharge characteristics in the cell, because a PDP cell is too small to diagnose. Fluid simulation is a most practical method for a high pressure gas discharge. It gives a reasonable result in a short running time, although there are many assumptions compared with fully solved particle-in-cell simulation. Coplanar structure is the most practical model for an AC PDP. In this presentation, we investigated the discharge characteristics with the change of electrode angle using a two-dimensional fluid simulation codes. We show the result using diagnostics for the electric field intensity, charged and excited particles distributions. When the angle between two coplanar electrodes is changed, discharge characteristics changed very much. A convex electrode structure is good to reduce the driving voltage. A concave structure is effective to increase the luminance and luminous efficacy. When the amplitude of the angle increased, whether in a concave or a convex structure, the effect increased significantly.

The effects of electrode structures on the luminous efficacy of micro dielectric barrier discharges

A high efficacy alternating current plasma display panel (PDP) utilizing vertically raised multilayer bus electrodes (MBE) is simulated by using a three-dimensional fluid code for the investigation of the effects of cell structures on the discharge characteristics of a PDP cell. The raised bus electrodes provide an opposite discharge mode with a low discharge current in a relatively long gap, and thus provide higher luminance and lower current simultaneously. The luminous efficacy of an MBE-PDP with a gap distance of 350 m was found to be twice higher than that of a conventional coplanar PDP structure having an electrode gap of 60 m. The fluid simulation coupled with visible ray-trace calculation shows the light-emission patterns that vary with the electrode structures, which explain the mechanism of the improvement of the luminous efficacy. Emission spectra and spatio-temporal distributions of infra-red radiation in a PDP cell discharge were measured experimentally and are compared with simulation results.