Increasing Input Power Research Articles

Effect of process parameters on properties of argon–nitrogen plasma for titanium nitride film deposition

In this study, the effect of working pressure and input power on the physical properties and sputtering efficiencies of argon–nitrogen (Ar/N2) plasma in direct current magnetron discharge is investigated. The discharge in Ar/N2 is used to deposit TiN films on high speed steel substrate. The physical plasma parameters are determined by using Langmuir probe and optical emission spectroscopy. On the basis of the different reactions in the gas phase, the variation of plasma parameters and sputtering rate are explained. A prominent change of electron temperature, electron density, ion density, and degree of ionization of Ar is found as a function of working pressure and input power. The results also show that increasing working pressure exerts a negative effect on film deposition rate while increasing input power has a positive impact on the same. To confirm the observed physical properties and evaluate the texture growth as a function of deposition parameters, x-ray diffraction study of deposited TiN films is also done.

Effect of Gas Composition on Removal of NO by Dielectric Barrier Discharge

In order to understand the reaction mechanisms of NO removal in Dielectric Barrier Discharge reactor, the effect of gas composition on plasma reduction of NO was studied. In this experiment, single-layer barrier tube plasma reactor was used to study the influence of O2and C2H4(ethylene) to NO removal rate. The result indicated that: with the increase of input power, NO removal efficiency increased gradually in the N2/NO system; The O2added to the gas caused removal efficiency to reduce. There was no significant effect on removal of NO with C2H4added alone. In the N2/NO/O2/C2H4gas condition, C2H4will promote the conversion from NO to NO2, the removal efficiency of NO increased as more C2H4was added. And the presence of C2H4was conductive to reduce input power.

Intensities of H<sub>β</sub> and H<sub>γ</sub> in Hydrogen Plasma Spectrum with High RF Power Levels at ICP

In high-power RF ion source, three different regions of the Hβand Hγintensities in the Balmer series of spectral lines for atomic hydrogen plasma were investigated. Three different regions of the Hβand Hγintensities were detected by the increase of input power (0-6 kW) at ICP. In hydrogen plasma spectrum, the Hβand Hγintensities showed three processes: slowly increase, quickly increase and stable saturation. The Stark effect in strong electrical field plays a crucial role in dominating the Balmer Hβand Hγemissions from high-density RF plasma.

Atmospheric Pressure Radio Frequency Dielectric Barrier Discharges in Nitrogen/Argon

This work reports the experimental results on the characteristics of radio frequency dielectric barrier N2/Ar discharges. Depending on the nitrogen content in the feed gas and the input power, the discharge can operate in two different modes: a homogeneous glow discharge and a constricted discharge. With increasing input power, the number of discharge columns increases. The discharge columns have starlike structures and exhibit symmetric self-organized arrangement. Optical emission spectroscopy was performed to estimate the plasma temperature. Spatially resolved gas temperature measurements, determined from NO emission rotational spectroscopy were taken across the 4.4 mm gap filled by the discharge. Gas temperature in the middle of the gas gap is lower than that close to the electrodes.

아크 플라즈마를 이용한 과불화합물 처리공정에서 반응가스에 의한 효과

화학적으로 안정한 과불화합물을 처리하기 위해서는 많은 양의 에너지를 필요로 한다. 이러한 단점을 극복하기 위해서 저전력 아크 플라즈마 시스템을 개발하였다. 분해대상은 <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX>, <TEX>$NF_3$</TEX>가 플라즈마 토치로 직접 주입되었으며, 아크 플라즈마 토치의 열효율을 측정하여 실출력을 계산하였다. 실출력과 폐기체 유량 변화 그리고 추가적인 반응가스에 의한 분해효율을 확인하였다. 또한 열역학적 평형조성 분석을 수행하여 실험 결과와 비교하였다. 토치의 열효율은 60~66%의 결과를 보였으며 폐가스 유량이 증가함에 따라 분해효율이 감소하였고 입력전력이 늘어남에 따라 분해효율이 상승되었다. 추가적인 반응 가스가 없이 <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX>, <TEX>$NF_3$</TEX>의 분해효율은 입력전력이 3 kW, 폐가스 유량이 70 L/min인 조건에서 각각 4, 15, 90%를 보였다. 반응가스로 산소와 수소를 이용하여 분해효율을 급격하게 증가시킬 수 있었으며, 실험 결과 산소보다 수소를 사용하였을 경우가 분해효율 상승효과와 부산물 제어에 효과적인 것을 알 수 있었다. 수소의 경우, 발생되는 부산물은 불화수소산이었으며 이는 일반적인 습식 스크러버를 이용하여 처리가 용이한 물질이다. 수소를 이용한 화학반응에서 입력전력이 3 kW, 폐가스유량이 100 L/min인 조건에서 <TEX>$CF_4$</TEX>가 25%, <TEX>$SF_6$</TEX>가 39%, <TEX>$NF_3$</TEX>가 99%의 분해효율을 각각 나타냈다. The treatment of chemically stable perflourocompounds (PFCs) requires a large amount of energy. An energy efficient arc plasma system has been developed to overcome such disadvantage. <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX> and <TEX>$NF_3$</TEX> were injected into the plasma torch directly, and net plasma power was estimated from the measurement of thermal efficiency of the system. Effects of net plasma power, waste gas flow rate and additive gases on the destruction and removal efficiency (DRE) of PFCs were examined. The calculation of thermodynamic equilibrium composition was also conducted to compare with experimental results. The average thermal efficiency was ranged from 60 to 66% with increasing waste gas flow rate, while DRE of PFCs was decreased with increasing gas flow rate. On the other hand, DRE of each PFCs was increased with the increasing input power. Maximum DREs of <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX> and <TEX>$NF_3$</TEX> were 4%, 15% and 90%, respectively, without reaction gas at the fixed input power and waste gas flow rate of 3 kW and 70 L/min. A rapid increase of DRE was found using hydrogen or oxygen additional gases. Hydrogen was more effective than oxygen to decompose PFCs and to control by-products. The major by-product in the arc plasma process with hydrogen was hydrofluoric acid that is easy to be removed by a wet scrubber. DREs of <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX> and <TEX>$NF_3$</TEX> were 25%, 39% and 99%, respectively, using hydrogen additional gas at the waste gas flow rate of 100 L/min and the input power of 3 kW.

An experimental and analytical investigation into the effects of process vibrations on material removal rates during polishing

Experimental testing, using both commercially available polishing machines and a specially built test platform, demonstrates that material removal rates (MRRs) observed during polishing of fused silica are strongly affected by nanometer-scale vibration amplitudes. Specifically, a nanometer level increase in system vibrations can produce MRRs approximately 150% higher than on an inherently smoother running machine. Moreover the higher spatial frequency surface roughness values are little-effected by the spectral content of the polishing machine. Polishing under controlled conditions, using the test platform, shows that for vibration amplitudes, A ≲ 1.6 μm, and over a fairly wide range of vibration frequencies, MRR increases almost linearly with increasing input power. By contrast, for A ≳ 10 μm, MRR exhibits a rapid decay with increasing A. Order of magnitude analyses and physical arguments are presented in order to explain the qualitatively distinct MRR trends observed. In the small-amplitude limit, A ≲ 1.6 μm, two arguments are presented which suggest that the total observed removal rate, MRRtot, reflects the superposed action of chemical-mechanical removal, MRRcm, and vibration-driven, flow-induced removal, MRRflow, i.e., MRRtot=MRRcm+MRRflow. The analyses further indicate that MRRflow primarily reflects cyclic viscous shears and pressure gradients extant within the thin, non-Newtonian slurry film that exists between the polishing tool and workpiece. Shears and pressure gradients, and corresponding flow-induced MRRs, are, in turn, found to scale as A/doω, where A is the vibration amplitude, do is the characteristic gap thickness between the tool and workpiece, and ω is the vibration frequency. In the large-amplitude limit, A ≳ 5 μm, experimental measurements and a simple scaling argument show that the polishing slurry film becomes thick enough that the workpiece and polishing tool lose direct contact. In this limit, observed MRRs thus reflect strictly vibration-driven, flow-induced removal. Comparisons of theoretical material removal rates, derived from the scale analyses presented, with experimentally measured removal rates, as observed in both the small- and large-amplitude limits, show that the models proposed provide reasonable predictions of observed removal rates.

Plasma polymerised thin films for flexible electronic applications

The significant advancement and growth of organic and flexible electronic applications demand materials with enhanced properties. This paper reports the fabrication of a nonsynthetic polymer thin film using radio frequency plasma polymerisation of 3,7-dimethyl-1,6-octadien-3-ol. The fabricated optically transparent thin film exhibited refractive index of approximately 1.55 at 500nm and rate of deposition was estimated to be 40nm/min. The surface morphology and chemical properties of the thin films were also reported in this paper. The optical band gap of the material is around 2.8eV. The force of adhesion and Young's modulus of the linalool polymer thin films were measured using force-displacement curves obtained from a scanning probe microscope. The friction coefficient of linalool polymer thin films was measured using the nanoscratch test. The calculated Young's modulus increased linearly with increase in input power while the friction coefficient decreased.

Incorporation of nanoparticle clusters into a liquid using a proprietary design mixer, Ytron Y Jet

This paper reports the comparative performance of a proprietary design mixer, Ytron Y Jet, on the incorporation of clusters of nanoscale silica powder into water. Two sets of characteristic power curves were obtained for Ytron Y Jet depending on whether the valve on feed tube was open or closed. Whilst there was little difference at low speeds, as the speed was increased entrainment from the feed tube decreased Po which would be as a consequence of a decrease of the pressure difference between the two sides of the rotating blades. Drawdown time values determined for surface additions followed the same trends reported for traditional impellers. Powder incorporation became faster with increasing power input at a given concentration and for incremental additions of 1% (w:w), incorporation rate decreased steeply with increasing concentration. With the use of the feed tube, which is part of the design, particles could be introduced into the impeller region, and incorporation rate could be maintained constant over a wide concentration range. This suggests that whilst the flow field in the vicinity of the impeller is not significantly modified with changes in viscosity and rheology, away from the impeller, close to liquid surface liquid velocities die out quickly. When a highly non-Newtonian rheology (Bingham plastic) developed with further particle addition, incorporation rate decreased. Ability to feed into the impeller region is the main advantage this design offers for this application.

Modification of Activated Carbon by Means of Microwave Heating and its Effects on the Pore Texture and Surface Chemistry

Two kinds of typical activated carbons (coal based AC and coconut shell based AC) were modified in a flow of N₂ gas has been carried out using a microwave device operating at 2450 MHz and different input power, instead of a conventional furnace. The samples were analyzed by means of low temperature N₂ adsorption, elemental analysis and Boehm titration. The results show that microwave heating is an effective means of activated carbon modification. The temperature of activated carbon increases rapidly under microwave heating and then gradual increase to a quasi-stationary temperature. The pore texture of activated carbon changes slightly after microwave treatment and the two activated carbons still keep rich pore structure. The oxygen functional groups decompose and evolve with the form of CO and CO₂. This in turn gives rise to a significant decrease in oxygen content. These changes of oxygen contents increase as the microwave input power increases. During microwave treatment, a gradual decrease in the surface acidic functional groups is observed. More important, with the removal of the surface acidic groups, the number of the basic group increased gradually, the activated carbon with oxygen functional groups become basic properties material.

Modification of Activated Carbon by Means of Microwave Heating and Its Effects on the Pore Texture and Surface Chemistry

Two kinds of typical Activated Carbons (coal based AC and coconut shell based AC) were modified in a flow of N₂ gas has been carried out using a microwave device operating at 2450 MHz and different input power, instead of a conventional furnace. The samples were analyzed by means of low temperature N₂ adsorption, elemental analysis and Boehm titration. The results show that microwave heating is an effective means of activated carbon modification. The temperature of activated carbon increases rapidly under microwave heating and then gradual increase to a quasi-stationary temperature. The pore texture of activated carbon changes slightly after microwave treatment and the two activated carbons still keep rich pore structure. The oxygen functional groups decompose and evolve with the form of CO and CO₂. This in turn gives rise to a significant decrease in oxygen content. These changes of oxygen contents increase as the microwave input power increases. During microwave treatment, a gradual decrease in the surface acidic functional groups is observed. More important, with the removal of the surface acidic groups, the number of the basic group increased gradually, the activated carbon with oxygen functional groups become basic properties material.

Investigation of Material Removal Characteristics in EDM of Nonconductive ZrO2 Ceramic

The use of nonconductive ceramic materials is increasing rapidly in industrial and engineering applications due to its high hardness, low thermal conductivity, and resistance to oxidation. Machining operations for fabricating structures from nonconductive ceramic materials are difficult and most of the traditional machining techniques are not applicable because of its high brittleness. Electro discharge machining (EDM) technique, a noncontact machining process, is applied for processing nonconductive ceramic ZrO2 using assisting electrode. In this technique, pyrolytic carbon layer on the ceramic surface formed by the cracked carbon from the carbonic dielectric, plays the key role for continuous EDM. The formation of pyrolytic carbon and its stability depends upon the input power, workpiece material, tool electrode material, dielectric substance, polarity, and discharge duration. In this study, experiments were done to investigate the effect of input power on the material removal rate (MRR) and to explore the material removal mechanism. The experimental results show that the material is removed in EDM of nonconductive ZrO2 ceramic mostly by spalling and it increases with the increase of input power.

Deformation Behavior of Doubly Curved SS400 Thick Metal Plates by High Frequency Induction-Based Line Heating

Line heating-induced deformation behavior of an SS400 thick plate was investigated through both numerical analysis and experimental counterpart by applying induction heating (IH) as a heat source. The drastic increase of temperature gradient upon increasing input power could mainly be predicted by numerical analysis, which attributes to the amount of permanent bending deformation of the thick plate. After plotting the amount of vertical deformation as a function of various positions from top surface of the plate, we found that the higher input power, the more thermomechanical deformation can be generated, regardless of the purposed doubly curved shapes such as concave and saddle-type plates. Also there is good agreement between the numerical analysis and experimental measurement in terms of the transverse curvature.

Helicon double layer thruster operation in a low magnetic field mode

Direct thrust measurements are made of a helicon double layer thruster operating in a low magnetic field mode. The relationship between the imposed axial magnetic field and generated thrust is investigated for a radio frequency input power range 200–500 W for propellant flow rates of 16.5 and 20 sccm (0.46 and 0.55 mg s−1) of argon. The measured thrust shows a strong dependence on the magnetic field strength, increasing by up to a factor of 5 compared with the minimum thrust level recorded. A peak thrust of 0.4–1.1 mN depending on thruster operating conditions is obtained. This increase is observed to take place over a small range of peak magnetic field strengths in the region of 70–110 G. The magnitude of the thrust and the corresponding magnitude of the magnetic field at which the peak thrust occurs is shown to increase with increasing input power for a given propellant flow rate. The ion current determined using a retarding field energy analyser and the electron number density found using a microwave resonator probe both correlate with the observed trend in thrust as a function of applied magnetic field.

High-power properties and miniature ultrasonic motor of (Sr,Ca)2NaNb5O15 piezoelectric ceramics

Abstract We investigated the high-power properties of lead-free piezoelectric ceramics with (Sr,Ca) 2 NaNb 5 O 15 (SCNN), and clarified the properties of miniature cantilever-type ultrasonic motor of array-type multilayer piezoelectric ceramics of SCNN (SCNN–A–MLPC) as the lead-free-piezoelectric application. The jump phenomena of SCNN ceramics with constant-voltage driving produced mirror-reversed images relative to those of Pb(Zr,Ti)O 3 -based (PZT) ceramics. The nonlinear behavior was caused by the hard-spring effect of SCNN ceramics which possess notable elastic properties among the piezoelectric materials. Under high vibration velocity with constant-motional-current driving, SCNN ceramics showed that the temperature rise was lower than that of PZT ceramics and the degradation of the quality factor was limited, resulting in a gradual increase in the equivalent mechanical resistance. SCNN ceramics have superior high-power properties. The cantilever-type ultrasonic motor was fabricated using SCNN–A–MLPC and the driving properties were evaluated. The output power of the motor increased linearly with increasing input power up to 110 mW without heat generation. The output power density was high in comparison with that of the commercialized motor of PZT ceramics. Furthermore, the refined motor with build in preload mechanism was fabricated and the driving properties were evaluated. The motor was able to rotate with 200 rpm and 40 μN m at 2.6 V p−p . It appeared that the motors have a high potential as an environmental friendly piezoelectric device with excellent properties, reflecting the high-power properties of SCNN ceramics.

Distortion-cancellation of GaAs-HBT amplifier using bias-voltage droop control

Presented is a simple design method to improve the linearity of (hetero-junction) bipolar junction transistor (HBT or BJT) power amplifiers (PAs) designed in the class-AB or B mode. The introduced approach controls the dynamic drooping characteristic of the base-emitter DC bias-voltage of HBTs as input power increases, resulting in correcting the nonlinear AM-AM and AM-PM conversions. Measurements for the demonstrated single-stage GaAs-HBT PAs with 29 dBm saturated output power show 6.5 dB improvement in the adjacent channel power ratio (ACPR) at 15 dBm average output power and 0.6 dB increase of the linear output power where the ACPR crosses −40 dBc.

Numerical investigation of edge plasma phenomena in an enhanced D-alpha discharge at Alcator C-Mod: Parallel heat flux and quasi-coherent edge oscillations

Reduced-model scrape-off layer turbulence (SOLT) simulations of an enhanced D-alpha (EDA) H-mode shot observed in the Alcator C-Mod tokamak were conducted to compare with observed variations in the scrape-off-layer (SOL) width of the parallel heat flux profile. In particular, the role of the competition between sheath- and conduction-limited parallel heat fluxes in determining that width was studied for the turbulent SOL plasma that emerged from the simulations. The SOL width decreases with increasing input power and with increasing separatrix temperature in both the experiment and the simulation, consistent with the strong temperature dependence of the parallel heat flux in balance with the perpendicular transport by turbulence and blobs. The particularly strong temperature dependence observed in the case analyzed is attributed to the fact that these simulations produce SOL plasmas which are in the conduction-limited regime for the parallel heat flux. A persistent quasi-coherent (QC) mode dominates the SOLT simulations and bears considerable resemblance to the QC mode observed in C-Mod EDA operation. The SOLT QC mode consists of nonlinearly saturated wave-fronts located just inside the separatrix that are convected poloidally by the mean flow, continuously transporting particles and energy and intermittently emitting blobs into the SOL.

Properties of Miniature Cantilever-Type Ultrasonic Motor Using Lead-Free Array-Type Multilayer Piezoelectric Ceramics of (Sr,Ca)2NaNb5O15 under High Input Power

The properties of miniature cantilever-type ultrasonic motors using lead-free array-type multilayer piezoelectric ceramics of (Sr,Ca)2NaNb5O15 (SCNN) developed using the design rule were investigated under high input power by comparison with the high-power properties of SCNN ceramics. The frequency dependence of the revolution speed reflected the nonlinear behavior of SCNN ceramics with the hard-spring effect and showed a mirror-reversed image relative to that of the motor of Pb(Zr,Ti)O3 (PZT) ceramics. The output power increased linearly with increasing input power up to 110 mW without heat generation, and the driving properties were almost the same as the expectations under low input power. The output power density characteristics of the motors were high in comparison with those of the commercialized motors of PZT ceramics. It appeared that the motors have a high potential as an environmental friendly piezoelectric device with excellent properties, reflecting the high-power properties of SCNN ceramics.

Temperature diagnostics of ECR plasma by measurement of electron bremsstrahlung

The x-ray bremsstrahlung spectrum emitted by the electron population in a 14.5 GHz ECR plasma source has been measured using a NaI(Tl) detector, and hence the electron temperature of the higher energy electron population in the plasma has been determined. The x-ray spectra for Ne and Ar gases have been systematically studied as a function of inlet gas pressure from 7 × 10(-7) mbar to 7 × 10(-5) mbar and for input microwave power ∼1 W to ∼300 W. At the highest input power and optimum pressure conditions, the end point bremsstrahlung energies are seen to reach ∼700 keV. The estimated electron temperatures (T(e)) were found to be in the range 20 keV-80 keV. The T(e) is found to be peaking at a pressure of 1 × 10(-5) mbar for both gases. The T(e) is seen to increase with increasing input power in the intermediate power region, i.e., between 100 and 200 W, but shows different behaviour for different gases in the low and high power regions. Both gases show very weak dependence of electron temperature on inlet gas pressure, but the trends in each gas are different.

Degradation of Aqueous 3, 4-Dichloroaniline by Wire-Cylinder Dielectric Barrier Discharge Reactor

Degradation of aqueous 3, 4-dichloroaniline (3, 4-DCA) by wire-cylinder dielectric barrier discharge reactor was carried out in the present paper. Generation of reactive species was analyzed, changes of aqueous ozone concentration and solution pH values were examined; meanwhile, the effect of input power and initial pH value on the degradation efficiency of 3, 4-DCA were investigated. The results showed that the degradation efficiency of 3, 4-DCA increased with increasing input power when the input power was increased from 70 W to 90 W, while it decreased with increasing input power when the input power was increased from 90 W to 110 W; and the same changing trend was observed in the change of aqueous ozone concentration. At alkaline conditions and acidic conditions, 3, 4-DCA degradation rate was significantly higher than that of neutrality conditions. In addition, there was a remarkable decline of the solution pH values during 3, 4-DCA degradation.

BIAS-free analog predistorters with L-TYPE attenuator for RF power amplifiers

Parallel forward-reverse Schottky-diode paths and a L-type attenuator form a bias-free predistorter that effectively reduces the intermodulation distortion of an RF power amplifier.The predistorter exhibits a constant insertion loss at the low input power and its insertion loss decreases when the input power increases. The resistor in the L-type attenuator serves as the transmission path when the input power is small. When the input power is large, on the other hand, the diode paths are activated to serve as the linearization vehicle for the predistorter. An improvement of extended operating power level up to 5 dB with the limit of −30 dBm adjacent-channel leakage power is obtained for a 5-watt amplifier at 1.9 GHz. Measured results are presented to illustrate the effectiveness of the predistorter. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:920–923, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26712