Man Hyeop Han

Experimental Analysis of Reduced Electric Field during Time-Variable Pulsed Dielectric Barrier Discharge

Time-variable pulsed dielectric barrier discharges in open air have been investigated to calculate the reduced electric field at breakdown using a simple electrical circuit. In this calculation, charges accumulated on the dielectric surface before discharge breakdown, were integrated to measure gap voltage and reduced electric field. Experimental result showed that in the case of pulse discharge, the gap voltage at pulsed breakdown experimentally showed a Paschen curve with decreasing gap distance. The simulation result obtained using the Boltzmann equation solver shows that the electron energy distribution changed with gap voltage and reduced electric field. We also conclude that pulse rise time plays an important role in determining reduced electric field, and finally electron energy.

Improvement of the vacuum ultraviolet efficiency of low pressure Xe discharge by nitrogen admixture

We investigated Xe–N2 gas discharge primarily as a source of vacuum ultraviolet for florescent lamps. The discharge performances of Xe based nitrogen admixture gas are improved when compared with the results of pure Xe discharge. The experimental results come from investigating the Xe positive column and were determined by measuring the infrared radiation during the discharge operation. These results suggest that the integrated infrared area is increased by about 40% under optimal conditions. This efficiency increase occurs because low energy electrons contribute to the production of exited nitrogen, which can excite Xe gas.

Plasma expansion of ZnO-coated surface barrier discharge in open air and its optical analysis

Characteristics of the ZnO-coated surface barrier discharge in open air were diagnosed optically. Highly conductive ZnO film was deposited on the dielectric surface. We found that the increase of the surface conductivity induces wider discharge area. Moreover we analyzed the optical behavior of plasma transition of two barrier discharges by optical emission spectroscopy. Discharge characteristic of the normal dielectric barrier discharge is divided into only two modes: streamer and glow discharge. But in the case of ZnO-coated dielectric barrier discharge, pd range of glowlike discharge exists widely and this can be also an evidence of the enhancement of plasma uniformity.

Improvement of plasma uniformity using ZnO-coated dielectric barrier discharge in open air

Summary form only given. The discharge behavior in atmospheric pressure dielectric barrier discharge (DBD) using ZnO-coated dielectric layer are examined. Using RF magnetron sputtering, ZnO thin film deposited on the alumina surface represents the higher surface conductivity of about 106 orders than bare alumina surface. And we made two types of DBD reactor, normal DBD using bare alumina and ZnO-coated DBD. The size of the area was 5 cmtimes2 cm for dielectric layer and 3 cmtimes1 cm for copper electrode. Negative DC pulse power was applied to each reactor. And the pulse was generated by thyratron switching element and applied frequency is 1 kHz. Experimental result shows that in case of ZnO-coated DBD, discharge uniformity is improved definitely. Increase of surface conductivity causes charge spreading over the dielectric surface widely and these charges play a role of seed electrons for the initiation of consecutive streamer. Therefore the radius of microdischarge in air is decreased but fine and numerous current pulses are generated. This situation enhances the uniformity and stability of atmospheric pressure discharge in open air

Large area silicon dioxide deposition using rf atmospheric pressure glow discharge at low termperature

Summary form only given. RF APGD (atmospheric pressure glow discharge) is nonequilibrium plasma and low temperature plasma. This plasma source is of interest for the deposition of materials because low temperature deposition without a vacuum system is possible. Moreover, remote plasma deposition process using atmospheric pressure plasma jet has some advantages due to suppression of ion bombardment effect. Silicon dioxide films were deposited using an atmospheric pressure plasma jet composed of two planar electrodes with an area of 50 mm times 30 mm at a distance of 1 mm. The planar jet was operated with helium of 20 slm, O2 of 400 sccm and RF (13.56 MHz) power of 60-100 W was applied. He-TEOS mixture (99% He, 1% TEOS) was injected into the plasma region directly. The films were deposited on silicon substrates with heating 100-300 Z. We investigated the deposition rate at various conditions by controlling power, oxygen pressure and TEOS pressure, substrate temperature. And we analyzed the film properties with former variables by SEM, FTIR, AFM and hardness test. Finally, large area SiO2 deposition was accomplished uniformly by only one directional scan system since the plate jet has linear shape

Publisher's Note: Efficient Inverted Top-Emitting Organic Light Emitting Diodes with Transparent and Surface-Modified Multilayer Anodes [ Electrochem. Solid-State Lett. , 13 , J43 (2010) ]

Publisher’s Note: Efficient Inverted Top-Emitting Organic Light Emitting Diodes with Transparent and Surface-Modified Multilayer Anodes [Electrochem. Solid-State Lett., 13, J43 (2010)] Seung Yoon Ryu, Chang Ho Lee, Il Soo Oh, Seung Yong Song, Kyu Hwan Hwang, Hyeon Seok Hwang, Man Hyeop Han, Byoung Har Hwang, Hong Koo Baik, Youn Sang Kim, and Jun Yeob Lee Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea Samsung Mobile Display, Company, Limited, Yongin-City, Gyeonggi 449-577, Korea Department of Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742, Korea Department of Polymer Science and Engineering, Dankook University, Yongin-City 448-701, Korea

Plasma decontamination of chemical & biological warfare agents by a cold arc plasma jet at atmospheric pressure

The cold arc plasma jet was introduced to decontaminate chemical and biological warfare (CBW) agents for the application of a portable CBW decontamination system. The cold arc plasma jet is a low temperature, high density plasma that produces highly reactive species such as oxygen atoms and ozone. Moreover, it is possible to maintain stable plasma without He or Ar. The discharge operated on N2-02 mixture of 30 L/min, and the high voltage pulse (23 kHz, 30% duty ratio) power was applied to the inner electrode. In the decontamination experiments, Bacillus subtilis and Escherichia Coli were chosen as simulants for biological agents and DMMP (Dimethylmethylphosphonate) was chosen as a simulant for chemical agents. The experimental results showed that B. subtilis and E. coli were efficiently decontaminated. Also, DMMP absorbed on the metal substrate and the glass substrate was removed after plasma treatment. Finally, we identified that DMMP was decomposed very well in the plasma effluent.

The efficient plasma plume extraction from atmospheric pressure parallal dielectric barrier discharge jet

Summary form only given. Planar dielectric barrier discharges (DBDs) have a large number of industrial applications because of simple structure and no need for cumbersome impedance matching systems. However, planar DBD still have some disadvantages such as the limit of gap distance and the non-uniformity due to the characteristics of microdischarge intercepting electrodes. Therefore the DBD jet has been introduced. Other known atmospheric pressure plasma jet devices can generate very short plumes in the millimeter range. Recently Laroussi et al. developed a new plasma jet with long plume in the centimeter range. However, this type has difficulty in making large area plasma plume. Teschke et al. showed the possibility of long and large area plasma plume using coplanar DBD structure. Using coplanar DBD structure, we developed novel parallel DBD jet. The plasma source consisted of two coplanar DBD, which were made of two thin copper strips and alumina plate with 1 mm thickness. Each coplanar DBD was positioned as facing alumina plane with 1 mm gap. The helium was flowed into the gap with flow rate in the 10-40 l/min. A high voltage with frequency ranging from 1-30 kHz and amplitude up to 10 kV was supplied between two copper strips of each coplanar DBD. Experimental results showed the long and large plasma plume in the centimeter range. The length of the plume depended on the helium flow rate and the magnitude of the applied voltage

Adhesion enhancement of polymer-coated tin plate using atmospheric plasma treatment

Summary form only given. Adhesion characteristics of tin plate with polymer-coating is investigated after atmospheric plasma treatment. We have used atmospheric dielectric barrier discharge plasma for treatment and contact angle, XPS, SEM for surface analysis. It is observed that contact angle is decreased remarkably. It indicates surface energy is increased, that provides more driving force for adhesion. And we have observed that carbon ratio is decreased and at the same time oxygen ratio is increased. It is thought to be a carbon cleaning effect and oxidation effect which makes functional groups on the tin plate. It may cause the increase of adhesion. We have observed the enhancement of adhesion between tin plate and polymer coating as a result of taping test. Besides, the number of pin hole, which causes elusion of metal contents, is decreased. Therefore plasma treatment can be effective tool for adhesion enhancement of tin plate used for cans which contain edible foods