Showing papers on "Chamber pressure published in 2003"

Design of an artificial lung compliance chamber for pulmonary replacement.

Abstract: Matching the impedance of an artificial lung for pulmonary replacement to native pulmonary impedance is important in preventing right ventricular dysfunction. A lumped-parameter theoretical model and bench-top experiments were used to investigate the effect of a prototype compliance chamber on input impedance. The bench-top simulation consisted of a pulsatile flow generator, a prototype compliance chamber, and a low resistance artificial lung connected in series. Effective compliance was varied using pneumatic compression. The theoretical model considered a similar circuit with resistors before and after a compliance element. The bundle flow pulsatility (flow amplitude divided by average flow) and input impedance were calculated in the theoretical and experimental models. More compliance and lower upstream resistance result in lower bundle flow pulsatility and reduced first harmonic impedance. Matching the time scale of the circuit to the period of pulsatile flow also reduces impedance. The bench-top circuit demonstrated an optimal chamber pressure at which first harmonic impedance is reduced by 80%. The prototype compliance chamber in series with the artificial lung more closely matches native pulmonary impedance. The lumped-parameter model and the bench-top simulation will aid in the design and testing of compliance chamber modifications to improve its efficiency.

Adhesion characteristics of carbon/epoxy composites treated with low- and atmospheric pressure plasmas

Abstract: Although an adhesive joint can distribute load over a larger area than a mechanical joint, requires no holes, adds very little weight to structures and has superior fatigue resistance, it requires careful surface preparation of adherends for reliable joining and low susceptibility to service environments. The load transmission capability of adhesive joints can be improved by increasing the surface free energy of the adherends with suitable surface treatments. In this study, two types of surface treatment, namely the low pressure and the atmospheric pressure plasma treatment, were performed to enhance the mechanical load transmission capabilities of carbon/epoxy composite adhesive joints. The suitable surface treatment conditions for carbon/epoxy composite adhesive joints for both low and atmospheric pressure plasma systems were experimentally investigated with respect to chamber pressure, power intensity and surface treatment time by measuring the surface free energies of the specimens. The change in surf...

Method for fabricating semiconductor device

Abstract: After forming a resist pattern on an insulating film deposited on a semiconductor substrate, the insulating film is subjected to plasma etching using an etching gas including carbon and fluorine with the resist pattern used as a mask. A polymer film having been deposited on the resist pattern during the plasma etching is subjected to a first stage of ashing with a relatively low chamber pressure and relatively low plasma generation power by using an oxygen gas or a gas including oxygen as a principal constituent. A residual polymer present on the insulating film in completing the first stage of the ashing is subjected to a second stage of the ashing with a relatively high chamber pressure and relatively high plasma generation power by using an oxygen gas or a gas including oxygen as a principal constituent.

External combustion rotary piston engine

Abstract: An engine (400) is disclosed and comprises: a compressor (428) which periodically defines a chamber and carries out a pressurization process wherein the chamber volume is decreased to produce pressurized air; a combuster (426) which combusts fuel with the pressurized air to produce primary exhaust; an air motor (408) which is driven by the primary exhaust to produce power and secondary exhaust; an expander (410) which expands the secondary exhaust to produce tertiary exhaust and power; and a shaft (314) which directs power produced by the motor (408) and the expander (410) to the compressor (428) and any load. The combuster (426) is adapted to receive varying amounts of fuel, thereby to vary the power to the load. The compressor (428), during pressurization, releases air from the chamber such that the chamber pressure during pressurization and the primary exhaust pressure is substantially constant at steady state conditions, said constant being a function of the load being driven by the power.

Temperature controlled burner apparatus

Abstract: A fluid flow control valve uses a servo valve to control the pressure in a main diaphragm chamber defined by a main diaphragm. The main diaphragm carries a main valve element that assumes either a low flow or a high flow position relative to a valve seat depending on which of two states the servo valve is in. When the servo valve is in the one of the two states creating the low flow position of the main valve element, the main diaphragm chamber pressure is regulated by a pressure divider comprising two flow restrictors in series connection between the inlet and outlet chambers of the valve. When in the other of the two states, the servo valve disables the pressure divider and allows the main diaphragm chamber pressure to reach the outlet pressure. The disclosure shows two versions of the invention. One version of the valve enters its low flow state when the servo valve is closed, and the other when its servo valve is open.

Experimental Study of a Nanoparticle Virtual Impactor

Abstract: A nanoparticle virtual impactor was constructed and its performance under different operating conditions was investigated. Experimental evaluations showed that the nanoparticle virtual impactor has a 50% cutoff size ranging from 15 to 60nm. Further, the cutoff size of 60nm can be achieved at an impactor chamber pressure of 220torr when the nozzle upstream pressure is 760torr. This pressure level is much higher than that of thin-plate orifice nozzle impactors, which require 12torr to achieve the cutoff size of 66nm. Thus, the proposed virtual impactor can be operated with a small vacuum pump, which is more preferable for practical applications.

Splat microstructure of plasma sprayed cast iron with different chamber pressures

Abstract: Achieving a plasma sprayed cast iron coating containing graphite requires stringent control on spray parameters that synergistically influence the coating properties and thus the performance. The microstructure of cast iron splats greatly depends on spray parameters such as substrate temperature, chamber pressure, and spray distance. This paper presents the effect of chamber pressure on the splat microstructure, including oxides and graphite. At low chamber pressures, most splats exhibit a disk shape with high flattening ratios, whereas star-shaped splats extensively appear at high chamber pressures. Spraying at high chamber pressures causes the formation of pores and thick oxide zones at the splat/substrate interface, mainly due to the atmospheric gases, which are responsible for a decrease in splat adhesion. Spraying in Ar atmosphere reduces the splat oxidation due to a decrease in the oxygen partial pressure. Small deformed substrate ridges are observed adjacent to the periphery of splats sprayed at low chamber pressures whereas no ridges are detected at high chamber pressures. Ridge formation generates a kind of mechanical bond, which increases the adhesive strength. Since the molten droplets impinge with high velocity and thus high flattening ratio at low chamber pressures, the solidification rate becomes faster, and graphite formation is resultantly hindered.

Apparatus for controlling the pressure in a process chamber and method of operating same

Abstract: A method of operating apparatus for controlling the pressure in a process chamber (10), the apparatus comprising a first pump unit (14) having an inlet in fluid connection with an outlet of said process chamber, and a second pump unit (16) having an inlet in fluid connection with an outlet of the first pump unit via a flow control unit (18) comprising a variable flow control device (20; 28) having variable conductance for controlling outlet fluid pressure at the outlet of the first pump unit, the method comprises controlling speed of the first pump unit to increase the range of chamber pressures over which control of the outlet fluid pressure produces changes in said chamber pressure without exceeding the thermal limit and/or motor stall limit of the first pump unit.

Evaluation of Negative-Ion-Beam Driver Concepts for Heavy Ion Fusion

Abstract: The feasibility of producing and using atomically neutral heavy ion beams produced from negative ions as drivers for an inertial confinement fusion reactor is evaluated. Bromine and iodine appear to be the most attractive elements for the driver beams. Fluorine and chlorine appear to be the most appropriate feedstocks for initial tests of extractable negative-ion current densities. With regard to ion sources, photodetachment neutralizers, and vacuum requirements for accelerators and beam transport, this approach appears feasible within existing technology, and the vacuum requirements are essentially identical to those for positive-ion drivers except in the target chamber. The principal constraint is that this approach requires harder vacuums in the target chamber than do space-charge-neutralized positive-ion drivers. With realistic (but perhaps pessimistic) estimates of the total ionization cross section, limiting the ionization of a neutral beam to <5% while traversing a 3-m path would require a chamber pressure of no more than 1.3 x 10{sup -5} torr. However, it appears that substantial improvements in the beam spot size on target might be achieved at pressures a factor of 10 or more higher than this. Alternatively, even at still higher chamber pressures that would strongly ionize atomically neutral beams, the negative-ion approach maymore » still have significant appeal, since it precludes the possibly challenging problem of electron contamination of a positive-ion beam during acceleration, drift compression, and focusing.« less

Liquefied gas fuel supply device for diesel engine

Abstract: In a diesel engine system of a liquefied gas fuel, the present invention aims at the prevention of storing of the liquefied gas fuel in a cam chamber even when a diesel engine repeats stopping and operation thereof without returning the liquefied gas fuel in a fuel gallery of a fuel pressurizing device such as a supply pump or an injection pump to a fuel tank. An electrically-operated compressor 16 e is subjected to an ON/OFF control by a cam chamber pressure regulating part 20. In the inside of a cam chamber 12, a cam chamber pressure sensor 121 which detects a pressure in the inside of the cam chamber 12 is arranged. A cam chamber pressure regulating part 20 performs an OFF control of the electrically-operated compressor 16 e when a detected pressure of the cam chamber pressure sensor 121 is a predetermined value or less, and performs an ON control of the electrically-operated compressor 16 e so as to reduce the pressure in the inside of the cam chamber 12 to the predetermined pressure or less at a point of time that the detected pressure of the cam chamber pressure sensor 121 exceeds the predetermined pressure thus reducing the pressure in the inside of the cam chamber 12 by suction.

Easily loaded and unloaded getter device for reducing evacuation time and contamination in a vacuum chamber and method for use of same

Abstract: A getter device is shaped like a substrate used in a deposition process Embodiments of the device include a powdered getter material coated onto one or both sides of a support with a narrow rim portion left uncoated so that the device can be manipulated by automatic handling equipment A method for using the getter device includes providing a vacuum chamber and automatic handling equipment, loading the device into the chamber, reducing the chamber pressure to a desired value by using the getter device in conjunction with an external pump, removing the getter device and replacing it with a substrate, and depositing a thin film on the substrate The getter device can be in an activated state when loaded into the chamber, or it can be activated after being loaded by employing heating equipment ordinarily used to heat substrates placed in the chamber The getter material of the device may also be activated in a separate activation chamber before the getter device is loaded into the vacuum chamber

Hydraulic brake has control piston interacting with spring element so force is transferred from spring element to brake piston in actuation direction after removing hydraulic pressure chamber pressure

Abstract: The hydraulic vehicle brake has a parking brake device, a working pressure chamber bounded by a brake piston on which the parking brake acts and a device for locking the parking brake device in the applied state. A hydraulic pressure chamber is bounded by a control piston that interacts with a spring element so force is transferred from the spring element to the brake piston after removing the pressure in the hydraulic pressure chamber. The hydraulic vehicle brake has a parking brake device, a housing in which a hydraulic operating pressure chamber (7) is bounded by a brake piston (6) on which the parking brake acts and a locking device with which the parking brake device can be locked in the applied state. A hydraulic pressure chamber (13) connected to the operating pressure chamber is bounded by a control piston (12) that interacts with a spring element (14) so that force is transferred from the spring element to the brake piston in the actuation direction after removing the pressure in the hydraulic pressure chamber.

Hot flow pressure map of a vacuum facility as a function of flow rate to study facility effects

Abstract: A neutral background pressure map of the Large Vacuum Test Facility (LVTF) at the University of Michigan is presented. The LVTF was mapped at hot anode (i.e., discharge on) flow rates of 5.25 and 10.46 mg/s, corresponding to P5 Hall thruster operating conditions of 1.5 and 3.0 kW. The chamber pressure was mapped at nominal xenon pumping speeds of 140,000 and 240,000 l/s, corresponding to base pressures of 1.3x10 -6 Torr and 7.3x10 -7 Torr, respectively. The pressure map was performed with a rake consisting of five calibrated Bayard-Alpert (BA) hot-cathode ionization gauges. Analysis of axial pressure profiles on the LVTF's centerline shows that the plume pressure decreases from a maximum at the thruster exit plane down to the facility background pressure at approximately 2 m downstream of the exit plane. In addition, a neutral gas background pressure map of Vacuum Facility 12 (VF-12) at the NASA Glenn Research Center is presented. VF-12 was mapped at a series of cold anode flow rates corresponding to P5 Hall thruster operating conditions of 1.5, 3.0 and 9.0 kW. The chamber pressure was mapped at a nominal xenon pumping speed of 282,000 l/s with a rake consisting of the same five BA hot-cathode ionization gauges used in the LVTF. The cold flow pressure in VF-12 rapidly decreases out to approximately 2 m downstream of the thruster exit plane. From this point, the pressure slowly, but continually drops as the cryosurfaces are approached. Cryopump location affects the neutral density gradients within a vacuum facility and should be carefully considered when analyzing plume and performance data or designing a new Hall thruster facility. The hot flow neutral density profiles of each facility will be used to help correct performance and plume measurements for facility effects.

Manufacturing method for semiconductor device

Abstract: PROBLEM TO BE SOLVED: To prevent surface roughness in an insulating film when the insulating film is subjected to wet cleaning after a polymer film is removed by ashing which polymer film is deposited on a resist pattern, when the insulating film is subjected to plasma etching using an etching gas containing carbon and fluorine. SOLUTION: An insulating film 201 is subjected to plasma etching using an etching gas composed of fluorocarbon gas and a resist pattern 202 as a mask. A polymer film 206 deposited on the resist pattern 202 is subjected to ashing of first stage using oxygen gas or a gas containing oxygen as the main ingredient under the conditions of relatively low chamber pressure and plasma production power settings. The residual polymer present on the insulating film 201 is subjected to ashing of second stage using oxygen gas or a gas containing oxygen as the main gradient under the conditions of relatively high chamber pressure and plasma production power setting.

Method for preventing bounce oscillations of inertial masses caused by accelerations in hydraulically powered equipment

Abstract: When a swinging boom (15) driven by a hydraulic cylinder (19) stops, inertia causes continued motion of the boom which increases pressure in a chamber (40,42) of the hydraulic cylinder. Eventually that pressure reaches a level which causes the boom to reverse direction. Then pressure in an opposite cylinder chamber (42,40) increases until reaching a level that causes the boom movement to reverse again. This oscillation continues until the motion is dampened by other forces acting on the boom. As a result, an operator has difficulty in properly positioning the boom. To reduce this oscillating effect, a sensor (48,49) detects when the cylinder chamber pressure increases above a given magnitude and then a determination is made when the rate of change of that pressure is less than a defined threshold. Upon that occurrence, a control value (33,34) is opened to relieve the pressure in that cylinder chamber (42,40).

Enthalpy Probe Technique for Thermal Plasma Diagnostics

Abstract: The measuring principle and experimental results of the enthalpy probe technique for thermal plasma diagnostics are presented. Its calibration and errors are discussed. Typical results are presented for the system operation in an Ar/H2(5%H2) plasma arc jet under a reactor chamber pressure of 101.3 kPa. The plasma temperature and velocity profiles are measured. The center temperature and velocity are 6600 K and 850 m/s for plasma power 9 kW at axial location of 17 mm.

Selective oxidation methods and transistor fabrication methods

Abstract: The invention includes selective oxidation methods and transistor fabrication methods. In one implementation, a selective oxidation method includes positioning a substrate within a chamber. The substrate has first and second different oxidizable materials. The substrate is therein exposed to a gas mixture comprising an oxidizer and a reducer under conditions effective to selectively grow an oxide layer on the first material relative to the second material. The oxidizer oxidizes the first and second materials under the conditions. The reducer reduces oxidized second material under the conditions back to the second material. After selectively growing the oxide layer on the first material relative to the second material, partial pressure of the oxidizer and the reducer is reduced within the chamber by flowing an inert gas to the chamber while chamber pressure and chamber temperature are at or above those of the conditions during the exposing. Other aspects and implementations are contemplated.

Frequency domain modeling of a piezohydraulic actuator

Abstract: A frequency domain model is developed to quantify the dynamics of a piezohydraulic hybrid actuator. The analysis treats the hydraulic circuit as a series of fluid transmission lines each represented by a transfer matrix that relates pressure and velocity fluctuations at the inlet to pressure and velocity fluctuations at the outlet. A distributed parameter model is used to simulate the fluid viscosity and a first order square root approximation is used to simplify the equations which are then solved in the frequency domain. Various system variables like the pumping chamber pressure and output displacement are computed as a function of pumping frequency up to 1 kHz. The predicted output shaft displacement is compared with measurements made on a prototype piezohydraulic actuator. The modeling results indicate that the frequency response of the system is dominated by the dynamics of the hydraulic circuit and that operating the device at resonance may be an eective strategy for increasing the power output of the device.

The apparatus for handling air and method thereof

Abstract: PURPOSE: A variable air volume air conditioner and a method of the same are provided to keep necessary amount of fresh outside air appropriately for fluctuation of amount of oxygen dioxide in a room and to supply more accurate and stable amount of air despite fluctuation of air volume due to change of indoor load by applying mixed chamber pressure control method. CONSTITUTION: An air conditioner includes a first sensor(58) installed on an end of a ventilation duct ventilating a room to measure concentration of oxygen dioxide, temperature and humidity at set intervals; a second sensor(54) placed on an exhaust/ventilation chamber to measure pressure in the exhaust/ventilation chamber at set intervals; a third sensor(64) placed in an outside air/mixed air chamber to measure pressure in the outside air/mixed air chamber at set intervals; a fourth sensor(78) placed on an indoor end of an air supply duct to measure static pressure; a fifth sensor(72) measuring temperature and humidity of outside air; and a controller receiving measurements from the sensors to control.

Electro-hydraulic brake booster

Abstract: A brake booster (11, 83) amplifies driver brake pedal input into an output force and travel for operating a master cylinder A power unit (55, 129) builds and stores high pressure fluid to provide boost Inlet (59, 133, 139) and outlet (81, 135) solenoid valves regulate pressurized fluid to the amplifying mechanism In one embodiment, a single boost chamber (21) provides fluid pressure to operate the master cylinder and to provide a brake pressure indicative opposing force to driver input One travel sensor (29) monitors the position and movement of an input rod and piston (23), and a second travel sensor (31) monitors the position and movement of an output piston (15) An ECU (63, 143) monitors system parameters and controls a motor pump (77), inlet (59, 133) and outlet (81, 135, 139) valves and peripherals In another embodiment, the opposing force to the brake pedal input is provided by a separate pressure fluid chamber (111) located within and movable with the output piston (87) Boost chamber pressure and, optionally, output piston travel are monitored to provide a braking force indication An ECU (143) monitors system parameters including input travel (115) and boost chamber pressure (141), and controls the inlet (133, 139) and outlets valves (135) and peripherals

Quantitative Vapor Phase Exciplex Fluorescence Measurements at High Ambient Temperature and Pressure

Abstract: The exciplex fluorescence technique with the TMPD (tetamethyl-p-phenylene-diamine) / naphthalene dopant system was applied in a combustion-type constant-volume spray chamber. A detailed set of calibration experiments has been performed in order to quantify the TMPD fluorescence signal. It has been demonstrated that the TMPD fluorescence intensity was directly proportional to concentration, was independent of the chamber pressure, and was not sensitive to quenching by either water vapor or carbon dioxide. Using a dual heated-jet experiment, the temperature dependence of TMPD fluorescence up to 1000 K was measured. The temperature field in the spray images was determined using a simple mixing model, and an iterative solution method was used to determine the concentration and temperature field including the additional effects of the laser sheet extinction. The integrated fuel vapor concentration compared favorably with the measured amount of injected fuel when all of the liquid fuel had evaporated.

Pressure control in centrifugal evaporators

Abstract: A method of controlling the pressure within a chamber (12) of a drying apparatus (10) from which air and vapour is removed by a pump (30), which is operated continuously during the drying process. If both of a vent valve (18) and a pressure control valve (32) is opened, air at atmospheric pressure is drawn by the pump (30) directly from the pressure control valve (32), and via the chamber (12) and a non-return valve (26) from the vent valve (18). When the pressure in the chamber (12) is to be reduced both vent and pressure control valves (18, 32) are closed to allow the pump (30) to remove air, gas and vapour from the chamber (12) via the non-return valve.(26). After a required chamber pressure has been reached, the pressure control valve (32) is opened while the vent valve (18) remains closed

Neutral Beam Evolution in the KSTAR NBI Test Stand

Abstract: The pressure distributions in the test stand built for developing KSTAR NBI ion sources were obtained using a network system composed of conductance elements modeling the ion source, the neutralizer, and other beam line components The allowable regime was defined on the coordinates of the gas supply rate to the ion source and the neutralizer, considering the proper conditions of the three critical parameters, the ion source pressure for good arc discharge, the pressure integral in the neutralizer for sufficient neutralization, and the chamber pressure for minimum neutral beam loss The neutral beam evolution along the path from the ion source extraction grid to the calorimeter through the neutralizer, the bending magnet and the vacuum chamber was estimated for typical pressure distributions

Obserbation of lox/hydrogen combustion flame in a rocket chamber during chugging instability

Abstract: To obtain concrete information on the mechanism of unstable combustion of liquid oxygen-hydrogen rocket engines, a rectangular rocket chamber with four glass windows was developed. The designed maximum chamber pressure was 3.5 MPa and the thrust was 12.6 kN. The chamber included 12 actual size coaxial injection elements. The height of the chamber was designed to simulate first tangential mode instability of a 100-kN-sized cylindrical rocket chamber with the first transverse mode instability of the rectangular chamber. Combustion tests were conducted at a chamber pressure of 1.7 MPa. Two kinds of low frequency instability were observed in the tests. One was found to be related to the two-phase flow of liquid oxygen, which was observed during the start-up transient, and the other was related to low propellant injection pressure drops, which were observed at steady state. Combustion flames and oxygen jets were visualized for both conditions with a high-speed video at a rate of 4000 frame/sec. Oxygen jet images were obtained with a backlight. The results indicated interesting phenomena. For example, the combustion chamber pressure, the intensity of combustion flame and the breakup length oscillated in phase and the flame always attached behind the oxygen post during the chugging instability. Stability analysis based on the double time lag model by Szuch was conducted to clarify the cause of the start-up transient instability.

Manufacturing method of pressure sensor, and measuring device for use in the manufacturing method

Abstract: PROBLEM TO BE SOLVED: To provide a sensitivity measuring device for a pressure sensor that can measure sensitivity on a wafer basis. SOLUTION: The measuring device comprises a stage 20 mountable with a wafer 10 in which pressure detection parts for outputting an electrical signal corresponding to pressure are formed in chip units, a stage pressure control part 21, 40 and 51 for applying a controllable pressure to the wafer 10 from the side of the stage 20, a chamber pressure control part 52 and 110 capable of controlling the pressure in a pressure chamber 30, a stage drive part 60 and 70 capable of moving the stage 20 to a desirable position in the pressure chamber 30, and a probe 80 capable of detecting an electrical signal corresponding to the pressure in the pressure chamber 30 output from an individual pressure detection part in the wafer 10. The wafer 10 mounted on the stage 20 is fixed on the stage 20 by a pressure difference between the pressure from the side of the stage 20 and the pressure in the pressure chamber 30. COPYRIGHT: (C)2004,JPO