Showing papers on "Chamber pressure published in 1998"

An experimental study of combustion dynamics of a premixed swirl injector

Abstract: A comprehensive experimental study has been conducted on combustion instabilities in a premixed swirler injector system at various equivalence ratios, chamber pressures, and inlet air temperatures. A stability map has been determined to indicate the range of operating conditions conductive to the occurrence of instabilities. The amplitude of instabilities was found to be a strong function of the equivalence ratio, with pressure oscillations as high as 20% of the mean chamber pressure and unsteady velocities comparable to the mean flow values observed for equivalence ratios around 0.6. On the other hand, beyond an initial threshold value of inlet air temperature at which instability suddenly initiated, variations in inlet air temperature had minimal effect on the strength of instabilities. Measurements of steady and unsteady flame structures carried out using CH chemiluminescence and photographic imaging techniques indicate that the onset of instabilities can potentially cause significant alterations in flame structure, sometimes even causing near extinction of the flame during certain periods of the oscillation cycle. Coupled longitudinal oscillations were observed in the combustion chamber and upstream duct. Instability characteristics such as frequency, mode shape, and phase obtained through pressure measurements were found to be in excellent agreement with predictions from a linear acoustic analysis. A strong correlation was found between the heat release and pressure fluctuations near the dump plane, indicating a possible mechanism for creating and sustaining instabilities.

Reactive sputter faceting of silicon dioxide to enhance gap fill of spaces between metal lines

Abstract: An embodiment of the present invention teaches a semiconductor device fabrication process for reducing bread-loafing of an insulative layer at the gaps between a plurality of patterned conductive lines, by sputter faceting an existing SiO 2 layer overlying the patterned conductive lines by flowing in argon gas at a rate of approximately 50 sccm, with a reactive CF 4 gas having a flow rate range of approximately 1-4 sccm, into a chamber having a chamber pressure set at approximately 30 mTorr that is equipped with a magnetic field set at approximately 60 Gauss.

Initial Growth Rate and Visual Characteristics of a Round Jet into a Sub- to Supercritical Environment of Relevance to Rocket, Gas Turbine, and Diesel Engines

Abstract: : The combustion chamber temperature and pressure in many liquid rocket, gas turbine, and diesel engines are quite high and can reach levels above the critical point for the injected fuels and/or oxidizers. A high pressure chamber is used to investigate and understand the nature of the interaction between the injected fluid and the environment under such conditions. Pure N2 He, and O2 fluids are injected. Several chamber media are selected including, N2, He, and mixtures of CO+N2. The effects of chamber pressure ranging from a subcritical (i.e. relative pressure, P(sub r) = P/P (sub injectant critical 1) value at a supercritical chamber temperature (relative temperature T sub r = T/T sub injectant critical >1) are photographically observed and documented near the injector hole exit region using a CCD camera illuminated by a short-duration back-lit strobe light. At low subcritical chamber pressures, the jets exhibit surface irregularities that amplify downstream, looking intact, shiny, but wavy (sinuous) on the surface that eventually break up into irregularly-shaped small entities.

Spectroscopic determination of carbon dimer densities in and plasmas

Abstract: In contrast to conventional methods of diamond chemical vapour deposition (CVD), nanocrystalline diamond CVD takes place with only a small fraction of feed gas hydrogen. Minimal amounts of , believed critical in hydrogen-rich CVD, are expected to be produced in hydrogen-deficient systems and alternative mechanisms for diamond growth must be considered. The carbon dimer, , is believed to be an important species in these growth environments. We have experimentally determined the density of gas phase in and microwave plasmas used to deposit nanocrystalline diamond. The density is monitored using high-sensitivity absorption spectroscopy of the (0, 0) band as chamber pressure, microwave power, substrate temperature and feed gas mixtures are varied for these two chemical systems. The absolute density of is most sensitive to the total chamber pressure and fraction of carbon in all molecular species in the feed gas in discharges and to the total chamber pressure and substrate temperature in plasmas. We discuss possible production channels in both chemical systems. The efficiency of production from fullerene precursors is over an order of magnitude greater than that from hydrocarbon precursors.

Viscous effects in supersonic mems-fabricated micronozzles

Abstract: A contoured converging-diverging micronozzle has been created for the acceleration of gas flows to supersonic velocities. Extruded two-dimensional devices, with minimum throat widths averaging 19 microns and 35 microns, are etched using deep reactive ion etching. Mass flow efficiencies through the nozzles range from 87% to 98% and are within experimental error to those predicted by a 2-D NavierStokes fluid simulation for Reynolds numbers 350-3800. The thrust of a 16.9 to 1 expansion ratio nozzle was measured to be 11.3 mN at 97 psia chamber pressure. This corresponds to an exit velocity of 590 m/s, which is Mach 3.8 for a chamber temperature of 300 K. Thrust efficiency is found to deviate considerably from the 2-D numerical model at low Reynolds numbers due to the development of sidewall boundary layers.

Methods for drying and cleaning of objects using aerosols and inert gases

Abstract: Methods for cleaning and/or drying objects that may have been wetted or contaminated in a manufacturing process. The objects are submerged in a rinse liquid in an enclosed chamber, and aerosol particles from a selected liquid are introduced into the chamber above the rinse liquid surface, forming a thin film on this surface. As the rinse liquid is slowly drained, some aerosol particles settle onto the exposed surfaces of the objects, and displace and remove rinse liquid residues from the exposed surfaces, possibly by a "chemical squeegeeing" effect. Surface contaminants are also removed by this process which may be performed at about room temperature. Chamber pressure is maintained at or near the external environment pressure as the rinse liquid is drained from the chamber. Inert gas flow is employed to provide aerosol particles of smaller size and/or with greater dispersion within the chamber. Continuous filtering and shunt filtering are employed to remove most contaminants from the selected liquid. A flow deflector redirects initial flow of the selected liquid to a supplementary filter, to remove most of the contaminant particle "spike" that appears when a system is first (re)activated. An improved surface for aerosol particle production is provided.

Brake control method having booster runout and pedal force estimation

Abstract: An electrically augmented brake control method in which vacuum booster run-out and pedal force are accurately predicted as a function of master cylinder pressure and engine vacuum, thereby eliminating the expense of dedicated sensors for measuring the same. A mathematical model of the vacuum booster is used to estimate the apply chamber pressure and the operator brake pedal force, based on measured values of engine vacuum (or manifold absolute pressure) and master cylinder pressure. The point of vacuum booster runout can be detected as the point at which the estimated apply chamber pressure reaches atmospheric pressure. In a preferred embodiment, a force-balance approach is used to carry out the estimation in an accurate but simple manner that is especially amenable to real-time control in an automotive on-board micro-controller.

Method of controlling the operating temperature and pressure of a coke oven

Abstract: The pressure in the coking chamber of a coke oven is held at about atmospheric pressure, and the temperatures at the opposite longitudinal ends of the combustion chamber are independently controlled. Fuel gas is supplied to hold the temperature at the opposite longitudinal ends to be at least about 1000° C. separately from a main burner for the combustion chamber, and the pressure in the coking chamber during the first part of coking is kept in a range from 5 mmH2 O below atmospheric to 10 mmH2 O above atmospheric pressure. This allows efficient coke production even with low moisture content coking coal, and coal crumbling near the oven doors is not a problem. The process is typically carried out in a coke oven having a pressure control system for each coking chamber including plural piping devices for supplying a pressure fluid and switching valves for selectively applying the pressure fluid to the nozzle in the rising pipe through any selected one of the piping systems. The fluid pressure applied to the nozzle and the pressure in the coking chamber are preferably changed over time based calculated relationships between carbonization time, coking chamber pressure, and fluid pressure applied to the nozzle.

Characterization of Fuel Regression in a Radial Flow Hybrid Rocket

Abstract: Reliable ignition and stable combustion have been achieved in a lab-scale radial-e ow hybrid rocket engine. The device utilizes 85% hydrogen peroxide and polyethylene and was tested at chamber pressures ranging from 118 to 238 psia. Fuel regression behavior was characterized with respect to initial geometry and mass e ux. The measured regression rates are greater than observed in axial port designs at the same e ux and chamber pressure levels. Although the regression behavior is effected locally by the three-dimensional e ow structure, the results were more uniform than predicted by lumped parameter ballistics approximations. For this reason, radial-e ow designs with acceptable fuel utilization appear to be feasible.

Evaluation of trifluoroacetic anhydride as an alternative plasma enhanced chemical vapor deposition chamber clean chemistry

Abstract: One environmental issue currently facing the semiconductor industry is the emission of perfluorinated compounds (PFCs) from a variety of processes including chamber cleaning following plasma enhanced chemical vapor deposition (PECVD) of dielectrics. The emission of PFCs has been targeted for reduction due to the contribution of these species to global warming. An option under investigation is the use of alternative compounds that emit lower amounts of global warming species. The current study presents chamber cleaning times and emissions from the use of one such species, trifluoroacetic anhydride (TFAA), in a widely used commercial PECVD tool, the Novellus Concept One 200. A central composite design-of-experiments was employed to calculate response surfaces for the chamber clean time and PFC emission concentrations as the chamber pressure, TFAA flow rate, and oxygen flow rate were varied. The chamber clean times were measured using optical emission spectroscopy, quadrupole mass spectrometry, as well as Fo...

Fluid dynamic study of direct current plasma jets for plasma spraying applications

Abstract: Recently, direct current (dc) plasma torches equipped with converging-diverging (Laval) nozzles, instead of standard cylindrical ones, have been shown to present several advantages for both vacuum and atmospheric plasma spraying, such as diminishing the gradients of temperature and velocity and reducing the turbulence intensity in the jet fringes. The present study was concerned with the diagnostics of the plasma jets produced by three nozzles of various contours: a standard cylindrical anode and a Mach 2.5 and Mach 3 Laval nozzle. Emission spectroscopy (absolute intensity) and enthalpy probe techniques were used to measure temperature and velocity fields. Special attention was given to the effects of spray chamber pressure on flow regime inside the nozzles and to the distribution of the temperature and velocity fields in the plasma jet. Results showed that under the chamber pressure conditions used (vacuum), for which Laval nozzles originally were designed, the generated plasma jets had greater centerline velocities and larger high temperature zones compared to standard cylindrical nozzles. The results showed significant improvement in the deposition efficiency by using nozzles with these computed contours.

Plasma etch method for forming metal-fluoropolymer residue free vias through silicon containing dielectric layers

Abstract: A plasma etch method for forming a patterned silicon containing dielectric layer within a microelectronics fabrication. There is first provided a plasma reactor chamber. There is then fixed within the plasma reactor chamber a microelectronics fabrication. The microelectronics fabrication comprises: (1) a substrate employed within the microelectronics fabrication; (2) a metal layer formed over the substrate; (3) a silicon containing dielectric layer formed upon the metal layer; and (4) a patterned photoresist layer formed upon the silicon containing dielectric layer. There is then etched through use of a plasma etch method at a first plasma reactor chamber pressure while employing the patterned photoresist layer as a photoresist etch mask layer the silicon containing dielectric layer to form a patterned silicon containing dielectric layer while reaching and etching the metal layer to form an etched metal layer. The plasma etch method employs an etchant gas composition comprising a fluorine containing etchant gas. Finally, there is pumped the plasma reactor chamber to a second plasma reactor chamber pressure lower than the first plasma reactor chamber pressure for a time sufficient to attenuate formation of a metal-fluoropolymer residue layer upon the etched metal layer.

Freeze drying apparatus and method employing vapor flow monitoring and/or vacuum pressure control

Abstract: Freeze drying apparatus and associated lyophilization procedures are provided employing vapor flow detection and/or vacuum control for monitoring and control of the lyophilization process. The vapor flow detector, such as a windmill sensor, is disposed to monitor vapor flow from product undergoing lyophilization. In a batch process, vapor flow is collectively monitored with the vapor flow detector between the process chamber and condenser chamber, while in a manifold configuration separate vapor flow detectors are employed at each flask attachment port. A windmill sensor provides visual feedback to an operator and/or electronic feedback to a system controller. A vacuum control system is also provided for use with or independent of vapor flow detection. This vacuum control disconnects the vacuum source from the process chamber when pressure within the process chamber falls below a first predefined set point. The vacuum source is then reconnected if process chamber pressure rises above a second predefined set point.

Estimation of the activation energy for Ar/Cl2 plasma etching of InP via holes using electron cyclotron resonance

Abstract: The temperature dependence of the via hole etch rate is reported for argon/chlorine plasma etching of indium phosphide in an electron cyclotron resonance etcher. The indium phosphide via hole etch rate was first established for several wafer chuck temperatures. Then the temperature of the wafer was estimated by measuring the heating effect of the plasma and the cooling effect of the helium backside cooling. The wafer temperature was then substituted for the wafer chuck temperature. The etch rate as a function of wafer temperature was found to exist in two regimes. The first regime is where the vapor pressure of the etch by product gas (indium chloride) is below the etcher chamber pressure. In this first regime the activation energy was calculated to be 0.45±0.05 eV. The second regime is where the vapor pressure of the etch by product gas (indium chloride) is above the etcher chamber pressure. In the second regime the activation energy was calculated to be 0.06±0.03 eV.

Flow field prediction within liquid film cooled combustion chambers of storable bi-propellant rocket engines

Abstract: The ROCFLAM software, an inhouse development of Daimler-Benz Aerospace AG (Dasa) under ESTEC contract, is used to simulate the complex flow field within the liquid film cooled combustion chamber of a storable bi-propellant rocket engine. The paper briefly outlines the modeling which is applied to approximate the physics and combustion chemistry within such a thruster. Simulating Dasa's 400 N MMH/NTO apogee thruster, it is demonstrated that the code is capable to handle the three existing and interacting physical phases, namely the reactive gas mixture, the dispersed propellant droplets and the annular liquid cooling film. Especially the prescription of initial spray patterns instead of an accurate resolution of the liquid jet break-up is shown to be well-suited to reflect global thrust chamber characteristics. Available fullscale test data (chamber pressure, thrust and external wall temperature distribution) are used to evaluate the simulation results. Finally, the dependence and sensitivity of such threephase flow simulations on the estimated spray characteristics are illustrated. Good agreement of ROCFLAM simulation and measurement is obtained.

Valve cartridge having pressure sensor for agriculture and weed control

Abstract: An agricultural spray implement includes a plurality of removable valve/filter/nozzle cartridges. Each removable cartridge has a housing that retains a high speed solenoid valve and a spray nozzle. When the solenoid valve is open, an agricultural liquid (for example, herbicide) flows through the solenoid valve, through a chamber in the housing, and through the nozzle. To monitor cartridge operation and/or to detect cartridge failures (for example, a solenoid valve that is stuck open or closed or a nozzle that is clogged), a pressure sensor is provided that detects a pressure in the chamber. A chamber pressure that does not change when the solenoid valve is controlled to open and/or close is indicative of cartridge failure. Operation of each of the many spray cartridges of the agricultural spray implement is monitored from a single display.

Vane Tip Detachment in a Positive Displacement Vane Pump

Abstract: This paper reports on the theoretical study of the transient chamber, pressure and vane motion in a positive displacement vane pump which widely used in the automotive power steering systems. For analyzing the vane detachment, dynamic equation of vane motion and flow continuity equations are derived and then solved simultaneously using the numerical integration. Vane detachment is shown to be a function of the chamber pressure, rotational speed, and the design geometry of pump. Vane detachment occurs due to excess compression of chamber volume, and it can be reduced by adjustment of design parameters. Specially, silencing V-groove in side plate and radius reduction ratio of compression zone in the cam ring are important design factors for reducing the vane detachment.

The determination of the current-voltage characteristics of a closed-field unbalanced magnetron sputtering system

Abstract: An investigation has been carried out into the current-voltage ( I-V ) characteristics of a closed-field unbalanced magnetron sputtering system (CFUBMS). CFUBMS is a versatile technique for the high-rate deposition of high quality metal, alloy and ceramic coatings. A key factor in this system is the ability to transport high ion currents to the substrate. This can enhance the formation of fully dense coatings at relatively low values of homologous temperature. A study has been made of the parameters that determine the I-V characteristics of this system, at both the target and the substrate. From this, empirical relationships have been developed to describe the substrate ion current density and the substrate self-bias potential. Measurements have been taken of the discharge voltage, the substrate self-bias voltage, and substrate current using aluminium, zirconium, tungsten, and copper targets, at target currents of up to 8 A, over the pressure range 0.5-3 mTorr, and at substrate-to-target separations of 80 mm, 110 mm and 150 mm. The discharge voltage, VT, follows the established relationship I T = β ( V T − V 0 ) 2 , where I T is the discharge current and V 0 is the minimum voltage required to strike a discharge. The variations of β and V 0 with target material and pressure are discussed. At the substrate, a linear relationship, I s = mI T , was observed between the ion current drawn at the substrate, I s , and the discharge current, I T , where the coefficient of proportionality, m , varies with chamber pressure and substrate-to-target separation. Also, self-bias voltages, in the range −17 to −30 V, were measured. The value was largely independent of target material and substrate-to-target separation, but depended strongly on chamber pressure.

Investigation of CF3I as an Environmentally Benign Dielectric Etchant

Abstract: In this study, trifluoroiodomethane (CF3I), a non-global-warming gas, has been investigated as a substitute for typical PFC’s currently used in wafer patterning and CVD chamber cleaning processes. Dielectric films consisting of plasma enhanced chemically vapor deposited silicon dioxide and silicon nitride were comparatively etched in CF3I and C2F6/O2 plasma environments. The etch rate of these films was ascertained as a function of applied rf power, etchant gas flow rate, reaction chamber pressure, and CF3I: O2 ratio. Destruction efficiencies of CF3I at different processing parameters were evaluated. Depending on the flow rate, rf power, and chamber pressure, utilization efficiency of CF3I varied from as low as 10% to as high as 68%. CF4, C2F6, COF2, and CO2 were the predominant by-products found in the exhaust stream; however, their concentrations were very low compared to the traditional process employing C2F6/O2 mixtures.

Force transmission device e.g. for engine common rail fuel injection system

Abstract: The force transfer arrangement has a working chamber (3) contg. fluid (4) under a chamber pressure, a control drive (5), a housing (1) with at least one bore (2) bounding on the working chamber, a piston (6) per bore axially movable in the bore and a restoring device (7) per piston which presses the piston in the direction of the working chamber. At rest, a mechanical force connection exists between the control drive (5) and piston (6) via the working chamber. By moving the control drive the piston is mechanically displaced whilst increasing the chamber pressure until it is displaced solely by hydraulic conversion.

Method for producing a two chamber pressure pack and a device for carrying out the same

Abstract: A method for manufacturing a pressurized two-chambered container in the form of an aerosol can, in which a housing is provided with an opening that can be sealed tightly by a spray or aerosol valve. A product chamber and a propellant chamber are formed separately fluid-tight from each other by a flexible diaphragm in the housing. The product chamber can be charged with a product which can be release through said valve. The propellant chamber can be charged, on the other hand, with a compressed propellant. The product chamber communicates with the product-release opening. At least one end of a blank is left open to constitute subsequently the housing. The diaphragm is inserted into the blank through the open end, and the blank then is formed into the housing. An edge of the open end of the blank is reformed to narrow it into an integral mouthpiece that accommodates the product-release opening.

Experimental investigation of a metallized cryogenic hybrid rocket engine

Abstract: Hybrid propulsion systems offer many attractive characteristics such as their inherent simplicity, safe and inexpensive operations, environmentally friendly exhaust, and the capability for throttling. However, the slow burning nature of the classical hybrid fuels requires complex grain geometries and relatively large initial port volumes to achieve the required surface area for producing sufficient fuel mass flow rates, and consequently, thrust levels. Substantial increases in hybrid regression rates could eliminate the need for these complex geometries and would enable more efficient volumetric loading of the fuel through a reduction in both initial port volume requirements and grain sliver mass at burnout. Orbital Technologies Corporation has addressed these issues by the development and testing of a new class of cryogenic hybrid rocket engines that regress 20 to 40 times faster than conventional HTPB-based fuels. Many different hybrid propellant combinations have been tested. This paper focuses on subscale SCHVGOX and SCHt-Al/GOX hybrid development that was conducted under a Phase II NASA/LeRC SBIR. The objectives of the program were to: (1) research the liquid to solid fuel grain formation process, (2) research the gas to solid fuel grain formation process, (3) conduct parametric testing of SCHt/GOX and SCEU-Al/GOX hybrids, and (4) investigate the effects of different types and amounts of aluminum loading. The major findings were: (1) the SCHVGOX and SCHt-AyGOX hybrid firings exhibit smooth, relatively flat and predictable chamber pressure traces, (2) the SCEL^/GOX and SCHt-Al/GOX hybrids obey the classical hybrid regression law and have a similar dependence on mass flux as HTPB-based fuels, but regress 10-20 times faster, (3) as the percent of Al in the grain was increased, the hybrid regression rate decreased, and (4) reducing the initial temperature of SCH4 grains reduces the fuel regression rate. In addition to exhibiting extremely high regression rates, these propellant combinations offer substantial increases in * Member AIAA f Associate Fellow AIAA * Senior Member AIAA * Member AIAA Isp compared to classical hybrid fuels, and are competitive alternatives to bi-propellant and solid propulsion systems. Potential applications include: upper stages, orbit transfer, planetary ascent/decent, and launch vehicles. TEST ENGINES AND SUPPORTING HARDWARE Two hybrid engines were developed and tested during the program. A Low-Cost Hybrid Engine/Freezer was used to research the liquid to solid grain formation process and investigate the effects of different Al loadings. ORBITEC's Mark II engine was used to research the gas to solid fuel formation process and to conduct SCHt/GOX and SCH»Al/GOX firings. The concept behind the Low-Cost Cryogenic Hybrid Engine was to keep it simple, inexpensive, and versatile. This was accomplished by making the main engine components from off-the-shelf pipe fittings. A schematic and photograph of the hardware are shown in Figures 1 and 2, respectively. The engine chamber consisted of a 5-cm ID pipe surrounded by a coolant bath open to the atmosphere. A 5-cm pipe coupling welded to the center of the base plate allowed the main chamber to be screwed into the top and the aft chamber to be screwed into the bottom. A pipe cap with threaded ports for the ignitor, main oxygen, and pressure transducer, screwed onto the top of the main chamber and a copper heat sink nozzle screwed onto the aft chamber. An insulation ring surrounded the coolant bath. The main oxygen, ignitor oxygen, and ignitor methane solenoid valves along with the ignitor glow plug were all computer controlled with ORBrrEC's flexible computer control system. The computer recorded event timing and chamber pressure. A schematic of the Mark II Engine is shown in Figure 3. The engine is encased in a vacuum chamber to Copyright © 1998 by Orbital Technologies Corporation (ORBITECTM) Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. 1 American Institute of Aeronautics and Astronautics allow the radiation shield (not shown) to function. A coolant (LHe or LN2) fills the outer engine dewar and chills the wall of the center tube. The methane gas is admitted into the chamber which is maintained at a pressure below the methane triple point, causing the methane gas to freeze directly onto the inner wall of the center tube. When the engine is ready to fire, the inner chamber is exposed to an atmospheric GHe purge and then an ignitor flame. Gaseous oxygen is then injected at the top of the grain. The firing begins and the grain is depleted over time, producing a hot gas emission/thrust. Figure 4 shows the side view of the Mark-II system located in ORBITEC's test facility. All event timing and data acquisition were computer controlled using ORBITEC's cryogenic touchscreen control system.

Method for forming a contact opening with multilevel etching

Abstract: A multilevel contact etching method to form a contact opening is provided. The method contains using an inductively coupled plasma (ICP) etcher to produce a high plasma density condition. The plasma gas etchant is composed of C4 F8 /CH2 F2 /CO/Ar with a ratio of 3:4:12:80 so that silicon nitride can be selectively etched while the silicon and silicide are not etched. Each content ratio of the plasma gas etchant allows a variance of about 20%. Wall temperature of the ICP etcher is about 100° C.-300° C. A cooling system for a wafer pad is about -20° C.-20° C. Chamber pressure is about 5-100 mtorr. Bias power on the wafer pad is about 1000 W-3000 W. Source power of an inductance coil is about 500 W-3000 W.

Determination of Pressure Dependence of Burning Rate in Solid Motors Using Ultrasonic Technique

Abstract: The instantaneous burning rate of an aluminized composite solid propellant in a ballistic evaluation motor was measured continuously using an ultrasonic pulse-echo technique. The motor was designed to operate over a range of pressure from 2.5 to 4.5 MPa during its burning period. Hence, the burning-rate data could be obtained at different pressures directly from a single motor Ž ring itself, and the data were used to determine the pressure dependence of the burning rate. Thus, the technique is shown to overcome the need for carrying out several strand tests or ballistic evaluation motor tests, each at a different pressure, for characterizing a solid propellant burning rate.

Excimer lamp-induced decomposition of palladium metalorganic films for electroless copper plating

Abstract: Photo-assisted activation of non-catalytic substrates using an excimer lamp for subsequent electroless copper plating is described. The palladium films formed and the π-methallyl-dibenzoylmethyl-palladium(II) layers used were characterized using ultraviolet spectrophotometry and Fourier transform infrared spectroscopy. The variables which are important to the process are discussed, including the exposure time, UV intensity and chamber pressure. The photo-decomposition of the palladium compounds was found to be a function of both the UV dose and chamber pressure during irradiation. The selectivity of subsequent metal electroless plating using a commercial copper bath was demonstrated by irradiating the surfaces through a quartz contact mask.

Method and apparatus for melting and pouring specialty metals

Abstract: Specialty metals and alloys are melted in a crucible typically holding no more than about 100 lbs. of the metal and disposed in a furnace the interior of which is filled with a desired, e.g. inert, gas and subjected to a vacuum in the range of about 5% to 32% of atmospheric pressure. For special circumstances, it would be possible to start in the specified pressure range and then increase the melt chamber pressure to atmospheric or above. The vacuum permits the initiation and formation of long electric discharge arcs between the electrode of an immovable plasma torch mounted to the furnace and the inside of the crucible to provide enough space for charging of the crucible with fresh metal laterally through a charge opening in the upright side wall of the furnace and a vacuum chamber operatively connected with the charge opening. The melted metal is drained from the crucible through a drain hole in the bottom into molds which typically have close to the desired finished shape of the article and which can be removed from the furnace without the need to break the vacuum therein. A skull forming along the inside surfaces of the crucible is lifted off the crucible surfaces after each pour with a closure plate that is pushed from below into the drain hole. The skull is then melted with the plasma torch so that resulting melted metal collecting in the drain forms a drain plug upon solidification.

Performance of an Axisymmetric Rocket Based Combined Cycle Engine During Rocket Only Operation Using Linear Regression Analysis

Abstract: The all rocket mode of operation is shown to be a critical factor in the overall performance of a rocket based combined cycle (RBCC) vehicle An axisymmetric RBCC engine was used to determine specific impulse efficiency values based upon both full flow and gas generator configurations Design of experiments methodology was used to construct a test matrix and multiple linear regression analysis was used to build parametric models The main parameters investigated in this study were: rocket chamber pressure, rocket exit area ratio, injected secondary flow, mixer-ejector inlet area, mixer-ejector area ratio, and mixer-ejector length-to-inlet diameter ratio A perfect gas computational fluid dynamics analysis, using both the Spalart-Allmaras and k-omega turbulence models, was performed with the NPARC code to obtain values of vacuum specific impulse Results from the multiple linear regression analysis showed that for both the full flow and gas generator configurations increasing mixer-ejector area ratio and rocket area ratio increase performance, while increasing mixer-ejector inlet area ratio and mixer-ejector length-to-diameter ratio decrease performance Increasing injected secondary flow increased performance for the gas generator analysis, but was not statistically significant for the full flow analysis Chamber pressure was found to be not statistically significant

Diverse thermal, pressure and vacuum treatment for e.g. moist foods, cosmetics, chemical and pharmaceutical products

Abstract: After heating, the products are cooled by release to vacuum An Independent claim is included for the equipment to carry out the process, applications (please see uses section) and diverse products made. Preferred features: Heating takes place at 0.8 bar or more, using wet or superheated steam. Before heating, chamber pressure is lowered below 0.2 bar. Cooling is achieved by lowering pressure to 0.5 bar or less. Rate of pressure reduction causes expansion of less than 1.5 times. Initially, all operational parameters, including heating temperature and duration, rate of depression, steam temperature and pressure, are set to eliminate microorganisms and assure keeping qualities. Depression rate control, avoids altering product texture. Treatment affects surfaces of product portions, optionally reducing free surface water. The product is subsequently treated under vacuum or gas, to promote keeping, the duration depending on product nature, treatment, packing and storage. After treatment the product is cooled by airflow.