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The design of efficient plasma reformers requires both efficient fuel conversion of fuel and chemical energy extraction. In this regard, liquid fuels provide the advantages of high gravimetric and volumetric energy densities, therefore yielding high energy; in particular, diesel is promising for use in plasma reformers. In this study, we investigated the ignition process in a diesel reformer driven by a rotating gliding arc using a high-speed camera. The locations of the flame kernel generated by the arc were clearly identified under different power conditions. At high power, the flame kernel was generated at the nozzle tip, which grew into a fully developed flame. This indicates that the period for fuel vaporization and mixing with air (which is a necessary step prior to chemical reactions and is typically longer than the characteristic chemical reaction time) is extremely short. Moreover, with low oxygen concentrations, we observed a rotating flame kernel. At low power, the flame kernel was generated at a distance from the nozzle tip and the arc. This result indicates that the generation mechanism of the flame kernel in the plasma reformer is not straightforward; flow and arc dynamics also influence the interactions between the arc and fuel droplets.

Controllability of the kinetic path of methane conversion in plasma driven oxidation reaction is investigated. Different geometries in a rotating gliding arc reactor are adopted to control reaction paths in methane oxidation reaction. Diverging and converging type reactor product different reaction environments in view point of both the reaction time and the degree of thermal activation. In the diverging reactor, the partial oxidation process is dominant with high methane conversion because the diverging section facilitates to elongate the arc length and decrease the flow velocity. Thus, the convective and radiative heat transfer from the arc column to the reactants could be enhanced. The role of plasma in the diverging reactor is mainly igniting and sustaining the partial oxidation, which is rather different from that in the converging reactor where the plasma plays as a heat source for thermal pyrolysis of methane with the help of focusing thermal energy of the arc.

Plasma catalysis has been extensively investigated on both plasma and catalyst sides to explore the possible synergies, with most studies focusing on reactivity enhancement and the search for pathways other than those of simple plasma or catalytic reactions. However, there is currently much room for plasma applications beyond reactivity control in catalyst preparation and regeneration phases. This review introduces the use of plasma for accelerated catalyst regeneration and proposes a corresponding mechanistic explanation, showing that the effectiveness of this regeneration can be ascribed to the chemical and/or thermal effects of plasma such as the formation of reactive reductants/oxidants and cost-effective catalyst heat-up. Moreover, plasma-assisted catalyst regeneration is shown to involve low-temperature activation and gas-phase radical–based reactions, be a viable method of avoiding catalyst sintering during conventional high-temperature regeneration, and exhibit the advantage of cost effectiveness.

The on-board reforming technique for de-NOx is attracting increasing interest because of the fast start-up and size of the device. However, due to the limited amount of energy available from the battery, a full understanding of the characteristics of the plasma reforming reaction is important to optimise this technology to achieve hydrogen production with minimal power consumption. This paper reports the relative role of the thermal effect of plasma in octane oxidation induced by rotating arc plasma. The thermal effect or gas temperature increased with increased electric power; the conversion of the electric energy to heat was estimated to be higher than 40%. The increased thermal effect was the main consequence of further increasing the plasma power, which controlled the syngas yield and was the main determinant of the energy efficiency of the reaction. In comparison, although the O-2/C ratio was the main parameter determining the thermal environment in the reactor, it had only a small influence on the energy efficiency of the reaction. The optimal O-2/C ratio for maximum energy efficiency depends on the electric power (e.g. the optimal O-2/C was 0.8 at 80 W and 0.5 at 280 W). The results provide guidance for determining the optimal conditions for plasma-driven reforming processes.

Arc plasma has been applied in diverse reactions because it can provide the mechanism for highly thermal activations. However, the efficiency of conversion from electrical energy to thermal energy for the reactant is not sufficiently high, resulting in challenges in practical applications of the arc in various chemical processes. In this study, a method is introduced to enhance the energy usage efficiency for the reactant. The enhancement is based on the control of the arc length elongation. An increase in the arc length results in an enhanced heat transfer from the arc column to the reactant, followed by the reduction of the conductive heat loss to the reactor body. The existing DC arc technologies cannot easily extend the arc length because of the arc instability. However, in this study, a novel AC arc technology was adopted that can support a stable arc with a sufficiently elongated length. Correspondingly, a comparative study on different arc lengths was conducted for the dry reforming (as a model reaction). The increased arc length results in an enhanced heat transfer to the gas or a higher gas temperature. This is followed by the enhancement of the conversions of the reactants for the same supplied electric power. The results provide a firm physical basis for further optimizations of the arc process for chemical reactions.

A novel concurrent process for CO2 reduction and plastic upcycling was successfully developed based on a rotating gliding arc plasma process, where CO2 gas and Low-density polyethylene (LDPE) powder were used as reactants for the process. Herein, the LDPE powder was regarded as an alternative of plastic waste, and the high temperature of the plasma jet thermochemically decomposed the plastic powder. Based on gas chromatography analyses, the yields of the C1 and C2 chemicals were confirmed, which demonstrated the possibility for the chemical upcycling of the plastic powder with CO2 plasma jet. At the same time, the conversion of CO2 at the exhaust gas increased with increasing electric power of the plasma jet. In addition, as the electric power further enhanced, the reverse reactions were efficiently suppressed by the chemical quenching process due to complete depletion of the oxygen by the light hydrocarbon gases generated from the pyrolysis of the plastic powder. Based on the molecular balance of C and O, the calculated syngas to CO2 ratio was achieved up to 32 % in a batch-type plasma reactor with a power supply of 1170 W. It is rational inference that the efficiency will be significantly improved if a plug-in type plasma reactor with higher power supply is implemented. In conclusion, this novel concurrent process would be a promising approach for an efficient and scalable technology of CO2 utilization.

A plasma process for methane conversion into acetylene is proposed. Acetylene is one of the basic materials used in the chemical industry and its production is predominantly based on chemical processing of naphtha and CaC 2 . The recent increase in shale gas production makes acetylene production from methane a feasible expectation. This study provides data on the lowest cost of acetylene production from methane by a plasma process. The proposed plasma process is based on an effective rotating arc reactor. The rotating arc provides a relatively low reaction temperature, achieving a high carbon balance. Through a study of reaction parameters and the effect of H 2 as a reactant additive, the mechanism of methane conversion was analyzed. The proposed process showed a high efficiency with a minimum process cost of approximately 9 kWh/kg-C 2 H 2 .

This study reports the effects of the driving voltage on interactions between plasma jets and electrolytes. Plasma jets over electrolytes, which were generated using five kinds of driving voltages, were characterized by distinct optical emissions from the gas region and the gas–liquid interface with unique electrical characteristics. The generated plasma jets over electrolytes resemble the characteristics of dielectric barrier discharges; the plasma–liquid interactions are affected by external driving voltages that vary the surface charge at the gas–liquid interface because of the conductive and dielectric nature of the electrolyte. The findings suggest that selecting an adequate driving voltage waveform is critical for specific applications utilizing plasma–liquid interactions.

Activated carbon has been extensively utilized to adsorb pollutants generated by industrial activities. There have been many attempts to efficiently produce activated carbon from spent coffee grounds in the field of environmental technology. In this study, the feasibility of the novel production of activated carbon from coffee ground waste using a plasma jet was evaluated. A rotating gliding arc generator was designed that used an N2 plasma jet for the carbonization process and a CO2 plasma jet for the activation process. It was confirmed that the coffee ground waste could be carbonized and activated by the two plasma jets in the same reactor. The characteristics of the surface morphologies of the activated carbon samples varied depending on the plasma treatment conditions, such as the electric power of the plasma jet and the treatment time. The results implied that the adsorption capacity of the activated carbon could be optimized by regulating the pore size and distribution based on the plasma treatment conditions with regard to the molecular size of the target adsorbate.

The effect of working pressure on the properties of Al2O3 films was investigated in direct-type plasma-enhanced atomic layer deposition. Increasing pressure yielded a denser Al2O3 film and a thinner SiOx interlayer, but only slightly affected the Al2O3 film thickness. The diffusivity of O atoms was evaluated by using time-averaged emission intensities of the He I and O I lines. The consumption rate of O radicals and the production rate of H radicals, as functions of plasma exposure time, were deduced from analyzing temporal evolutions of emission intensities of the O I and Hα lines, respectively. The amounts of C and H impurities in the film were confirmed by using an X-ray photoelectron spectroscopy. Finally, the mechanisms by which the working pressure affected the properties of Al2O3 films were discussed based on the experimental results.

Feasibility tests of abating and stabilizing pollutants emitted during semiconductor manufacturing are performed by using a plasma reactor placed before a vacuum pump. Abatement characteristics of N2O, CF4, CHF3, NF3, C3H6, and TEMAZ are investigated by analyzing the data obtained by using Fourier transform infrared spectroscopy and gas chromatography. The size of byproduct particles is identified by using a particle sampler. Analysis is focused on the role of reactant gases (O2 or H2O) during abatement. Finally, the applicability of low-pressure plasma after-treatment technology is discussed from the environmental and economic points of view.

One of the environmental issues in semiconductor and flat panel manufacturing industries is to reduce emission of perfluorocarbons(PFCs) used in etching process and cleaning CVD chambers [1]. At present, several types of PFCs abatement device are already installed in the industries, which are incinerator, catalytic combustor, and plasma treatment systems. Removal of CF 4 has been tried via catalytic reaction of CF 4 decomposition. This study exploits a possible way of plasma-catalyst combination for the removal of CF 4 . Rotating arc reactor that can produceone of thermal plasma [2] and following catalyst bed has been applied. In this configuration, arc plasma itself destroys CF 4 and also provides heat required for the catalytic reaction. From experiments, the removal rate of CF 4 was estimated by plasma only and plasma-catalyst combination system. The quantity of water vapor which can prevent reverse reaction of decomposed CF 4 was also considered to present optimal quantity of water in CF4 removal reaction.From this work, the feasibility of the combination of plasma and catalyst is confirmed and further studies are needed to realize this hybrid system in an optimal way for real applications.

Thin film deposition processes emit large amounts of NF3 and by-product particles, which are of great concerns in the semiconductor industry, from the environmental and economic points of view. With an objective to overcome these concerns, plasmas are generated from a cylindrical reactor placed before a vacuum pump. The discharge stability is evaluated by monitoring the changes in the plasma images with the pressure. By using a particle sampler and a particle trap, the size and quantity of the by-product particles are compared during plasma-on and plasma-off. The effects of adding O2 and H2O to the by-products of the NF3 abatement process are investigated by analyzing the spectra obtained with a Fourier transform infrared spectroscopy. Further, the H2O flow rate is optimized for the highest destruction and removal efficiency of NF3. Finally, the applicability of our device to the after-treatment equipment is discussed.

This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films.

The influence of catalyst electric conductivity on methane activation in a planar-type dielectric barrier discharge reactor is investigated by empirically comparing the degree of methane conversion of bare Al2O3 with that of Pt/Al2O3; from this, it is determined that the latter catalyst converts less methane owing to the presence of Pt. Calculations and comparisons of electric fields with and without Pt show that the presence of a Pt catalyst results in a lower electric field than does bare Al2O3. An analysis of product gases based on the correlation between the fragmentation of radicals and the electric field also indicates that the electric field is decreased by using Pt. From these results, it can be concluded that the synergies between the plasma and the conductive catalysts need to be reassessed for different electric field conditions, and that further studies of non-conductive catalysts that can enhance methane activation and synergistic effects are needed.

Plasma-reforming process has been widely studied for over a decade, with a focus on diverse fuels and plasma parameters for finding the optimum conditions. This study evaluates the effect of thermal activation on the chemistry and energy efficiency of the methane-reforming process. Based on the empirical evaluation, a correlation was found among the methane conversion rate, reaction composition, reactant temperature, and plasma power. Moreover, the plasma chemistry did not change with the reactant temperature within the temperature range evaluated. In addition, it was found that the ratio of the plasma power to the heating input power was an important parameter for enhancing the efficiency of the partial oxidation of methane.

An attempt has been made to optimize elongated rotating arc plasma scrubber. Among diverse semiconductor processes, diffusion and implantation process inevitably produce as byproduct and efficient dry process for the decomposition of is required. Plasma process does not produce NOx that is commonly produced in combustion process and there is no problem of deactivation, usually experienced in catalyst process. However, plasma process uses electrical energy and needs to be optimized to achieve feasibility of application. In this work, mode control of rotating arc is presented as tentative solution for the possible optimization of the process. Based on existing rotating arc, scale-up and following mode mapping was tried. Proposed reactor design was evaluated in the decomposition process and revealed that optimization scheme is at hand. In the experiment of full scale scrubber including heat exchanger, the process gave more stable and efficient process of decomposition.

Accelerated global warming resulted in diverse regulations for possible removal of greenhouse gases. N2O is one of global warming gases that is produced in the course of combustion process and incomplete reduction of NOx. Removal of N2O has been tried via catalytic reaction of N2O decomposition1. This study exploits possible way of plasma-catalytic removal of N2O. MnO2/Al2O3 and Ru/Al2O3 are considered as a catalyst for plasma-catalysis2. Thermal plasma and following catalyst bed has been applied. In this configuration, arc plasma itself destroys N2O and also provides heat required for the catalytic reaction. In the experiment that adopted Ru/Al2O3 as catalyst showed good removal efficiency. As byproducts, small amount of NO2 that can be removed by a scrubber is measured, but NO is not detected. From this work, the feasibility of the combination of plasma and catalyst is confirmed and further studies are needed to realize this hybrid system in an optimal way for real applications.

Regulations on the emission of greenhouse gases have been made stricter worldwide for mitigating global warming. The semiconductor and display industries emit significant amounts of greenhouse gases, such as N2O and F-gases. We investigated the electrode length effect on the abatement characteristics of N2O in a low-pressure plasma reactor. N2O is extensively used in SiO2 thin film depositions, SiCl2 + 2N2O → SiO2(s) + 2N2 + Cl2, and its global warming potential (GWP) is 310 (GWP of CO2 = 1). The destruction and removal efficiency (DRE) of N2O was evaluated by using Fourier transform infrared (FTIR) spectroscopy. The DRE of N2O was reduced with increasing the N2O flow rate or decreasing the pressure. A larger electrode length yields a higher DRE, especially for higher N2O flow rate and lower pressure conditions. For understanding this phenomenon, the discharge characteristics were analyzed by using optical emission spectroscopy (OES). Molecular emissions from N2(C-B) and N2+(B-X) bands were measured together with atomic emissions from O I (777 and 844 nm) lines, by varying the electrode length. The reason for a larger electrode length to achieve a higher DRE was explained in terms of the plasma property and gas residence time.

Homogeneous non-thermal plasma at atmospheric pressure is highly effective for surface treatment of various polymeric substrates. We propose a dielectric barrier discharge (DBD) reactor consisting of two back-to-back L-shaped electrodes, driven by bipolar voltage pulses of opposite polarity. This structure and driving scheme allow the discharge to be initiated earlier inside the reactor than outside the reactor. The plasma formed inside the reactor is ejected through a slit and moves toward the substrate. As a result, an abundance of electrons is provided to the outside region of the reactor at its breakdown stage. These electrons play a role in suppressing the filamentary mode, and hence, homogeneous discharge in He and Ar can be achieved under an open air configuration. The discharge characteristics inside and outside the reactor are analyzed by using the discharge current and the temporal evolution of emission intensity, respectively. The importance of seed electrons available at the gas breakdown stage in achieving a homogeneous discharge is discussed together with the differences between the discharge characteristics of helium and argon gases.

A role of plasma chemistry and relative contribution to the overall reaction is explained. Considering relative contribution of thermo chemistry and plasma chemistry, reactions are classified into three different regimes. The way plasma affects kinetic pathways differs according to these regimes. This review introduces how plasma chemistry affects overall reaction and determines kinetic pathways based on the classified regimes. Among these three regimes, In the case of weakly exothermic reactions, discernible role of plasma chemistry is most confusing because plasma chemistry provokes both electron and excited species induced activation and thermal activation that are competitive and interactive. This review introduces the way how to understand the discern plasma chemistry in these reactions. There is possibility of misleading in evaluation of thermal efficiency of process if the concept of warm plasma is not defined correctly. Efficiency and process design also should be based on the classification of the regimes and this review can provide the insight on the understanding specific role and function of plasma chemistry in diverse plasma applied processes.

A plasma-assisted staged combustor that can reduce NOx generation is introduced. This combustor is based on a commercial combustor. Only the internal structure of the commercial combustor head was ...

Onboard plasma reforming has strong potential for use in supplying reductants for hydrocarbon selective catalytic reduction (HC SCR) of NO x in vehicle exhaust. However, the role of hydrogen as an additional reductant with various catalysts at various temperatures remains unclear. Here we investigated the de-NO x performance of HC SCR with Pt-based and Ag/Al 2 O 3 catalysts at various temperatures using hydrogen and hydrocarbons supplied directly or generated onboard by plasma reforming using engine bench-level tests. Further, we clarified the specific role of hydrogen in the process. We found that with Pt-based catalysts, hydrogen is oxidized to H 2 O or promotes full oxidation of hydrocarbon, thus having no positive effect. By contrast, with Ag/Al 2 O 3 , hydrogen only promotes partial oxidation of hydrocarbon to yield surface intermediates that significantly facilitate SCR. Furthermore, reductants generated by plasma reforming exhibit better de-NO x performance than directly supplied gas mixtures. Thus, onboard plasma onboard reforming can be an important strategy for effective HC SCR.

The interactive phenomena between a rotating arc and a premixed methane/air flame have been investigated. The effects of the rotating arc on the flame were observed: both lean and rich flammability limit was extended with the rotating arc on. More interestingly, the opposite interactions, i.e., the effects of the flame on the rotating arc, were also observed: the arc length, angular speed, and electrical characteristics are affected by the flame. An analysis of the optical emission spectra showed that the rotating arc generates chemically active species such as excited N2 molecules and O and H atoms. An analysis of the gas products indicated that the concentrations of the major gas products such as CO2, CO, and H2 were not significantly affected by the rotating arc, although the flammability limit are significantly extended. Unlike these major gas products, minor products like NOx emissions increased by an order of magnitude in the presence of a rotating arc under certain air/fuel conditions.

Reforming of methane with carbon dioxide has been carried out using a bipolar pulse driven elongated arc reactor operating at atmospheric pressure and non-equilibrium regime. This plasma reactor is driven by two kinds of power supply, characterized by different voltage-current characteristics under the same operating power and frequency. Varying the ratio and the discharge power, the conversion rate, yield, and reforming efficiency for the two power supplies are investigated in conjunction with the static and dynamic behaviors of voltage and current. It is found that not only the values of voltage and current but also their shapes give an influence on the reforming performances. Finally, a better electrical operation regime for the efficient plasma reforming is proposed based on the relationship between the voltage-current characteristics and the reforming performance.

Plasma is receiving attention as a prospective tool for the reforming process of obtaining synthesis gas and hydrogen. Although many reports on plasma-induced reforming have been introduced, detailed correlations between the reaction paths and plasma parameters remain unclear. Therefore, to figure out the relative role and dominance of plasma-controlled chemistry in the reforming process, we investigate diverse reaction paths in reforming CH4. The arc column length is proposed as a universal process parameter of the plasma-reforming process, and a rationale to support the proposition is provided As a result, the dependence of the reforming process on the arc column length is explained. Three different reaction regimes, defined according to the arc column length and plasma chemistry in each regime, are addressed. The arc column length controls the thermal environment of the reaction and activates different reaction pathways depending on its length. This concept of control also enables the discovery of efficient ways of reforming. The increase in thermal efficiency by controlling the arc column reveals possibilities for optimizing the plasma-induced reforming process.

removal characteristics were investigated using an elongated arc reactor. The advantage of the elongated arc reactor includes direct use of treated gas as plasma operating gas and the enhancement of the removal reaction by using a thermo-chemistry and a plasma induced chemistry at the same time. Geometrical configurations, such as the length of the reactor and the shape of a throat, were tested to get an optimized removal efficiency with low power consumption. As results, over 95% of removal was obtained with 300 lpm of total flowrate for various concentration (0.1~1%). Corresponding specific energy density (SED), which means required electrical energy to treat the unit volume of treated gas, is about 3.5 kJ/L, The present technique can be applied to real applications by satisfying three major concerns, those are the high flowrate of treated gas, high removal efficiency (> 95%), and low power consumption (

A Dielectric barrier discharge (DBD) is a promising candidate to remove carbon tetrafluoride (CF/sub 4/) because the DBD has been successfully used for generating ozone (O/sub 3/) and decomposing nitrogen oxide (NO). A streamer- and glow-mode operations of DBD were carried out in a coaxial cylinder reactor by coupling 10-kHz alternate current (ac) power. The effect of oxygen on the CF/sub 4/ decompositions was investigated and the optimum oxygen concentrations were found. We compared N/sub 2/-streamer, N/sub 2/-glow, and He-glow modes operated in a DBD to investigate the effect of plasma mode on CF/sub 4/ removal. The results showed that the most efficient CF/sub 4/ removal was obtained in He-glow mode, while N/sub 2/-streamer and N/sub 2/-glow modes demonstrated similar performances. With a practical point of view, we investigated an optimized geometrical configuration of streamer discharge. A micro hole-size perforated DBD showed significant increases in CF/sub 4/ removal efficiency compared to the normal N/sub 2/-streamer mode.

To activate a catalyst efficiently at low temperature by plasma for environmental control, we developed a hybrid reactor that combines plasma with a honeycomb-structured catalyst in a practical manner. The reactor developed generated stable cold plasma at atmospheric pressure because of the dielectric and conductive nature of the honeycomb catalyst by consuming low amounts of power. In this reactor, the applied voltage and temperature determined the balance between the oxidation and adsorption by the plasma and catalyst. The synergistic reaction of the plasma and catalyst was more effective at low temperatures, resulting in a reduction in a lowered light-off temperature.

We studied the effect of plasma treatment on polymer comparing alternating-current (AC) and radio-frequency (RF) driven plasmas using dielectric-barrier discharge (DBD) reactor. The developed reactor shows spatially homogeneous plasmas in helium without streamers, and it produces abundant nitrogen and oxygen radicals by intruding ambient air. Because of electron density and temperature difference, AC and RF driven plasmas present distinct radical generation characteristics. Polymer surface chemical composition supports that formation of functional-groups over the surface are closely related to the generated radical species determined by specific plasma characteristics. Finally, this contribution will discuss effective polymer treatment by selecting adequate plasmas between AC and RF power operation.

Summary form only given. Low surface energy of polymers is the chief obstacle to prevention of their wide application. Homogeneous non-thermal plasma at atmospheric pressure allows functional groups to be grafted on the surface of polymeric substrates, which is highly effective for the improvement in their printability and adhesion. We propose a dielectric barrier discharge (DBD) reactor consisting of two back-to-back L-shaped electrodes, driven by bipolar voltage pulses of opposite polarity. The discharge characteristics inside and outside the reactor are analyzed with the help of specifically designed reactor structure. The time-averaged image and temporal evolution of the discharge are taken by using an intensified charge-coupled device for different voltages. The discharge image is synchronized with the voltage-current waveforms by using the trigger pulse from the power supply. Finally, the applicability of the DBD reactor to the polymer surface treatment is discussed based on the experimental results.

The mechanism of accelerated reduction of oxidized metal catalysts by plasma was herein explored. Hydrogen radicals produced by discharge are important for generating energetic hydroxyl radicals by an Eley–Rideal-type reaction, and these radicals in turn undergo desorption without further reaction. The desorbed hydroxyl radicals react with hydrogen radicals to produce gas-phase water. The results obtained herein discuss the advantages of employing plasma catalysis for surface reactions.

Summary form only given. Cold plasma jet operated at atmospheric pressure is a promising tool for biomedical application. Considering direct plasma jet treatment for human skin, control of discharge current is the most important factor to avoid electric shock and unpleasant feeling. In this reason, it is a key technology to achieve higher reactive species with lower discharge current toward a living tissue.

Summary form only given. Atmospheric pressure cold plasma jets have been focused on their potential applications to material processing and medical use. For the extensive use of plasma jets, it is essential to generate and transport abundant reactive species. But the amount of additive gas is limited because it easily reduces plasma density and temperature. In this reason, effective gas mixing and injection is necessary. This work aims to point out that selection of gas injection and mixing methods is a critical factor to generate and transport reactive species effectively in a plasma jet.

Summary form only given. Dust particles are considered as an important source of device contamination in the semiconductor industry. Deposition process is followed by cleaning process, when dust particles are changed into volatile gaseous species that are exhausted from a processing chamber. Cleaning process, however, can't completely remove dust particles so that large amounts of residual particles still head downstream of the processing chamber. These byproduct particles are accumulated on internal components of a vacuum pump, which results in a decrease in vacuum pump durability. A plasma reactor placed before a vacuum pump is proposed for reducing the size of byproduct particles, thereby for increasing the vacuum pump lifetime. The sizes of byproduct particles for plasma on and off are compared using the scanning electron microscope. The influence of the plasma reactor on the byproduct gases is investigated by analyzing the spectra resulting from Fourier transform infrared spectroscopy measurements. Finally, the applicability of low-pressure plasmas to the extension of vacuum pump lifetime is discussed based on the experimental results.

This paper reports the construction of a microchannel reactor that eliminates arc transitions and streamer generation under atmospheric conditions. The micromachined dielectric barrier discharge reactor suppresses streamer generation resulting in homogeneous discharges even in a high electric field of 170kV/cm. Only electric field without discharge exists in the microchannel reactor when cells suspended in a fluid are passed through the reactor. The electric field of NTAP induces cell death.Copyright © 2011 by ASME

Reforming of methane with carbon dioxide has been carried out using a bipolar pulse driven plasma reactor operated at atmospheric pressure and non-equilibrium regime. This plasma reactor is driven by two kinds of power supply, characterized by different voltage-current characteristics under the same operating power and frequency. Varying the CO 2 /CH 4 ratio and the discharge power, conversion rate, yield, and reforming efficiency for the two power supplies are investigated in conjunction with the static and dynamic behaviors of voltage and current. It is found that not only the values of voltage and current but also their shapes give an influence on the reforming performances. Finally, a better electrical operation regime for the efficient plasma reforming is proposed based on the relationship between the voltage-current characteristics and the reforming performance.

Summary form only given, as follows. Numerical analysis of the streamer in PCD and DBD are carried out for a deeper insight into the plasma induced chemical reactions. Streamer analysis in PCD. We have developed a 3-D numerical simulation model to predict more reliable streamer propagation in a wire-cylinder reactor. As a result, inherent 3-D nature of the streamer propagation is successfully obtained. In addition, interaction phenomena between the neighboring streamers are more deeply investigated with this novel 3-D approach. Streamer analysis in DBD. It is experimentally well known that streamers take place during the rising phase of AC voltage and they show recurrent phenomena as well. Until now, however, numerical verifications have not been found yet, so, a new approach was carried out with considering the surface charge behavior on the barrier materials. The present simulation result, apparently shows the conduction loss of the surface charges is a key factor in recurrence phenomena in DBD. It is also found that a fast voltage rise produces electrons with high energies, while a slow voltage fall sustains the streamers for a longer period.

Summary form only given, as follows. In this comparison study, optical measurements of light emission, theoretical estimation of the electron energy distributions, and performance of NO/sub x/ treatments for both types of non-thermal plasma have been conducted.

The surface-streamer propagation on the surface of a HSY zeolite was measured using a microscope-intensified-charge-coupled-device-camera system. Two different modes of a discharge plasma was observed. Partial-discharge mode only appeared at the onset voltage. As the applied voltage further increased, the surface streamer appeared together with the partial discharge.

We investigated the characteristics of the discharge generated by an atmospheric pressure plasma reactor that used two L-shaped electrodes and was driven by bipolar pulses having opposite polarity. Due to the difference in the surface charge distributions on the electrodes, the discharge behaviours vary greatly between the rising and falling stages of the voltage pulse. In all cases, the plasma formed inside the reactor plays an important role in suppressing a filamentary mode outside the reactor, and hence, homogeneous discharge in He can be achieved under an open-air configuration.

This work is devoted to the investigation of the discharge characteristics of an ac arc plasma torch with a well-type cathode working in air and CO2. The electrical characteristics, plasma jet image and optical emission profile are investigated by varying the discharge power and the gas flow rate. The dynamic behaviour of arc voltage and current is characterized by smooth-shaped waveforms, regularly iterated with a driving frequency. The moving of arc spot positions is inferred from the measured waveforms, and compared with that observed in dc torches. A simple lifetime test is performed to verify the speculation that the arc spots in ac operation move continuously over a wide region with a very high speed. The result shows that the electrode lifetime can be enhanced by combining the vortex motion of arc gas with the ac driving.