Showing papers on "Chamber pressure published in 1995"

System and method for treating water

Abstract: This invention is a method and system for treating wastewater and for purifying and disinfecting drinking water. The treatment includes the addition of pressurized ozonated air to the pumped raw water stream by use of a venturi injector and then achieving well-mixed ozonated water by an in-line static mixer. This promotes the ozone reaction with pollutants in the raw water. The stream is then injected into the ultraviolet (UV) reaction chamber by a static impinger in the form of a conical spray nozzle. This breaks up the stream into a fine mist of one-micron diameter droplets falling down through the chamber. Air released from the droplets is suitably vented to keep the chamber pressure near atmospheric. At a lower plane in the chamber, a UV light source in the form of a uniform grid of essentially coplanar UV lamps irradiates the falling droplets to kill bacteria and viruses and also to catalyze the still ongoing ozone reaction. In the bottom of the chamber, the now treated water forms a pool which is pumped out through filters to its final point of use. A very effective treatment system with a low residence time of two minutes results from optimum process criteria and chamber geometry. The former include a 20:1 mixture ratio of raw water to ozonated air in the inflow and a pressure of several atmospheres going into the spray nozzle. The latter include a conical chamber roof to facilitate proper droplet motion, the specified placement of the UV light source in a horizontal plane, and a curved chamber bottom to keep any particulates in suspension and enhance drainage of the treated water.

Experimental studies of the plasma-propellant interface for electrothermal-chemical launchers

Abstract: A plasma-propellant interaction experiment "PIPE" has been constructed to investigate the plasma-propellant interface physics, and plasma augmentation to the propellant burn rate of electrothermal-chemical launchers. The experimental facility consists of an electrothermal plasma source that injects plasma to the surface of solid or liquid propellants. The source is powered by a 340 /spl mu/F Maxwell capacitor (17 kJ at 10 kV, up to 100 kA, 400 /spl mu/s pulse duration) via a pulse forming network. Experiments with JA2 granular solid propellant under vacuum operation (20 Torr base pressure) showed incomplete burn of the propellant. However, the overall chamber pressure is a factor of two higher than that without propellant. Preliminary measurements showed that the burn rate with plasma injection has been increased by a factor of three at a pressure of 0.7 kbar compared to conventional ignition. >

Hydrogen Peroxide as an Alternate Oxidizer for a Hybrid Rocket Booster

Abstract: TECHNICAL NOTES are short manuscripts describing new developments or important results of a preliminary nature. These Notes cannot exceed 6 manuscript pages and 3 figures; a page of text may be substituted for a figure and vice versa. After informal review by the editors, they may be published within a few months of the date of receipt. Style requirements are the same as for regular contributions (see inside back cover).

Numerical study of a supersonic open cavity flow and pressure oscillation control

Abstract: Numerical experiments were performed to study the flow structure and suppression of pressure oscillation in the M.,. = 2.5 supersonic open cavity flow problem. Numerical results show that the large pressure variation within the cavity induced by the shear layer's wavy shape produces new vortices not found in situations where M.,. < 2.5. The proposed suppression device imposes mass transfer on the cavity's aft bulkhead. The proposal is tested by replacing one of the cavity walls with a porous wall and adjoining vent chamber. Constant porosity and uniform vent-chamber pressure are assumed. Replacing the aft bulkhead with a porous wall/vent chamber combination provides the most effective suppression of pressure fluctuation, even with a porosity value as small as 0.1 for vent-chamber pressure ranging from p, to l.5py.. Mass transfer at the cavity floor and forward bulkhead are also examined, but they are found to be less effective.

Multiple ratio automatic transmission and torque converter

Abstract: A control system for engaging and releasing a torque converter bypass clutch and for varying the torque capacity of the clutch by adjusting the torque converter torus chamber pressure in accordance with changing operating variables, the bypass clutch including a clutch release pressure chamber that is maintained at a calibrated pressure threshold valve whereby pressure clutch capacity control is achieved by controlling pressure differential in the converter.

Fluid pressure regulator establishing a stable output fluid pressure

Abstract: A multi-stage pneumatic pressure regulator establishes a constant output pressure with a change in the output flow. The regulator includes a poppet valve connecting the input and output. A relief valve mounted on the poppet valve includes a first positioning diaphragm subjected to output chamber pressure and a vent hole to atmosphere. A pilot valve is mounted on the relief valve and includes a pressure chamber with a positioning diaphragm of a lesser area than the first diaphragm, coupled to the relief valve and opposing the first position diaphragm. A precision bleed orifice connects the pressure chamber to the input chamber and establishes a precise bleed. A presettable spring load orifice unit in the pilot valve couples the pressure chamber to the output chamber and passes the bleed flow to the output chamber and venting atmosphere. The pilot chamber pressure is greater than the output pressure and prevents feedback of the bleed. The poppet valve and pilot orifice have novel constructions. An alternative bleed passage for a single stage regulator is also disclosed.

The evolution of hydriding and nitriding reactions during ball milling of titanium in ammonia

Abstract: Recently it has been demonstrated that a range of metal nitrides can be easily produced by ball milling elemental metals at room temperature in an environment of nitrogen or ammonia [1, 2]. However, details of the reaction processes which take place during milling and the possible phase transformations which occur during subsequent annealing have not been established. In many cases, milling in ammonia is found to enhance the nitriding process compared with milling in nitrogen gas [3, 4]. This raises the question of the role of ammonia in determining the reaction sequence leading to the final nitride phase. In a previous study [5], we reported on the formation of Ti2A1N by ball milling of Ti-A1 elemental mixtures in an ammonia atmosphere. The reaction process was studied by monitoring changes in gas pressure during milling. It was found that the adsorption of ammonia gas on newly exposed particle surfaces created by ball impact or shearing resulted in an initial decrease of the milling chamber pressure. Further milling appeared to induce the decomposition of adsorbed ammonia and, ultimately, the evolution of hydrogen as indicated by an increase in the milling chamber pressure. In this paper, we have studied the reaction process of a simple gas-solid system NH3-Ti in some detail by monitoring gas pressure changes and correlating these with compositional and phase analysis of milled powders. Our results provide considerable insight into the mechanochemical process occurring during milling. In this experiment, we used high purity elemental titanium powders (99.9%, 100 mesh) and anhydrous ammonia as starting materials. The milling process was performed in a vertical planetary ball mill. A stainless steel cell was loaded with 4 g of Ti powder and several hardened steel balls (diameter = 12 mm), and sealed with a Viton o-ring. In order to avoid oxygen contamination, the mill was purged with N H 3 several times and a pressure of 200 kPa was maintained prior to milling. The pressure of the milling chamber was monitored with a pressure gauge, over the pressure range from -100 kPa to 300 kPa. The structural development of powders at various stages of milling was investigated by X-ray diffraction (XRD) analysis using Co radiation (Z= 0.1789 nm). The annealing behaviour of milled powders was studied using a Shimadzu differential thermal analyser (DTA) at a heating rate of 20 °C/min in a dried argon flow. The H and N contents of as-milled powders were determined using combustion elemental analysis (Carlo Erba 1106). Fig. 1 shows the observed pressure variations as a function of milling time. The pressure initially decreased rapidly, dropping to a minimum pressure of -95 + 5 kPa (partial vacuum) at the end of 51 h. During further milling the pressure increased and attained the maximum measurement limit of the gauge (300 kPa) after 120 h milling. This pressure was maintained during continued milling up to 329 h. This final pressure is much higher than the starting ammonia pressure (200 kPa). Such a pressure variation is similar to that observed in the TiAI-NH3 system [5]. In order to establish the relation between the powder composition, structural changes and observed pressure variations, the milling process was halted at different milling times to give samples corresponding to different pressure changes. These samples were firstly examined for composition and the analysis results are illustrated in Fig. 2. It is clear that the N content increases with increased milling time, but the H content decreases for milling at times beyond the minimum in the mill chamber pressure. The evolution of microstructure during milling is illustrated by the typical XRD patterns of the milled samples in Fig. 3. A sample milled for 18 h, where the pressure had dropped to 50 kPa, has a complex structure. An fcc TiN phase appears to have been formed as indicated by peaks represented by the solid symbols. Appreciable unreacted Ti (crosses) was also found. A third phase (indicated by the open

An ultrasonic fuel regression rate measurement technique for mixture ratio control of a hybrid motor

Abstract: A method for real-time control of mixture ratio and chamber pressure in a hybrid motor using an ultrasonic pulse-echo technique is discussed. The technique allows rapid sequential measurement of fuel web thickness during motor operation at multiple combustion port axial locations, thereby enabling direct computation of instantaneous fuel regression rate, fuel flow rate, and, ultimately, motor operating mixture ratio. Using such data, oxidizer flows into motor combustion ports and the aft mixing chamber of a hybrid motor can be varied to achieve operation at a constant pressure and constant mixture ratio. This technique can be used to generate a constant enthalpy combustion gas environment useful for a variety of ablative material thermal response and characterization studies. In related work, the technique can provide accurate spatialltemporal regression rate histories to assist in anchoring computational fluid dynamics analytical models used for regression rate prediction. Methods of coupling ultrasonic transducers to the fuel grains of 11and 24-in. hybrid motors during motor operation, to image the regressing fuel surface with a portable ultrasonic regression rate analysis system, are discussed, and data resulting from system feasibility testing is presented. INTRODUCTION results in measuring regressing fuel or solid propellant surfaces in operating ramjets and solid rocket motors were reported using transducers operating at a frequency of 2.25 MHz to penetrate fuel or solid propellant web thicknesses of approximately 1.5 in. In the application discussed here, ultrasonic pulse-echo methods were developed to penetrate approximately 5 in. of a highdensity hybrid fuel and image the regressing fuel surface. The work was conducted as part of an initiative to develop a feedback control system for regulation of mixture ratio and chamber pressure in a hybrid motor for NASA's Large Scale Solid Rocket Combustion Simulator (LSSRCS) program (NAS~-39874).4 The objective of the LSSRCS program is to reproduce the nozzle throat aerothermodynarnic environment generated during solid rocket combustion by using a hybrid gas generator. To accomplish this task, both mixture ratio and combustion pressure must be controlled to specified levels during tests in the LSSRCS. These tasks may be best accomplished by providing real-time data on hybrid fuel consumption, which can be compared with instantaneous data for oxygen flow rate and motor pressure. A control system can then make adjustments to motor oxygen flow rate to ensure that both motor pressure and mixture ratio always remain within the tolerances desired for solid rocket combustion simulation. Combustion Simulation Use of ultrasonic techniques to measure the burning rate in solid rocket motors and fuel surface regression rate in solid fuel ramjets has been explored by ort tin^,' ~ r a i n e a u , ~ and ~ i j k s t r a . ~ Ultrasonic methods employed by these and other experimenters have been oriented toward furthering the understanding of motor internal combustion and grain burnback mechanisms. Good Figure 1 illustrates the conceptual operation of a constant-pressure, constant-mixture ratio hybrid gas generator. Given a specific fuel formulation, the general problem of constant enthalpy operation is one of varying the oxidizer flow rates to the fuel grain combustion ports (mOF) and aft mixing chamber (mOA) so as to maintain constant chamber pressure and mixture ratio as the throat

Gaseous or fluidic medium pump e.g. for hydraulic control and regulation systems

Abstract: An electromagnetic convertor (SE) stimulates a standing acoustic wave in a first chamber (PK) of the pump housing (G). This chamber (PK) is filled with the gas or fluid to be pumped. At least one inlet (E) and at least one outlet (A) open out into the first chamber (PK) at a place where the chamber pressure periodically varies. The inlet (E) and outlet (A) are formed such that they present to the medium flowing into or out of the first chamber (PK) a resistance less than that presented to the medium flowing in the opposite direction. The electromagnetic convertor (SE) preferably has an actuator (P) whose dimensions and/or shape can be varied, e.g. a piezoelectric, electrostrictive, magnetostrictive, electromagnetic or electrodynamic actuator (P).

Contaminant reduction improvements for plasma etch chambers

Abstract: A plasma etch chamber includes a modified focus ring which is used in conjunction with chamber pressure throttling to eject contaminants in the focus ring away from the substrate just before the etching cycle is completed. Additionally, process gas is directed against the inner wall of the chamber to create a swirling flow of plasma within the chamber and thus disturb any contaminant-generating field adjacent the chamber wall. A process gas, or a non-reactive purge gas, may also be supplied from a diffuser atop the cathode, to direct a gas layer along the top and sides of the chamber to reduce contaminant build-up on the chamber surfaces.

Influence of product thickness, chamber pressure and heating conditions on production rate of freeze-dried yoghurt

Abstract: The effects of product thickness, chamber pressure and heating conditions on product temperature profiles and production rate of freeze-dried yoghurt were investigated experimentally. Three sample thicknesses - 3.8 mm, 6.2 mm and 9.4 mm - were tested at chamber pressures of 0.01 and 0.5 mmHg. The production rate increased by decreasing product thickness in contact heating through the bottom of the frozen layer, whereas no significant change was observed in radiant heating. A reduction in chamber pressure from 0.50 to 0.01 mmHg increased the drying time in radiant heating. Maximum production rate was obtained when the thickness of dried product was 6.2 mm, when heat was transferred simultaneously through the frozen and dried layers, and the chamber pressure was at 0.01 mmHg. Use of the product tray developed in this study prevents the growth of dry layers at the contact surfaces.

Crank chamber pressure controlled swash plate compressor with suction passage opening delay during initial load condition

Abstract: A compressor has a swash plate tiltable between maximum and minimum inclining angles with respect to a plane perpendicular to an axis of a drive shaft according to a difference between pressures in a crank chamber and a suction chamber. An internal gas passage includes the crank chamber, the suction chamber and a discharge chamber. The internal gas passage is connected to an external circuit separately provided from the compressor. The rotation of the drive shaft is converted to a reciprocating movement of a piston to vary a capacity of a cylinder bore. The piston compresses a gas supplied from the external circuit to the internal gas passage and discharges the gas to the external circuit. A inhibiting apparatus inhibits the circulation of the gas through the internal gas passage and the external circuit when the swash plate is located between the minimum inclining angle and a first inclining angle. The first inclining angle is greater than the minimum inclining angle of the swash plate.

Process and equipment for drying wood

Abstract: Disclosed is a drying process which comprises primary drying in which many pieces of wood (logs with bark (1)) in a drying chamber (A) equipped with an exhaust system (5) for maintaining a chamber pressure at a normal pressure or in a state close thereto, are heated up with only live steam fed into the drying chamber (A) to heat a chamber interior from a normal temperature up to 90 to 100°C, thereby heating the whole inner part ranging from a surface layer to a central layer of the wood; secondary drying that the chamber interior is heated quickly up to a temperature of 100 to 200°C by the use of a heater (9), thereby boiling moisture in the wood for the purpose of high-temperature treatment up to a fiber saturation point in order to obtain a target percentage of moisture content; and finally, tertiary drying that the dry-bulb temperature and the wet-bulb temperature in the drying chamber are changed according to the dried condition of the wood to thereby treat the wood at low temperatures and moisture down to the target percentage of moisture content under the temperature conditions. According to this process, it is possible to form drying conditions in the drying chamber under which drying speeds (a rate of decrease in the percentage of moisture content) on the surface layer side and the central layer side of the wood can be equalized or brought as close to each other as possible, thereby enabling to dry logs without a crack.

Structurally compliant rocket engine combustion chamber - Experimental and analytical validation

Abstract: A new, structurally compliant rocket engine combustion chamber design has been validated through analysis and experiment. Subscale, tubular channel chambers have been cyclically tested and analytically evaluated. Cyclic lives were determined to have a potential for 1000 percent increase over those of rectangular channel designs, the current state of the art. Greater structural compliance in the circumferential direction gave rise to lower thermal strains during hot firing, resulting in lower thermal strain ratcheting and longer predicted fatigue lives. Thermal, structural, and durability analyses of the combustion chamber design, involving cyclic temperatures, strains, and low-cycle fatigue lives, have corroborated the experimental observations.

Ion implantation device with a closed-loop process chamber pressure control system

Abstract: An ion implantation device is presented having a closed-loop pressure control system to reduce pressure fluctuations within a process chamber during ion implantation. A pressure probe extends through a wall of the process chamber or a wall of a beam chamber in gaseous communication with the process chamber. A vacuum measurement unit, coupled to the pressure probe, is configured to produce an electrical pressure signal corresponding to the pressure sensed by the pressure probe. An interface electronics unit coupled to the vacuum measurement unit converts the electrical pressure signal into an electrical control signal for a flow control valve. The flow control valve is coupled to receive the electrical control signal and is configured to control a flow of an inert gas from an inert gas source to a gas inlet port in a wall of the process chamber. The inert gas may comprise argon, nitrogen, or any other gas inert to a wafer fabrication process. Fluctuations in the pressure within the process chamber are reduced by additions of appropriate amounts of inert gas when the pressure sensed by the vacuum measurement unit drops below a predetermined pressure threshold value.

Gas transferring method and gas transferring apparatus

Abstract: PURPOSE:To make arrival of gas at a target place accurate in gas transfer wherein the gas to be transferred is made to arrive at the target place, by blowing the gas into a space from an outlet port toward the target place. CONSTITUTION:As a method of transferring gas, the gas G to be transferred, which is blown from an outlet part 2, is advanced in a space O toward a target place M in a state of a ring shape and in a state that, as a cross-sectional shape orthogonal to the peripheral direction of the ring shape, ring-forming gas assumes the form of an eddy ring R whirling around the central part in a cross section. Further, as an apparatus to be used for the method of transferring the gas, its constitution is provided with a gas chamber forming the outlet port 2, a supply means for feeding the gas G to the gas chamber and an operation means for pulsatively changing a chamber pressure in the gas chamber to a positive pressure side.

Valved suction mechanism of a refrigerant compressor

Abstract: A compressor has a housing divided by a valve plate into a first chamber and a second chamber. The second chamber has a suction chamber and a discharge chamber. The valve plate includes discharge conduits communicating the first chamber with the discharge chamber and suction conduits communicating the first chamber with the suction chamber. A suction valve member bends to open and close the suction conduits in response to changes in discharge chamber pressure and the resulting pressure difference between the first chamber and the suction chamber. A suction valve control mechanism includes a regulator for regulating opening and closing of the suction valve between a maximum opening position and a minimum opening position in response to changes in discharge chamber pressure.

Dry-etch of indium and tin oxides with C2H5I gas

Abstract: An RIE method and apparatus for etching through the material layer of a transparent-electrode (ITO) in a single continuous step at a rate better than 100 Å/min and with a selectivity better than 20 to 1 is disclosed. Chamber pressure is maintained at least as low as 60 mTorr. A reactive gas that includes ethyl iodide C2 H5 I) is used alone or in combination with another gas such as O2. Plasma-induced light emissions of reaction products and/or the reactants are monitored to determine the time point of effective etch-through.

Test Experience, 490-N High-Performance (321-s Specific Impulse) Engine

Abstract: The technology readiness of a new class of high-performa nce Earth-storable bipropellant engines has been demonstrated at the 490-N thrust level. These new-generation engines derive their high performance from a fine pattern platelet injector and a high-temperature indium/rheniu m chamber, in combination with a regenerative thermal management system that eliminates 1) the need for performance degrading and spacecraft contaminating fuel film cooling and 2) undesirable hot front-end attachments. The iridium-coated rhenium chamber greatly increases the thermal margin over existing engine designs, which use disilicide-coated columbium thrust chambers, by increasing the allowable operating temperature to 2204°C (4000°F). The companion technologies for providing metallurgical joints between the different materials used for the injector, chamber, and high area ratio skirt have been demonstrated and incorporated into flight-type engine designs. Hot-fire test results for the nitrogen tetroxide/monomethylhydrazine bipropellant combination are presented for several engine configurations. An all-welded engine assembly tested in vacuum at the 286:1 area ratio confirmed the performance projection of 321 Ibf-s/lbm for the engine and the thermal model, indicating a 315°C (600°F) design margin for the chamber based on maximum engine operating temperature and an acceptable postfire heat soak.

Pressure effect on YBa2Cu3O7 thin film growth in off‐axis radio frequency magnetron sputtering

Abstract: YBa2Cu3O7−x (123) thin films were fabricated on (100) MgO substrates by off‐axis single target radio frequency (rf) magnetron sputtering. Our study focused on the effect of chamber pressure on the composition, microstructure, and superconductive properties on transition behavior and Tc of the grown film studied. An empirical formula was derived to explain the dependence of the deposition rate of various components on the pressure. Next, we compared the transport mechanism of the sputtered particles between the off‐axis rf and the on‐axis direct current sputtering and determined the processing conditions that result in superconducting films of better quality. According to our findings, growth at higher pressures (≳100 mTorr) produces more homogeneous and higher Tc superconducting films.

Device to equalize the pressure in tires

Abstract: The described device maintains an equal pressure in each associated tire as long as that pressure is above an adjustable, threshold amount and isolates the tires when the pressure attempts to go below the threshold. The apparatus comprises a body with ports (each communicating with a tire) having in series a conventional tire valve (each of which is actuated simultaneously by one pressure sensitive piston). One end of each of the conventional tire valves communicates with a chamber in the body that can be pressurized. The pressure sensitive piston comprises an adjustable spring outside of the chamber bearing on the piston through a flexible diaphragm such that the force produced by the pressure difference between inside and outside the chamber across the diaphragm acts with the force produced by the spring to cause the piston to open all of the conventional valves when the chamber pressure (which is also the tire pressure) exceeds a value and the piston to close all of the conventional valves when the chamber pressure is less than the value. The transition value of pressure may be set by adjusting the compression of the spring. In the preferred embodiment of the present invention, the axis of the conventional tire valves are parallel to the axis of the piston. In an alterative embodiment, the axis of the conventional tire valves are perpendicular to the axis of the piston.

Intermittently acting IC engine fuel injection valve

Abstract: A nozzle needle (4) is axially slidable between a stop and open position in the valve housing (9). In the stop position it is pressed against a nozzle needle seat (6) with injection ports (5) by a piston (5). A control chamber (2) is coupled to the valve (1) fuel inlet (7) via one or more closable ducts (14), with the control chamber pressure actuating the piston. Into a valve seat (15) in the control chamber opens an intermediate chamber (12), coupled to the fuel inlet and to the control chamber, which has an outflow port (10) closable by a servo-member (8). In the connecting line between the control and intermediate chambers is located a stop valve for the fuel flow to the control chamber.

Electron cyclotron resonance plasma generation using a planar ring‐cusp magnetic field and a reentrant coaxial cavity

Abstract: An electron cyclotron resonance (ECR) plasma source 16 cm in diameter using a planar ring‐cusp magnetic field and a reentrant coaxial cavity was developed. The planar ring‐cusp magnetic field produces a large‐area ECR surface. The reentrant coaxial cavity forces microwaves to be introduced into the ECR surface from an annular window of a discharge chamber sidewall. This plasma source generated large‐area, uniform, and stable plasmas. At 0.079 Pa of discharge chamber pressure for Ar, the plasma uniformity was 11.1% within a 12‐cm‐diam plane. Above 184 W of forward power, overdense plasmas were produced on the center axis at 0.079 Pa. The maximum Ar plasma density of 1.14×1011 cm−3 was achieved on the center axis at a discharge chamber pressure of 0.079 Pa with a forward power of 437 W.

Effects of Slag Ejection on Solid Rocket Motor Performance

Abstract: In past firings of the Reusable Solid Rocket Motor (RSRM) both static test and flight motors have shown small pressure perturbations occurring primarily between 65 and 80 seconds. A joint NASA/Thiokol team investigation concluded that the cause of the pressure perturbations was the periodic ingestion and ejection of molten aluminum oxide slag from the cavity around the submerged nozzle nose which tends to trap and collect individual aluminum oxide droplets from the approach flow. The conclusions of the team were supported by numerous data and observations from special tests including high speed photographic films, real time radiography, plume calorimeters, accelerometers, strain gauges, nozzle TVC system force gauges, and motor pressure and thrust data. A simplistic slag ballistics model was formulated to relate a given pressure perturbation to a required slag quantity. Also, a cold flow model using air and water was developed to provide data on the relationship between the slag flow rate and the chamber pressure increase. Both the motor and the cold flow model exhibited low frequency oscillations in conjunction with periods of slag ejection. Motor and model frequencies were related to scaling parameters. The data indicate that there is a periodicity to the slag entrainment and ejection phenomena which is possibly related to organized oscillations from instabilities in the dividing streamline shear layer which impinges on the underneath surface of the nozzle.

Plasma purge method for plasma process particle control

Abstract: A method for limiting contaminant particle deposition upon integrated circuit layers within plasma assisted process reactor chambers. First, a plasma assisted process is undertaken upon an integrated circuit layer within a plasma assisted process reactor chamber. The plasma assisted process employs a first reactant gas composition, a first radio frequency power and a first reactor chamber pressure appropriate to the plasma assisted process and the integrated circuit layer. Immediately following the plasma assisted process is undertaken a first plasma purge step. The first plasma purge step employs a first concentration of an oxidizing reactant gas, a first concentration of a non-oxidizing reactant gas, a second radio frequency power and a second reactor chamber pressure. The second radio frequency power is lower than the first radio frequency power and the second reactor chamber pressure is higher than the first reactor chamber pressure. Finally, there is undertaken immediately following the first plasma purge step a second plasma purge step. The second plasma purge step employs a second concentration of the oxidizing reactant gas, a second concentration of the non-oxidizing reactant gas, a third radio frequency power and a third reactor chamber pressure. The third radio frequency power is less than the second radio frequency power, and the third reactor chamber pressure is lower than the second reactor chamber pressure.

High Pressure Earth Storable Rocket Technology Program summary

Abstract: The High Pressure Earth Storable Rockct Technology (HIPES) Basic Program was conducted due to the potential for higher performance at high pressure and the reduced length and volume of the engine. It has become clear that the higher pressure engine is the only method of using high performance engines due to volume and length constraints on lightsat spacecraft applications. System studies reviewed potential applications of NASA, DOD and commercial spacecraft to assess uses for the HlPES engine. Pressure-fed and pump-fed systems for these applications were studied using both N204-N2& and N 2 0 4 W . The Nz04-N2H4 system indicated it provided the maximum payload for large, medium and lightsat satellites. The major benefits of the HIPES engine are high performance within a confined length resulting in maximization of payload for lightsats which are both length and volume constrained. The nominal engine design based on systedengine requirements follows: Propellants N~OCNZH~ Thrust F,) 50 Ibf Chamber Pressure (Pc) 500 psia Specific Impulse (Isp,) 330 sec Nozzle Expansion (E) 150 A design was developed for the HlPES engine consisting of a workhorse copper heatsink, watercoded and rhenium thrust chambers with the flexible TRW pintle injector. The engine hardware was fabricated and tested to establish engine performance and thermal characteristics at various chamber pressures at constant thrust. Very high performance was achieved with thermal characteristics compatible with rhenium engine operation. Combustion efficiency of 98.5% (ODE C*) was achieved and based on TDK Cf (including boundary layer losses) indicated a specific impulse (Isp,) of 337 Ibf-secflbm (~=150). 'd

Ablative material testing for low-pressure, low-cost rocket engines

Abstract: The results of an experimental evaluation of ablative materials suitable for the production of light weight, low cost rocket engine combustion chambers and nozzles are presented. Ten individual specimens of four different compositions of silica cloth-reinforced phenolic resin materials were evaluated for comparative erosion in a subscale rocket engine combustion chamber. Gaseous hydrogen and gaseous oxygen were used as propellants, operating at a nominal chamber pressure of 1138 kPa (165 psi) and a nominal mixture ratio (O/F) of 3.3. These conditions were used to thermally simulate operation with RP-1 and liquid oxygen, and achieved a specimen throat gas temperature of approximately 2456 K (4420 R). Two high-density composition materials exhibited high erosion resistance, while two low-density compositions exhibited approximately 6-75 times lower average erosion resistance. The results compare favorably with previous testing by NASA and provide adequate data for selection of ablatives for low pressure, low cost rocket engines.

Transmission control valves

Abstract: Shift control valves for controlling the engagement of a transmission friction devices have a solenoid control chamber pressurized to initiate shifting and a latch chamber pressurized to sustain the selective friction device in an engaged position. The latching chamber pressure is delivered through a latch valve which is also solenoid controlled to direct pressure to the chamber when the solenoid is de-energized and to exhaust the latch chamber when the solenoid is energized.