Showing papers on "Chamber pressure published in 2008"

Flowable dielectric equipment and processes

Abstract: Substrate processing systems are described that may include a processing chamber having an interior capable of holding an internal chamber pressure different from an external chamber pressure. The systems may also include a remote plasma system operable to generate a plasma outside the interior of the processing chamber. In addition, the systems may include a first process gas channel operable to transport a first process gas from the remote plasma system to the interior of the processing chamber, and a second process gas channel operable to transport a second process gas that is not treated by the remote plasma system. The second process gas channel has a distal end that opens into the interior of the processing chamber, and that is at least partially surrounded by the first process gas channel.

Virtual Metrology Modeling for Plasma Etch Operations

Abstract: The objective of this paper is to present the utilization of information produced during plasma etching for the prediction of etch bias. A plasma etching process typically relies on the concentration of electrically activated chemical species in a reaction chambers over time, depending on chamber pressure, gas flow rate, power level, and other chamber and wafer properties. Plasma properties, as well as equipment factors, are complex and vary over time. In this paper, we will use various statistical techniques to address challenges due to the nature of plasma data: high dimensionality, colinearity, parameter interactions and nonlinearities, variation of data structure due to equipment condition changing over time, etc. The emphasis will be data integrity, variable selection, accommodation for process dynamics, and model-building methods. Different techniques will be evaluated with an industrial dataset.

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas

Abstract: A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume, high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated, 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation, the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve, and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique, large-volume (1000 cm3), high electron density (on the order of 1011–12 cm−3), 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project ...

In-Line Control of a Freeze-Drying Process in Vials

Abstract: This article deals with the control of a freeze-drying process in vials. Firstly, the results that can be obtained when the operation is carried out at constant chamber pressure and shelf temperature are predicted by means of mathematical simulations, using a previously validated detailed model, thus allowing off-line optimization of the process. Further improvements can be obtained if the shelf temperature is varied during the process in such a way that the product temperature is always maintained at the maximum allowable value. This strategy for the in-line control of the process allows to minimize the time required for the primary drying, besides satisfying the process constraints. The possibility of manipulating the chamber pressure for control purposes is also discussed. An alternative strategy based on a simple feedback controller, with proportional-integral action, is also investigated: it is able to control the product temperature at a predetermined value, giving stable and fast responses. The con...

System and method for improved pressure adjustment

Abstract: A method for adjusting pressure within an air bed comprises providing an air bed that includes an air chamber and a pump having a pump housing, selecting a desired pressure setpoint for the air chamber, calculating a pressure target, adjusting pressure within the air chamber until a pressure within the pump housing is substantially equal to the pressure target, determining an actual chamber pressure within the air chamber, and comparing the actual chamber pressure to the desired pressure setpoint to determine an adjustment factor error. The pressure target may be calculated based upon the desired pressure setpoint and a pressure adjustment factor. Furthermore, the pressure adjustment factor may be modified based upon the adjustment factor error determined by comparing the actual chamber pressure to the desired pressure setpoint.

Pressure-Sensitive Paint Measurement of Pressure Distribution in a Supersonic Micronozzle

Abstract: Micronozzles have recently commanded considerable attention because of their potential applications, such as in flow control of microspacecraft. It is difficult to understand fundamental physical phenomena in microscale flow due to the lack of suitable quantitative measurement tools (pressure and temperature sensors, etc.). Pressure-sensitive paint is one of the most promising options for global distribution measurement in microscale flow. In this paper, pressure distribution in a supersonic micronozzle with a nozzle throat of 250 μm was investigated using pressure-sensitive paint, and the experimental results were compared with numerical simulation by Reynolds-averaged Navier-Stokes equations in three-dimensional space. The pressure-sensitive paint measurement technique demonstrated its validity for quantitative measurement of pressure distribution in microscale flow and revealed that the performance of the present micronozzle is critically affected by the boundary layer along the side wall.

Combustion Effects in Confined Explosions

Abstract: Results of shock-dispersed-fuel (SDF) explosion experiments are presented. The SDF charge consisted of a spherical 0.5-g PETN booster surrounded by 1 g of fuel, either flake aluminum (Al) powder or TNT. The charge was placed at the center of a sealed chamber. Three cylindrical chambers (volumes of 6.6, 20, and 40 l with L/D = 1) and three tunnels (L/D = 3.8, 4.65, and 12.5) were used to explore the influence of chamber volume and geometry on completeness of combustion. Detonation of the SDF charge created an expanding cloud of explosion product gases and hot fuel (Al or TNT). When this fuel mixed with air, it formed a turbulent combustion cloud that consumed the fuel and liberated additional energy (31 kJ/g for Al or 15 kJ/g for TNT) over and above detonation of the booster (6 kJ/g) that created the explosion. Static pressure gauges were the main diagnostic. Pressure and impulse histories for explosions in air were much greater than those recorded for explosions in nitrogen—thereby demonstrating that combustion has a dramatic effect on the chamber pressure. This effect increases as the confinement volume decreases and the excess air ratio approaches values between 2 and 3.5.

Low pressure recovery process for acceleration of in-situ bitumen recovery

Abstract: A method for recovery of hydrocarbons from a subterranean reservoir by operating adjacent injector producer well pairs under conditions of steam assisted gravity drainage (SAGD) with a lateral drainage well between and substantially parallel to them; the lateral drainage well is operated under conditions of intermittent steam injection and alternating oil, water and gas production; NCG is co-injected with steam into both the injector wells and the lateral drainage well at selected intervals, and in selected quantities in order to control the steam saturation of the SAGD steam chamber and the rise of the steam chamber, and to encourage lateral fluid communication between the adjacent well pairs and the LD well; controlling gas injection and production in order to control the rise of the steam chamber to improve production of oil; operating the well pairs and the LD well under conditions of a steam chamber pressure that is initially and briefly high to establish a steam chamber, but thereafter may be reduced to as low as 200 kPa; operating this low pressure SAGD in reservoirs that are at low pressure, due to factors such as depleted gas caps, regional geology, lack of cap rock, thief zones, or other low pressure zone or loss zones.

Counter-balanced substrate support

Abstract: A semiconductor processing system is described. The system includes a processing chamber having an interior capable of holding an internal chamber pressure below ambient atmospheric pressure. The system also includes a pumping system coupled to the chamber and adapted to remove material from the processing chamber. The system further includes a substrate support pedestal, where the substrate support pedestal is rigidly coupled to a substrate support shaft extending through a wall of the processing chamber. A bracket located outside the processing chamber is provided which is rigidly and sometimes rotatably coupled to the substrate support shaft. A motor coupled to the bracket can be actuated to vertically translate the substrate support pedestal, shaft and bracket from a first position to a second position closer to a processing plate. A piston mounted on an end of the bracket provides a counter-balancing force to a tilting force, where the tilting force is generated by a change in the internal chamber pressure and causes a deflection in the position of the bracket and the substrate support. The counter-balancing force reduces the deflection of the bracket and the substrate support.

Opportunities for a Liquid Rocket Feed System Based on Electric Pumps

Abstract: A feed system for liquid-propellant rocket engines based on electric pumps powered by batteries is proposed. It is proven to stand as a viable alternative to the pressure-gas feed system. The dependence of the feed system mass on the different operating parameters is obtained so as to identify the conditions favoring its adoption, that is, a relatively long burning time and a fairly high chamber pressure. Under such conditions, the proposed system is shown to offer significant mass savings with respect to the pressure-gas system when advanced batteries are used. This advantage is further enhanced by the beneficial effect of chamber pressure on the engine effective exhaust velocity. A test case for a low Earth orbit to geostationary equatorial orbit transfer is also presented to identify the optimum value of the burning time, deriving from the competition between the feed system mass and the effect of gravitational losses.

Polymeric particle formation through electrospraying at low atmospheric pressure.

Abstract: Electrospraying is a simple and versatile technique capable of producing polymeric particles. However, most investigations carried out thus far have been performed at ambient atmospheric pressure without studying the influences of pressure on the formation of polymeric particles. Here, we report our investigation on the effects of varying the pressure and the solution concentration on the microstructures of electrosprayed polymeric particles. Pressures are varied from ambient atmospheric pressure to 380 mmHg below ambient pressure, and solution concentrations are varied over a range of 3-7 w/v %. By varying these parameters, we manipulated the rate of solvent evaporation and the solidification of the electrosprayed particles. The results show that changes to the pressure had significant effects on the microstructure and morphology of poly(epsilon-caprolactone) (PCL) particles. The average particle size became larger as the chamber pressure decreased. At a solution concentration of 5 w/v % and a pressure 150 mmHg below ambient pressure, uniform and spherical PCL particles were generated. Electrospun fibers were formed when a solution concentration of 7 w/v % was used. The developed technique can be applied to prepare polymeric drug delivery carriers though a low-pressure-assisted spray-drying method, and is particularly suitable for fabricating delivery microspheres encapsulated with temperature-sensitive drugs and biomolecules.

Methods for optimizing thin film formation with reactive gases

Abstract: A method for producing a Group IV semiconductor thin film in a chamber is disclosed. The method includes positioning a substrate in the chamber, wherein the chamber further has a chamber pressure. The method further includes depositing a nanoparticle ink on the substrate, the nanoparticle ink including set of Group IV semiconductor nanoparticles and a solvent, wherein each nanoparticle of the set of Group IV semiconductor nanoparticles includes a nanoparticle surface, wherein a layer of Group IV semiconductor nanoparticles is formed. The method also includes striking a hydrogen plasma; and heating the layer of Group IV semiconductor nanoparticles to a fabrication temperature of between about 300° C. and about 1350° C., and between about 1 nanosecond and about 10 minutes; wherein the Group IV semiconductor thin film is formed.

Coupled analysis of flow and surface ablation in carbon-carbon rocket nozzles

Abstract: A study is conducted to predict C/C nozzle recession behavior in solid rocket motors for broad variations of propellant formulations and motor operating conditions. The numerical model considers the turbulent flow in the nozzle, heterogeneous chemical reactions at the nozzle surface, variable transport and thermodynamic properties, and heat conduction in the nozzle material. Results show that the recession rate is largely determined by the diffusion of the major oxidizing species (H2O, CO2, OH) to the nozzle surface. Both the concentration of the major oxidizing species -affected by the aluminum content of the propellant- and the chamber pressure exert a strong influence on the recession rate. The erosion rate increases almost linearly with chamber pressure and decreases with propellants with higher aluminum content. The calculated results show a very good agreement with the experimental data from the BATES motor firings.

Analytical model for an electrostatically actuated miniature diaphragm compressor

Abstract: This paper presents a new analytical approach for quasi-static modeling of an electrostatically actuated diaphragm compressor that could be employed in a miniature scale refrigeration system. The compressor consists of a flexible circular diaphragm clamped at its circumference. A conformal chamber encloses the diaphragm completely. The membrane and the chamber surfaces are coated with metallic electrodes. A potential difference applied between the diaphragm and the chamber pulls the diaphragm toward the chamber surface progressively from the outer circumference toward the center. This zipping actuation reduces the volume available to the refrigerant gas, thereby increasing its pressure. A segmentation technique is proposed for analysis of the compressor by which the domain is divided into multiple segments for each of which the forces acting on the diaphragm are estimated. The pull-down voltage to completely zip each individual segment is thus obtained. The required voltage for obtaining a specific pressure rise in the chamber can thus be determined. Predictions from the model compare well with other simulation results from the literature, as well as to experimental measurements of the diaphragm displacement and chamber pressure rise in a custom-built setup.

Performance of a Rocket-Ramjet Combined-Cycle Engine Model in Ejector Mode Operation

Abstract: A rocket-ramjet combined cycle engine model, embedding twin rocket chamber on top wall side of a scramjet flow-pass, was tested in its ejector-mode operation under sea-level static conditions. The rocket chamber was driven with gaseous hydrogen and oxygen at nominal operation condition of 3 MPa in chamber pressure and 6.5~7.5 in mixture ratio. Gaseous hydrogen was also injected through secondary injector orifices to pressurize the ramjet combustor. Mixing between the hot rocket plume and cold airflow as well as combustion of residual fuel within the plume with the airflow caused entropy and static pressure increases in the constant-area mixing duct in our original flow-pass design, resulting in a high back-pressure to the incoming airflow and a limited airflow rate. Thus, the mixing duct was re-designed to have divergence from its onset to compensate the pressure-rise. With this modified flow-pass configuration, the airflow rate was increased by 40%. However, this flow-pass geometry resulted in generation of low speed area, through which pressure-rise due to secondary combustion (and flow-pass exit contraction to simulate secondary combustion) penetrate the mixing duct and reduced the incoming airflow rate. A contraction on the incoming airflow enabled choking condition of the incoming airflow to sustaining the airflow rate, while the rate itself was reduced. Contraction at the exit of the engine enhanced mixing, however, choking condition was not attained due to the higher pressure level associated with the high exit contraction. Balancing these factors and additional mixing enhancement are required. The engine performances were summarized.

Process to produce a silencer tube with minimal wall thickness

Abstract: A method for reducing the weight of a silencer without compromising durability. By reducing the silencer housing wall thickness weight is removed from the silencer module. Areas on the housing where material is removed are primarily selected based on the internal pressure generated in a given chamber of the silencer. Further, removal of external material is selected based on the baffle arrangement. Individual chamber pressure is influenced by the muzzle pressure of the host firearm and the baffle style and baffle orientation within the silencer being used.

Effects of Nozzle Length and Process Parameters on Highly Constricted Oxygen Plasma Cutting Arc

Abstract: The influence of nozzle length and two process parameters (arc current, mass flow rate) on the plasma cutting arc is investigated. Modeling results show that nozzle length and these two process parameters have essential effects on plasma arc characteristics. Long nozzle torch can provide high velocity plasma jet with high heat flux. Both arc voltage and chamber pressure increase with the nozzle length. High arc current increases plasma velocity and temperature, enhances heat flux and augments chamber pressure and thus, the shock wave. Strong mass flow has pinch effect on plasma arc inside the torch, enhances the arc voltage and power, therefore increases plasma velocity, temperature and heat flux.

Gap Adjustable Molten Metal DoD Inkjet System With Cone-Shaped Piston Head

Abstract: In this paper, we present the design, fabrication, and performance test of a gap adjustable molten metal drop-on-demand (DoD) inkjet system with a cone-shaped piston head, which can eject a droplet of lead-free molten solder at high temperature. The gap adjustable mechanism with the cone-shaped piston head is proposed for optimizing the gap distance between the chamber wall and piston head. The droplet diameter and velocity can be controlled in a wide range by moving the initial gap distance and minutely by controlling the chamber pressure. Stability and satellite can be partly adjusted by controlling the initial gap distance and the chamber pressure, respectively. The working temperature is improved by locating the piezoelectric actuator at the outside of the furnace and by inserting the insulation block between the print head and the actuator. From a practical point of view, the molten metal DoD inkjet system presents a simple structure for easily interchangeable nozzle parts, even though the nozzle is choked. The gap adjustable molten metal DoD inkjet system with cone-shaped piston head has great potential as a manufacturing tool for direct printing a viscous material at various temperatures. It is expected to be applicable in many industrial fields including semiconductor packaging, electrode bonding, printed electronics, information, and display industry.

Laboratory Scale Survey of Pentad Injector Stability Characteristics

Abstract: This work provides an initial assessment of an experimental method for characterizing combustion stability of liquid rocket injectors. The experimental technique assumes mixing as the dominant factor leading to high frequency combustion instability. The research has shown that the single element subscale methodology is capable of creating high frequency combustion instability with gaseous methane and oxygen. Modified pentad impinging jet injectors were selected for the stability survey. The maximum time domain peak to peak dynamic pressure recorded in the chamber was 27% of the mean chamber pressure. The other factors indicating instability include injector manifold pressure pulsations as well as twofold chamber temperature increase from steady operation. The testing evidenced that the flame structure varies with the onset of unstable combustion as well as mode transition. As the oxygen mass flow rate was increased beyond the region of pure radial instability, the flame transitioned to a new mode of instability through a bifurcation process. The testing also showed that there were significant differences in stability characteristics which were a function of fuel impingement angle. All injectors went unstable at the first radial mode and the first radial, second tangential combined mode.

Turbulent Transport in Rocket Motor Unsteady Flowfield

Abstract: Nomenclature Ab = pressure coupling admittance function Ay = velocity coupling admittance function #o = mean speed of sound er,eo,ez = unit vectors in r, 0, and z directions E^ = normalization constant for mode m km = wave number for axial mode m L chamber length m = mode number Mb = mach number at burning surface n outward pointing unit normal vector p = pressure PQ = mean chamber pressure r = radial position R = chamber radius S = Strouhal number, km/Mb t = time t = unit vector tangent to burning surface u oscillatory velocity vector amplitude Ur,Uz = mean flow velocity components Vb = mean radial velocity at wall

The Effects of the Ambient Pressure on Self-Pulsation Characteristics of a Gas/Liquid Swirl Coaxial Injector

Abstract: Self-pulsation gas strong influences on the atomization and mixing process and accompanies strong noises. A strong pressure and flow rate oscillation are detected when self-pulsation occurs. A sharp and narrow increase in frequency spectrum by self-pulsation is observed at a certain frequency. In this study, the effects of the ambient pressure on selfpulsation characteristics of a gas/liquid swirl coaxial injector are studied experimentally. A gas/liquid swirl coaxial injector is mounted in the high pressure chamber and the ambient pressure increased up to 1 MPa. The spray patterns were investigated according to the ambient pressure using digital camera and stroboscope. Also, acoustic and spray characteristics of self-pulsation are investigated with various injection and recess length conditions using acoustic device and laser system. From the results, it is found that the ambient pressure has great effects on self-pulsation and the mechanism of self-pulsation is suggested. Nomenclature do = inner orifice diameter Pc = chamber pressure Reg = axial gas Reynolds number Rel = axial liquid Reynolds number RR = recess ratio vg = axial gas velocity vl = axial liquid velocity ρg = gas density ρL = liquid density

Development of Evaluation Technologies for Microtubular SOFCs Under Pressurized Conditions

Abstract: We developed evaluation technologies for microtubular solid oxide fuel cells under pressurized conditions. The pressurized cell evaluation system for the single cell was produced. The chamber temperature of the evaluation system can be controlled up to 750 °C, and the maximum chamber pressure is 0.8 MPa. It was possible to manually control the pressure difference between air and fuel gas within ±3 kPa during the pressure increase. The hard sealing technique was introduced for the evaluation under pressurized conditions. Using two different types of commercial inorganic ceramic adhesives, the gas leakage was controlled at approximately 2%. Differential pressure control between fuel and air is effective for the stable open circuit voltage and power generation. The power generation under pressurized conditions was successful at 650°C, and the pressurized effect was clearly confirmed.

Characterization of Gas -Centered Swirl -Coaxial Injector Stability in a Subscale Multi -Element Combustor

Abstract: Experimental testing of trans verse combustion instabilities from a gas -centered swirl coaxial injector are presented in this paper . Results show that the same time lag determined from longitudinal instability experiments can be used to design a n unstable multi -element chamber for tran sverse instability testing . The transverse instabilities were strong and well defined spatially . Results indicate that the mechanism causing instability was related to the shedding of vortices containing partially mixed propellants . Design parameters relat ed to the instability are the oxidizer post gas velocity, and the spacing between the oxidizer post and the wall and adjacent element. Nomenclature Pc = chamber pressure P’ = pressure oscillation peak to peak amplitude u’ = velocity oscillation peak to pea k amplitude h = injector step height L = vortex impingement point u = oxidizer post free stream velocity

Method for controlling pressure in pressure accumulator chamber of pressure accumulation type fuel injector, and pressure controller

Abstract: A method of and a device for controlling a pressure is provided in which control performance of accumulation chamber pressure is not deteriorated even in the presence of a disturbance by estimating, with observer control, a disturbance pressure that acts on an accumulation chamber (common rail) constituting an accumulator fuel injection apparatus adapted for use in a diesel engine and the like, and by correcting a pump discharge command with a compensation value capable of compensating for the estimated disturbance pressure. Provision of a feedback control unit 42 capable of calculating a pump discharge command value of a fuel pump based on a pressure difference between an actual accumulation chamber pressure detected by a fuel pressure sensor 46 and a target pressure of an accumulation chamber and a disturbance observer control unit 44 capable of deriving a compensation value compensating the disturbance by the numerical model of the pump discharge command value to the fuel pump, the disturbance pressure acting on the accumulation chamber, and an accumulation chamber pressure by using a transfer function of the fuel pump and by estimating the disturbance pressure from the numerical model, and an output from the feedback control unit 42 is corrected with the disturbance compensation value from the disturbance observer control unit 44.

Atomic layer deposition of strontium oxide via N-propyltetramethyl cyclopentadiendyl precursor

Abstract: A method of depositing oxide materials on a substrate is provided. A deposition chamber holds the substrate, where the substrate is at a specified temperature, and the chamber has a chamber pressure and wall temperature. A precursor molecule containing a cation material atom is provided to the chamber, where the precursor has a line temperature and a source temperature. An oxidant is provided to the chamber, where the oxidant has a source flow rate. Water is provided to the chamber, where the water has a source temperature. By alternating precursor pulses, the water and the oxidant are integrated with purges of the chamber to provide low contamination levels and high growth rates of oxide material on the substrate, where the pulses and the purge have durations and flow rates. A repeatable growth cycle includes pulsing the precursor, purging the chamber, pulsing the water, pulsing the oxidant, and purging the chamber.