Surface Discharge Plasma Research Articles

Examination of Maskless Etching Technique Using a Localized Surface Discharge Plasma

AbstractA maskless etching technique which is useful for solar cell manufacturing and microelectronics was examined using the localized surface discharge plasma at atmospheric pressure. Etchings were carried out on a crystalline silicon (Si) substrate and a silicon nitride (SiN) film coated on a Si substrate. Two‐ and three‐dimensional etching profiles were investigated. Based on the results, etching rates and an etching mechanism were discussed. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Heat transfer between tungsten surface and glow discharge plasmas in argon and CO2

A hot-filament method is used to study the heat transfer between tungsten surface and hollow-cathode glow discharge plasmas in argon and CO2. The dependence of the electric power supplied to a tungsten wire on the discharge current is determined for argon and carbon dioxide in the temperature range between 1000 and 1700 K. A difference in heat transfer at the tungsten wire surface is found between experiments on argon and carbon dioxide. The difference is attributed to heterogeneous recombination in CO2 plasma.

Plasma Grooving System Using Atmospheric Pressure Surface Discharge Plasma

To fabricate narrow front contact grooves on a single crystalline silicon solar cell, we carried out etching of a silicon nitride film on a silicon substrate using the surface discharge plasma operated at atmospheric pressure. The control of groove width by changing the discharge voltage (V d) and the length of a back electrode (l) used for formation of the surface discharge was examined. It was found that narrower electrode grooves could be obtained when l was short. For the case of l = 2 mm, the narrowest groove of 116 μm was obtained at V d = 3.5 kV and the processing time (t e) of 10 s.

Development of 120-mm Electro-Thermal Chemical Launcher

The unique properties of the plasma utilized in ETC guns, such as the low viscosity, high momentum and high temperature, can lead to a more uniform ignition over the entire cartridge volume, even in large-caliber guns. Since 2002, the united research group leaded by Beijing Institute of Special Electromechanical Technology (BISET) has completed a lot of experiments with a novel surface discharge plasma igniter, which generates plasma from a cylindrical surface and distributes it through radial port. The results of these experiments have shown this igniter can present perfect ignition. This paper presents an overview of this ETC program including the igniter, pulsed power supply, 120 mm ETC launchers, and some experimental results. The further experimental studies are being continued.

Features of the functional condition of the central nervous system and quality of mental functions in children of 5–7 years with a delay of intellectual development

This paper describes the effects of “runaway” electrons and the formation of an electron beam in a nanosecond surface discharge plasma at a pressure of Р≤10−2 mm mercury column. The application of those effects enables the production of a positively charged plasma with a concentration of n≥1014 cm−3 in the discharge chamber volume. Such positively charged plasma can be used in various systems of electric propulsion thrusters. An example of electrostatic EPT implementation that produces up-to-date specific characteristics was considered.

The Destruction of Atmospheric Pressure Propane and Propene Using a Surface Discharge Plasma Reactor

Surface discharge plasma reactors (SDRs) have been shown to be effective in removing a wide range of pollutants. In this study, the effectiveness of a SDR for the removal of propane and propene from an atmospheric pressure air stream was investigated. For an input energy of 100 J L-1, the conversions were found to be 16% and 68% for propane and propene, respectively. The total carbon recovery was found to increase with increasing specific input energy (SIE) for both hydrocarbons. FTIR analysis showed that CO and CO2 are the major end-products, and GC-MS identified formic acid as a significant byproduct. The effect of initial propane concentration was also investigated. The reaction chemistry involved in the oxidative plasma conversion of propane and propene is discussed.

Development of Atmospheric Pressure Low Temperature Surface Discharge Plasma Torch and Application to Polypropylene Surface Treatment

We have finally succeeded in producing the plasma jet by use of the surface discharge plasma torch that can be expected to make larger the diameter of torch in the comparatively easy way. It can be checked that the active species in the jet obtained are different depending on the direction of connection, and also it was clearly found that much O and N2 is included in them. Consequently, etching was confirmed at the position of 10 mm from the torch end in the surface treatment of polypropylene film, but etching was not confirmed at the position of 20 mm.

Simulation of Direct-Current Surface Plasma Discharge Phenomena in High-Speed Flow Actuation

We present a self-consistent 2-D multispecies multi-temperature model of dc nonequilibrium surface plasma discharge phenomena in the presence of a low-pressure imposed high-speed convective flow. For pressures of a few torr and voltages of a few kilovolts, a nonequilibrium glow discharge is generated between the electrodes. Peak charge densities in the discharge on the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , electron temperatures on the order of 1 eV, and gas temperatures on the order of 2000 K are observed. Increasing voltages are found to increase the charge density in the discharge and also cause a constriction of the discharge volume. The same trend is also observed with an increase in the discharge pressure. The discharge is highly asymmetric owing to the high-speed convective flow, with the discharge activity restricted to the flow downstream edge of the cathode surface. The convective flow also causes a quasi-neutral plasma-tail-like feature that provides a major loss mechanism for charged and neutral species in the discharge. Despite sufficient cathode surface area, the discharge operates in an abnormal glow mode, with a positive differential resistivity, owing to a flow-induced constricted cathode attachment. Relatively large cathode sheath dimensions on the order of 1 cm are observed with a net electrostatic forcing restricted to this region. The net electrostatic forcing is largely vertical toward the cathode surface, but also has a component in the direction against the flow.

Polymer Surface Treatment by Atmospheric Pressure Low Temperature Surface Discharge Plasma: Its Characteristics and Comparison with Low Pressure Oxygen Plasma Treatment

The polymer treatment with a low-temperature plasma jet generated onthe atmospheric pressure surface discharge (SD) plasma is performed.The change of the surface property over time, in comparison with lowpressure oxygen (O2) plasma treatment, is examined. As onecompares the treatment by atmospheric pressure plasma to that by thelow pressure O2 plasma of PS (polystyrene) the treatment effectswere almost in complete agreement. However, when the atmosphericpressure plasma was used for PP(polypropylene), it producedremarkablehydrophilic effects.

Preparation of a CVD thin film by an atmospheric pressure low temperature surface discharge plasma torch

We describe the preparation of a chemical vapour deposition (CVD) thin film using the low temperature surface discharge plasma torch of our previous paper, and examine the influences of preparation distance, applied voltage and preparation time on the thin film structure. The composition of the obtained CVD thin film was altered by the applied voltage and preparation distance, and it was made from an inorganic composition with a state of SiO2 under a high-applied voltage and long preparation distance.

On the nature of the Vorob’evs effect in pulse breakdown of solid dielectrics

The Vorob’evs effect consists in certain features of the discharge observed when a solid dielectric in contact with two rodlike electrodes is placed in a liquid dielectric medium and a voltage pulse with increasing front is applied to the electrodes. When the pulse front slope is small, the discharge develops in the liquid over the solid dielectric surface; whereas the discharge at a sufficiently large slope of the pulse front penetrates into the solid and produces its fracture with cleavage of the surface fragments. In order to explain this phenomenon, it is suggested that, at a sufficiently high voltage buildup rate, a displacement current that is related to the motion of the surface discharge plasma passes through a microprotrusion occurring on the electrode surface at the contact site and causes the electric explosion of this microprotrusion. The metal plasma jet generated as a result of this explosion penetrates into the solid dielectric and forms a discharge channel in depth of this material. The surface discharge plasma formed at a small slope of the voltage pulse front closes the electrode circuit, thus preventing the discharge penetration in depth of the solid.

The effect of glow discharge plasma surface modification of polymers on the osteogenic differentiation of committed human mesenchymal stem cells

Little is known of the effect of material surfaces on stem cell differentiation. The present study has addressed the hypothesis that the interaction of mesenchymal stem cells (MSCs) with material surfaces modified by glow discharge plasma is a major regulator of osteogenic differentiation. We found that biaxially oriented polypropylene (BOPP) plasma treated in ammonia significantly reduced up-regulation of expression of osteogenic marker genes, such as alkaline phosphatase (ALP), bone sialoprotein (BSP) and osteocalcin (OC). In contrast, ALP expression was up-regulated when cultured on treated Nylon-6 polyamide (Ny-t) but was substantially reduced when cultured on its pristine counterpart (Ny-p) on day 3. On day 7, ALP expression was down-regulated with MSCs cultured on Ny-t although its expression level was up again on day 14. BSP was expressed weakly on day 3, but was up-regulated when cultured on Ny-t and Ny-p. Its expression reached its maximum on day 14 when cultured on a polystyrene control, while it was cyclically up-regulated on Ny-t. Similarly, there was a slight increase in OC expression when MSCs were cultured on Ny-t and Ny-p on day 3, when compared to control. Thus, the nature of the surface can directly influence MSCs differentiation, ultimately affecting the quality of new tissue formation with BOPP-t suppressing osteogenic differentiation.

Zeolite-combined plasma reactor for decomposition of toluene

Toluene was decomposed in a surface-discharge plasma reactor and the combined effect of zeolite in the plasma reactor was studied. The decomposition of toluene and the product compositions depended on the reactor configuration and the capacity of zeolite to adsorb toluene. Toluene adsorbed on the zeolite (micro-pores) was not properly decomposed in the head of the plasma (P1), while it was readily decomposed not only in the tail of the plasma (P2) but also in the second reactor (P3) out of the plasma region because the oxidation of adsorbed toluene was enhanced by ozone as well as by atomic oxygen species derived from the plasma region. The synergistic effect of zeolite was attributed to its capacity to adsorb toluene and the cyclic plasma operation, which reduced the input energy.

Study of Titanizing the Surface of Copper Substrates by the Double Glow Discharge Plasma Surface Alloying Technique

This paper discusses a study in which Ti surface alloying has been performed on copper substrates by means of a double glow discharge plasma surface alloying technique. The micro-structure, the phase structure, the micro-hardness and the distribution of Ti concentration of alloying layer were investigated in detail by XRD, SEM and so on. The effect of process parameters on the alloying layer was studied. The experimental results show that a Ti solid solution with the precipitation Cu4Ti alloying layer has been formed on the copper surface. The thickness of the alloying layer is about 120 μm and the surface titanium concentration gradually decreases from w (Ti) = 87% to w (Ti) = 4%. The micro-hardness of the alloying layer is between 300 HV-800 HV. Source sputtering, surface absorption, ion bombarding and high temperature diffusion are the major factors that affect the alloying layer.

Angular dependence of the ion energy, charge, and mass distributions in surface discharge plasma

Previously, the ion energy, charge, and mass distributions in vacuum discharge plasma at the surface of polymeric insulators were studied using an analyzer oriented perpendicularly to the surface, and both multiply charged and high-energy ions were found in the plasma. This Letter presents the first experimental results on the dependence of the ion energy, charge, and mass distributions in the plasma on the particle take-off angle relative to the insulator surface.

Synergy of nonthermal plasma and catalysts in the decomposition of fluorinated hydrocarbons

In the decomposition of hydrofluorocarbons such as HFC-32 and HFC-23 with silent discharge plasma or surface discharge plasma, MnO 2, TiO 2–SiO 2, and AlPO 4 show catalytic effects. MnO 2 and TiO 2–SiO 2 promote the oxidative decomposition of HFCs and FC-14 in the presence of gaseous oxygen, while AlPO 4 promotes the cleavage of C–F bonds in them.

Effect of zeolite in surface discharge plasma on the decomposition of toluene

Toluene was decomposed in a surface discharge plasma reactor packed with various zeolites. The positioning effect of the zeolite bed was also investigated Reactor-B, in which the zeolite bed was located upstream, performed much better than Reactor-A, in which the zeolite bed was located downstream. Furthermore, the decomposition efficiency in Reactor-B increased with the capacity for toluene adsorption on zeolite, while that in Reactor-A did not. The toluene adsorbed in micropores was not decomposed effectively by direct electron impact, but was decomposed by active oxygen species generated in the plasma zone on the zeolite surface. A good correlation was also observed between toluene decomposition and ozone consumption in the downward-type reactor.

Ion energy, charge, and mass distributions in nanosecond surface discharge plasma

We have studied the composition of plasma formed during nanosecond high-voltage discharge at the surface of various insulators in vacuum. The flows of ions with velocities on the order of 102 km/s have been revealed. The energy distribution of ions in the plasma extends from several hundred electronvolts to a few kilo-electronvolts.

Effects of catalysts and additives on fluorocarbon removal with surface discharge plasma

The decomposition of fluorocarbons (1%) in Ar was investigated using a surface discharge-type plasma reactor. To enhance the effectiveness of plasma chemical processing, we investigated the effects of catalysts and additives. The removal rate increased when the plasma reactor was packed with TiO2 pellets as a catalyst. The catalytic effect seems to be derived from the direct activation of the TiO2 surface by the plasma discharge, because significant UV emission and temperature increase were not observed in the plasma reactor. The removal rate was also enhanced when water vapor, oxygen, or hydrogen was added to the reactant. In addition, the presence of TiO2 or the additional gases or both depressed byproduct formation. Analysis of the reaction products suggested that the catalysts and additives enhanced the process by preventing the recombination of decomposed fragments.

Hazards by meteoroid impacts onto operational spacecraft

Operational spacecraft in Earth orbit or on interplanetary trajectories are exposed to high-velocity particles that can cause damage to sensitive on-board instrumentation. Asteroids and Comets produce small solid particles as they disintegrate. The meteoroids stay on bound orbits around the Sun if they are larger than a few micrometres in size. Because of their high velocities they create different kinds of hazards to operational spacecraft. Here we discuss the impact hazards that lead to surface degradation, hull penetration, and plasma discharge. Surface degradation is mainly caused by meteoroids in the 0.01 to 0.1 mm range, hull penetration by meteoroids above 1 mm, and plasma discharge by meteoroids between 1 and 10 μm.