Sample records for vacuum-high conductance piston

  1. Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors

    NASA Astrophysics Data System (ADS)

    Prasad, D. N.; Ayyappan, R.; Kamble, L. P.; Singh, J. P.; Muralikrishna, L. V.; Alex, M.; Balagi, V.; Mukhopadhyay, P. K.

    2008-05-01

    Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ~1 × 10-5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mm×160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face & diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6×10-9 m bar ltr/sec in vacuum mode and 2×10-7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5×10-5 mbar, the new valve achieved vacuum 7.4×10-6mbar in the same time under the same conditions.

  2. Fluctuation of a Piston in Vacuum Induced by Thermal Radiation Pressure

    NASA Astrophysics Data System (ADS)

    Inui, Norio

    2017-10-01

    We consider the displacement of a piston dividing a vacuum cavity at a finite temperature T induced by fluctuations in the thermal radiation pressure. The correlation function of the thermal radiation pressure is calculated using the theoretical framework developed by Barton, which was first applied to the fluctuation of the Casimir force at absolute zero. We show that the variance of the radiation pressure at a fixed point is proportional to T8 and evaluate the mean square displacement for a piston with a small cross section in a characteristic correlation timescale ħ/(kBT). At room temperature, the contribution of the thermal radiation to the fluctuation is larger than that of the vacuum fluctuation.

  3. Reduction of the uncertainty of the PTB vacuum pressure scale by a new large area non-rotating piston gauge

    NASA Astrophysics Data System (ADS)

    Bock, Th; Ahrendt, H.; Jousten, K.

    2009-10-01

    This paper describes the metrological characterization of a new large area piston gauge (FRS5, Furness Rosenberg Standard) installed at the vacuum metrology laboratory of the Physikalisch-Technische Bundesanstalt (PTB). The operational procedure and the uncertainty budget for pressures between 30 Pa and 11 kPa are given. Comparisons between the FRS5 and a mercury manometer, a rotary piston gauge and a force-balanced piston gauge are described. We show that the reproducibility of the calibration values of capacitance diaphragm gauges is enhanced by a factor of 6 compared with a static expansion primary standard (SE2). Improvements of the SE2 performance by reducing the number of expansions and smaller uncertainties of expansion ratios are discussed.

  4. Assembly for electrical conductivity measurements in the piston cylinder device

    DOEpatents

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  5. Remote controlled vacuum joint closure mechanism

    DOEpatents

    Doll, D.W.; Hager, E.R.

    1984-02-22

    A remotely operable and maintainable vacuum joint closure mechanism for a noncircular aperture is disclosed. The closure mechanism includes an extendible bellows coupled at one end to a noncircular duct and at its other end to a flange assembly having sealed grooves for establishing a high vacuum seal with the abutting surface of a facing flange which includes an aperture forming part of the system to be evacuated. A plurality of generally linear arrangements of pivotally coupled linkages and piston combinations are mounted around the outer surface of the duct and aligned along the length thereof. Each of the piston/linkage assemblies is adapted to engage the flange assembly by means of a respective piston and is further coupled to a remote controlled piston drive shaft to permit each of the linkages positioned on a respective flat outer surface of the duct to simultaneously and uniformly displace a corresponding piston and the flange assembly with which it is in contact along the length of the duct in extending the bellows to provide a high vacuum seal between the movable flange and the facing flange. A plurality of latch mechanisms are also pivotally mounted on the outside of the duct. A first end of each of the latch mechanisms is coupled to a remotely controlled latch control shaft for displacing the latch mechanism about its pivot point. In response to the pivoting displacement of the latch mechanism, a second end thereof is displaced so as to securely engage the facing flange and maintain the high vacuum seal established by the displacement of the flange assembly and extension of the bellows without displacing the entire duct.

  6. Research on thermal conductivity of HGMs at vacuum in room temperature

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Liao, Bin; An, Zhenguo; Yan, Kaiqi; Zhang, Jingjie

    2018-05-01

    Hollow glass microspheres (HGMs) can be used as thermal insulation materials owing to its hollow structure which brings excellent thermal insulation property and low density. At present, most researches on thermal conductivity of HGMs are focused on polymer matrix/HGMs composite materials. However, thermal conductivity of HGMs at vacuum in room temperature has rarely been investigated. In this work, thermal conductivity of six types of HGMs (T17 (0.17g/cm3), T20 (0.20g/cm3), T22 (0.22g/cm3), T25 (0.25g/cm3), T32 (0.32g/cm3) and T40 (0.40g/cm3)) at vacuum in room temperature were calculated by heat transfer of solid conduction and radiation. The calculation results showed that thermal conductivity of HGMs would be decreased by an order of magnitude compared with no vacuum. In order to verify the calculation and study vacuum thermal insulation properties of HGMs, thermal conductivity of above-mentioned HGMs at no vacuum and high vacuum in room temperature were measured by a self-made thermal conductivity measuring apparatus which was based on the transient plane source (TPS) method. The experimental results showed that thermal conductivity of HGMs were in the range of 4.2030E-02 to 6.3300E-02 W/m.K (at no vacuum) and 3.8160E-03 to 4.9660E-03 W/m.K (at high vacuum). The results indicated that experimental thermal conductivity was consistent with the calculation results and both of them were all decreased by 8-13 times at vacuum compared with no vacuum. In addition, the relationship with physical properties and thermal conductivity of HGMs has been discussed in detail. In conclusion, HGMs possess excellent thermal insulation performance at high vacuum in room temperature and have potential to further reduce thermal conductivity at the same conditions.

  7. Remote controlled vacuum joint closure mechanism

    DOEpatents

    Doll, David W.; Hager, E. Randolph

    1986-01-01

    A remotely operable and maintainable vacuum joint closure mechanism for a noncircular aperture is disclosed. The closure mechanism includes an extendible bellows coupled at one end to a noncircular duct and at its other end to a flange assembly having sealed grooves for establishing a high vacuum seal with the abutting surface of a facing flange which includes an aperture forming part of the system to be evacuated. A plurality of generally linear arrangements of pivotally coupled linkages and piston combinations are mounted around the outer surface of the duct and aligned along the length thereof. Each of the piston/linkage assemblies is adapted to engage the flange assembly by means of a respective piston and is further coupled to a remote controlled piston drive shaft to permit each of the linkages positioned on a respective flat outer surface of the duct to simultaneously and uniformly displace a corresponding piston and the flange assembly with which it is in contact along the length of the duct in extending the bellows to provide a high vacuum seal between the movable flange and the facing flange. A plurality of latch mechanisms are also pivotally mounted on the outside of the duct. A first end of each of the latch mechanisms is coupled to a remotely controlled latch control shaft for displacing the latch mechanism about its pivot point. In response to the pivoting displacement of the latch mechanism, a second end thereof is displaced so as to securely engage the facing flange.

  8. Composite piston

    NASA Technical Reports Server (NTRS)

    Taylor, Allan H. (Inventor)

    1988-01-01

    A composite piston structure is disclosed which provides a simple and reliable means for joining a carbon-carbon or ceramic piston cap with a metallic piston body. Attachment is achieved by means of a special geometry which compensates for differences in thermal expansion without complicated mechanical fastening devices. The shape employs a flange created by opposed frustoconical shapes with coincident vertices intersecting on the radial centerline of the piston in order to retain the piston cap. The use of carbon-carbon for the piston cap material allows a close fit between the piston and a cylinder wall, eliminating the need for piston rings. The elimination of extra mechanical parts of previous composite pistons provides a lightweight composite piston capable of extended high temperature operation.

  9. High pressure rotary piston coal feeder for coal gasification applications

    DOEpatents

    Gencsoy, Hasan T.

    1977-05-24

    The subject development is directed to an apparatus for feeding pulverized coal into a coal gasifier operating at relatively high pressures and elevated temperatures. This apparatus is a rotary piston feeder which comprises a circular casing having a coal loading opening therein diametrically opposed from a coal discharge and contains a rotatable discoid rotor having a cylinder in which a reciprocateable piston is disposed. The reciprocation of the piston within the cylinder is provided by a stationary conjugate cam arrangement whereby the pulverized coal from a coal hopper at atmospheric pressure can be introduced into the cylinder cavity and then discharged therefrom into the high-pressure gasifier without the loss of high pressure gases from within the latter.

  10. A linear motor and compact cylinder-piston driver for left ventricular bypass.

    PubMed

    Qian, K X

    1990-01-01

    A simple, portable, reliable and noise-free pneumatic driver has been developed. It consists of a linear motor attached to a cylinder piston, in one unit. The motor coil is directly wound on the cylinder, and the permanent magnet is fixed to the piston. As a continuous voltage square wave is applied to the coil, the cylinder reciprocates on the piston periodically, producing air pressure and vacuum alternately. In conjunction with a locally made diaphragm pump, the driver was tested in vitro and in vivo. Results demonstrated that the device could drive the diaphragm pump and so support the circulation of an experimental animal. The driver weighs 12 kg. For 200 mmHg air pressure and -80 mmHg vacuum the power consumed is 30 W. Its noise is about 30 dB, less than that of an artificial valve and pump.

  11. Tests of oil scraper piston ring and piston fitted with oil drain holes

    NASA Technical Reports Server (NTRS)

    Mcdewell, H S

    1922-01-01

    Tests were conducted to determine whether or not a properly located and properly designed oil scraper piston ring, installed on a piston provided with oil drain holes of sufficient area, would prevent the excessive oiling of the Liberty engine, particularly with the engine running at idling speed with full oil pressure. Results showed that excessive oiling was in fact prevented. It is strongly recommended that scraper rings and pistons be adopted for aircraft engines.

  12. New Laboratory Technique to Determine Thermal Conductivity of Complex Regolith Simulants Under High Vacuum

    NASA Astrophysics Data System (ADS)

    Ryan, A. J.; Christensen, P. R.

    2016-12-01

    Laboratory measurements have been necessary to interpret thermal data of planetary surfaces for decades. We present a novel radiometric laboratory method to determine temperature-dependent thermal conductivity of complex regolith simulants under high vacuum and across a wide range of temperatures. Here, we present our laboratory method, strategy, and initial results. This method relies on radiometric temperature measurements instead of contact measurements, eliminating the need to disturb the sample with thermal probes. We intend to determine the conductivity of grains that are up to 2 cm in diameter and to parameterize the effects of angularity, sorting, layering, composition, and cementation. These results will support the efforts of the OSIRIS-REx team in selecting a site on asteroid Bennu that is safe and meets grain size requirements for sampling. Our system consists of a cryostat vacuum chamber with an internal liquid nitrogen dewar. A granular sample is contained in a cylindrical cup that is 4 cm in diameter and 1 to 6 cm deep. The surface of the sample is exposed to vacuum and is surrounded by a black liquid nitrogen cold shroud. Once the system has equilibrated at 80 K, the base of the sample cup is rapidly heated to 450 K. An infrared camera observes the sample from above to monitor its temperature change over time. We have built a time-dependent finite element model of the experiment in COMSOL Multiphysics. Boundary temperature conditions and all known material properties (including surface emissivities) are included to replicate the experiment as closely as possible. The Optimization module in COMSOL is specifically designed for parameter estimation. Sample thermal conductivity is assumed to be a quadratic or cubic polynomial function of temperature. We thus use gradient-based optimization methods in COMSOL to vary the polynomial coefficients in an effort to reduce the least squares error between the measured and modeled sample surface temperature.

  13. Experimental Evaluation and Comparison of Thermal Conductivity of High-Voltage Insulation Materials for Vacuum Electronic Devices

    NASA Astrophysics Data System (ADS)

    Suresh, C.; Srikrishna, P.

    2017-07-01

    Vacuum electronic devices operate with very high voltage differences between their sub-assemblies which are separated by very small distances. These devices also emit large amounts of heat that needs to be dissipated. Hence, there exists a requirement for high-voltage insulators with good thermal conductivity for voltage isolation and efficient heat dissipation. However, these voltage insulators are generally poor conductors of heat. In the present work, an effort has been made to obtain good high-voltage insulation materials with substantial improvement in their thermal conductivity. New mixtures of composites were formed by blending varying percentages (by volumes) of aluminum nitride powders with that of neat room-temperature vulcanizing (RTV) silicone elastomer compound. In this work, a thermal conductivity test setup has been devised for the quantification of the thermal conductivity of the insulators. The thermal conductivities and high-voltage isolation capabilities of various blended composites were quantified and were compared with that of neat RTV to evaluate the relative improvement.

  14. Researches on the Piston Ring

    NASA Technical Reports Server (NTRS)

    Ehihara, Keikiti

    1944-01-01

    In internal combustion engines, steam engines, air compressors, and so forth, the piston ring plays an important role. Especially, the recent development of Diesel engines which require a high compression pressure for their working, makes, nowadays, the packing action of the piston ring far more important than ever. Though a number of papers have been published in regard to researches on the problem of the piston ring, none has yet dealt with an exact measurement of pressure exerted on the cylinder wall at any given point of the ring. The only paper that can be traced on this subject so far is Mr. Nakagawa's report on the determination of the relative distribution of pressure on the cylinder wall, but the measuring method adopted therein appears to need further consideration. No exact idea has yet been obtained as to how the obturation of gas between the piston and cylinder, the frictional resistance of the piston, and the wear of the cylinder wall are affected by the intensity and the distribution of the radial pressure of the piston ring. Consequently, the author has endeavored, by employing an apparatus of his own invention, to get an exact determination of the pressure distribution of the piston ring. By means of a newly devised ring tester, to which piezoelectricity of quartz was applied, the distribution of the radial pressure of many sample rings on the market was accurately determined. Since many famous piston rings show very irregular pressure distribution, the author investigated and achieved a manufacturing process of the piston ring which will exert uniform pressure on the cylinder wall. Temperature effects on the configuration and on the mean spring power have also been studied. Further, the tests were performed to ascertain how the gas tightness of the piston ring may be affected by the number or spring power. The researches as to the frictional resistance between the piston ring and the cylinder wall were carried out, too. The procedure of study, and

  15. Cooled spool piston compressor

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.

  16. Investigation on the radial micro-motion about piston of axial piston pump

    NASA Astrophysics Data System (ADS)

    Xu, Bing; Zhang, Junhui; Yang, Huayong; Zhang, Bin

    2013-03-01

    The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key friction pairs are always a key and difficult problem in the research on axial piston pump. In the traditional research on piston/cylinder pair, the assembly relationship of piston and cylinder bore is simplified into ideal cylindrical pair, which can not be used to analyze the influences of radial micro-motion of piston on the distribution characteristics of oil-film thickness and pressure in details. In this paper, based on the lubrication theory of the oil film, a numerical simulation model is built, taking the influences of roughness, elastic deformation of piston and pressure-viscosity effect into consideration. With the simulation model, the dynamic characteristics of the radial micro-motion and pressure distribution are analyzed, and the relationships between radial micro-motion and carrying ability, lubrication condition, and abrasion are discussed. Furthermore, a model pump for pressure distribution measurement of oil film between piston and cylinder bore is designed. The comparison of simulation and experimental results of pressure distribution shows that the simulation model has high accuracy. The experiment and simulation results demonstrate that the pressure distribution has peak values that are much higher than the boundary pressure in the piston chamber due to the radial micro-motion, and the abrasion of piston takes place mainly on the hand close to piston ball. In addition, improvement of manufacturing roundness and straightness of piston and cylinder bore is helpful to improve the carrying ability of piston/cylinder pair. The proposed research provides references for designing piston/cylinder pair, and helps to prolong the service life of axial piston pump.

  17. Double bowl piston

    DOEpatents

    Meffert, Darrel Henry; Urven, Jr., Roger Leroy; Brown, Cory Andrew; Runge, Mark Harold

    2007-03-06

    A piston for an internal combustion engine is disclosed. The piston has a piston crown with a face having an interior annular edge. The piston also has first piston bowl recessed within the face of the piston crown. The first piston bowl has a bottom surface and an outer wall. A line extending from the interior annular edge of the face and tangent with the outer wall forms an interior angle greater than 90 degrees with the face of the piston. The piston also has a second piston bowl that is centrally located and has an upper edge located below a face of the piston crown.

  18. Squeeze bottle apparatus with force multiplying pistons

    DOEpatents

    Moss, Owen R.; Gordon, Norman R.; DeFord, Henry S.; Eschbach, Eugene A.

    1994-01-01

    The present invention comprises a spray bottle in which the pressure resulting from the gripping force applied by the user is amplified and this increased pressure used in generating a spray such as an aerosol or fluid stream. In its preferred embodiment, the invention includes a high pressure chamber and a corresponding piston which is operative for driving fluid out of this chamber at high pressure through a spray nozzle and a low pressure chamber, and a corresponding piston which is acted upon by the hydraulic pressure within the bottle resulting from the gripping force. The low pressure chamber and piston are of larger size than the high pressure chamber and piston. The pistons are rigidly connected so that the force created by the pressure acting on the piston in the low pressure chamber is transmitted to the piston in the high pressure chamber where it is applied over a more limited area, thereby generating greater hydraulic pressure for use in forming the spray.

  19. Spray bottle apparatus with pressure multiplying pistons

    DOEpatents

    Moss, Owen R.; Gordon, Norman R.; DeFord, Henry S.

    1990-01-01

    The present invention comprises a spray bottle in which the pressure resulting from the gripping force applied by the user is amplified and this increased pressure used in generating a spray such as an aerosol or fluid stream. In its preferred embodiment, the invention includes a high pressure chamber and a corresponding piston which is operative for driving fluid out of this chamber at high pressure through a spray nozzle and a low pressure chamber and a corresponding piston which is acted upon the hydraulic pressure within the bottle resulting from the gripping force. The low pressure chamber and piston are of larger size than the high pressure chamber and piston. The pistons are rigidly connected so that the force created by the pressure acting on the piston in the low pressure chamber is transmitted to the piston in the high pressure chamber where it is applied over a more limited area thereby generating greater hydraulic pressure for use in forming the spray.

  20. Spray bottle apparatus with force multiply pistons

    DOEpatents

    Eschbach, Eugene A.

    1992-01-01

    The present invention comprises a spray bottle in which the pressure resulting from the gripping force applied by the user is amplified and this increased pressure used in generating a spray such as an aerosol or fluid stream. In its preferred embodiment, the invention includes a high pressure chamber and a corresponding piston which is operative for driving fluid out of this chamber at high pressure through a spray nozzle and a low pressure chamber and corresponding piston which is acted upon by the hydraulic pressure within the bottle resulting from the gripping force. The low pressure chamber and piston are of larger size than the high pressure chamber and piston. The pistons are rigidly connected so that the force created by the pressure acting on the piston in the low pressure chamber is transmitted to the piston in the high pressure chamber where it is applied over a more limited area thereby generating greater hydraulic pressure for use in forming the spray.

  1. Vacuum-Assisted, Constant-Force Exercise Device

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P.; Jensen, Scott

    2006-01-01

    The vacuum-assisted, constant-force exercise device (VAC-FED) has been proposed to fill a need for a safe, reliable exercise machine that would provide constant loads that could range from 20 to 250 lb (0.09 to 1.12 kN) with strokes that could range from 6 to 36 in. (0.15 to 0.91 m). The VAC-FED was originally intended to enable astronauts in microgravity to simulate the lifting of free weights, but it could just as well be used on Earth for simulated weight lifting and other constant-force exercises. Because the VAC-FED would utilize atmospheric/vacuum differential pressure instead of weights to generate force, it could weigh considerably less than either a set of free weights or a typical conventional exercise machine based on weights. Also, the use of atmospheric/ vacuum differential pressure to generate force would render the VAC-FED inherently safer, relative to free weights and to conventional exercise machines that utilize springs to generate forces. The overall function of the VAC-FED would be to generate a constant tensile force in an output cable, which would be attached to a bar, handle, or other exercise interface. The primary force generator in the VAC-FED would be a piston in a cylinder. The piston would separate a volume vented to atmosphere at one end of the cylinder from an evacuated volume at the other end of the cylinder (see figure). Hence, neglecting friction at the piston seals, the force generated would be nearly constant equal to the area of the piston multiplied by the atmospheric/vacuum differential pressure. In the vented volume in the cylinder, a direct-force cable would be looped around a pulley on the piston, doubling the stroke and halving the tension. One end of the direct-force cable would be anchored to a cylinder cap; the other end of the direct-force cable would be wrapped around a variable-ratio pulley that would couple tension to the output cable. As its name suggests, the variable-ratio pulley would contain a mechanism that

  2. Free-piston engine

    DOEpatents

    Van Blarigan, Peter

    2001-01-01

    A combustion system which can utilize high compression ratios, short burn durations, and homogeneous fuel/air mixtures in conjunction with low equivalence ratios. In particular, a free-piston, two-stroke autoignition internal combustion engine including an electrical generator having a linear alternator with a double-ended free piston that oscillates inside a closed cylinder is provided. Fuel and air are introduced in a two-stroke cycle fashion on each end, where the cylinder charge is compressed to the point of autoignition without spark plugs. The piston is driven in an oscillating motion as combustion occurs successively on each end. This leads to rapid combustion at almost constant volume for any fuel/air equivalence ratio mixture at very high compression ratios. The engine is characterized by high thermal efficiency and low NO.sub.x emissions. The engine is particularly suited for generating electrical current in a hybrid automobile.

  3. Improving Free-Piston Stirling Engine Power Density

    NASA Technical Reports Server (NTRS)

    Briggs, Maxwell H.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58% using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14%. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  4. Compact high-efficiency linear cryocooler in single-piston moving magnet design for HOT detectors

    NASA Astrophysics Data System (ADS)

    Rühlich, I.; Mai, M.; Rosenhagen, C.; Withopf, A.; Zehner, S.

    2012-06-01

    State of the art Mid Wave IR-technology has the potential to rise the FPA temperature from 77K to 130-150K (High Operation Temperature, HOT). Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore, compact high performance cryocoolers are mandatory. AIM has developed the SX040 cooler, optimized for FPA temperatures of about 95K (presented at SPIE 2010). The SX040 cooler incorporates a high efficient dual piston driving mechanism resulting in a very compact compressor of less than 100mm length. Higher compactness - especially shorter compressors - can be achieved by change from dual to single piston design. The new SX030 compressor has such a single piston Moving Magnet driving mechanism resulting in a compressor length of about 60mm. Common for SX040 and SX030 family is a Moving Magnet driving mechanism with coils placed outside the helium vessel. In combination with high performance plastics for the piston surfaces this design enables lifetimes in excess of 20,000h MTTF. Because of the higher FPA temperature and a higher operating frequency also a new displacer needs to be developed. Based on the existing 1/4" coldfinger interface AIM developed a new displacer optimized for an FPA temperature of 140K and above. This paper gives an overview on the development of this new compact single piston cryocooler. Technical details and performance data will be shown.

  5. MEMS scanner with 2D tilt, piston, and focus motion

    NASA Astrophysics Data System (ADS)

    Lani, S.; Bayat, D.; Petremand, Y.; Regamey, Y.-J.; Onillon, E.; Pierer, J.; Grossmann, S.

    2017-02-01

    A MEMS scanner with a high level of motion freedom has been developed. It includes a 2D mechanical tilting capability of +/- 15°, a piston motion of 50μm and a focus/defocus control system of a 2mm diameter mirror. The tilt and piston motion is achieved with an electromagnetic actuation (moving magnet) and the focus control with a deformation of the reflective surface with pneumatic actuation. This required the fabrication of at least one channel on the compliant membrane and a closed cavity below the mirror surface and connected to an external pressure regulator (vacuum to several bars). The fabrication relies on 3 SOI wafers, 2 for forming the compliant membranes and the integrated channel, and 1 to form the cavity mirror. All wafers were then assembled by fusion bonding. Pneumatic actuation for focus control can be achieved from front or back side; function of packaging concept. A reflective coating can be added at the mirror surface depending of the application. The tilt and piston actuation is achieved by electromagnetic actuation for which a magnet is fixed on the moving part of the MEMS device. Finally the MEMS device is mounted on a ceramic PCB, containing the actuation micro-coils. Concept, fabrication, and testing of the devices will be presented. A case study for application in an endoscope with an integrated high power laser and a MEMS steering mechanism will be presented.

  6. Piston rod seal

    DOEpatents

    Lindskoug, Stefan

    1984-01-01

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position.

  7. Geothermal expansion spool piston

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reed, L. T.

    1985-08-06

    A packing supporting piston assembly removably securable to an end section of a production casing of a geothermal well, which end section is disposed above a well head. The piston assembly when so mounted has packing in abutting sealing contact with the end section of the production casing and also has packing that is in slidable sealing contact with the interior surface of the expansion spool. The piston assembly is of such structure that the pressures exerted by the packing on the end section of the casing and on the interior surface of the expansion spool are independently adjustable tomore » desired magnitudes. The degree of pressure exerted by the packing on the interior surface of the expansion spool is adjustable after the packing has been disposed within the confines of the spool. The piston assembly in a preferred form includes a circumferentially extending high temperature resisting grease seal situated within the confines of the piston assembly. In addition to the preferred form of the piston assembly, alternate forms of the piston assembly are provided, each of which permits the pressure exerted by the packing on the interior surface of the expansion spool to be adjusted to a desired magnitude and periodically varied as the same becomes necessary to maintain an effective seal.« less

  8. Drift stabilizer for reciprocating free-piston devices

    DOEpatents

    Ward, William C.; Corey, John A.; Swift, Gregory W.

    2003-05-20

    A free-piston device has a stabilized piston drift. A piston having a frequency of reciprocation over a stroke length and with first and second sides facing first and second variable volumes, respectively, for containing a working fluid defining an acoustic wavelength at the frequency of reciprocation. A bypass tube waveguide connects the first and second variable volumes at all times during reciprocation of the piston. The waveguide has a relatively low impedance for steady flow and a relatively high impedance for oscillating flow at the frequency of reciprocation of the piston, so that steady flow returns fluid leakage from about the piston between the first and second volumes while oscillating flow is not diverted through the waveguide. Thus, net leakage about the piston is returned during each stroke of the piston while oscillating leakage is not allowed and pressure buildup on either the first or second side of the piston is avoided to provide a stable piston location.

  9. Compression of helium to high pressures and temperatures using a ballistic piston apparatus

    NASA Technical Reports Server (NTRS)

    Roman, B. P.; Rovel, G. P.; Lewis, M. J.

    1971-01-01

    Some preliminary experiments are described which were carried out in a high enthalpy laboratory to investigate the compression of helium, a typical shock-tube driver gas, to very high pressures and temperatures by means of a ballistic piston. The purpose of these measurements was to identify any problem areas in the compression process, to determine the importance of real gas effects duDC 47355s process, and to establish the feasibility of using a ballistic piston apparatus to achieve temperatures in helium in excess of 10,000 K.

  10. Improving Power Density of Free-Piston Stirling Engines

    NASA Technical Reports Server (NTRS)

    Briggs, Maxwell H.; Prahl, Joseph; Loparo, Kenneth

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  11. Improved piston ring materials for 650 deg C service

    NASA Technical Reports Server (NTRS)

    Bjorndahl, W. D.

    1986-01-01

    A program to develop piston ring material systems which will operate at 650C was performed. In this program, two candidate high temperature piston ring substrate materials, Carpenter 709-2 and 440B, were hot formed into the piston ring shape and subsequently evaluated. In a parallel development effort ceramic and metallic piston ring coating materials were applied to cast iron rings by various processing techniques and then subjected to thermal shock and wear evaluation. Finally, promising candidate coatings were applied to the most thermally stable hot formed substrate. The results of evaluation tests of the hot formed substrate show that Carpenter 709-2 has greater thermal stability than 440B. Of the candidate coatings, plasma transferred arc (PTA) applied tungsten carbide and molybdenum based systems exhibit the greatest resistance to thermal shock. For the ceramic based systems, thermal shock resistance was improved by bond coat grading. Wear testing was conducted to 650C (1202F). For ceramic systems, the alumina/titania/zirconia/yttria composition showed highest wear resistance. For the PTA applied systems, the tungsten carbide based system showed highest wear resistance.

  12. Internal position and limit sensor for free piston machines

    NASA Technical Reports Server (NTRS)

    Holliday, Ezekiel S. (Inventor); Wood, James Gary (Inventor)

    2012-01-01

    A sensor for sensing the position of a reciprocating free piston in a free piston Stirling machine. The sensor has a disk mounted to an end face of the power piston coaxially with its cylinder and reciprocating with the piston The disk includes a rim around its outer perimeter formed of an electrically conductive material A coil is wound coaxially with the cylinder, spaced outwardly from the outer perimeter of the disk and mounted in fixed position relative to the pressure vessel, preferably on the exterior of the pressure vessel wall.

  13. Thermal conductivity model for powdered materials under vacuum based on experimental studies

    NASA Astrophysics Data System (ADS)

    Sakatani, N.; Ogawa, K.; Iijima, Y.; Arakawa, M.; Honda, R.; Tanaka, S.

    2017-01-01

    The thermal conductivity of powdered media is characteristically very low in vacuum, and is effectively dependent on many parameters of their constituent particles and packing structure. Understanding of the heat transfer mechanism within powder layers in vacuum and theoretical modeling of their thermal conductivity are of great importance for several scientific and engineering problems. In this paper, we report the results of systematic thermal conductivity measurements of powdered media of varied particle size, porosity, and temperature under vacuum using glass beads as a model material. Based on the obtained experimental data, we investigated the heat transfer mechanism in powdered media in detail, and constructed a new theoretical thermal conductivity model for the vacuum condition. This model enables an absolute thermal conductivity to be calculated for a powder with the input of a set of powder parameters including particle size, porosity, temperature, and compressional stress or gravity, and vice versa. Our model is expected to be a competent tool for several scientific and engineering fields of study related to powders, such as the thermal infrared observation of air-less planetary bodies, thermal evolution of planetesimals, and performance of thermal insulators and heat storage powders.

  14. Improving Power Density of Free-Piston Stirling Engines

    NASA Technical Reports Server (NTRS)

    Briggs, Maxwell H.; Prahl, Joseph M.; Loparo, Kenneth A.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free-piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 percent using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a piston power increase of as much as 14 percent. Analytical predictions are compared to experimental data and show close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  15. Optical free piston cell with constant diameter for use under high pressure

    NASA Astrophysics Data System (ADS)

    Ishihara, Koji; Takagi, Masahiro

    1994-02-01

    An optical free piston cell (a modified le Noble and Schlott type optical cell) is described for use in spectrophotometric study under high pressure. The cell consists of a disk, a cylinder, and a free piston, which are made of quartz and are mounted within a stainless-steel holder. A small amount of sample solution (˜0.6 cm3), which only contacts with quartz, is required for measurements. The path length is fixed (1.2 cm) at ambient pressure, but is self-adjusting at elevated pressure so that no compressibility corrections are necessary.

  16. 21. VIEW TO NORTHWEST, ENGINE/PUMP HOUSE EXTENSION, HIGH PRESSURE PISTON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. VIEW TO NORTHWEST, ENGINE/PUMP HOUSE EXTENSION, HIGH PRESSURE PISTON OF STEAM ENGINE NO. 4; CONTROL PANEL MOUNTED ON THE ENGINE; FLOOR VALVES CONTROL THE STEAM. - Deer Island Pumping Station, Boston, Suffolk County, MA

  17. Piston-Driven Fluid Ejectors In Silicon Mems

    DOEpatents

    Galambos, Paul C.; Benavides, Gilbert L.; Jokiel, Jr., Bernhard; Jakubczak II, Jerome F.

    2005-05-03

    A surface-micromachined fluid-ejection apparatus is disclosed which utilizes a piston to provide for the ejection of jets or drops of a fluid (e.g. for ink-jet printing). The piston, which is located at least partially inside a fluid reservoir, is moveable into a cylindrical fluid-ejection chamber connected to the reservoir by a microelectromechanical (MEM) actuator which is located outside the reservoir. In this way, the reservoir and fluid-ejection chamber can be maintained as electric-field-free regions thereby allowing the apparatus to be used with fluids that are electrically conductive or which may react or break down in the presence of a high electric field. The MEM actuator can comprise either an electrostatic actuator or a thermal actuator.

  18. Piston and connecting rod assembly

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  19. Free-piston regenerative hot gas hydraulic engine

    NASA Technical Reports Server (NTRS)

    Beremand, D. G. (Inventor)

    1980-01-01

    A displacer piston which is driven pneumatically by a high-pressure or low-pressure gas is included in a free-piston regenerative hydraulic engine. Actuation of the displacer piston circulates the working fluid through a heater, a regenerator and a cooler. The present invention includes an inertial mass such as a piston or a hydraulic fluid column to effectively store and supply energy during portions of the cycle. Power is transmitted from the working fluid to a hydraulic fluid across a diaphragm or lightweight piston to achieve a hydraulic power out-put. The displacer piston of the present invention may be driven pneumatically, hydraulically or electromagnetically. In addition, the displacer piston and the inertial mass of the present invention may be positioned on the same side of the diaphragm member or may be separated by the diaphragm member.

  20. Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study

    DTIC Science & Technology

    2011-01-01

    Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study Samuel A. Spear1 and James V. Crawford2 1 48th Medical Group, ENT...cited. Objective. To visually compare the Nitinol “smart” stapes prosthesis to conventional manual crimping stapes pistons in temporal bone cadaver...answer questions about each stapes piston. The answers to the survey were then recorded for analysis. Results. 8 of 9 Nitinol pistons were described as

  1. Reciprocating piston pump system with screw drive

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor); Moore, Nicholas R. (Inventor)

    1981-01-01

    A pump system of the reciprocating piston type is described, which facilitates direct motor drive and cylinder sealing. A threaded middle potion of the piston is engaged by a nut connected to rotate with the rotor of an electric motor, in a manner that minimizes loading on the rotor by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded piston portion, with an oil-carrying groove in the nut being interrupted. A fluid emitting seal located at the entrance to each cylinder, can serve to center the piston within the cylinder, wash the piston, and to aid in sealing. The piston can have a long stroke to diameter ratio to minimize reciprocations and wear on valves at high pressures. The voltage applied to the motor can be reversed prior to the piston reaching the end of its stroke, to permit pressure on the piston to aid in reversing the motor.

  2. Carbon-carbon piston development

    NASA Technical Reports Server (NTRS)

    Gorton, Mark P.

    1994-01-01

    A new piston concept, made of carbon-carbon refractory-composite material, has been developed that overcomes a number of the shortcomings of aluminum pistons. Carbon-carbon material, developed in the early 1960's, is lighter in weight than aluminum, has higher strength and stiffness than aluminum and maintains these properties at temperatures over 2500 F. In addition, carbon-carbon material has a low coefficient of thermal expansion and excellent resistance to thermal shock. An effort, called the Advanced Carbon-Carbon Piston Program was started in 1986 to develop and test carbon-carbon pistons for use in spark ignition engines. The carbon-carbon pistons were designed to be replacements for existing aluminum pistons, using standard piston pin assemblies and using standard rings. Carbon-carbon pistons can potentially enable engines to be more reliable, more efficient and have greater power output. By utilizing the unique characteristics of carbon-carbon material a piston can: (1) have greater resistance to structural damage caused by overheating, lean air-fuel mixture conditions and detonation; (2) be designed to be lighter than an aluminum piston thus, reducing the reciprocating mass of an engine, and (3) be operated in a higher combustion temperature environment without failure.

  3. Design and Fabrication of a Stirling Thermal Vacuum Test

    NASA Technical Reports Server (NTRS)

    Oriti, Salvatore M.; Schreiber, Jeffrey G.

    2004-01-01

    A Stirling Radioisotope Generator (SRG110) is being developed for potential use on future NASA space science missions. The development effort is being conducted by Lockheed Martin under contract to the Department of Energy (DOE). The Stirling Technology Company supplies the free-piston Stirling power convertors, and NASA Glenn Research Center (GRC) provides support to the effort in a range of technologies. This generator features higher efficiency and specific power compared to the currently used alternatives. One potential application for the generator would entail significant cruise time in the vacuum of deep space. A test has been conceived at GRC to demonstrate functionality of the Stirling convertors in a thermal vacuum environment. The test article resembles the configuration of the SRG, however the requirement for low mass was not considered. This test will demonstrate the operation of the Stirling convertors in the thermal vacuum environment, simulating deep space, over an extended period of operation. The analysis, design, and fabrication of the test article will be described in this paper.

  4. Hot piston ring tests

    NASA Technical Reports Server (NTRS)

    Allen, David J.; Tomazic, William A.

    1987-01-01

    As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

  5. Design and performance of vacuum system for high heat flux test facility

    NASA Astrophysics Data System (ADS)

    Swamy Kidambi, Rajamannar; Mokaria, Prakash; Khirwadkar, Samir; Belsare, Sunil; Khan, M. S.; Patel, Tushar; Krishnan, Deepu S.

    2017-04-01

    High heat flux test facility (HHFTF) at IPR is used for testing thermal performance of plasma facing materials or components. It consists of various subsystems like vacuum system, high power electron beam system, diagnostic and calibration system, data acquisition and control system and high pressure high temperature water circulation system. Vacuum system consists of large D-shaped chamber, target handling system, pumping systems and support structure. The net volume of vacuum chamber is 5 m3 was maintained at the base pressure of the order of 10-6 mbar for operation of electron gun with minimum beam diameter which is achieved with turbo-molecular pump (TMP) and cryo pump. A variable conductance gate valve is used for maintaining required vacuum in the chamber. Initial pumping of the chamber was carried out by using suitable rotary and root pumps. PXI and PLC based faster real time data acquisition and control system is implemented for performing the various operations like remote operation, online vacuum data measurements, display and status indication of all vacuum equipments. This paper describes in detail the design and implementation of various vacuum system for HHFTF.

  6. Nitrited-Steel Piston Rings for Engines of High Specific Power

    NASA Technical Reports Server (NTRS)

    Collins, John H; Bisson, Edmond E; Schmiedlin, Ralph F

    1945-01-01

    Stability and control characteristics determined from tests in the Langley 19-foot pressure tunnel of a 0.2375-scale model of the Douglas XA-26 airplane are compared with those measured in flight tests of a Douglas A-26b airplane. Several designs of nitrided-steel piston rings were performance-tested under variable conditions of output. The necessity of good surface finish and conformity of the ring to the bore was indicated in the preliminary tests. Nitrided-steel rings of the same dimensions as cast-iron rings operating on the original piston were unsatisfactory, and the final design was a lighter, rectangular, thin-face-width ring used on a piston having a maximum cross-head area and a revised skirt shape. Results were obtained from single-cylinder and multicylinder engine runs.

  7. Thermal conductivity of aerogel blanket insulation under cryogenic-vacuum conditions in different gas environments

    NASA Astrophysics Data System (ADS)

    E Fesmire, J.; Ancipink, J. B.; Swanger, A. M.; White, S.; Yarbrough, D.

    2017-12-01

    Thermal conductivity of low-density materials in thermal insulation systems varies dramatically with the environment: cold vacuum pressure, residual gas composition, and boundary temperatures. Using a reference material of aerogel composite blanket (reinforcement fibers surrounded by silica aerogel), an experimental basis for the physical heat transmission model of aerogel composites and other low-density, porous materials is suggested. Cryogenic-vacuum testing between the boundary temperatures of 78 K and 293 K is performed using a one meter cylindrical, absolute heat flow calorimeter with an aerogel blanket specimen exposed to different gas environments of nitrogen, helium, argon, or CO2. Cold vacuum pressures include the full range from 1×10-5 torr to 760 torr. The soft vacuum region, from about 0.1 torr to 10 torr, is complex and difficult to model because all modes of heat transfer - solid conduction, radiation, gas conduction, and convection - are significant contributors to the total heat flow. Therefore, the soft vacuum tests are emphasized for both heat transfer analysis and practical thermal data. Results for the aerogel composite blanket are analyzed and compared to data for its component materials. With the new thermal conductivity data, future applications of aerogel-based insulation systems are also surveyed. These include Mars exploration and surface systems in the 5 torr CO2 environment, field joints for vacuum-jacketed cryogenic piping systems, common bulkhead panels for cryogenic tanks on space launch vehicles, and liquid hydrogen cryofuel systems with helium purged conduits or enclosures.

  8. Overview of free-piston Stirling technology at the NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Slaby, J. G.

    1985-01-01

    An overview of the National Aeronautics and Space Administration (NASA) Lewis Research Center (Lewis) free-piston Stirling engine activities is presented. These activities include: (1) a generic free-piston Stirling technology project being conducted to develop technologies synergistic to both space power and terrestrial heat pump applications in a cooperative, cost-shared effort with the Department of Energy (DOE/Oak Ridge National Laboratory (ONRL)), and (2) a free-piston Stirling space-power technology demonstration project as part of the SP-100 program being conducted in support of the Department of Defense (DOD), DOE, and NASA/Lewis. The generic technology effort includes extensive parametric testing of a 1 kw free-piston Stirling engine (RE-1000), development and validation of a free-piston Stirling performance computer code, and fabrication and initial testing of an hydraulic output modification for the RE-1000 engine. The space power technology effort, under SP-100, addresses the status of the 25 kWe Space Power Demonstrator Engine (SPDE) including early test results.

  9. Influence of a high vacuum on the precise positioning using an ultrasonic linear motor.

    PubMed

    Kim, Wan-Soo; Lee, Dong-Jin; Lee, Sun-Kyu

    2011-01-01

    This paper presents an investigation of the ultrasonic linear motor stage for use in a high vacuum environment. The slider table is driven by the hybrid bolt-clamped Langevin-type ultrasonic linear motor, which is excited with its different modes of natural frequencies in both lateral and longitudinal directions. In general, the friction behavior in a vacuum environment becomes different from that in an environment of atmospheric pressure and this difference significantly affects the performance of the ultrasonic linear motor. In this paper, to consistently provide stable and high power of output in a high vacuum, frequency matching was conducted. Moreover, to achieve the fine control performance in the vacuum environment, a modified nominal characteristic trajectory following control method was adopted. Finally, the stage was operated under high vacuum condition, and the operating performances were investigated compared with that of a conventional PI compensator. As a result, robustness of positioning was accomplished in a high vacuum condition with nanometer-level accuracy.

  10. High pressure rotary piston coal feeder

    NASA Technical Reports Server (NTRS)

    Gardner, J. F.; Gencsoy, H. T.; Strimbeck, D. C.

    1977-01-01

    This feeder concept uniquely combines the functions of solids feeding, metering, and pressurization into one compact system. Success with the rotary-piston concept would provide a lower-cost alternative to lock-hopper systems. The design of the feeder is presented, with special emphasis on the difficult problem of seal design. Initial tests will be to check seal performance. Subsequent tests will evaluate solids-feeding ability.

  11. Germanium detector vacuum encapsulation

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-01-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

  12. Analysis of Piston Slap Motion

    NASA Astrophysics Data System (ADS)

    Narayan, S.

    2015-05-01

    Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  13. Piston Temperatures in an Air-Cooled Engine for Various Operating Conditions

    NASA Technical Reports Server (NTRS)

    Manganiello, Eugene J

    1940-01-01

    As part of a program for the study of piston cooling, this report presents the results of tests conducted on a single-cylinder, air-cooled, carburetor engine to determine the effect of engine operating conditions on the temperatures at five locations on the piston.

  14. Integral Ring Carbon-Carbon Piston

    NASA Technical Reports Server (NTRS)

    Northam, G. Burton (Inventor)

    1999-01-01

    An improved structure for a reciprocating internal combustion engine or compressor piston fabricate from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variations in thermal expansion differences between the piston and cylinder liner.

  15. Determination of thermal contact conductance in vacuum-bagged thermoplastic prepreg stacks using infrared thermography

    NASA Astrophysics Data System (ADS)

    Baumard, Théo; De Almeida, Olivier; Menary, Gary; Le Maoult, Yannick; Schmidt, Fabrice; Bikard, Jérôme

    2016-10-01

    The infrared heating of a vacuum-bagged, thermoplastic prepreg stack of glass/PA66 was studied to investigate the influence of vacuum level on thermal contact resistance between plies. A higher vacuum level was shown experimentally to decrease the transverse heat transfer efficiency, indicating that considering only the effect of heat conduction at the plies interfaces is not sufficient to predict the temperature distribution. An inverse analysis was used to retrieve the contact resistance coefficients as a function of vacuum pressure.

  16. Hot piston ring/cylinder liner materials: Selection and evaluation

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1988-01-01

    In current designs of the automotive (kinematic) Stirling engine, the piston rings are made of a reinforced polymer and are located below the pistons because they cannot withstand the high temperatures in the upper cylinder area. Theoretically, efficiency could be improved if hot piston rings were located near the top of the pistons. Described is a program to select piston ring and cylinder coating materials to test this theory. Candidate materials were screened, then subjected to a pin or disk friction and wear test machine. Tests were performed in hydrogen at specimen temperatures up to 760 C to simulate environmental conditions in the region of the hot piston ring reversal. Based on the results of these tests, a cobalt based alloy, Stellite 6B, was chosen for the piston rings and PS200, which consists of a metal-bonded chromium carbide matrix with dispersed solid lubricants, was chosen as the cylinder coating. Tests of a modified engine and a baseline engine showed that the hot ring reduced specific fuel consumption by up to 7 percent for some operating conditions and averaged about 3 percent for all conditions evaluated. Related applications of high-temperature coatings for shaft seals and as back-up lubricants are also described.

  17. Research on Melt Degassing Processes of High Conductivity Hard Drawn Aluminum Wire

    NASA Astrophysics Data System (ADS)

    Xu, Xuexia; Feng, Yanting; Wang, Qing; Li, Wenbin; Fan, Hui; Wang, Yong; Li, Guowei; Zhang, Daoqian

    2018-03-01

    Degassing effects of ultrasonic and vacuum processes on high conductivity hard drawn aluminum melt were studied. Results showed that the degassing efficiency improved with the increase of ultrasonic power within certain range, stabilizing at 70% with 240W. For vacuum degassing process, hydrogen content of aluminum melt decreased with the loading time and was linear with logarithm of vacuum degree. Comparison of degassing effects of ultrasonic, vacuum, vacuum-ultrasonic degassing process showed that vacuum-ultrasonic process presented optimal effect.

  18. 49 CFR 229.55 - Piston travel.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total possible...

  19. Piston Ring Pressure Distribution

    NASA Technical Reports Server (NTRS)

    Kuhn, M.

    1943-01-01

    The discovery and introduction of the internal combustion engine has resulted in a very rapid development in machines utilizing the action of a piston. Design has been limited by the internal components of the engine, which has been subjected to ever increasing thermal and mechanical stresses, Of these internal engine components, the piston and piston rings are of particular importance and the momentary position of engine development is not seldom dependent upon the development of both of the components, The piston ring is a well-known component and has been used in its present shape in the steam engine of the last century, Corresponding to its importance, the piston ring has been a rich field for creative activity and it is noteworthy that in spite of this the ring has maintained its shape through the many years. From the many and complicated designs which have been suggested as a packing between piston and cylinder wall hardly one suggestion has remained which does not resemble the original design of cast iron rectangular ring.

  20. Durability, Performance, and Emission of Diesel Engines Using Carbon Fiber Piston and Liner

    NASA Technical Reports Server (NTRS)

    Afify, E. M.; Roberts, W. L.

    1999-01-01

    This report summarizes the research conducted by NC State University in investigating the durability, performance and emission of a carbon fiber piston and liner in our single cylinder research Diesel engine. Both the piston and liner were supplied to NC State University by NASA LaRC and manufactured by C-CAT under a separate contract to NASA LaRC. The carbon-carbon material used to manufacture the piston and liner has significantly lower thermal conductivity, coefficient of thermal expansion, and superior strength characteristics at elevated temperatures when compared to conventional piston materials such as aluminum. The results of the carbon-carbon fiber piston testing were compared to a baseline configuration, which used a conventional aluminum piston in a steel liner. The parameters measured were the brake specific fuel consumption, ignition delay, frictional horsepower, volumetric efficiency, and durability characteristics of the two pistons. Testing was performed using a naturally aspirated Labeco Direct Injection single cylinder diesel engine. Two test cases were performed over a range of loads and speeds. The fixed test condition between the aluminum and carbon-carbon piston configurations was the brake mean effective pressure. The measured data was the fuel consumption rate, volumetric efficiency, load, speed, cylinder pressure, needle lift, and exhaust gas temperature. The cylinder pressure, and fuel consumption, exhaust gas temperature, and needle lift were recorded using a National Instruments DAQ board and a PC. All test cases used Diesel no. 2 for fuel.

  1. [Laser-induced breakdown spectroscopy system for elements analysis in high-temperature and vacuum environment].

    PubMed

    Pan, Cong-Yuan; Du, Xue-Wei; An, Ning; Han, Zhen-Yu; Wang, Sheng-Bo; Wei, Wei; Wang, Qiu-Ping

    2013-12-01

    Laser-induced breakdown spectroscopy (LIBS) is one of the most promising technologies to be applied to metallurgical composition online monitoring in these days. In order to study the spectral characters of LIBS spectrum and to investigate the quantitative analysis method of material composition under vacuum and high temperature environment, a LIBS measurement system was designed and set up which can be used for conducting experiments with high-temperature or molten samples in different vacuum environment. The system consists of a Q-switched Nd : YAG laser used as the light source, lens with different focus lengths used for laser focusing and spectrum signal collecting, a spectrometer used for detecting the signal of LIBS spectrums, and a vacuum system for holding and heating the samples while supplying a vacuum environment. The vacuum was achieved and maintained by a vacuum pump and an electric induction furnace was used for heating the system. The induction coil was integrated to the vacuum system by attaching to a ceramic sealing flange. The system was installed and testified, and the results indicate that the vacuum of the system can reach 1X 10(-4) Pa without heating, while the heating temperature could be about 1 600 degreeC, the system can be used for melting metal samples such as steel and aluminum and get the LIBS spectrum of the samples at the same time. Utilizing this system, LIBS experiments were conducted using standard steel samples under different vacuum or high-temperature conditions. Results of comparison between LIBS spectrums of solid steel samples under different vacuum were achieved, and so are the spectrums of molten and solid steel samples under vacuum environment. Through data processing and theoretical analyzing of these spectrums, the initial results of those experiments are in good agreement with the results that are presently reported, which indicates that the whole system functions well and is available for molten metal LIBS experiment

  2. Free-piston cutting machine

    DOEpatents

    Ciccarelli, Gaby; Subudhi, Manomohan; Hall, Robert E.

    2000-01-01

    A cutting machine includes a gun barrel for receiving a projectile. A compression tube is disposed in flow communication with the barrel and includes a piston therein. A reservoir is disposed in flow communication with the tube and receives a first gas under pressure. A second gas fills the compression tube on a front face of the piston. And, the pressurized first gas is discharged into the tube on a back face of the piston to accelerate the piston through the tube for compressing the second gas, and in turn launching the projectile through the barrel to impact a workpiece.

  3. Cooled-Spool Piston Compressor

    NASA Technical Reports Server (NTRS)

    Morris, Brian G.

    1994-01-01

    Proposed cooled-spool piston compressor driven by hydraulic power and features internal cooling of piston by flowing hydraulic fluid to limit temperature of compressed gas. Provides sufficient cooling for higher compression ratios or reactive gases. Unlike conventional piston compressors, all parts of compressed gas lie at all times within relatively short distance of cooled surface so that gas cooled more effectively.

  4. A Linear Electromagnetic Piston Pump

    NASA Astrophysics Data System (ADS)

    Hogan, Paul H.

    Advancements in mobile hydraulics for human-scale applications have increased demand for a compact hydraulic power supply. Conventional designs couple a rotating electric motor to a hydraulic pump, which increases the package volume and requires several energy conversions. This thesis investigates the use of a free piston as the moving element in a linear motor to eliminate multiple energy conversions and decrease the overall package volume. A coupled model used a quasi-static magnetic equivalent circuit to calculate the motor inductance and the electromagnetic force acting on the piston. The force was an input to a time domain model to evaluate the mechanical and pressure dynamics. The magnetic circuit model was validated with finite element analysis and an experimental prototype linear motor. The coupled model was optimized using a multi-objective genetic algorithm to explore the parameter space and maximize power density and efficiency. An experimental prototype linear pump coupled pistons to an off-the-shelf linear motor to validate the mechanical and pressure dynamics models. The magnetic circuit force calculation agreed within 3% of finite element analysis, and within 8% of experimental data from the unoptimized prototype linear motor. The optimized motor geometry also had good agreement with FEA; at zero piston displacement, the magnetic circuit calculates optimized motor force within 10% of FEA in less than 1/1000 the computational time. This makes it well suited to genetic optimization algorithms. The mechanical model agrees very well with the experimental piston pump position data when tuned for additional unmodeled mechanical friction. Optimized results suggest that an improvement of 400% of the state of the art power density is attainable with as high as 85% net efficiency. This demonstrates that a linear electromagnetic piston pump has potential to serve as a more compact and efficient supply of fluid power for the human scale.

  5. Quantum vacuum effects from boundaries of designer potentials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Konopka, Tomasz

    2009-04-15

    Vacuum energy in quantum field theory, being the sum of zero-point energies of all field modes, is formally infinite but yet, after regularization or renormalization, can give rise to finite observable effects. One way of understanding how these effects arise is to compute the vacuum energy in an idealized system such as a large cavity divided into disjoint regions by pistons. In this paper, this type of calculation is carried out for situations where the potential affecting a field is not the same in all regions of the cavity. It is shown that the observable parts of the vacuum energymore » in such potentials do not fall off to zero as the region where the potential is nontrivial becomes large. This unusual behavior might be interesting for tests involving quantum vacuum effects and for studies on the relation between vacuum energy in quantum field theory and geometry.« less

  6. Study on a high capacity two-stage free piston Stirling cryocooler working around 30 K

    NASA Astrophysics Data System (ADS)

    Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Dai, Wei; Li, Ke; Pang, Xiaomin; Yu, Guoyao; Luo, Ercang

    2016-12-01

    This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated.

  7. Carbon-Carbon Piston Architectures

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved structure for carbon-carbon composite piston architectures is disclosed. The improvement consists of replacing the knitted fiber, three-dimensional piston preform architecture described in U.S. Pat.No. 4,909,133 (Taylor et al.) with a two-dimensional lay-up or molding of carbon fiber fabric or tape. Initially, the carbon fabric of tape layers are prepregged with carbonaceous organic resins and/or pitches and are laid up or molded about a mandrel, to form a carbon-fiber reinforced organic-matrix composite part shaped like a "U" channel, a "T"-bar, or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks are cored from the "U"-channel, "T"-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst. When compared to conventional steel or aluminum alloy pistons, the use of carbon-carbon composite pistons reduces the overall weight of the engine; allows for operation at higher temperatures without a loss of strength; allows for quieter operation; reduces the heat loss; and reduces the level of hydrocarbon emissions.

  8. Carbon-Carbon Piston Architectures

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    1999-01-01

    An improved structure for carbon-carbon composite piston architectures consists of replacing the knitted fiber, three-dimensional piston preform architecture described in U.S. Pat. No. 4.909,133 (Taylor et al.) with a two-dimensional lay-up or molding of carbon fiber fabric or tape. Initially. the carbon fabric or tape layers are prepregged with carbonaceous organic resins and/or pitches and are laid up or molded about a mandrel. to form a carbon-fiber reinforced organic-matrix composite part shaped like a "U" channel, a "T"-bar. or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks are cored from the "U" channel, "T"-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also be accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst. When compared to conventional steel or aluminum-alloy pistons, the use of carbon-carbon composite pistons reduces the overall weight of the engine; allows for operation at higher temperatures without a loss of strength; allows for quieter operation; reduces the heat loss; and reduces the level of hydrocarbon emissions.

  9. Sibling cycle piston and valving method

    NASA Technical Reports Server (NTRS)

    Mitchell, Matthew P. (Inventor); Bauwens, Luc (Inventor)

    1990-01-01

    A double-acting, rotating piston reciprocating in a cylinder with the motion of the piston providing the valving action of the Sibling Cycle through the medium of passages between the piston and cylinder wall. The rotating piston contains regenerators ported to the walls of the piston. The piston fits closely in the cylinder at each end of the cylinder except in areas where the wall of the cylinder is relieved to provide passages between the cylinder wall and the piston leading to the expansion and compression spaces, respectively. The piston reciprocates as it rotates. The cylinder and piston together comprise an integral valve that seqentially opens and closes the ports at the ends of the regenerators alternately allowing them to communicate with the expansion space and compression space and blocking that communication. The relieved passages in the cylinder and the ports in the piston are so arranged that each regenerator is sequentially (1) charged with compressed working gas from the compression space; (2) isolated from both expansion and compression spaces; (3) discharged of working gas into the expansion space; and (4) simultaneously charged with working gas from the expansion space while being discharged of working gas into the compression space, in the manner of the Sibling Cycle. In an alterate embodiment, heat exchangers are external to the cylinder and ports in the cylinder wall are alternately closed by the wall of the piston and opened to the expansion and compression spaces through relieved passages in the wall of the reciprocating, rotating piston.

  10. Free piston inertia compressor

    DOEpatents

    Richards, W.D.C.; Bilodeau, D.; Marusak, T.; Dutram, L. Jr.; Brady, J.

    A free piston inertia compressor comprises a piston assembly including a connecting rod having pistons on both ends, the cylinder being split into two substantially identical portions by a seal through which the connecting rod passes. Vents in the cylinder wall are provided near the seal to permit gas to escape the cylinder until the piston covers the vent whereupon the remaining gas in the cylinder functions as a gas spring and cushions the piston against impact on the seal. The connecting rod has a central portion of relatively small diameter providing free play of the connecting rod through the seal and end portions of relatively large diameter providing a limited tolerance between the connecting rod and the seal. Finally, the seal comprises a seal ring assembly consisting of a dampener plate, a free floating seal at the center of the dampener plate and a seal retainer plate in one face of the dampener plate.

  11. Free piston inertia compressor

    DOEpatents

    Richards, William D. C.; Bilodeau, Denis; Marusak, Thomas; Dutram, Jr., Leonard; Brady, Joseph

    1981-01-01

    A free piston inertia compressor comprises a piston assembly including a connecting rod having pistons on both ends, the cylinder being split into two substantially identical portions by a seal through which the connecting rod passes. Vents in the cylinder wall are provided near the seal to permit gas to excape the cylinder until the piston covers the vent whereupon the remaining gas in the cylinder functions as a gas spring and cushions the piston against impact on the seal. The connecting rod has a central portion of relatively small diameter providing free play of the connecting rod through the seal and end portions of relatively large diameter providing a limited tolerance between the connecting rod and the seal. Finally, the seal comprises a seal ring assembly consisting of a dampener plate, a free floating seal at the center of the dampener plate and a seal retainer plate in one face of the dampener plate.

  12. Vacuum-annealing induced enhancements in the transparent conducting properties of Mo  +  F doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Dineshbabu, N.; Ravichandran, K.

    2017-09-01

    The decisive aim of the present study is to enhance the transparent conducting properties of Mo  +  F co-doped ZnO films through annealing. In this work, Mo  +  F co-doped ZnO (MFZO) films were deposited on glass substrates at a deposition temperature of 350 °C using a home-made nebulizer spray pyrolysis technique and the prepared samples were annealed under air and vacuum atmosphere at 400 °C for 2 h. The structural, electrical, optical, surface morphological and elemental properties of as-deposited, air-annealed and vacuum-annealed samples were compared using various analytical techniques. The vacuum-annealed sample shows lowest resistivity of 1.364  ×  10-3 Ω cm and high transmittance of 90% in the visible region with high ohmic conducting nature. The optical bandgap of the sample was found to be increased to 3.36 eV after vacuum annealing treatment. The XRD patterns of the films confirmed the polycrystalline nature. The PL measurements show the defect levels of the deposited films. The FESEM and AFM studies show an increase in the grain size and roughness of the films, respectively, after vacuum-annealing treatment. The presence of the elements before and after annealing treatment was confirmed using XPS analysis.

  13. Piston-Skirt Lubrication System For Compressor

    NASA Technical Reports Server (NTRS)

    Schroeder, Edgar C.; Burzynski, Marion, Jr.

    1994-01-01

    Piston-skirt lubrication system provides steady supply of oil to piston rings of gas compressor. No need for oil-filled crankcase or external oil pump. Instead, part of each piston acts as its own oil pump circulating oil from reservoir. Annular space at bottom of piston and cylinder constitutes working volume of small oil pump. Depending on application, reservoir open to atmosphere, or sealed and pressurized in bellows to prevent contact between oil and atmosphere. Filter removes particles worn away from piston rings and cylinder wall during normal operation.

  14. Overview of NASA Lewis Research Center free-piston Stirling engine activities

    NASA Technical Reports Server (NTRS)

    Slaby, J. G.

    1984-01-01

    A generic free-piston Stirling technology project is being conducted to develop technologies generic to both space power and terrestrial heat pump applications in a cooperative, cost-shared effort. The generic technology effort includes extensive parametric testing of a 1 kW free-piston Stirling engine (RE-1000), development of a free-piston Stirling performance computer code, design and fabrication under contract of a hydraulic output modification for RE-1000 engine tests, and a 1000-hour endurance test, under contract, of a 3 kWe free-piston Stirling/alternator engine. A newly initiated space power technology feasibility demonstration effort addresses the capability of scaling a free-piston Stirling/alternator system to about 25 kWe; developing thermodynamic cycle efficiency or equal to 70 percent of Carnot at temperature ratios in the order of 1.5 to 2.0; achieving a power conversion unit specific weight of 6 kg/kWe; operating with noncontacting gas bearings; and dynamically balancing the system. Planned engine and component design and test efforts are described.

  15. Vacuum Outgassing of High Density Polyethylene

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dinh, L N; Sze, J; Schildbach, M A

    A combination of thermogravimetric analysis (TGA) and temperature programmed decomposition (TPD) was employed to identify the outgassing species, the total amount of outgassing, and the outgassing kinetics of high density polyethylene (HDPE) in a vacuum environment. The isoconversional kinetic analysis was then used to analyze the outgassing kinetics and to predict the long-term outgassing of HDPE in vacuum applications at ambient temperature. H{sub 2}O and C{sub n}H{sub x} with n as high as 9 and x centering around 2n are the major outgassing species from solid HDPE, but the quantities evolved can be significantly reduced by vacuum baking at 368more » K for a few hours prior to device assembly.« less

  16. A large high vacuum, high pumping speed space simulation chamber for electric propulsion

    NASA Technical Reports Server (NTRS)

    Grisnik, Stanley P.; Parkes, James E.

    1994-01-01

    Testing high power electric propulsion devices poses unique requirements on space simulation facilities. Very high pumping speeds are required to maintain high vacuum levels while handling large volumes of exhaust products. These pumping speeds are significantly higher than those available in most existing vacuum facilities. There is also a requirement for relatively large vacuum chamber dimensions to minimize facility wall/thruster plume interactions and to accommodate far field plume diagnostic measurements. A 4.57 m (15 ft) diameter by 19.2 m (63 ft) long vacuum chamber at NASA Lewis Research Center is described. The chamber utilizes oil diffusion pumps in combination with cryopanels to achieve high vacuum pumping speeds at high vacuum levels. The facility is computer controlled for all phases of operation from start-up, through testing, to shutdown. The computer control system increases the utilization of the facility and reduces the manpower requirements needed for facility operations.

  17. Ultra high vacuum broad band high power microwave window

    DOEpatents

    Nguyen-Tuong, V.; Dylla, H.F. III

    1997-11-04

    An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost. 5 figs.

  18. Ultra high vacuum broad band high power microwave window

    DOEpatents

    Nguyen-Tuong, Viet; Dylla, III, Henry Frederick

    1997-01-01

    An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost.

  19. Band gap and conductivity variations of ZnO nano structured thin films annealed under Vacuum

    NASA Astrophysics Data System (ADS)

    Vattappalam, Sunil C.; Thomas, Deepu; T, Raju Mathew; Augustine, Simon; Mathew, Sunny

    2015-02-01

    Zinc Oxide thin films were prepared by Successive Ionic layer adsorption and reaction technique(SILAR). The samples were annealed under vacuum and conductivity of the samples were taken at different temperatures. UV Spectrograph of the samples were taken and the band gap of each sample was found from the data. All the results were compared with that of the sample annealed under air. It was observed that the band gap decreases and concequently conductivity of the samples increases when the samples are annealed under vacuum.

  20. Wear compensating seal means for rotary piston coal feeder

    DOEpatents

    Gencsoy, Hasan T.; Gardner, John F.

    1979-01-01

    The present invention is directed to a wear compensating seal arrangement for use in a rotary piston feeder utilized for feeding pulverized coal into a gasifier operating at relatively high pressures and elevated temperatures. The rotary piston feeder has a circular casing with a coal loading opening therein diametrically opposed from a coal discharge and contains a rotatable disoidal rotor having a cylinder in which a reciprocatable piston is disposed. The reciprocation of the piston within the cylinder is provided by a stationary conjugate cam whereby pulverized coal from a coal hopper at atmospheric pressure can be introduced into the cylinder and then discharged therefrom into the high pressure gasifier while maintaining minimal losses of producer gas and the expenditure of minimal energy which would detract from the efficiency of the gasification. The seal arrangement of the present invention is disposed between the rotor and the casing about the coal discharge and prevents the high pressure gases from within the gasifier from escaping between these relatively movable parts during operation of the coal feeder. The seal utilizes a primary seal in contact with the rotor and a secondary seal supporting the primary seal. The primary seal is continuously urged towards the rotor by springs and the high pressure producer gas.

  1. Two piston V-type Stirling engine

    DOEpatents

    Corey, John A.

    1987-01-01

    A two piston Stirling engine which includes a heat exchanger arrangement placing the cooler and regenerator directly adjacent the compression space for minimal cold duct volume; a sealing arrangement which eliminates the need for piston seals, crossheads and piston rods; and a simplified power control system.

  2. A wireline piston core barrel for sampling cohesionless sand and gravel below the water table

    USGS Publications Warehouse

    Zapico, Michael M.; Vales, Samuel; Cherry, John A.

    1987-01-01

    A coring device has been developed to obtain long and minimally disturbed samples of saturated cohesionless sand and gravel. The coring device, which includes a wireline and piston, was developed specifically for use during hollow-stem auger drilling but it also offers possibilities for cable tool and rotary drilling. The core barrel consists of an inner liner made of inexpensive aluminum or plastic tubing, a piston for core recovery, and an exterior steel housing that protects the liner when the core barrel is driven into the aquifer. The core barrel, which is approximately 1.6m (5.6 feet) long, is advanced ahead of the lead auger by hammering at the surface on drill rods that are attached to the core barrel. After the sampler has been driven 1.5m (5 feet), the drill rods are detached and a wireline is used to hoist the core barrel, with the sample contained in the aluminum or plastic liner, to the surface. A vacuum developed by the piston during the coring operation provides good recovery of both the sediment and aquifer fluids contained in the sediment. In the field the sample tubes can be easily split along their length for on-site inspection or they can be capped with the pore water fluids inside and transported to the laboratory. The cores are 5cm (2 inches) in diameter by 1.5m (5 feet) long. Core acquisition to depths of 35m (115 feet), with a recovery greater than 90 percent, has become routine in University of Waterloo aquifer studies. A large diameter (12.7cm [5 inch]) version has also been used successfully. Nearly continuous sample sequences from sand and gravel aquifers have been obtained for studies of sedimentology, hydraulic conductivity, hydrogeochemistry and microbiology.

  3. Multiple Cylinder Free-Piston Stirling Machinery

    NASA Astrophysics Data System (ADS)

    Berchowitz, David M.; Kwon, Yong-Rak

    In order to improve the specific power of piston-cylinder type machinery, there is a point in capacity or power where an advantage accrues with increasing number of piston-cylinder assemblies. In the case of Stirling machinery where primary energy is transferred across the casing wall of the machine, this consideration is even more important. This is due primarily to the difference in scaling of basic power and the required heat transfer. Heat transfer is found to be progressively limited as the size of the machine increases. Multiple cylinder machines tend to preserve the surface area to volume ratio at more favorable levels. In addition, the spring effect of the working gas in the so-called alpha configuration is often sufficient to provide a high frequency resonance point that improves the specific power. There are a number of possible multiple cylinder configurations. The simplest is an opposed pair of piston-displacer machines (beta configuration). A three-cylinder machine requires stepped pistons to obtain proper volume phase relationships. Four to six cylinder configurations are also possible. A small demonstrator inline four cylinder alpha machine has been built to demonstrate both cooling operation and power generation. Data from this machine verifies theoretical expectations and is used to extrapolate the performance of future machines. Vibration levels are discussed and it is argued that some multiple cylinder machines have no linear component to the casing vibration but may have a nutating couple. Example applications are discussed ranging from general purpose coolers, computer cooling, exhaust heat power extraction and some high power engines.

  4. Inexpensive high vacuum feedthroughs.

    NASA Technical Reports Server (NTRS)

    Gerber, S.; Post, D.

    1973-01-01

    Description of the use of rigid coaxial cable in the construction of high vacuum coaxial and coaxial push-pull rotary motion feedthroughs. This type of feedthroughs is shown to be extremely cheap and simple to make and modify. It can be used for moderately high voltages and provides a continuous, well shielded, low-noise feedthrough cable in any desired configuration.

  5. Drive piston assembly for a valve actuator assembly

    DOEpatents

    Sun, Zongxuan

    2010-02-23

    A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

  6. Stabilizing Gas Bearings In Free-Piston Machines

    NASA Technical Reports Server (NTRS)

    Dhar, Manmohan

    1995-01-01

    Gas bearings and clearance seals between pistons and cylinders in free-piston machines designed to reduce undesired dynamic forces and torques on pistons, gas bearings, and cylinders. Circumferential grooves and drain galleries added to piston or cylinder in improved design. Provides stabilization without significant reduction in length of seal, or significant increase in leakage and consequent reduction of efficiency.

  7. Assessing stapes piston position using computed tomography: a cadaveric study.

    PubMed

    Hahn, Yoav; Diaz, Rodney; Hartman, Jonathan; Bobinski, Matthew; Brodie, Hilary

    2009-02-01

    Temporal bone computed tomographic (CT) scanning in the postoperative stapedotomy patient is inaccurate in assessing stapes piston position within the vestibule. Poststapedotomy patients that have persistent vertigo may undergo CT scanning to assess the position of the stapes piston within the vestibule to rule out overly deep insertion. Vertigo is a recognized complication of the deep piston, and CT evaluation is often recommended. The accuracy of CT scan in this setting is unestablished. Stapedotomy was performed on 12 cadaver ears, and stainless steel McGee pistons were placed. The cadaver heads were then scanned using a fine-cut temporal bone protocol. Temporal bone dissection was performed with microscopic measurement of the piston depth in the vestibule. These values were compared with depth of intravestibular penetration measured on CT scan by 4 independent measurements. The intravestibular penetration as assessed by computed tomography was consistently greater than the value found on cadaveric anatomic dissection. The radiographic bias was greater when piston location within the vestibule was shallower. The axial CT scan measurement was 0.53 mm greater, on average, than the anatomic measurement. On average, the coronal CT measurement was 0.68 mm greater than the anatomic measurement. The degree of overestimation of penetration, however, was highly inconsistent. Standard temporal bone CT scan is neither an accurate nor precise examination of stapes piston depth within the vestibule. We found that CT measurement consistently overstated intravestibular piston depth. Computed tomography is not a useful study in the evaluation of piston depth for poststapedectomy vertigo and is of limited value in this setting.

  8. Piston cylinder cell for high pressure ultrasonic pulse echo measurements.

    PubMed

    Kepa, M W; Ridley, C J; Kamenev, K V; Huxley, A D

    2016-08-01

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe2.

  9. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    NASA Astrophysics Data System (ADS)

    Kepa, M. W.; Ridley, C. J.; Kamenev, K. V.; Huxley, A. D.

    2016-08-01

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe2.

  10. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  11. A squeezed light source operated under high vacuum

    PubMed Central

    Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.

    2015-01-01

    Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments. PMID:26657616

  12. A squeezed light source operated under high vacuum

    NASA Astrophysics Data System (ADS)

    Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.

    2015-12-01

    Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments.

  13. Development of High vacuum facility for baking and cool down experiments for SST-1 Tokamak components

    NASA Astrophysics Data System (ADS)

    Khan, Ziauddin; Pathan, Firozkhan S.; Yuvakiran, Paravastu; George, Siju; Manthena, Himabindu; Raval, Dilip C.; Thankey, Prashant L.; Dhanani, Kalpesh R.; Gupta, Manoj Kumar; Pradhan, Subrata

    2012-11-01

    SST-1 Tokamak, a steady state super-conducting device, is under refurbishment to demonstrate the plasma discharge for the duration of 1000 second. The major fabricated components of SST-1 like vacuum vessel, thermal shields, superconducting magnets etc have to be tested for their functional parameters. During machine operation, vacuum vessel will be baked at 150 °C, thermal shields will be operated at 85 K and magnet system will be operated at 4.5 K. All these components must have helium leak tightness under these conditions so far as the machine operation is concerned. In order to validate the helium leak tightness of these components, in-house high vacuum chamber is fabricated. This paper describes the analysis, design and fabrication of high vacuum chamber to demonstrate these functionalities. Also some results will be presented.

  14. New generation of free-piston shock tunnels

    NASA Technical Reports Server (NTRS)

    Morrison, W. R. B.; Stalker, R. J.; Duffin, J.

    1990-01-01

    Consideration is given to three free-piston driven hypersonic tunnels under construction that will greatly enhance existing test capabilities. The tunnel being built at Caltech will feature energy capabilities about 40 percent higher than those of the world's largest operational free-piston tunnel to date. The second tunnel under construction will allow full-size engine hardware at near-orbital speeds. The third facility is a high-performance expansion tube that will be capable of generating high enthalpy flows at speeds of up to 9 km/sec. It will provide flows with dissociation levels much lower than are attainable with a reflected shock tunnel, approaching actual flight conditions. A table shows the tunnels' characteristics.

  15. Features of the gas dynamics and local heat transfer in intake system of piston engine with supercharging

    NASA Astrophysics Data System (ADS)

    Plotnikov, L. V.

    2017-09-01

    Comparison of experimental research results of gas dynamics and instantaneous local heat transfer in the intake pipes for piston internal combustion engines (ICE) without and with supercharging are presented in the article. Studies were conducted on full-scale experimental setups in terms of gas dynamic nonstationarity, which is characteristic of piston engines. It has been established that the turbocharger installation in a gas-air system of piston internal combustion engine leads to significant differences in the patterns of change in gas-dynamic and heat transfer characteristics of flows. These data can be used in a modernization of piston engines due to installation of a turbocharger or in a development of gas-air systems for piston ICE with supercharging.

  16. Development and Testing of a Novel Green Propellant Piston Tank

    NASA Technical Reports Server (NTRS)

    Diaz, C. E.; Cavender, D. P.; Higdon, K.; Abrams, J.; Duchek, M. E.; Mader, H.

    2017-01-01

    Analytical Mechanics Associates (AMA), in cooperation with NASA Marshall Space Flight Center's (MSFC's) Spacecraft Propulsion Systems Branch, developed and tested a novel propellant tank design that employs an internal piston pressurized with an inert gas to expel propellant to thrusters. During the course of this activity, AMA designed, oversaw fabrication, and delivered to MSFC for testing, a piston propellant tank sized for 3U or larger CubeSats. MSFC conducted liquid expulsion testing using ethylene glycol as a referee fluid to map the tank's performance at different pressures and piston positions. Following the expulsion test campaign, the tank is planned to be integrated into a propulsion system test bed for hot fire tests with a 100mN monopropellant thruster to evaluate the tank's influence on thruster performance when operated in a flight like manner. Described in this paper is a comprehensive summary of how the tanks were designed, built, and tested. The fundamental knowledge gained through the fabrication and testing of these tanks gives evidence that the piston tank design may be scalable to meet the requirements and constraints of other small satellites.

  17. Comparison of titanium and Robinson stainless steel stapes piston prostheses.

    PubMed

    Lippy, William H; Burkey, John M; Schuring, Arnold G; Berenholz, Leonard P

    2005-09-01

    Although stainless steel stapes prostheses have generally been considered magnetic resonance imaging safe, there is concern that this may change with the development of more powerful imaging systems. The objective of the study was to determine whether a titanium piston stapes prosthesis would be audiometrically and surgically equivalent to a Robinson stainless steel piston for stapedectomy. Retrospective chart review. Private otology practice. In all, 50 patients underwent stapedectomy with a Gyrus titanium piston prosthesis. These patients were matched on the basis of age and preoperative bone-conduction scores with patients who underwent stapedectomy with a Robinson stainless steel piston prosthesis. Audiometric results are analyzed, and surgical complications noted. There was no significant difference between groups in hearing improvement or postoperative air-bone gap. The mean four-frequency hearing improvement was 27.7 dB for the stainless steel group and 27.8 dB for the titanium group. The mean postoperative air-bone gap was 2.65 dB for the stainless steel group and 2.60 for the titanium group. Neither group had a surgical complication. The titanium stapes prosthesis is a good alternative to a stainless steel prosthesis.

  18. Ultra-high-vacuum electrical feedthrough

    NASA Technical Reports Server (NTRS)

    Gavaler, J. R.; Janocko, M. A.

    1976-01-01

    Device for cathodic sputtering utilizes cathode dark-space region adjacent to high negative-potential surfaces. Feedthrough is made of metal and glass, is helium leaktight, and is bakeable; it can be incorporated into any vacuum apparatus.

  19. Liquid-metal-piston MHD generator

    NASA Technical Reports Server (NTRS)

    Palmer, J. P.

    1969-01-01

    Magnetohydrodynamic generator uses a slug or piston of liquid potassium as the working fluid. An expanding vapor of the metal is allowed to reciprocate the liquid-metal-piston through a magnetic field and the expansion energy is converted directly into electrical energy.

  20. Activating the nuclear piston mechanism of 3D migration in tumor cells

    PubMed Central

    2017-01-01

    Primary human fibroblasts have the remarkable ability to use their nucleus like a piston, switching from low- to high-pressure protrusions in response to the surrounding three-dimensional (3D) matrix. Although migrating tumor cells can also change how they migrate in response to the 3D matrix, it is not clear if they can switch between high- and low-pressure protrusions like primary fibroblasts. We report that unlike primary fibroblasts, the nuclear piston is not active in fibrosarcoma cells. Protease inhibition rescued the nuclear piston mechanism in polarized HT1080 and SW684 cells and generated compartmentalized pressure. Achieving compartmentalized pressure required the nucleoskeleton–cytoskeleton linker protein nesprin 3, actomyosin contractility, and integrin-mediated adhesion, consistent with lobopodia-based fibroblast migration. In addition, this activation of the nuclear piston mechanism slowed the 3D movement of HT1080 cells. Together, these data indicate that inhibiting protease activity during polarized tumor cell 3D migration is sufficient to restore the nuclear piston migration mechanism with compartmentalized pressure characteristic of nonmalignant cells. PMID:27998990

  1. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kepa, M. W., E-mail: mkepa@staffmail.ed.ac.uk; Huxley, A. D.; Ridley, C. J.

    2016-08-15

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a singlemore » crystal of the ferromagnetic superconductor UGe{sub 2}.« less

  2. 49 CFR 230.76 - Piston travel.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and...) Maximum piston travel. The maximum piston travel when steam locomotive is standing shall be as follows...

  3. Highly sensitive vacuum ion pump current measurement system

    DOEpatents

    Hansknecht, John Christopher [Williamsburg, VA

    2006-02-21

    A vacuum system comprising: 1) an ion pump; 2) power supply; 3) a high voltage DC--DC converter drawing power from the power supply and powering the vacuum pump; 4) a feedback network comprising an ammeter circuit including an operational amplifier and a series of relay controlled scaling resistors of different resistance for detecting circuit feedback; 5) an optional power block section intermediate the power supply and the high voltage DC--DC converter; and 6) a microprocessor receiving feedback information from the feedback network, controlling which of the scaling resistors should be in the circuit and manipulating data from the feedback network to provide accurate vacuum measurement to an operator.

  4. Vacuum-free laminated top electrode with conductive tapes for scalable manufacturing of efficient perovskite solar cells

    DOE PAGES

    Shao, Yuchuan; Wang, Qi; Dong, Qingfeng; ...

    2015-06-25

    The efficiency of organometal trihalide perovskites (OTP) solar cells have reached that parity of single crystal silicon, and its nature abundant raw material and solution-process capability promise a bright future for commercialization. However, the vacuum based techniques for metal electrode deposition and additional encapsulation layer increase the cost of the perovskite solar cells dramatically and impede their commercialization process. Here, we report a vacuum-free low temperature lamination technique to fabricate the top electrode by commercial conductive tapes (C-tape). The simple fabrication method yields good quality contact and high efficiency device of 12.7%. The C-tapes also encapsulated the devices effectively, resultingmore » in greatly improved device stability. As a result, the combination of lamination of electrodes and encapsulation layers into a single step significantly reduce the cost of device fabrication.« less

  5. Changes in CR-39 proton sensitivity due to prolonged exposure to high vacuums relevant to the National Ignition Facility and OMEGA.

    PubMed

    Manuel, M J-E; Rosenberg, M J; Sinenian, N; Rinderknecht, H; Zylstra, A B; Séguin, F H; Frenje, J; Li, C K; Petrasso, R D

    2011-09-01

    When used at facilities like OMEGA and the NIF, CR-39 is exposed to high vacuum environments before and after irradiation by charged particles and neutrons. Using an electrostatic linear accelerator at MIT, studies have been conducted to investigate the effects of high vacuum exposure on the sensitivity of CR-39 to fusion protons in the ~1-9 MeV energy range. High vacuum conditions, of order 10(-5) Torr, experienced by CR-39 samples at these facilities were emulated. It is shown that vacuum exposure times longer than ~16 h before proton irradiation result in a decrease in proton sensitivity, whereas no effect was observed for up to 67 h of vacuum exposure after proton irradiation. CR-39 sensitivity curves are presented for samples with prolonged exposure to high vacuum before and after proton irradiation. © 2011 American Institute of Physics

  6. Comparison of Fluoroplastic Causse Loop Piston and Titanium Soft-Clip in Stapedotomy

    PubMed Central

    Faramarzi, Mohammad; Gilanifar, Nafiseh; Roosta, Sareh

    2017-01-01

    Introduction: Different types of prosthesis are available for stapes replacement. Because there has been no published report on the efficacy of the titanium soft-clip vs the fluoroplastic Causse loop Teflon piston, we compared short-term hearing results of both types of prosthesis in patients who underwent stapedotomy due to otosclerosis. Materials and Methods: A total of 57 ears were included in the soft-clip group and 63 ears were included in the Teflon-piston group. Pre-operative and post-operative air conduction, bone conduction, air-bone gaps, speech discrimination score, and speech reception thresholds were analyzed. Results: Post-operative speech reception threshold gains did not differ significantly between the two groups (P=0.919). However, better post-operative air-bone gap improvement at low frequencies was observed in the Teflon-piston group over the short-term follow-up (at frequencies of 0.25 and 0.50 kHz; P=0.007 and P=0.001, respectively). Conclusion: Similar post-operative hearing results were observed in the two groups in the short-term. PMID:28229059

  7. Critical needs for piston engine overhaul centre in Malaysia

    NASA Astrophysics Data System (ADS)

    Khairuddin, M. H.; Yahya, M. Y.; Johari, M. K.

    2017-12-01

    Piston engine overhaul centre (PEOC) is the branch of aviation Maintenance, Repair and Overhaul (MRO) providers, which plays a pivotal role in maintaining the fleet of business and commercial aircraft in the world. The centre typically offers three main MRO capabilities: airframe, engine and component services. Companies holding a PEOC(s) are all subjected to stringent procedures and conditions regulated and audited by the International Civil Aviation Organization. Currently, piston engine maintenance and repair for Asian countries is conducted only in Singapore. The focus of this study is to establish the needs for a PEOC in Malaysia, which will cater almost all small local aircraft companies such as transport and flying school companies.

  8. High pressure induced crossover between metal and insulator conductivity type in low dimensionality electron systems

    NASA Astrophysics Data System (ADS)

    Dizhur, E.; Voronovskii, A.; Kostyleva, I.; Kotel'nikov, I.; Zaitsev-Zotov, S.

    2011-12-01

    We report the results of our recent experimental studies concerned with electron systems of lower dimensionality the conductivity of which may be toggled between metallic and insulating regime appliing high pressure. The objects under present study include: a) tunneling through Shottky barrier into two-dimension (2D) electron system formed in the δ-doped layer in GaAs under hydrostatic pressure up to 3 GPa in a cylinder-piston cell; b) quasi-one-dimension (1D) `insulator' crystals NbS3 which obtain metallic conductivity type at pressures above 5.5 GPa in `toroid' anvils.

  9. Indian Vacuum Society: The Indian Vacuum Society

    NASA Astrophysics Data System (ADS)

    Saha, T. K.

    2008-03-01

    The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

  10. Piston-pump-type high frequency oscillatory ventilation for neonates with congenital diaphragmatic hernia: a new protocol.

    PubMed

    Tamura, M; Tsuchida, Y; Kawano, T; Honna, T; Ishibashi, R; Iwanaka, T; Morita, Y; Hashimoto, H; Tada, H; Miyasaka, K

    1988-05-01

    High frequency ventilation and extracorporeal membrane oxygenation (ECMO) are devices that are expected to save the lives of newborn infants whose pulmonary conditions have deteriorated. A piston-pump-type high-frequency oscillator (HFO), developed by Bryan and Miyasaka called "Hummingbird," is considered to be superior to high frequency "jet" ventilators or those of the flow-interrupter type, and was used successfully in two neonates with congenital diaphragmatic hernia (CDH) in a high-risk group. The first baby was on a conventional ventilator with pharmacologic support for the first 54 hours and then operated on. Postoperative deterioration necessitated the use of HFO for the next eight days. The infant then recovered uneventfully. For the second baby, HFO was necessary both preoperatively and postoperatively. This baby had a major diaphragmatic defect and her case was complicated with pneumothorax. There was a long stormy course on HFO (total, 70 days), but the patient was successfully extubated on the 75th day postoperatively and is now doing well. We believe active long preoperative stabilization with pharmacologic support and preoperative and postoperative hyperventilation with a piston-pump-type HFO may be a new innovative strategy for the management of severe CDH patients.

  11. Overview of free-piston Stirling engine technology for space power application

    NASA Technical Reports Server (NTRS)

    Slaby, Jack G.

    1987-01-01

    An overview is presented of free-piston Stirling engine activities, directed toward space power applications. One of the major elements of the program is the development of advanced power conversion. Under this program the status of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) is presented. Initial differences between predicted and experimental power outputs and power output influenced by variations in regenerators are discussed. Technology work was conducted on heat-exchanger concepts to minimize the number of joints as well as to enhance the heat transfer in the heater. Design parameters and conceptual design features are also presented for a 25 kWe, single-cylinder free-piston Stirling space power converter. Projections are made for future space power requirements over the next few decades along with a recommendation to consider the use of dynamic power conversion systems, either solar or nuclear. A cursory comparison is presented showing the mass benefits of a Stirling system over a Brayton system for the same peak temperature and output power. A description of a study to investigate the feasibility of scaling a single-cylinder free-piston Stirling space power module to the 150 kWe power range is presented.

  12. A 1987 overview of free-piston Stirling technology for space power application

    NASA Technical Reports Server (NTRS)

    Slaby, Jack G.; Alger, Donald L.

    1987-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space-power application. NASA Lewis serves as the project office to manage the newly initiated NASA SP-100 Advanced Technology Program. One of the major elements of this five-year program is the development of advanced power conversion concepts of which the Stirling cycle is a viable growth candidate. Under this program the status of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) is presented. Included in the SPDE discussion are comparisons between predicted and experimental engine performance, enhanced performance resulting from regenerator modification, increased operating stroke brought about by isolating the gas bearing flow between the displacer and power piston, identifying excessive energy losses and recommending corrective action, and a better understanding of linear alternator design and operation. Technology work is also conducted on heat exchanger concepts, both design and fabrication. Design parameters and conceptual design features are also presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter.

  13. Vacuum-integrated electrospray deposition for highly reliable polymer thin film.

    PubMed

    Park, Soohyung; Lee, Younjoo; Yi, Yeonjin

    2012-10-01

    Vacuum electrospray deposition (ESD) equipment was designed to prepare polymer thin films. The polymer solution can be injected directly into vacuum system through multi-stage pumping line, so that the solvent residues and ambient contaminants are highly reduced. To test the performance of ESD system, we fabricated organic photovoltaic cells (OPVCs) by injecting polymer solution directly onto the substrate inside a high vacuum chamber. The OPVC fabricated has the structure of Al∕P3HT:PCBM∕PEDOT:PSS∕ITO and was optimized by varying the speed of solution injection and concentration of the solution. The power conversion efficiency (PCE) of the optimized OPVC is 3.14% under AM 1.5G irradiation without any buffer layer at the cathode side. To test the advantages of the vacuum ESD, we exposed the device to atmosphere between the deposition steps of the active layer and cathode. This showed that the PCE of the vacuum processed device is 24% higher than that of the air exposed device and confirms the advantages of the vacuum prepared polymer film for high performance devices.

  14. Vacuum Brazing of Accelerator Components

    NASA Astrophysics Data System (ADS)

    Singh, Rajvir; Pant, K. K.; Lal, Shankar; Yadav, D. P.; Garg, S. R.; Raghuvanshi, V. K.; Mundra, G.

    2012-11-01

    Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.

  15. Overview of High Power Vacuum Dry RF Load Designs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krasnykh, Anatoly

    2015-08-27

    A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is tomore » use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.« less

  16. The thermal conductance of solid-lubricated bearings at cryogenic temperatures in vacuum

    NASA Technical Reports Server (NTRS)

    Anderson, M. J.

    1996-01-01

    The thermal conductance of Hertzian contacts is of great importance to cryogenic spacecraft mechanisms such as the Infra-Red Space Observatory (ISO) and the Far Infra-Red Space Telescope (FIRST). At cryogenic temperatures, cooling of mechanism shafts and associated components occurs via conduction through the bearings. When fluid lubricants are cooled below their pour points, they no longer lubricate effectively, and it is necessary to use low shear strength solid lubricants. Currently, only very limited low temperature data exists on the thermal conductance of Hertzian contacts in both unlubricated and lubricated conditions. This paper reports on measurements of thermal conductance made on stationary ball bearings under cryo-vacuum conditions. Quantitative data is provided to support the development of computer models predicting the thermal conductance of Hertzian contacts and solid lubricants at cryogenic temperatures.

  17. Densification control and analysis of outer shell of new high-temperature vacuum insulated composite

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Chen, Zhaofeng; Jiang, Yun; Yu, Shengjie; Xu, Tengzhou; Li, Binbin; Chen, Zhou

    2017-11-01

    A novel high temperature vacuum insulated composite with low thermal conductivity composed of SiC foam core material and sealing outer shell is discussed, which will have a great potential to be used as thermal protection system material. In this composite, the outer shell is the key to maintain its internal vacuum, which is consisted of 2.5D C/C and SiC coating. So the densification processes of outer shell, including 2.5D braiding process, chemical vapor infiltration (CVI) pyrolytic carbon (PyC) process, polymer infiltration and pyrolysis (PIP) glassy carbon (GC) process and chemical vapor deposition (CVD) SiC process, are focused in this paper. The measuring result of the gas transmission quantity of outer shell is only 0.14 cm3/m2 · d · Pa after 5 times CVD processes, which is two order of magnitude lower than that sample deposited one time. After 10 times thermal shock cycles, the gas transmission quantity increases to 1.2 cm3/m2 · d · Pa. The effective thermal conductivity of high temperature vacuum insulated composite ranged from 0.19 W m-1 K-1 to 0.747 W m-1 K-1 within the temperature from 20 °C to 900 °C. Even after 10 thermal shock cycles, the variation of the effective thermal conductivity is still consistent with that without treatments.

  18. An investigation of the fluid-structure interaction of piston/cylinder interface

    NASA Astrophysics Data System (ADS)

    Pelosi, Matteo

    The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.

  19. Low-Cost, Rugged High-Vacuum System

    NASA Technical Reports Server (NTRS)

    Sorensen, Paul; Kline-Schoder, Robert

    2012-01-01

    A need exists for miniaturized, rugged, low-cost high-vacuum systems. Recent advances in sensor technology have led to the development of very small mass spectrometer detectors as well as other analytical instruments such as scanning electron microscopes. However, the vacuum systems to support these sensors remain large, heavy, and power-hungry. To meet this need, a miniaturized vacuum system was developed based on a very small, rugged, and inexpensive-to-manufacture molecular drag pump (MDP). The MDP is enabled by a miniature, very-high-speed (200,000 rpm), rugged, low-power, brushless DC motor optimized for wide temperature operation and long life. The key advantages of the pump are reduced cost and improved ruggedness compared to other mechanical hig-hvacuum pumps. The machining of the rotor and stators is very simple compared to that necessary to fabricate rotor and stator blades for other pump designs. Also, the symmetry of the rotor is such that dynamic balancing of the rotor will likely not be necessary. Finally, the number of parts in the unit is cut by nearly a factor of three over competing designs. The new pump forms the heart of a complete vacuum system optimized to support analytical instruments in terrestrial applications and on spacecraft and planetary landers. The MDP achieves high vacuum coupled to a ruggedized diaphragm rough pump. Instead of the relatively complicated rotor and stator blades used in turbomolecular pumps, the rotor in the MDP consists of a simple, smooth cylinder of aluminum. This will turn at approximately 200,000 rpm inside an outer stator housing. The pump stator comprises a cylindrical aluminum housing with one or more specially designed grooves that serve as flow channels. To minimize the length of the pump, the gas is forced down the flow channels of the outer stator to the base of the pump. The gas is then turned and pulled toward the top through a second set of channels cut into an inner stator housing that surrounds the

  20. Collapsible pistons for light-gas guns

    NASA Technical Reports Server (NTRS)

    Teng, R. N.

    1973-01-01

    Moving and expandable parts of gun consist of pump-tube diaphragm, piston, launch-tube diaphragm, and saboted projectile. As a result of improved piston design, pressure cycle has been significantly improved by smoother buildup, increasing muzzle velocities up to 50%.

  1. Magnetic bearings for free-piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Curwen, P. W.; Flemig, D. P.; Rao, D. K.; Wilson, D. S.

    1992-01-01

    The feasibility and efficiency of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficieny points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

  2. Magnetic bearings for free-piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Curwen, P. W.; Fleming, D. P.; Rao, D. K.; Wilson, D. S.

    1992-01-01

    The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

  3. High-Sensitivity, Broad-Range Vacuum Gauge Using Nanotubes for Micromachined Cavities

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Kaul, Anupama B.

    2011-01-01

    A broad-range vacuum gauge has been created by suspending a single-walled carbon nanotube (SWNT) (metallic or semiconducting) in a Schottky diode format or in a bridge conductor format, between two electrically charged mesas. SWNTs are highly sensitive to molecular collisions because of their extremely small diameters in the range of 1 to 3 nanometers. The measurement parameter will be the change in conductivity of SWNT due to decreasing rate of molecular collisions as the pressure inside a chamber decreases. The rate of heat removal approaches a saturation limit as the mean free path (m.f.p.) lengths of molecules increase due to decreasing pressure. Only those sensing elements that have a long relaxation time can produce a measureable response when m.f.p. of molecules increases (or time between two consecutive collisions increases). A suspended SWNT offers such a capability because of its one-dimensional nature and ultrasmall diameter. In the initial approach, similar architecture was used as that of a SWNT-Schottky diode that has been developed at JPL, and has its changing conductivity measured as the test chamber is pumped down from atmospheric pressure to high vacuum (10(exp -7) Torr). Continuous response of decreasing conductivity has been measured as a function of decreasing pressure (SWNT is a negative thermal coefficient material) from atmosphere to less than 10(exp -6) Torr. A measureable current change in the hundreds of nA range has been recorded in the 10(exp -6) Torr regime.

  4. Spherical Joint Piston and Connecting Rod Developed

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Under an interagency agreement with the Department of Energy, the NASA Lewis Research Center manages a Heavy-Duty Diesel Engine Technology (HDET) research program. The overall program objectives are to reduce fuel consumption through increased engine efficiency, reduce engine exhaust emissions, and provide options for the use of alternative fuels. The program is administered with a balance of research contracts, university research grants, and focused in-house research. The Cummins Engine Company participates in the HDET program under a cost-sharing research contract. Cummins is researching and developing in-cylinder component technologies for heavy-duty diesel engines. An objective of the Cummins research is to develop technologies for a low-emissions, 55-percent thermal efficiency (LE-55) engine. The best current-production engines in this class achieve about 46-percent thermal efficiency. Federal emissions regulations are driving this technology. Regulations for heavy duty diesel engines were tightened in 1994, more demanding emissions regulations are scheduled for 1998, and another step is planned for 2002. The LE-55 engine emissions goal is set at half of the 1998 regulation level and is consistent with plans for 2002 emissions regulations. LE-55 engine design requirements to meet the efficiency target dictate a need to operate at higher peak cylinder pressures. A key technology being developed and evaluated under the Cummins Engine Company LE-55 engine concept is the spherical joint piston and connecting rod. Unlike conventional piston and connecting rod arrangements which are joined by a pin forming a hinged joint, the spherical joint piston and connecting rod use a ball-and-socket joint. The ball-and-socket arrangement enables the piston to have an axisymmetric design allowing rotation within the cylinder. The potential benefits of piston symmetry and rotation are reduced scuffing, improved piston ring sealing, improved lubrication, mechanical and thermal

  5. Electromagnetic liquid pistons for capillarity-based pumping.

    PubMed

    Malouin, Bernard A; Vogel, Michael J; Olles, Joseph D; Cheng, Lili; Hirsa, Amir H

    2011-02-07

    The small scales associated with lab-on-a-chip technologies lend themselves well to capillarity-dominated phenomena. We demonstrate a new capillarity-dominated system where two adjoining ferrofluid droplets can behave as an electronically-controlled oscillator or switch by an appropriate balance of magnetic, capillary, and inertial forces. Their oscillatory motion can be exploited to displace a surrounding liquid (akin to an axial piston pump), forming electromagnetic "liquid pistons." Such ferrofluid pistons can pump a precise volume of liquid via finely tunable amplitudes (cf. pump stroke) or resonant frequencies (cf. pump speed) with no solid moving parts for long-term operation without wear in a small device. Furthermore, the rapid propagation of electromagnetic fields and the favorable scaling of capillary forces with size permit micron sized devices with very fast operating speeds (∼kHz). The pumping dynamics and performance of these liquid pistons is explored, with experimental measurements showing good agreement with a spherical cap model. While these liquid pistons may find numerous applications in micro- and mesoscale fluidic devices (e.g., remotely activated drug delivery), here we demonstrate the use of these liquid pistons in capillarity-dominated systems for chip-level, fast-acting adaptive liquid lenses with nearly perfect spherical interfaces.

  6. Method of Fabricating Chopped-Fiber Composite Piston

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

    1999-01-01

    A three-dimensional piston molding is fabricated from a mixture of chopped, carbon tow filaments of variable length, which are prepregged with carbonaceous organic resins and/or pitches and molded by conventional molding processes into a near net shape, to form a carbon-fiber reinforced organic-matrix composite part. Continuous reinforcement in the form of carbon-carbon composite tapes or pieces of fabric can be also laid in the mold before or during the charging of the mold with the chopped-fiber mixture, to enhance the strength in the crown and wrist-pin areas. The molded chopped-fiber reinforced organic-matrix composite parts are then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. These pyrolized parts are then densified by reimpregnation with resins or pitches, which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston molds are machined to final piston dimensions, and piston ring grooves are added. To prevent oxidation and/or to seal the piston surface or near surface, the chopped-fiber piston is coated with ceramic and/or metallic sealants: and/or coated with a catalyst.

  7. Overview of the 1986 free-piston Stirling activities at NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Alger, Donald L.

    1986-01-01

    An overview of the NASA Lewis Research Center's free-piston Stirling engine research is presented, including efforts to improve and advance its design for use in specific space power applications. These efforts are a part of the SP-100 program being conducted to support the Department of Defense (DOD), Department of Energy (DOE) and NASA. Such efforts include: (1) the testing and improvement of 25 kWe Stirling Space Power Demonstrator Engine (SPDE); (2) the preliminary design of 25 kWe single-cylinder Experimental stirling Space Engine (ESSE); and, (3) a study to determine the feasibility of scaling a single-cylinder free-piston Stirling engine/linear alternator to 150 kWe. Other NASA Lewis free-piston Stirling engine activities will be described, directed toward the advancement of general free-piston Stirling engine technology and its application in specific terrestrial applications. One such effort, supported by DOE/Oak Ridge National Laboratory (DRNL), is the development of a free-piston Stirling engine which produces hydraulic power. Finally, a terrestrial solar application involving a conceptual design of a 25 kWe Solar Advanced Stirling Conversion System (ASCS) capable of delivering power to an electric utility grid will be discussed. The latter work is supported by DOE/Sandia National Laboratory (SNLA).

  8. Developmental Considerations on the Free-Piston Stirling Power Convertor for Use in Space

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    2006-01-01

    Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines with rotary alternators to convert heat to electricity. These systems were proposed with lightly loaded linkages to achieve the necessary life. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability. These features have consistently been recognized by teams that have studied technology options for radioisotope power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: demonstration of life and reliability, the success achieved by Stirling cryocoolers in flight, and the overall developmental maturity of the technology for both flight and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status, and discuss the challenges that remain.

  9. Developmental Considerations on the Free-piston Stirling Power Convertor for Use in Space

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    2007-01-01

    Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines with rotary alternators to convert heat to electricity. These systems were proposed with lightly loaded linkages to achieve the necessary life. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability. These features have consistently been recognized by teams that have studied technology options for radioisotope power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: demonstration of life and reliability, the success achieved by Stirling cryocoolers in flight, and the overall developmental maturity of the technology for both flight and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status, and discuss the challenges that remain.

  10. Adjustable expandable cryogenic piston and ring

    DOEpatents

    Mazur, Peter O.; Pallaver, Carl B.

    1980-01-01

    The operation of a reciprocating expansion engine for cryogenic refrigeration is improved by changing the pistons and rings so that the piston can be operated from outside the engine to vary the groove in which the piston ring is located. This causes the ring, which is of a flexible material, to be squeezed so that its contact with the wall is subject to external control. This control may be made manually or it may be made automatically in response to instruments that sense the amount of blow-by of the cryogenic fluid and adjust for an optimum blow-by.

  11. Improving Free-Piston Stirling Engine Specific Power

    NASA Technical Reports Server (NTRS)

    Briggs, Maxwell Henry

    2014-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling Engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  12. Improving Free-Piston Stirling Engine Specific Power

    NASA Technical Reports Server (NTRS)

    Briggs, Maxwell H.

    2015-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  13. Piston flow in a two-dimensional channel

    NASA Astrophysics Data System (ADS)

    Katopodes, Fotini V.; Davis, A. M. J.; Stone, H. A.

    2000-05-01

    A solution using biorthogonal eigenfunctions is presented for viscous flow caused by a piston in a two-dimensional channel. The resulting infinite set of linear equations is solved using Spence's optimal weighting function method [IMA J. Appl. Math. 30, 107 (1983)]. The solution is compared to that with a shear-free piston surface; in the latter configuration the fluid more rapidly approaches the Poiseuille flow profile established away from the face of the piston.

  14. Extended Operation of Stirling Convertors in a Thermal Vacuum Environment

    NASA Technical Reports Server (NTRS)

    Oriti, Salvatore M.

    2006-01-01

    A 110 watt Stirling Radioisotope Generator (SRG110) is being developed for potential use on future NASA exploration missions. The development effort is being performed by Lockheed Martin under contract to the Department of Energy (DOE). Infinia, Corp. supplies the free-piston Stirling power convertors, and NASA Glenn Research Center (GRC) provides support to the effort in a range of technologies. This generator features higher efficiency and specific power compared to alternatives. One potential application for the generator would entail significant cruise time in the vacuum of deep space. A test has been initiated at GRC to demonstrate functionality of the Stirling convertors in a thermal vacuum environment. The test article resembles the configuration of the SRG110, however the requirement for low mass was not considered. This test demonstrates the operation of the Stirling convertors in the thermal vacuum environment, simulating deep space, over an extended period of operation. The status of the test as well as the data gathered will be presented in this paper.

  15. Staged combustion with piston engine and turbine engine supercharger

    DOEpatents

    Fischer, Larry E [Los Gatos, CA; Anderson, Brian L [Lodi, CA; O'Brien, Kevin C [San Ramon, CA

    2011-11-01

    A combustion engine method and system provides increased fuel efficiency and reduces polluting exhaust emissions by burning fuel in a two-stage combustion system. Fuel is combusted in a piston engine in a first stage producing piston engine exhaust gases. Fuel contained in the piston engine exhaust gases is combusted in a second stage turbine engine. Turbine engine exhaust gases are used to supercharge the piston engine.

  16. Staged combustion with piston engine and turbine engine supercharger

    DOEpatents

    Fischer, Larry E [Los Gatos, CA; Anderson, Brian L [Lodi, CA; O'Brien, Kevin C [San Ramon, CA

    2006-05-09

    A combustion engine method and system provides increased fuel efficiency and reduces polluting exhaust emissions by burning fuel in a two-stage combustion system. Fuel is combusted in a piston engine in a first stage producing piston engine exhaust gases. Fuel contained in the piston engine exhaust gases is combusted in a second stage turbine engine. Turbine engine exhaust gases are used to supercharge the piston engine.

  17. Simultaneous piston position and tilt angle sensing for large vertical displacement micromirrors by frequency detection inductive sensing

    NASA Astrophysics Data System (ADS)

    Tseng, V. F.-G.; Xie, H.

    2015-11-01

    This paper presents a frequency detection based inductive eddy current sensing mechanism to simultaneously sense the piston position and tilt angle of the mirror plate of large vertical displacement micromirrors that exhibit piston scan ranges above 100 μm. This is accomplished by sensing the inductance change, and thus resonant frequency shift, of two microfabricated sensing coils packaged underneath the mirror plate. For demonstration purpose, the coils were paired with discrete circuit components to oscillate at 11.9 MHz and 12.5 MHz, respectively. The piston position and tilt angle of the mirror plate could be simultaneously monitored over a 500 μm piston scan range, achieving a maximum piston sensitivity of 4.15 kHz/μm with a piston sensing resolution of 96 nm and a maximum tilt angle sensitivity of 60.5 kHz/° with a tilt angle sensing resolution of 0.0013°. Analytical modeling of the coil inductance change via image theory was also conducted, showing that the sensor sensitivity and resolution could be improved by increasing the coil oscillation frequency and decreasing the coil size.

  18. Ultra high vacuum heating and rotating specimen stage

    DOEpatents

    Coombs, III, Arthur W.

    1995-01-01

    A heating and rotating specimen stage provides for simultaneous specimen heating and rotating. The stage is ideally suited for operation in ultrahigh vacuum (1.times.10.sup.-9 torr or less), but is useful at atmosphere and in pressurized systems as well. A specimen is placed on a specimen holder that is attached to a heater that, in turn, is attached to a top housing. The top housing is rotated relative to a bottom housing and electrically connected thereto by electrically conductive brushes. This stage is made of materials that are compatible with UHV, able to withstand high temperatures, possess low outgassing rates, are gall and seize resistant, and are able to carry substantial electrical loading without overheating.

  19. Development of EPA aircraft piston engine emission standards. [for air quality

    NASA Technical Reports Server (NTRS)

    Houtman, W.

    1976-01-01

    Piston engine light aircraft are significant sources of carbon monoxide in the vicinity of high activity general aviation airports. Substantial reductions in carbon monoxide were achieved by fuel mixture leaning using improved fuel management systems. The air quality impact of the hydrocarbon and oxides of nitrogen emissions from piston engine light aircraft were insufficient to justify the design constraints being confronted in present control system developments.

  20. Emissions of piston engine aircraft using aviation gasoline (avgas) and motor gasoline (mogas) as fuel – a review

    NASA Astrophysics Data System (ADS)

    Thanikasalam, K.; Rahmat, M.; Fahmi, A. G. Mohammad; Zulkifli, A. M.; Shawal, N. Noor; Ilanchelvi, K.; Ananth, M.; Elayarasan, R.

    2018-05-01

    There are two categories of aircraft engines, namely, piston and gas turbine engines. Piston engine extracts energy from a combustion compartment through a piston and crank apparatus that engages the propellers, which in turn, provides an aircraft the needed momentum. On the other hand, gas turbine engine heats a compressed air in the combustion compartment resulting in propulsion that drives an aircraft. Piston engine aircrafts might appear small but together thousands of piston engine aircraft, which encompasses a bulk of the general aviation fleet, present a considerable health threat. That is because these aircraft, which depend on avgas and mogas to run, comprise major remaining sources of lead emissions. People exposed to even small levels of lead, particularly children, have tendencies to suffer from cognitive and neurological harm. Dissimilar from commercial airliners that do not utilize leaded fuels, piston engine aircraft account for nearly half of the lead discharge in skies. But, what is the extent of the impact caused by these airborne emissions on the country’s economy and public health? To answer this query, a thorough literature review on emissions of piston engine aircraft ought to be undertaken. This article conducts a literature review on emissions of piston engine aircraft using avgas as fuel and mogas as fuel.

  1. Study of cavity effect in micro-Pirani gauge chamber with improved sensitivity for high vacuum regime

    NASA Astrophysics Data System (ADS)

    Zhang, Guohe; Lai, Junhua; Kong, Yanmei; Jiao, Binbin; Yun, Shichang; Ye, Yuxin

    2018-05-01

    Ultra-low pressure application of Pirani gauge needs significant improvement of sensitivity and expansion of measureable low pressure limit. However, the performance of Pirani gauge in high vacuum regime remains critical concerns since gaseous thermal conduction with high percentage is essential requirement. In this work, the heat transfer mechanism of micro-Pirani gauge packaged in a non-hermetic chamber was investigated and analyzed compared with the one before wafer-level packaging. The cavity effect, extremely important for the efficient detection of low pressure, was numerically and experimentally analyzed considering the influence of the pressure, the temperature and the effective heat transfer area in micro-Pirani gauge chamber. The thermal conduction model is validated by experiment data of MEMS Pirani gauges with and without capping. It is found that nature gaseous convection in chamber, determined by the Rayleigh number, should be taken into consideration. The experiment and model calculated results show that thermal resistance increases in the molecule regime, and further increases after capping due to the suppression of gaseous convection. The gaseous thermal conduction accounts for an increasing percentage of thermal conduction at low pressure while little changes at high pressure after capping because of the existence of cavity effect improving the sensitivity of cavity-effect-influenced Pirani gauge for high vacuum regime.

  2. Use of space ultra-vacuum for high quality semiconductor thin film growth

    NASA Technical Reports Server (NTRS)

    Ignatiev, A.; Sterling, M.; Sega, R. M.

    1992-01-01

    The utilization of space for materials processing is being expanded through a unique concept of epitaxial thin film growth in the ultra-vacuum of low earth orbit (LEO). This condition can be created in the wake of an orbiting space vehicle; and assuming that the vehicle itself does not pertub the environment, vacuum levels of better than 10 exp -14 torr can be attained. This vacuum environment has the capacity of greatly enhancing epitaxial thin film growth and will be the focus of experiments conducted aboard the Wake Shield Facility (WSF) currently being developed by the Space Vacuum Epitaxy Center (SVEC), Industry, and NASA.

  3. Sealing Materials for Use in Vacuum at High Temperatures

    NASA Technical Reports Server (NTRS)

    Pettit, Donald R.; Camarda, Charles J.; Lee Vaughn, Wallace

    2012-01-01

    Sealing materials that can be applied and left in place in vacuum over a wide range of temperatures (especially temperatures of a few thousand degrees Celsius) have been conceived and investigated for potential utility in repairing thermal-protection tiles on the space shuttles in orbit before returning to Earth. These materials are also adaptable to numerous terrestrial applications that involve vacuum processing and/or repair of structures that must withstand high temperatures. These materials can be formulated to have mechanical handling characteristics ranging from almost freely flowing liquid-like consistency through paste-like consistency to stiff puttylike consistency, and to retain these characteristics in vacuum until heated to high curing temperatures. A sealing material of this type can be formulated to be used in any of several different ways for example, to be impregnated into a high-temperature-fabric patch, impregnated into a high-temperature-fabric gasket for sealing a patch, applied under a patch, or applied alone in the manner of putty or wallboard compound. The sealing material must be formulated to be compatible with, and adhere to, the structural material(s) to be repaired. In general, the material consists of a vacuum-compatible liquid containing one or more dissolved compound(s) and/or mixed with suspended solid particles. Depending on the intended application, the liquid can be chosen to be of a compound that can remain in place in vacuum for a time long enough to be useful, and/or to evaporate or decompose in a controlled way to leave a useful solid residue behind. The evaporation rate is determined by proper choice of vapor pressure, application of heat, and/or application of ultraviolet light or other optical radiation. The liquid chosen for the original space shuttle application is a commercial silicone vacuum-pump oil.

  4. A multi-functional high voltage experiment apparatus for vacuum surface flashover switch research.

    PubMed

    Zeng, Bo; Su, Jian-cang; Cheng, Jie; Wu, Xiao-long; Li, Rui; Zhao, Liang; Fang, Jin-peng; Wang, Li-min

    2015-04-01

    A multifunctional high voltage apparatus for experimental researches on surface flashover switch and high voltage insulation in vacuum has been developed. The apparatus is composed of five parts: pulse generating unit, axial field unit, radial field unit, and two switch units. Microsecond damped ringing pulse with peak-to-peak voltage 800 kV or unipolar pulse with maximum voltage 830 kV is generated, forming transient axial or radial electrical field. Different pulse waveforms and field distributions make up six experimental configurations in all. Based on this apparatus, preliminary experiments on vacuum surface flashover switch with different flashover dielectric materials have been conducted in the axial field unit, and nanosecond pulse is generated in the radial field unit which makes a pulse transmission line in the experiment. Basic work parameters of this kind of switch such as lifetime, breakdown voltage are obtained.

  5. The effect of preignition on cylinder temperatures, pressures, power output, and piston failures

    NASA Technical Reports Server (NTRS)

    Corrington, Lester C; Fisher, William F

    1947-01-01

    An investigation was conducted using a cylinder of a V-type liquid-cooled engine to observe the behavior of the cylinder when operated under preignition conditions. Data were recorded that showed cylinder-head temperatures, time of ignition, engine speed, power output, and change in maximum cylinder pressure as a function of time as the engine entered preignition and was allowed to operate under preignition conditions for a short time. The effects of the following variables on the engine behavior during preignition were investigated: fuel-air ratio, power level, aromatic content of fuel, engine speed, mixture temperature, and preignition source. The power levels at which preignition would cause complete piston failure for the selected engine operating conditions and the types of failure encountered when using various values of clearance between the piston and cylinder barrel were determined. The fuels used had performance numbers high enough to preclude any possibility of knock throughout the test program.

  6. Hearing results using the SMart piston prosthesis.

    PubMed

    Fayad, Jose N; Semaan, Maroun T; Meier, Josh C; House, John W

    2009-12-01

    SMart, a newly introduced piston prosthesis for stapedotomy, is a nitinol-based, heat-activated, self-crimping prosthesis. We review our hearing results and postoperative complications using this self-crimped piston prosthesis and compare them with those obtained using stainless steel or platinum piston prostheses. Audiometric results using the SMart piston are identical to those obtained using a conventional piston prosthesis. Retrospective chart review. Private neurotologic tertiary referral center. The 416 ears reviewed included 306 with a SMart prosthesis and 110 conventional prostheses. 61% were women. Mean follow-up time was 5.6 (standard deviation [SD], 6.3 mo) and 6.9 months (SD, 7.0 mo) for the 2 groups, respectively. Stapedotomy using the SMart or a conventional (non-SMart) prosthesis. Audiometric hearing results, including pure-tone average (PTA) and air-bone gap (ABG), and prevalence of postoperative complications. Mean postoperative PTA was 32.6 (SD, 16.8) dB for the SMart group and 29.4 (SD, 13.5) dB for the non-SMart group, with ABGs of 7.6 (SD, 8.9) and 6.0 (SD, 5.2) dB, respectively. Mean change (decrease) in ABG was 18.7 (SD, 13.1) dB for the SMart group and 19.9 (SD, 10.3) dB for the non-SMart group. High-frequency bone PTAs showed overclosure of 2.0 (SD, 7.9) dB for the SMart group and 3.6 (SD, 8.6) dB for the non-SMart group. Postoperative vertigo and tinnitus were infrequent. No significant differences in these audiometric outcomes or complication rates were noted between groups. There was no significant difference in rate of gap closure to within 10 dB (78.3 versus 84.2%, SMart and non-SMart, respectively) or 20 dB (94.2 and 98.0%). Compared with conventional stapes prostheses, the nitinol-based SMart is a safe and reliable stapes prosthesis that eliminates manual crimping without significantly altering the audiometric outcome. Complications are rare, but longer follow-up is needed before establishing long-term stability.

  7. Advanced Technology Spark-Ignition Aircraft Piston Engine Design Study

    NASA Technical Reports Server (NTRS)

    Stuckas, K. J.

    1980-01-01

    The advanced technology, spark ignition, aircraft piston engine design study was conducted to determine the improvements that could be made by taking advantage of technology that could reasonably be expected to be made available for an engine intended for production by January 1, 1990. Two engines were proposed to account for levels of technology considered to be moderate risk and high risk. The moderate risk technology engine is a homogeneous charge engine operating on avgas and offers a 40% improvement in transportation efficiency over present designs. The high risk technology engine, with a stratified charge combustion system using kerosene-based jet fuel, projects a 65% improvement in transportation efficiency. Technology enablement program plans are proposed herein to set a timetable for the successful integration of each item of required advanced technology into the engine design.

  8. Multi technical analysis of wear mechanisms in axial piston pumps

    NASA Astrophysics Data System (ADS)

    Schuhler, G.; Jourani, A.; Bouvier, S.; Perrochat, J.-M.

    2017-05-01

    Axial piston pumps convert a motor rotation motion into hydraulic or pneumatic power. Their compactness and efficiency of approximately 0.9 make them suitable for actuation applications especially in aeronautics. However, they suffer a limited life due to the wear of their components. In the literature, studies of axial piston pumps deal with contact between its different elements under lubrication conditions. Nevertheless, they are more focused on analytic or numerical approaches. This study consists in an experimental analysis of worn pump components to highlight and understand wear mechanisms. Piston shoes are central components in the axial piston pump since they are involved in three tribological contacts. These three contacts are thereby studied: piston shoes/swashplate, piston shoes/pistons and piston shoes/shoes hold down plate (SHDP). To perform this analysis, helicopter hydraulic pumps after different operating times have been studied. The wear damage mechanisms and wear debris are analysed using SEM observations. 3D surface roughness measurements are then used to characterize worn surfaces. The observations reveal that in the contact between shoes and swashplate, the main wear mechanism is three-body abrasive wear due to coarse carbides removal. Between shoes and pistons, wear occurs in a less severe way and is mainly due to the debris generated in the first contact and conveyed by the lubricating fluid. In the third contact, the debris are also the prime cause of the abrasive wear and the generation of deep craters in the piston shoes.

  9. Cooling and stabilization of graphene nanoplatelets in high vacuum

    NASA Astrophysics Data System (ADS)

    Nagornykh, Pavel

    The study of 2D materials is a rapidly growing area of research, where the ability to isolate and probe an individual single-layer specimen is of high importance. The levitation approach serves as a natural solution for this problem and can be used in ways complementary to the standard techniques. Experiments, including study of properties at high or close to melting temperatures, stretching, folding, vibration and functionalization, can be conducted on levitated 2D materials. As a first step towards realization of all these ideas, one needs to develop and test a system allowing for control over the thermal state and orientation of mono-layer flakes. In this thesis, I present the results of implementation of the parametric feedback cooling scheme in a quadrupole ion trap for stabilization and cooling of graphene nanopletelets. I have tested and showed that the feedback allows to stabilize levitated graphene nanoplatelets in high vacuum conditions (<1 microTorr) to have trapped life times longer than a week. Cooling of the center of mass motion to temperatures below 20 K for all translational degrees of freedom was observed. I have also studied the coupling of DC patch potentials, which were found to be present in the high vacuum chamber. Their effect on cooling was studied and the protocol for minimizing the noise coupling created by the DC fields was designed. We have shown that by varying DC voltages on a set of auxiliary DC electrodes, placed near the trap, one can balance out the DC fields and achieve the lowest cooling temperature. The settings corresponding to this temperature were measured to have a slow drift in time. Ability to tune the settings to balance this drift without breaking the vacuum was studied and found to be a viable solution for the drift cancellation. In addition, our effort in characterization of the flakes is presented. It was shown that the flake discharge quantization observed during the initial pumping down of the high vacuum chamber

  10. Microfabricated Millimeter-Wave High-Power Vacuum Electronic Amplifiers

    DTIC Science & Technology

    2015-01-01

    Applications filed 2012). In spite of the challenges, high power sources of electromagnetic radiation are needed in the mmW bands for advanced DoD...Research Laboratory is demonstrating and developing millimeter-wave vacuum electronic traveling wave tube amplifiers at W- and G- band in the 10’ s to 100... s of watts power range at several percent instantaneous bandwidth. Keywords: Traveling wave tube; millimeter wave; vacuum electron device

  11. Double acting stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1986-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  12. Ultra high vacuum test setup for electron gun

    NASA Astrophysics Data System (ADS)

    Pandiyar, M. L.; Prasad, M.; Jain, S. K.; Kumar, R.; Hannurkar, P. R.

    2008-05-01

    Ultra High Vacuum (UHV) test setup for electron gun testing has been developed. The development of next generation light sources and accelerators require development of klystron as a radio frequency power source, and in turn electron gun. This UHV electron gun test setup can be used to test the electron guns ranging from high average current, quasi-continuous wave to high peak current, single pulse etc. An electron gun has been designed, fabricated, assembled and tested for insulation up to 80 kV under the programme to develop high power klystron for future accelerators. Further testing includes the electron emission parameters characterization of the cathode, as it determines the development of a reliable and efficient electron gun with high electron emission current and high life time as well. This needs a clean ultra high vacuum to study these parameters particularly at high emission current. The cathode emission current, work function and vapour pressure of cathode surface material at high temperature studies will further help in design and development of high power electron gun The UHV electron gun test setup consists of Turbo Molecular Pump (TMP), Sputter Ion Pump (SIP), pressure gauge, high voltage and cathode power supplies, current measurement device, solenoid magnet and its power supply, residual gas analyser etc. The ultimate vacuum less than 2×10-9 mbar was achieved. This paper describes the UHV test setup for electron gun testing.

  13. High throughput vacuum chemical epitaxy

    NASA Astrophysics Data System (ADS)

    Fraas, L. M.; Malocsay, E.; Sundaram, V.; Baird, R. W.; Mao, B. Y.; Lee, G. Y.

    1990-10-01

    We have developed a vacuum chemical epitaxy (VCE) reactor which avoids the use of arsine and allows multiple wafers to be coated at one time. Our vacuum chemical epitaxy reactor closely resembles a molecular beam epitaxy system in that wafers are loaded into a stainless steel vacuum chamber through a load chamber. Also as in MBE, arsenic vapors are supplied as reactant by heating solid arsenic sources thereby avoiding the use of arsine. However, in our VCE reactor, a large number of wafers are coated at one time in a vacuum system by the substitution of Group III alkyl sources for the elemental metal sources traditionally used in MBE. Higher wafer throughput results because in VCE, the metal-alkyl sources for Ga, Al, and dopants can be mixed at room temperature and distributed uniformly though a large area injector to multiple substrates as a homogeneous array of mixed element molecular beams. The VCE reactor that we have built and that we shall describe here uniformly deposits films on 7 inch diameter substrate platters. Each platter contains seven two inch or three 3 inch diameter wafers. The load chamber contains up to nine platters. The vacuum chamber is equipped with two VCE growth zones and two arsenic ovens, one per growth zone. Finally, each oven has a 1 kg arsenic capacity. As of this writing, mirror smooth GaAs films have been grown at up to 4 μm/h growth rate on multiple wafers with good thickness uniformity. The background doping is p-type with a typical hole concentration and mobility of 1 × 10 16/cm 3 and 350 cm 2/V·s. This background doping level is low enough for the fabrication of MESFETs, solar cells, and photocathodes as well as other types of devices. We have fabricated MESFET devices using VCE-grown epi wafers with peak extrinsic transconductance as high as 210 mS/mm for a threshold voltage of - 3 V and a 0.6 μm gate length. We have also recently grown AlGaAs epi layers with up to 80% aluminum using TEAl as the aluminum alkyl source. The Al

  14. Ultra high vacuum heating and rotating specimen stage

    DOEpatents

    Coombs, A.W. III

    1995-05-02

    A heating and rotating specimen stage provides for simultaneous specimen heating and rotating. The stage is ideally suited for operation in ultrahigh vacuum (1{times}10{sup {minus}9} torr or less), but is useful at atmosphere and in pressurized systems as well. A specimen is placed on a specimen holder that is attached to a heater that, in turn, is attached to a top housing. The top housing is rotated relative to a bottom housing and electrically connected thereto by electrically conductive brushes. This stage is made of materials that are compatible with UHV, able to withstand high temperatures, possess low outgassing rates, are gall and seize resistant, and are able to carry substantial electrical loading without overheating. 5 figs.

  15. Free-piston reciprocating cryogenic expander utilizing phase controller

    NASA Astrophysics Data System (ADS)

    Cha, Jeongmin; Park, Jiho; Kim, Kyungjoong; Jeong, Sangkwon

    2017-02-01

    In a free-piston expander which eliminates mechanical linkages, a prescribed behaviour of the free-piston movement is the key to an expander performance. In this paper, we have proposed an idea of reducing complexity of the free-piston expander. It is to replace both multiple solenoid valves and reservoirs that are indispensable in a previous machine with a combination of a single orifice-reservoir assembly. It functions as a phase controller like that of a pulse tube refrigerator so that it generates time-delay of pressure variation between the warm-end and the reservoir resulting in the intended expansion of the cold-end volume down to the pre-set reservoir pressure. The modeling of this unique free-piston reciprocating expander utilizing phase controller is developed to understand and predict the performance of the new-type expander. Additionally, the operating parameters are analysed at the specified conditions to enable one to develop a more efficient free-piston type cryogenic expander.

  16. Free-piston Stirling technology for space power

    NASA Technical Reports Server (NTRS)

    Slaby, Jack G.

    1989-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space power. This work is being carried out under NASA's new Civil Space Technology Initiative (CSTI). The overall goal of CSTI's High Capacity Power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The Stirling cycle offers an attractive power conversion concept for space power needs. Discussed here is the completion of the Space Power Demonstrator Engine (SPDE) testing-culminating in the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was approximately 22 percent. The SPDE recently has been divided into two separate single-cylinder engines, called Space Power Research Engine (SPRE), that now serve as test beds for the evaluation of key technology disciplines. These disciplines include hydrodynamic gas bearings, high-efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding.

  17. Development of High Interruption Capability Vacuum Circuit Breaker -Technology of Vacuum Arc Control-

    NASA Astrophysics Data System (ADS)

    Niwa, Yoshimitsu; Kaneko, Eiji

    Vacuum circuit breakers (VCB) have been widely used for power distribution systems. Vacuum Interrupters, which are the current interruption unit, have been increased its interruption capability with the development of vacuum arc control technology by magnetic field. There are three major type electrodes: disk shaped electrodes, radial magnetic field electrodes, axial magnetic field (AMF) electrodes. In the disk shaped electrode, the vacuum arc between the electrodes is not controlled. In the AMF electrode, the vacuum arc is diffused and stabilized by an axial magnetic field, which is parallel to the arc current. In the last type of electrodes, the vacuum arc column is rotated by magnetic force generated by the current flowing in the electrodes. The interruption current and the voltage of one break VCB is increased to 100 kA, 144 kV respectively. This paper describes basic configurations and functions of VCB, vacuum arc control technology in vacuum interrupters, recent researches and applications of VCB.

  18. Final design of a free-piston hydraulic advanced Stirling conversion system

    NASA Technical Reports Server (NTRS)

    Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

    1991-01-01

    Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

  19. Final design of a free-piston hydraulic advanced Stirling conversion system

    NASA Astrophysics Data System (ADS)

    Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

    Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

  20. Collapsible pistons

    NASA Technical Reports Server (NTRS)

    Teng, R. N. (Inventor)

    1973-01-01

    A piston assembly is described for use in a hypervelocity gun comprising a forward cylindrical section longitudinally spaced from a rearward cylindrical section by an intermediate section. The intermediate section is longitudinally collapsible when subjected to a predetermined force, to allow the distance between the forward and rearward sections to be suddenly reduced.

  1. Experimental investigation of piston heat transfer under conventional diesel and reactivity-controlled compression ignition combustion regimes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Splitter, Derek A; Hendricks, Terry Lee; Ghandhi, Jaal B

    2014-01-01

    The piston of a heavy-duty single-cylinder research engine was instrumented with 11 fast-response surface thermocouples, and a commercial wireless telemetry system was used to transmit the signals from the moving piston. The raw thermocouple data were processed using an inverse heat conduction method that included Tikhonov regularization to recover transient heat flux. By applying symmetry, the data were compiled to provide time-resolved spatial maps of the piston heat flux and surface temperature. A detailed comparison was made between conventional diesel combustion and reactivity-controlled compression ignition combustion operations at matched conditions of load, speed, boost pressure, and combustion phasing. The integratedmore » piston heat transfer was found to be 24% lower, and the mean surface temperature was 25 C lower for reactivity-controlled compression ignition operation as compared to conventional diesel combustion, in spite of the higher peak heat release rate. Lower integrated piston heat transfer for reactivity-controlled compression ignition was found over all the operating conditions tested. The results showed that increasing speed decreased the integrated heat transfer for conventional diesel combustion and reactivity-controlled compression ignition. The effect of the start of injection timing was found to strongly influence conventional diesel combustion heat flux, but had a negligible effect on reactivity-controlled compression ignition heat flux, even in the limit of near top dead center high-reactivity fuel injection timings. These results suggest that the role of the high-reactivity fuel injection does not significantly affect the thermal environment even though it is important for controlling the ignition timing and heat release rate shape. The integrated heat transfer and the dynamic surface heat flux were found to be insensitive to changes in boost pressure for both conventional diesel combustion and reactivity-controlled compression

  2. VACUUM TRAP

    DOEpatents

    Gordon, H.S.

    1959-09-15

    An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

  3. Stochastic stability assessment of a semi-free piston engine generator concept

    NASA Astrophysics Data System (ADS)

    Kigezi, T. N.; Gonzalez Anaya, J. A.; Dunne, J. F.

    2016-09-01

    Small engines, as power generators with low-noise and vibration characteristics, are needed in two niche application areas: as electric vehicle range extenders and as domestic micro Combined Heat and Power systems. A recent semi-free piston design known as the AMOCATIC generator fully meets this requirement. The engine potentially allows for high energy conversion efficiencies at resonance derived from having a mass and spring assembly. As with free-piston engines in general, stability and control of piston motion has been cited as the prime challenge limiting the technology's widespread application. Using physical principles, we derive in this paper two important results: an energy balance criterion and a related general stability criterion for a semi-free piston engine. Control is achieved by systematically designing a Proportional Integral (PI) controller using a control-oriented engine model for which a specific stability condition is stated. All results are presented in closed form throughout the paper. Simulation results under stochastic pressure conditions show that the proposed energy balance, stability criterion, and PI controller, operate as predicted to yield stable engine operation at fixed compression ratio.

  4. Optimized photonic gauge of extreme high vacuum with Petawatt lasers

    NASA Astrophysics Data System (ADS)

    Paredes, Ángel; Novoa, David; Tommasini, Daniele; Mas, Héctor

    2014-03-01

    One of the latest proposed applications of ultra-intense laser pulses is their possible use to gauge extreme high vacuum by measuring the photon radiation resulting from nonlinear Thomson scattering within a vacuum tube. Here, we provide a complete analysis of the process, computing the expected rates and spectra, both for linear and circular polarizations of the laser pulses, taking into account the effect of the time envelope in a slowly varying envelope approximation. We also design a realistic experimental configuration allowing for the implementation of the idea and compute the corresponding geometric efficiencies. Finally, we develop an optimization procedure for this photonic gauge of extreme high vacuum at high repetition rate Petawatt and multi-Petawatt laser facilities, such as VEGA, JuSPARC and ELI.

  5. Design of the ZTH vacuum liner

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prince, P.P.; Dike, R.S.

    1987-01-01

    The current status of the ZTH vacuum liner design is covered by this report. ZTH will be the first experiment to be installed in the CPRF (Confinement Physics Research Facility) at the Los Alamos National Laboratory and is scheduled to be operational at the rated current of 4 MA in 1992. The vacuum vessel has a 2.4 m major radius and a 40 cm minor radius. Operating parameters which drive the vacuum vessel mechanical design include a 300 C bakeout temperature, an armour support system capable of withstanding 25 kV, a high toroidal resistance, 1250 kPa magnetic loading, a 10more » minute cycle time, and high positional accuracy with respect to the conducting shell. The vacuum vessel design features which satisfy the operating parameters are defined. The liner is constructed of Inconel 625 and has a geometry which alternates sections of thin walled bellows with rigid ribs. These composite sections span between pairs of the 16 diagnostic stations to complete the torus. The thin bellows sections maximize the liner toroidal resistance and the ribs provide support and positional accuracy for the armour in relation to the conducting shell. Heat transfer from the vessel is controlled by a blanket wrap of ceramic fiber insulation and the heat flux is dissipated to a water cooling jacket in the conducting shell.« less

  6. A highly miniaturized vacuum package for a trapped ion atomic clock

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schwindt, Peter D. D., E-mail: pschwin@sandia.gov; Jau, Yuan-Yu; Partner, Heather

    2016-05-15

    We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm{sup 3} in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it wasmore » sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of {sup 171}Y b{sup +}. The fractional frequency stability of the clock was measured to be 2 × 10{sup −11}/τ{sup 1/2}.« less

  7. A highly miniaturized vacuum package for a trapped ion atomic clock

    DOE PAGES

    Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; ...

    2016-05-12

    We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm 3 in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, the packagemore » was sealed with a copper pinch-off and was then pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of 171Yb +. The fractional frequency stability of the clock was measured to be 2 × 10 -11 / τ 1/2.« less

  8. Electromagnetic liquid pistons for capillarity-based pumping

    NASA Astrophysics Data System (ADS)

    Malouin, Bernard; Olles, Joseph; Cheng, Lili; Hirsa, Amir; Vogel, Michael

    2011-11-01

    Two adjoining ferrofluid droplets can behave as an electronically-controlled oscillator or switch by an appropriate balance of magnetic, capillary, and inertial forces. Their motion can be exploited to displace a surrounding liquid, forming electromagnetic liquid pistons. Such ferrofluid pistons can pump a precise volume of liquid via finely tunable amplitudes or resonant frequencies with no solid moving parts. Here we demonstrate the use of these liquid pistons in capillarity-dominated systems for variable focal distance liquid lenses with nearly perfect spherical interfaces. These liquid/liquid lenses feature many promising qualities not previously realized together in a liquid lens, including large apertures, immunity to evaporation, invariance to orientation relative to gravity, and low driving voltages. The dynamics of these liquid pistons is examined, with experimental measurements showing good agreement with a spherical cap model. A centimeter-scale lens was shown to respond in excess of 30 Hz, with resonant frequencies over 1 kHz predicted for scaled down systems.

  9. Overview of the 1986 free-piston Stirling SP-100 activities at the NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Slaby, J. G.

    1986-01-01

    An overview of the NASA Lewis Research Center SP-100 free-piston Stirling engine activities is presented. These activities include a free-piston Stirling space-power technology feasibility demonstration project as part of the SP-100 program being conducted in support of the Department of Defennse (DOD), Department of Energy (DOE), and NASA. The space-power Stirling advanced technology effort, under SP-100, addresses the status of the 25 kWe Space Power Demonstrator Engine (SPDE) including test results. Future space-power projections are presented along with a description of a study that will investigate the feasibility of scaling a single-cylinder free-piston Stirling space-power module to the 150 kW power range. Design parameters and conceptual design features will be presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter. A description of a hydrodynamic gas bearing concept is presented whereby the displacer of a 1 kWe free-piston Stirling engine is modified to demonstrate the bearing concept. And finally the goals of a conceptual design for a 25 kWe Solar Advanced Stirling Conversion System capable of delivering electric power to an electric utility grid are discussed.

  10. Overview of the 1986 free-piston Stirling SP-100 activities at the NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Slaby, J. G.

    1986-01-01

    An overview of the NASA Lewis Research Center SP-100 free-piston Stirling engine activities is presented. These activities include a free-piston Stirling space-power technology feasibility demonstration project as part of the SP-100 program being conducted in support of the Department of Defense (DOD), Department of Energy (DOE), and NASA. The space-power Stirling advanced technology effort, under SP-100, addresses the status of the 25 kWe Space Power Demonstrator Engine (SPDE) including test results. Future space-power projections are presented along with a description of a study that will investigate the feasibility of scaling a single-cylinder free-piston Stirling space-power module to the 150 kW power range. Design parameters and conceptual design features will be presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter. A description of a hydrodynamic gas bearing concept is presented whereby the displacer of a 1 kWe free-piston Stirling engine is modified to demonstrate the bearing concept. And finally the goals of a conceptual design for a 25 kWe Solar Advanced Stirling Conversion System capable of delivering electric power to an electric utility grid are discussed.

  11. Low-Dead-Volume Inlet for Vacuum Chamber

    NASA Technical Reports Server (NTRS)

    Naylor, Guy; Arkin, C.

    2010-01-01

    Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead -volume. As a result, a high -vacuum gas inlet was developed with low dead -volume, allowing the use of a very low conductance limit interface. Gas flows through the ConFlat flange at a relatively high flow rate at orders of magnitude greater than through the conductance limit. The small flow goes through a conductance limit that is a double-sided ConFlat.

  12. Low-Dead-Volume Inlet for Vacuum Chamber

    NASA Technical Reports Server (NTRS)

    Naylor, Guy; Arkin, C.

    2011-01-01

    Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead-volume. As a result, a high-vacuum gas inlet was developed with low dead-volume, allowing the use of a very low conductance limit interface. Gas flows through the ConFlat flange at a relatively high flow rate at orders of magnitude greater than through the conductance limit. The small flow goes through a conductance limit that is a double-sided ConFlat.

  13. [The length of the piston in otosclerosis surgery].

    PubMed

    Portmann, D; Alcantara, M; Vianna, M

    2007-01-01

    The measurement of the piston is always described as a significant stage of the surgery but its length is never clearly defined. The goal of this work is to determine the length of the prosthesis. From May 2003 to May 2005, 128 patients with otosclerosis, diagnosed on the basis of their clinical history and their audiogram, were included in this prospective study. Some of them were revision surgeries. The prosthesis generally used was the Portmann piston clip (Medtronic Xomed Inc Portmann Piston Clip Stainless Steel/Fluoroplastic). In stapedectomies, a Teflon piston of 0.6 mm of diameter was used (Pouret Company Fluoroplastic Stapes Prosthesis). These prostheses must be trimmed before their installation. The measurement technique is described. The length of the prosthesis was increased by 0.5 mm to include the thickness of the footplate. The Portmann piston clip was used 116 times (100 initial surgeries and 16 revisions surgeries) and the Teflon prosthesis of 0.6 mm of diameter only 13 times (6 primary stapedectomies and 7 revisions stapedectomies). The length of the prosthesis was between 3,5 mm and 5 mm. In the majority of cases, the length of the prosthesis was 4.75 mm (62 patients, 48.1%), followed by 4.5 mm (29 patients, 22.5%) and 5 mm (27 patients, 20.9%). In eleven cases (8.5%) the prosthesis measured less than 4,5 mm. None of the patients in this study experienced a postoperative sensorineural hearing loss. The measurement of the length of the piston is very significant, and in our study the majority of the pistons were cut at 4.75 mm which indicates an incus-footplate measurement of 4.25 mm.

  14. Vacuum MOCVD fabrication of high efficience cells

    NASA Technical Reports Server (NTRS)

    Partain, L. D.; Fraas, L. M.; Mcleod, P. S.; Cape, J. A.

    1985-01-01

    Vacuum metal-organic-chemical-vapor-deposition (MOCVD) is a new fabrication process with improved safety and easier scalability due to its metal rather than glass construction and its uniform multiport gas injection system. It uses source materials more efficiently than other methods because the vacuum molecular flow conditions allow the high sticking coefficient reactants to reach the substrates as undeflected molecular beams and the hot chamber walls cause the low sticking coefficient reactants to bounce off the walls and interact with the substrates many times. This high source utilization reduces the materials costs power device and substantially decreases the amounts of toxic materials that must be handled as process effluents. The molecular beams allow precise growth control. With improved source purifications, vacuum MOCVD has provided p GaAs layers with 10-micron minority carrier diffusion lengths and GaAs and GaAsSb solar cells with 20% AMO efficiencies at 59X and 99X sunlight concentration ratios. Mechanical stacking has been identified as the quickest, most direct and logical path to stacked multiple-junction solar cells that perform better than the best single-junction devices. The mechanical stack is configured for immediate use in solar arrays and allows interconnections that improve the system end-of-life performance in space.

  15. High power, high frequency, vacuum flange

    DOEpatents

    Felker, B.; McDaniel, M.R.

    1993-03-23

    An improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counter bores surrounding the waveguide tubes. When the sections are bolted together the counter bores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

  16. The Effect of Piston-Head Temperature on Knock-Limited Power

    NASA Technical Reports Server (NTRS)

    Imming, Harry S.

    1944-01-01

    To determine the effect of piston-head temperature on knock-limited power. Tests were made in a supercharged CFR engine over a range of fuel-air ratios from 0.055 to 0.120, using S-3 reference fuel, AN-F-28, Amendment-2, aviation gasoline, and AN-F-28 plus 2 percent xylidines by weight. Tests were run at a compression ratio of 7.0 with inlet-air temperatures of 150 F and 250 F and at a compression ratio of 8.0 with an inlet-air temperature of 250 F. All other engine conditions were held constant. The piston-head temperature was varied by circulation of oil through passages in the crown of a liquid-cooled piston. This method of piston cooling decreased the piston-head temperature about 80 F. The data are not intended to constitute a recommendation as to the advisability of piston cooling in practice.

  17. Continuing Development for Free-Piston Stirling Space Power Systems

    NASA Astrophysics Data System (ADS)

    Peterson, Allen A.; Qiu, Songgang; Redinger, Darin L.; Augenblick, John E.; Petersen, Stephen L.

    2004-02-01

    Long-life radioisotope power generators based on free-piston Stirling engines are an energy-conversion solution for future space applications. The high efficiency of Stirling machines makes them more attractive than the thermoelectric generators currently used in space. Stirling Technology Company (STC) has been developing free-piston Stirling machines for over 30 years, and its family of Stirling generators is ideally suited for reliable, maintenance-free operation. This paper describes recent progress and status of the STC RemoteGen™ 55 W-class Stirling generator (RG-55), presents an overview of recent testing, and discusses how the technology demonstration design has evolved toward space-qualified hardware.

  18. A study on the development of engineering plastic piston used in the shock absorber

    NASA Astrophysics Data System (ADS)

    Kim, Young-Ho; Bae, Won-Byong; Lim, Dong-Ju; Suh, Yun-Soo

    1998-08-01

    A piston is an important component of the shock absorber which determines comfortable riding and handling. Conventional piston is made of metal powder that is pressed in a mold, and then sintered at high temperatures below the melting point before machining processes such as drilling, sizing and teflon banding. This study aims at cutting down cost and weight, and improving the process by replacing the traditional sintering process used for manufacturing the shock absorber with the injection molding process adopting engineering plastics as raw material. To analyze the injection molding process, we used the commercial program, MOLDFLOW, and obtained an optimal combination of the process parameters. In addition, by comparing the engineering plastic piston with the metal powder piston through the formability and the performance experiments, we confirmed the availability of this alternative process suggested.

  19. High-Energy Vacuum Birefringence and Dichroism in an Ultrastrong Laser Field

    NASA Astrophysics Data System (ADS)

    Bragin, Sergey; Meuren, Sebastian; Keitel, Christoph H.; Di Piazza, Antonino

    2017-12-01

    A long-standing prediction of quantum electrodynamics, yet to be experimentally observed, is the interaction between real photons in vacuum. As a consequence of this interaction, the vacuum is expected to become birefringent and dichroic if a strong laser field polarizes its virtual particle-antiparticle dipoles. Here, we derive how a generally polarized probe photon beam is influenced by both vacuum birefringence and dichroism in a strong linearly polarized plane-wave laser field. Furthermore, we consider an experimental scheme to measure these effects in the nonperturbative high-energy regime, where the Euler-Heisenberg approximation breaks down. By employing circularly polarized high-energy probe photons, as opposed to the conventionally considered linearly polarized ones, the feasibility of quantitatively confirming the prediction of nonlinear QED for vacuum birefringence at the 5 σ confidence level on the time scale of a few days is demonstrated for upcoming 10 PW laser systems. Finally, dichroism and anomalous dispersion in vacuum are shown to be accessible at these facilities.

  20. Cermet insert high voltage holdoff for ceramic/metal vacuum devices

    DOEpatents

    Ierna, William F.

    1987-01-01

    An improved metal-to-ceramic seal is provided wherein the ceramic body of the seal contains an integral region of cermet material in electrical contact with the metallic member, e.g., an electrode, of the seal. The seal is useful in high voltage vacuum devices, e.g., vacuum switches, and increases the high-voltage holdoff capabilities of such devices. A method of fabricating such seals is also provided.

  1. A comparative reliability analysis of free-piston Stirling machines

    NASA Astrophysics Data System (ADS)

    Schreiber, Jeffrey G.

    2001-02-01

    A free-piston Stirling power convertor is being developed for use in an advanced radioisotope power system to provide electric power for NASA deep space missions. These missions are typically long lived, lasting for up to 14 years. The Department of Energy (DOE) is responsible for providing the radioisotope power system for the NASA missions, and has managed the development of the free-piston power convertor for this application. The NASA Glenn Research Center has been involved in the development of Stirling power conversion technology for over 25 years and is currently providing support to DOE. Due to the nature of the potential missions, long life and high reliability are important features for the power system. Substantial resources have been spent on the development of long life Stirling cryocoolers for space applications. As a very general statement, free-piston Stirling power convertors have many features in common with free-piston Stirling cryocoolers, however there are also significant differences. For example, designs exist for both power convertors and cryocoolers that use the flexure bearing support system to provide noncontacting operation of the close-clearance moving parts. This technology and the operating experience derived from one application may be readily applied to the other application. This similarity does not pertain in the case of outgassing and contamination. In the cryocooler, the contaminants normally condense in the critical heat exchangers and foul the performance. In the Stirling power convertor just the opposite is true as contaminants condense on non-critical surfaces. A methodology was recently published that provides a relative comparison of reliability, and is applicable to systems. The methodology has been applied to compare the reliability of a Stirling cryocooler relative to that of a free-piston Stirling power convertor. The reliability analysis indicates that the power convertor should be able to have superior reliability

  2. Precision optical slit for high heat load or ultra high vacuum

    DOEpatents

    Andresen, Nord C.; DiGennaro, Richard S.; Swain, Thomas L.

    1995-01-01

    This invention relates generally to slits used in optics that must be precisely aligned and adjusted. The optical slits of the present invention are useful in x-ray optics, x-ray beam lines, optical systems in which the entrance slit is critical for high wavelength resolution. The invention is particularly useful in ultra high vacuum systems where lubricants are difficult to use and designs which avoid the movement of metal parts against one another are important, such as monochrometers for high wavelength resolution with ultra high vacuum systems. The invention further relates to optical systems in which temperature characteristics of the slit materials is important. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line.

  3. Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at GRC

    NASA Astrophysics Data System (ADS)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center. Delivery of both the Stirling convertors and the linear alternator test rig is expected by October, 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

  4. Overview of Multi-kilowatt Free-Piston Stirling Power Conversion Research at GRC

    NASA Technical Reports Server (NTRS)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center. Delivery of both the Stirling convertors and the linear alternator test rig is expected by October, 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

  5. Characterization of selective solar absorber under high vacuum.

    PubMed

    Russo, Roberto; Monti, Matteo; di Giamberardino, Francesco; Palmieri, Vittorio G

    2018-05-14

    Total absorption and emission coefficients of selective solar absorbers are measured under high vacuum conditions from room temperature up to stagnation temperature. The sample under investigation is illuminated under vacuum @1000W/m 2 and the sample temperature is recorded during heat up, equilibrium and cool down. During stagnation, the absorber temperature exceeds 300°C without concentration. Data analysis allows evaluating the solar absorptance and thermal emittance at different temperatures. These in turn are useful to predict evacuated solar panel performances at operating conditions.

  6. Loss terms in free-piston Stirling engine models

    NASA Technical Reports Server (NTRS)

    Gordon, Lloyd B.

    1992-01-01

    Various models for free piston Stirling engines are reviewed. Initial models were developed primarily for design purposes and to predict operating parameters, especially efficiency. More recently, however, such models have been used to predict engine stability. Free piston Stirling engines have no kinematic constraints and stability may not only be sensitive to the load, but also to various nonlinear loss and spring constraints. The present understanding is reviewed of various loss mechanisms for free piston Stirling engines and how they have been incorporated into engine models is discussed.

  7. Superconducting Vacuum-Gap Crossovers for High Performance Microwave Applications

    NASA Technical Reports Server (NTRS)

    Denis, Kevin L.; Brown, Ari D.; Chang, Meng-Ping; Hu, Ron; U-Yen, Kongpop; Wollack, Edward J.

    2016-01-01

    The design and fabrication of low-loss wide-bandwidth superconducting vacuum-gap crossovers for high performance millimeter wave applications are described. In order to reduce ohmic and parasitic losses at millimeter wavelengths a vacuum gap is preferred relative to dielectric spacer. Here, vacuum-gap crossovers were realized by using a sacrificial polymer layer followed by niobium sputter deposition optimized for coating coverage over an underlying niobium signal layer. Both coplanar waveguide and microstrip crossover topologies have been explored in detail. The resulting fabrication process is compatible with a bulk micro-machining process for realizing waveguide coupled detectors, which includes sacrificial wax bonding, and wafer backside deep reactive ion etching for creation of leg isolated silicon membrane structures. Release of the vacuum gap structures along with the wax bonded wafer after DRIE is implemented in the same process step used to complete the detector fabrication. ?

  8. Development of Gas-Lubricated Pistons for Heavy Duty Diesel Engine Technology Program

    NASA Technical Reports Server (NTRS)

    Shapiro, W.

    1984-01-01

    Static testing of a segmented, gas-lubricated, piston-ring was accomplished. The ring utilizes high-pressure gas generated during the diesel cycle to energize a hydrostatic gas film between the piston and cylinder liner. The configuration was deficient in overall performance, because all segments of a ring set failed to form a fluid-film simultaneously, when exposed to internal preload. The difficulty was traced to the moment balance required to prevent the segments from overturning and contacting the cylinder walls. Some individual sectors formed a film and performed well in every respect including load capability to 6,000 N. These results produce optimism as to the ultimate feasibility of hydrostatic, gas-lubricated piston rings. In addition to test results, the principles of operation, and theoretical developments are presented. Breathable liner concepts are suggested for future consideration. In these configurations, solid hydrostatic pistons are coupled with flexible liners that elastically deform to form a gas-film under hydrostatic pressurization. Breathable liners afford the mechanical simplicity required for mass produced engines, and initial examination indicates satisfactory operation.

  9. Vacuum testing of high efficiency AMTEC cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schuller, M.; Phillips, P.H.; Sievers, R.

    1996-12-31

    The Phillips Laboratory Power and Thermal Management Division (PL/VTP), in cooperation with JPL, AMPS, Creare, and ORION, is performing vacuum testing of high performance Alkali Metal Thermal to Electric Conversion (AMTEC) cells, including the Micro-Machined Evaporator (MME) and PL-9A cells. The MME cell was designed to test an improved evaporator, which should allow long term operation at evaporator temperatures as high as 1,100 K. The PL-9A cell was designed and built by AMPS under contract to ORION to test an improved heat shield assembly. The testing at Phillips Lab is done in a vacuum test stand which simulates the environmentmore » of an AMTEC cell operating as part of a spacecraft power system. The test configuration consists of the MME cell (later replaced by by the PL-9A cell) in the center of an array of six other AMTEC cells. The seven cells are encased in multifoil insulation. Testing shows that there is little difference between cell current/voltage performance when measured in vacuum tests compared to guard heater tests. The author are also examining the differences between fast I-V curve sweeps, recorded manually, with the cell operating at constant heat input, over a period of five minutes or less, and equilibrium I-V curve sweeps, in which the cell reaches thermal equilibrium at each data point.« less

  10. Precision optical slit for high heat load or ultra high vacuum

    DOEpatents

    Andresen, N.C.; DiGennaro, R.S.; Swain, T.L.

    1995-01-24

    This invention relates generally to slits used in optics that must be precisely aligned and adjusted. The optical slits of the present invention are useful in x-ray optics, x-ray beam lines, optical systems in which the entrance slit is critical for high wavelength resolution. The invention is particularly useful in ultra high vacuum systems where lubricants are difficult to use and designs which avoid the movement of metal parts against one another are important, such as monochromators for high wavelength resolution with ultra high vacuum systems. The invention further relates to optical systems in which temperature characteristics of the slit materials is important. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line. 21 figures.

  11. A numerical model on thermodynamic analysis of free piston Stirling engines

    NASA Astrophysics Data System (ADS)

    Mou, Jian; Hong, Guotong

    2017-02-01

    In this paper, a new numerical thermodynamic model which bases on the energy conservation law has been used to analyze the free piston Stirling engine. In the model all data was taken from a real free piston Stirling engine which has been built in our laboratory. The energy conservation equations have been applied to expansion space and compression space of the engine. The equation includes internal energy, input power, output power, enthalpy and the heat losses. The heat losses include regenerative heat conduction loss, shuttle heat loss, seal leakage loss and the cavity wall heat conduction loss. The numerical results show that the temperature of expansion space and the temperature of compression space vary with the time. The higher regeneration effectiveness, the higher efficiency and bigger output work. It is also found that under different initial pressures, the heat source temperature, phase angle and engine work frequency pose different effects on the engine’s efficiency and power. As a result, the model is expected to be a useful tool for simulation, design and optimization of Stirling engines.

  12. Transient Characteristics of Free Piston Vuilleurnier Cycle Heat Pumps

    NASA Astrophysics Data System (ADS)

    Matsue, Junji; Fujimoto, Norioki; Shirai, Hiroyuki

    A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed using a time-stepping integration method to investigate transient characteristics under power controlling. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components. The force for pistons is mainly caused by the pressure change of working gas varying with piston displacements; moreover nonlinear viscous dissipative force due to the oscillating flow of working gas in heat exchangers and discontinuous damping force caused by solid friction at piston seals and rod seals are included. The displacements of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the transient characteristics of a proposed free piston Vuilleumier cycle heat pump machine when hot-side working gas temperatures and alternate force were changed, some calculations were performed and discussed. These calculation results make clear transient characteristics at starting and power controlling. It was further found that only a small amount of starter power is required in particular conditions. During controlling, the machine becomes unstable when there is ar elatively large reduction in cooling or heating power. Therefore, an auxiliary device is additionally needed to obtain stable operation, such as al inear motor.

  13. Optical rotation of levitated spheres in high vacuum

    NASA Astrophysics Data System (ADS)

    Monteiro, Fernando; Ghosh, Sumita; van Assendelft, Elizabeth C.; Moore, David C.

    2018-05-01

    A circularly polarized laser beam is used to levitate and control the rotation of microspheres in high vacuum. At low pressure, rotation frequencies as high as 6 MHz are observed for birefringent vaterite spheres, limited by centrifugal stresses. Due to the extremely low damping in high vacuum, the controlled optical rotation of amorphous SiO2 spheres is also observed at rates above several MHz. At 10-7 mbar, a damping time of 6 ×104 s is measured for a 10 -μ m -diam SiO2 sphere. No additional damping mechanisms are observed above gas damping, indicating that even longer damping times may be possible with operation at lower pressure. The controlled optical rotation of microspheres at MHz frequencies with low damping, including for materials that are not intrinsically birefringent, provides a tool for performing precision measurements using optically levitated systems.

  14. Fluorocarbon seal replaces metal piston ring in low density gas environment

    NASA Technical Reports Server (NTRS)

    Morath, W. D.; Morgan, N. E.

    1967-01-01

    Reinforced fluorocarbon cupseal, which provides an integral lip-type seal, replaces the metal piston rings in piston-cylinder configurations used in the compression of low density gases. The fluorocarbon seal may be used as cryogenic compressor piston seals.

  15. Fluid powered linear piston motor with harmonic coupling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Raymond, David W.

    2016-09-20

    A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.

  16. A Gas Pressure Scale Based on Primary Standard Piston Gauges

    PubMed Central

    Olson, Douglas A.; Driver, R. Greg; Bowers, Walter J.

    2010-01-01

    The National Institute of Standards and Technology (NIST) has redefined its gas pressure scale, up to 17 MPa, based on two primary standard piston gauges. The primary standard piston gauges are 35.8 mm in diameter and operate from 20 kPa to 1 MPa. Ten secondary standard piston gauges, two each of five series of the Ruska 2465 type, with successively smaller diameters form the scale extending up to 17 MPa. Six of the piston gauges were directly compared to the primary standards to determine their effective area and expanded (k = 2) uncertainty. Two piston gauges operating to 7 MPa were compared to the 1.4 MPa gauges, and two piston gauges operating to 17 MPa were compared to the 7 MPa gauges. Distortion in the 7 MPa piston gauges was determined by comparing those gauges to a DH Instruments PG7601 type piston gauge, whose distortion was calculated using elasticity theory. The relative standard uncertainties achieved by the primary standards range from 3.0 × 10−6 to 3.2 × 10−6. The relative standard uncertainty of the secondary standards is as low as 4.2 × 10−6 at 300 kPa. The effective areas and uncertainties were validated by comparison to standards of other National Metrology Institutes (NMIs). Results show agreement in all cases to better than the expanded (k = 2) uncertainty of the difference between NIST and the other NMIs, and in most cases to better than the standard (k = 1) uncertainty of the difference. PMID:27134793

  17. Free-piston Stirling Engine system considerations for various space power applications

    NASA Technical Reports Server (NTRS)

    Dochat, George R.; Dhar, Manmohan

    1991-01-01

    Free-Piston Stirling Engines (FPSE) have the potential to provide high reliability, long life, and efficient operation. Therefore, they are excellent candidates for the dynamic power conversion module of a space-based, power-generating system. FPSE can be coupled with many potential heat sources (radioisotope, solar, or nuclear reactor), various heat input systems (pumped loop, heat pipe), heat rejection (pumped loop or heat pipe), and various power management and distribution systems (ac, dc, high or low voltage, and fixed or variable load). This paper reviews potential space missions that can be met using free-piston Stirling engines and discusses options of various system integration approaches. This paper briefly outlines the program and recent progress.

  18. A low-background piston-cylinder-type hybrid high pressure cell for muon-spin rotation/relaxation experiments

    NASA Astrophysics Data System (ADS)

    Shermadini, Z.; Khasanov, R.; Elender, M.; Simutis, G.; Guguchia, Z.; Kamenev, K. V.; Amato, A.

    2017-10-01

    A low background double-wall piston-cylinder-type pressure cell is developed at the Paul Scherrer Institute. The cell is made from BERYLCO-25 (beryllium copper) and MP35N nonmagnetic alloys with the design and dimensions which are specifically adapted to muon-spin rotation/relaxation (μSR) measurements. The mechanical design and performance of the pressure cell are evaluated using finite-element analysis (FEA). By including the measured stress-strain characteristics of the materials into the finite-element model, the cell dimensions are optimized with the aim to reach the highest possible pressure while maintaining the sample space large (6 mm in diameter and 12 mm high). The presented unconventional design of the double-wall piston-cylinder pressure cell with a harder outer MP35N sleeve and a softer inner CuBe cylinder enables pressures of up to 2.6 GPa to be reached at ambient temperature, corresponding to 2.2 GPa at low temperatures without any irreversible damage to the pressure cell. The nature of the muon stopping distribution, mainly in the sample and in the CuBe cylinder, results in a low-background μSR signal.

  19. Aluminum Matrix Composite (AlSi7Mg2Sr0.03/SiCp) Pistons Obtained by Mechanical Mixing Method

    PubMed Central

    2017-01-01

    Metal matrix composites are undoubtedly a group of advanced engineering materials. Compared to unreinforced matrix material, they are characterized by increased strength, greater stiffness, increased wear resistance, better mechanical properties and dimensional stability at elevated temperatures as well as lower density. Due to its very favorable tribological properties for many years research has been conducted on the application of MMC in friction node. The article presents important technological aspects related to the production and properties of composite pistons. Under industrial conditions, a composite suspension (AlSi7Mg2Sr0.03/SiCp 10 vol %) was prepared to allow casting of the semi-finished pistons series. Machining parameters of the working surfaces of the piston were selected on the basis of the turning test made on PCD, PCNM and uncoated carbide tools. The tribological properties of the composite pistons were determined on the basis of the pin-on-disc and the abrasion wear. The scuffing tests carried out under real operating conditions have confirmed the possibility of using composite pistons in air compressors. PMID:29283419

  20. Piston pump and method of reducing vapor lock

    DOEpatents

    Phillips, Benjamin A.; Harvey, Michael N.

    2000-02-15

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  1. Piston pump and method of reducing vapor lock

    DOEpatents

    Phillips, Benjamin A.; Harvey, Michael N.

    2001-01-30

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  2. The surface topography of the choroid plexus. Environmental, low and high vacuum scanning electron microscopy.

    PubMed

    Mestres, Pedro; Pütz, Norbert; Garcia Gómez de Las Heras, Soledad; García Poblete, Eduardo; Morguet, Andrea; Laue, Michael

    2011-05-01

    Environmental scanning electron microscopy (ESEM) allows the examination of hydrated and dried specimens without a conductive metal coating which could be advantageous in the imaging of biological and medical objects. The aim of this study was to assess the performance and benefits of wet-mode and low vacuum ESEM in comparison to high vacuum scanning electron microscopy (SEM) using the choroid plexus of chicken embryos as a model, an organ of the brain involved in the formation of cerebrospinal fluid in vertebrates. Specimens were fixed with or without heavy metals and examined directly or after critical point drying with or without metal coating. For wet mode ESEM freshly excised specimens without any pre-treatment were also examined. Conventional high vacuum SEM revealed the characteristic morphology of the choroid plexus cells at a high resolution and served as reference. With low vacuum ESEM of dried but uncoated samples the structure appeared well preserved but charging was a problem. It could be reduced by a short beam dwell time and averaging of images or by using the backscattered electron detector instead of the gaseous secondary electron detector. However, resolution was lower than with conventional SEM. Wet mode imaging was only possible with tissue that had been stabilized by fixation. Not all surface details (e.g. microvilli) could be visualized and other structures, like the cilia, were deformed. In summary, ESEM is an additional option for the imaging of bio-medical samples but it is problematic with regard to resolution and sample stability during imaging. Copyright © 2011 Elsevier GmbH. All rights reserved.

  3. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E.

    1990-01-01

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  4. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E.

    1990-03-06

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  5. A vacuum spark ion source: High charge state metal ion beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P.

    2016-02-15

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less thanmore » 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.« less

  6. Free-piston engine linear generator for hybrid vehicles modeling study

    NASA Astrophysics Data System (ADS)

    Callahan, T. J.; Ingram, S. K.

    1995-05-01

    Development of a free piston engine linear generator was investigated for use as an auxiliary power unit for a hybrid electric vehicle. The main focus of the program was to develop an efficient linear generator concept to convert the piston motion directly into electrical power. Computer modeling techniques were used to evaluate five different designs for linear generators. These designs included permanent magnet generators, reluctance generators, linear DC generators, and two and three-coil induction generators. The efficiency of the linear generator was highly dependent on the design concept. The two-coil induction generator was determined to be the best design, with an efficiency of approximately 90 percent.

  7. System to measure accurate temperature dependence of electric conductivity down to 20 K in ultrahigh vacuum.

    PubMed

    Sakai, C; Takeda, S N; Daimon, H

    2013-07-01

    We have developed the new in situ electrical-conductivity measurement system which can be operated in ultrahigh vacuum (UHV) with accurate temperature measurement down to 20 K. This system is mainly composed of a new sample-holder fixing mechanism, a new movable conductivity-measurement mechanism, a cryostat, and two receptors for sample- and four-probe holders. Sample-holder is pushed strongly against the receptor, which is connected to a cryostat, by using this new sample-holder fixing mechanism to obtain high thermal conductivity. Test pieces on the sample-holders have been cooled down to about 20 K using this fixing mechanism, although they were cooled down to only about 60 K without this mechanism. Four probes are able to be touched to a sample surface using this new movable conductivity-measurement mechanism for measuring electrical conductivity after making film on substrates or obtaining clean surfaces by cleavage, flashing, and so on. Accurate temperature measurement is possible since the sample can be transferred with a thermocouple and∕or diode being attached directly to the sample. A single crystal of Bi-based copper oxide high-Tc superconductor (HTSC) was cleaved in UHV to obtain clean surface, and its superconducting critical temperature has been successfully measured in situ. The importance of in situ measurement of resistance in UHV was demonstrated for this HTSC before and after cesium (Cs) adsorption on its surface. The Tc onset increase and the Tc offset decrease by Cs adsorption were observed.

  8. BAKABLE ULTRA-HIGH VACUUM VALVE

    DOEpatents

    Mark, J.T.; Gantz, I.H.

    1962-07-10

    S>This patent relates to a valve useful in applications involving successively closing and opening a communication between a chamber evacuated to an ultra-high vacuum condition of the order of 10/sup -10/ millimeters of mercury and another chamber or the ambient. The valve is capable of withstanding extended baking at 450 deg C and repeated opening and closing without repiacement of the valve seat (approximately 200 cycle limit). The seal is formed by mutual interdiffusion weld, coerced by a pneumatic actuator. (AEC)

  9. Development of a non-piston MR suspension rod for variable mass systems

    NASA Astrophysics Data System (ADS)

    Deng, Huaxia; Han, Guanghui; Zhang, Jin; Wang, Mingxian; Ma, Mengchao; Zhong, Xiang; Yu, Liandong

    2018-06-01

    The semi-active suspension systems for variable mass systems require long work stroke and variable damping, while the currently piston structure limits the work stroke for the magnetorheological (MR) dampers. The main work of this paper is to design a semi-active non-piston MR (NPMR) suspension rod for the reduction of the vibration of an automatic impeller washing machine, which is a typical variable mass system. The designed suspension rod locates in the suspension system that links the internal tub to the washing machine cabinet. The NPMR suspension rod includes a MR part and a air part. The MR part can provide low initial damping force and the unlimited work stroke compared with the piston MR damper. The hysteretic response tests and vibration performance evaluation with different loadings are conducted to verify the dynamic performance for the designed rod. The measured damping force of the MR part varies from 5 to 20 N. Studies of dehydration mode experiments of the washing machine indicate that its vibration acceleration with the NPMR suspension rods can reduce to half of the original passive ones in certain conditions.

  10. Theoretical Evaluation of the Maximum Work of Free-Piston Engine Generators

    NASA Astrophysics Data System (ADS)

    Kojima, Shinji

    2017-01-01

    Utilizing the adjoint equations that originate from the calculus of variations, we have calculated the maximum thermal efficiency that is theoretically attainable by free-piston engine generators considering the work loss due to friction and Joule heat. Based on the adjoint equations with seven dimensionless parameters, the trajectory of the piston, the histories of the electric current, the work done, and the two kinds of losses have been derived in analytic forms. Using these we have conducted parametric studies for the optimized Otto and Brayton cycles. The smallness of the pressure ratio of the Brayton cycle makes the net work done negative even when the duration of heat addition is optimized to give the maximum amount of heat addition. For the Otto cycle, the net work done is positive, and both types of losses relative to the gross work done become smaller with the larger compression ratio. Another remarkable feature of the optimized Brayton cycle is that the piston trajectory of the heat addition/disposal process is expressed by the same equation as that of an adiabatic process. The maximum thermal efficiency of any combination of isochoric and isobaric heat addition/disposal processes, such as the Sabathe cycle, may be deduced by applying the methods described here.

  11. RE-1000 free-piston Stirling engine update

    NASA Technical Reports Server (NTRS)

    Schreiber, J. G.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  12. Entropic Damping of the Motion of a Piston

    ERIC Educational Resources Information Center

    Mungan, Carl E.

    2017-01-01

    The concept of an "entropic force" can be introduced by considering a familiar setup, namely a horizontal cylinder enclosing an ideal monatomic gas by a piston of cross-sectional area "A" and mass "m" that can slide without friction. The surrounding atmospheric pressure P[subscript atm] keeps the piston from flying…

  13. Preliminary test results from a free-piston Stirling engine technology demonstration program to support advanced radioisotope space power applications

    NASA Astrophysics Data System (ADS)

    White, Maurice A.; Qiu, Songgang; Augenblick, Jack E.

    2000-01-01

    Free-piston Stirling engines offer a relatively mature, proven, long-life technology that is well-suited for advanced, high-efficiency radioisotope space power systems. Contracts from DOE and NASA are being conducted by Stirling Technology Company (STC) for the purpose of demonstrating the Stirling technology in a configuration and power level that is representative of an eventual space power system. The long-term objective is to develop a power system with an efficiency exceeding 20% that can function with a high degree of reliability for up to 15 years on deep space missions. The current technology demonstration convertors (TDC's) are completing shakedown testing and have recently demonstrated performance levels that are virtually identical to projections made during the preliminary design phase. This paper describes preliminary test results for power output, efficiency, and vibration levels. These early results demonstrate the ability of the free-piston Stirling technology to exceed objectives by approximately quadrupling the efficiency of conventional radioisotope thermoelectric generators (RTG's). .

  14. Vibration reduction of pulse tube cryocooler driven by single piston compressor

    NASA Astrophysics Data System (ADS)

    Chen, Houlei; Xu, Nana; Liang, Jingtao; Yang, Luwei

    2012-12-01

    The development of pulse tube coolers has progressed significantly during the past two decades. A single piston linear compressor is used to in order to reduce the size and mass of a high frequency pulse tube cryocooler. The pulse tube achieved a no-load temperature of 61 K and a cooling power of 1 W@80 K with an operating frequency of 80 Hz and an electrical input power of 50 W. By itself, the single piston compressor generates a large vibration, so a set of leaf springs with an additional mass is used to reduce the vibration. The equation relating the mass, the elasticity coefficient of leaf spring and the working frequency is obtained through an empirical fit of the experimental data. The vibration amplitude is reduced from 55 mm/s to lower than 5 mm/s by using a proper leaf spring. This paper demonstrates that a single piston compressor with vibration reduction provides a good choice for a PTC.

  15. Cermet insert high voltage holdoff improvement for ceramic/metal vacuum devices

    DOEpatents

    Ierna, W.F.

    1986-03-11

    An improved metal-to-ceramic seal is provided wherein the ceramic body of the seal contains an integral region of cermet material in electrical contact with the metallic member, e.g., an electrode, of the seal. The seal is useful in high voltage vacuum devices, e.g., vacuum switches, and increases the high-voltage holdoff capabilities of such devices. A method of fabricating such seals is also provided.

  16. A theoretical analysis of vacuum arc thruster performance

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Sekerak, Mike; Ziemer, John K.; Schein, Jochen; Qi, Niansheng; Binder, Robert; Anders, Andre

    2001-01-01

    In vacuum arc discharges the current is conducted through vapor evaporated from the cathode surface. In these devices very dense, highly ionized plasmas can be created from any metallic or conducting solid used as the cathode. This paper describes theoretical models of performance for several thruster configurations which use vacuum arc plasma sources. This analysis suggests that thrusters using vacuum arc sources can be operated efficiently with a range of propellant options that gives great flexibility in specific impulse. In addition, the efficiency of plasma production in these devices appears to be largely independent of scale because the metal vapor is ionized within a few microns of the cathode electron emission sites, so this approach is well-suited for micropropulsion.

  17. Free piston space Stirling technology program

    NASA Technical Reports Server (NTRS)

    Dochat, G. R.; Dhar, M.

    1989-01-01

    MTI recently completed an initial technology feasibility program for NASA by designing, fabricating and testing a space power demonstrator engine (SPDE). This program, which confirms the potential of free-piston Stirling engines, provided the major impetus to initiate a free-piston Stirling space engine (SSE) technology program. The accomplishments of the SPDE program are reviewed, and an overview of the SSE technology program and technical status to date is provided. It is shown that progress in both programs continues to justify its potential for either nuclear or solar space power missions.

  18. Performance data of the new free-piston shock tunnel at GALCIT

    NASA Technical Reports Server (NTRS)

    Hornung, Hans G.

    1992-01-01

    The new free-piston shock tunnel has been partially calibrated, and a range of operating conditions has been found. A large number of difficulties were encountered during the shake-down period, of which the ablation of various parts was the most severe. Solutions to these problems were found. The general principles of high-enthalpy simulation are outlined, and the parameter space covered by T5 is given. Examples of the operating data show that, with care, excellent repeatability may be obtained. The temporal uniformity of the reservoir pressure is very good, even at high enthalpy, because it is possible to operate at tailored-interface and tuned-piston conditions over the whole enthalpy range. Examples of heat transfer and Pitot-pressure measurements are also presented.

  19. The provision of clearances accuracy in piston - cylinder mating

    NASA Astrophysics Data System (ADS)

    Glukhov, V. I.; Shalay, V. V.

    2017-08-01

    The paper is aimed at increasing the quality of the pumping equipment in oil and gas industry. The main purpose of the study is to stabilize maximum values of productivity and durability of the pumping equipment based on the selective assembly of the cylinder-piston kinematic mating by optimization criterion. It is shown that the minimum clearance in the piston-cylinder mating is formed by maximum material dimensions. It is proved that maximum material dimensions are characterized by their own laws of distribution within the tolerance limits for the diameters of the cylinder internal mirror and the outer cylindrical surface of the piston. At that, their dispersion zones should be divided into size groups with a group tolerance equal to half the tolerance for the minimum clearance. The techniques for measuring the material dimensions - the smallest cylinder diameter and the largest piston diameter according to the envelope condition - are developed for sorting them into size groups. Reliable control of the dimensions precision ensures optimal minimum clearances of the piston-cylinder mating in all the size groups of the pumping equipment, necessary for increasing the equipment productivity and durability during the production, operation and repair processes.

  20. Magnetogasdynamic spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes

    NASA Astrophysics Data System (ADS)

    Nath, G.; Vishwakarma, J. P.

    2016-11-01

    Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.

  1. Debris Albedo from Laser Ablation in Low and High Vacuum: Comparisons to Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, G.; Adams, P. M.; Alaan, D. R.; Panetta, C. J.

    The albedo of orbital debris fragments in space is a critical parameter used in the derivation of their physical sizes from optical measurements. The change in albedo results from scattering due to micron and sub-micron particles on the surface. There are however no known hypervelocity collision ground tests that simulate the high-vacuum conditions on-orbit. While hypervelocity impact experiments at a gun range can offer a realistic representation of the energy of impact and fragmentation, and can aid the understanding of albedo, they are conducted in low-pressure air that is not representative of the very high vacuum of 10-8 Torr or less that exists in the Low Earth Orbit environment. Laboratory simulation using laser ablation with a high power laser, on the same target materials as used in current satellite structures, is appealing because it allows for well-controlled investigations that can be coupled to optical albedo (reflectance) measurements of the resultant debris. This relatively low-cost laboratory approach can complement the significantly more elaborate and expensive field-testing of single-shot hypervelocity impact on representative satellite structures. Debris generated is optically characterized with UV-VIS-NIR reflectance, and particle size distributions can be measured. In-situ spectroscopic diagnostics (nanosecond time frame) provide an identification of atoms and ions in the plume, and plasma temperatures, allowing a correlation of the energetics of the ablated plume with resulting albedo and particle size distributions of ablated debris. Our laboratory experiments offer both a high-vacuum environment, and selection of any gaseous ambient, at any controlled pressure, thus allowing for comparison to the hypervelocity impact experiments in low-pressure air. Initial results from plume analysis, and size distribution and microstructure of debris collected on witness plates show that laser ablations in low-pressure air offer many similarities to the

  2. Gage measures total radiation, including vacuum UV, from ionized high-temperature gases

    NASA Technical Reports Server (NTRS)

    Wood, A. D.

    1969-01-01

    Transient-heat transfer gage measures the total radiation intensity from vacuum ultraviolet and ionized high temperature gases. The gage includes a sensitive piezoelectric crystal that is completely isolated from any ionized flow and vacuum ultraviolet irradiation.

  3. Thermal conductivity of lunar regolith simulant JSC-1A under vacuum

    NASA Astrophysics Data System (ADS)

    Sakatani, Naoya; Ogawa, Kazunori; Arakawa, Masahiko; Tanaka, Satoshi

    2018-07-01

    Many air-less planetary bodies, including the Moon, asteroids, and comets, are covered by regolith. The thermal conductivity of the regolith is an essential parameter controlling the surface temperature variation. A thermal conductivity model applicable to natural soils as well as planetary surface regolith is required to analyze infrared remote sensing data. In this study, we investigated the temperature and compressional stress dependence of the thermal conductivity of the lunar regolith simulant JSC-1A, and the temperature dependence of sieved JSC-1A samples under vacuum conditions. We confirmed that a series of the experimental data for JSC-1A are fitted well by our analytical model of the thermal conductivity (Sakatani et al., 2017). Comparison with the calibration data of the sieved samples with those for original JSC-1A indicates that the thermal conductivity of natural samples with a wide grain size distribution can be modeled as mono-sized grains with a volumetric median size. The calibrated model can be used to estimate the volumetric median grain size from infrared remote sensing data. Our experiments and the calibrated model indicates that uncompressed JSC-1A has similar thermal conductivity to lunar top-surface materials, but the lunar subsurface thermal conductivity cannot be explained only by the effects of the density and self-weighted compressional stress. We infer that the nature of the lunar subsurface regolith grains is much different from JSC-1A and lunar top-surface regolith, and/or the lunar subsurface regolith is over-consolidated and the compressional stress higher than the hydrostatic pressure is stored in the lunar regolith layer.

  4. Apparatus facilitates high-temperature tensile testing in vacuum

    NASA Technical Reports Server (NTRS)

    Sikora, P. F.

    1964-01-01

    An apparutus for heating refractory materials to high temperatures during tensile testing includes a water-cooled stainless steel vacuum chamber. This contains a resistance heater consisting of a slit tube of tantalum or tungsten to enclose the tensile test rod.

  5. Palm Power Free-Piston Stirling Engine Control Electronics

    NASA Astrophysics Data System (ADS)

    Keiter, Douglas E.; Holliday, Ezekiel

    2007-01-01

    A prototype 35We, JP-8 fueled, soldier-wearable power system for the DARPA Palm Power program has been developed and tested by Sunpower. A hermetically-sealed 42We Sunpower Free-Piston Stirling Engine (FPSE) with integral linear alternator is the prime mover for this system. To maximize system efficiency over a broad range of output power, a non-dissipative, highly efficient electronic control system which modulates engine output power by varying piston stroke and converts the AC output voltage of the FPSE into 28Vdc for the Palm Power end user, has been designed and demonstrated as an integral component of the Palm Power system. This paper reviews the current status and progress made in developing the control electronics for the Palm Power system, in addition to describing the operation and demonstrated performance of the engine controller in the context of the current JP-8 fueled Palm Power system.

  6. Cogging force investigation of a free piston permanent magnet linear generator

    NASA Astrophysics Data System (ADS)

    Abdalla, I. I.; Zainal, A. E. Z.; Ramlan, N. A.; Firmansyah; Aziz, A. R. A.; Heikal, M. R.

    2017-10-01

    Better performance and higher efficiency of the vehicles can be achieved by using free piston engine, in which the piston is connected directly to the linear generator and waiving of any mechanical means. The free piston engine has the ability to overcome or reduce many of the challenges, such as the carbon dioxide (CO2) emission and fossil fuel consumption. The cogging force produces undesired vibration and acoustic noise in the generator. However, the cogging force must be minimized as much as possible, in order to have a high performance. This paper studies the effects of ferromagnetic materials on the cogging force of the permanent magnet linear generator (PMLG) to be used in a free piston engine using nonlinear finite-element analysis (FEA) under ANSYS Maxwell. The comparisons have been established for the cogging force of the PMLG under various translator velocities and three different ferromagnetic materials for the stator core, namely, Silicon Steel laminations, Mild Steel and Somaloy. It has been shown that the PMLG with a stator core made of Somaloy has a lower cogging force among them. Furthermore, the induced voltage of the PMLG at different accelerations has been studied. It is found that the PMLG with Mild Steel and Somaloy, respectively give larger induced voltage. Moreover, as the translator speed increase the induced voltage increased.

  7. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    PubMed

    Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

    2008-02-01

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

  8. Cryogenic Insulation System for Soft Vacuum

    NASA Technical Reports Server (NTRS)

    Augustynowicz, S. D.; Fesmire, J. E.

    1999-01-01

    The development of a cryogenic insulation system for operation under soft vacuum is presented in this paper. Conventional insulation materials for cryogenic applications can be divided into three levels of thermal performance, in terms of apparent thermal conductivity [k-value in milliwatt per meter-kelvin (mW/m-K)]. System k-values below 0.1 can be achieved for multilayer insulation operating at a vacuum level below 1 x 10(exp -4) torr. For fiberglass or powder operating below 1 x 10(exp -3) torr, k-values of about 2 are obtained. For foam and other materials at ambient pressure, k-values around 30 are typical. New industry and aerospace applications require a versatile, robust, low-cost thermal insulation with performance in the intermediate range. The target for the new composite insulation system is a k-value below 4.8 mW/m-K (R-30) at a soft vacuum level (from 1 to 10 torr) and boundary temperatures of approximately 77 and 293 kelvin (K). Many combinations of radiation shields, spacers, and composite materials were tested from high vacuum to ambient pressure using cryostat boiloff methods. Significant improvement over conventional systems in the soft vacuum range was demonstrated. The new layered composite insulation system was also shown to provide key benefits for high vacuum applications as well.

  9. Ultra-high vacuum compatible induction-heated rod casting furnace

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Neubauer, A.; Münzer, W.; Regnat, A.; Benka, G.; Meven, M.; Pedersen, B.; Pfleiderer, C.

    2016-06-01

    We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on the choice of the mold, typical rods have a diameter between 6 mm and 10 mm and a length up to 90 mm, suitable for single-crystal growth by means of float-zoning. The setup is all-metal sealed and may be baked out. We find that the resulting ultra-high vacuum represents an important precondition for processing compounds with high vapor pressures under a high-purity argon atmosphere up to 3 bars. Using the rod casting furnace, we succeeded to prepare large high-quality single crystals of two half-Heusler compounds, namely, the itinerant antiferromagnet CuMnSb and the half-metallic ferromagnet NiMnSb.

  10. Ultra-high vacuum compatible induction-heated rod casting furnace.

    PubMed

    Bauer, A; Neubauer, A; Münzer, W; Regnat, A; Benka, G; Meven, M; Pedersen, B; Pfleiderer, C

    2016-06-01

    We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on the choice of the mold, typical rods have a diameter between 6 mm and 10 mm and a length up to 90 mm, suitable for single-crystal growth by means of float-zoning. The setup is all-metal sealed and may be baked out. We find that the resulting ultra-high vacuum represents an important precondition for processing compounds with high vapor pressures under a high-purity argon atmosphere up to 3 bars. Using the rod casting furnace, we succeeded to prepare large high-quality single crystals of two half-Heusler compounds, namely, the itinerant antiferromagnet CuMnSb and the half-metallic ferromagnet NiMnSb.

  11. The research on flow pulsation characteristics of axial piston pump

    NASA Astrophysics Data System (ADS)

    Wang, Bingchao; Wang, Yulin

    2017-01-01

    The flow pulsation is an important factor influencing the axial piston pump performance. In this paper we implement modeling and simulation of the axial piston pump with AMESim software to explore the flow pulsation characteristics under various factors . Theory analysis shows the loading pressure, angular speed, piston numbers and the accumulator impose evident influence on the flow pulsation characteristics. This simulation and analysis can be used for reducing the flow pulsation rate via properly setting the related factors.

  12. Design and analysis of piston by Al-GHS 1300, Al-GHY 1250, Al-Si-C, A6061 and A4032 composite material: A review

    NASA Astrophysics Data System (ADS)

    Misra, Sheelam; Agrawal, Ankush

    2018-05-01

    Over the past decades the piston is designed to transfer force to the crank shaft through a piston rod by the expansion of gases in the cylinder. During working piston has to tolerate the cyclic gas pressure and the inertial forces, due to which the piston experiences fatigue damages such as piston side wear, piston head cracks and so on. Earlier pistons were made up of cast iron or aluminium due to their lightweight and high heat transfer rate. After some experiments it was noted that on heating cast iron expands due to which it covers the clearance level that comes to seize the engine. This paper aims to design a piston using composite material such as Al-GHS 1300, Al-GHY 1250, Al-Si-C, A6061 and A4032 that will differ the material and the characteristics of the traditional engine piston. This paper describes the thermal and mechanical properties of the piston when the study is done by taking five different materials.

  13. Piston-rotaxanes as molecular shock absorbers.

    PubMed

    Sevick, E M; Williams, D R M

    2010-04-20

    We describe the thermomechanical response of a new molecular system that behaves as a shock absorber. The system consists of a rodlike rotaxane connected to a piston and tethered to a surface. The response of this system is dominated by the translational entropy of the rotaxane rings and can be calculated exactly. The force laws are contrasted with those for a rigid rod and a polymer. In some cases, the rotaxanes undergo a sudden transition to a tilted state when compressed. These piston-rotaxanes provide a potential motif for the design of a new class of materials with a novel thermomechanical response.

  14. Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at Glenn Research Center

    NASA Technical Reports Server (NTRS)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center (GRC). Delivery of both the Stirling convertors and the linear alternator test rig is expected by October 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.

  15. Test Method Designed to Evaluate Cylinder Liner-Piston Ring Coatings for Advanced Heat Engines

    NASA Technical Reports Server (NTRS)

    Radil, Kevin C.

    1997-01-01

    Research on advanced heat engine concepts, such as the low-heat-rejection engine, have shown the potential for increased thermal efficiency, reduced emissions, lighter weight, simpler design, and longer life in comparison to current diesel engine designs. A major obstacle in the development of a functional advanced heat engine is overcoming the problems caused by the high combustion temperatures at the piston ring/cylinder liner interface, specifically at top ring reversal (TRR). Therefore, advanced cylinder liner and piston ring materials are needed that can survive under these extreme conditions. To address this need, researchers at the NASA Lewis Research Center have designed a tribological test method to help evaluate candidate piston ring and cylinder liner materials for advanced diesel engines.

  16. Piston manometer as an absolute standard for vacuum-gage calibration in the range 2 to 500 millitorr

    NASA Technical Reports Server (NTRS)

    Warshawsky, I.

    1972-01-01

    A thin disk is suspended, with very small annular clearance, in a cylindrical opening in the base plate of a calibration chamber. A continuous flow of calibration gas passes through the chamber and annular opening to a downstream high vacuum pump. The ratio of pressures on the two faces of the disk is very large, so that the upstream pressure is substantially equal to net force on the disk divided by disk area. This force is measured with a dynamometer that is calibrated in place with dead weights. A probable error of + or - (0.2 millitorr plus 0.2 percent) is attainable when downstream pressure is known to 10 percent.

  17. Pump having pistons and valves made of electroactive actuators

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph (Inventor)

    1997-01-01

    The present invention provides a pump for inducing a displacement of a fluid from a first medium to a second medium, including a conduit coupled to the first and second media, a transducing material piston defining a pump chamber in the conduit and being transversely displaceable for increasing a volume of the chamber to extract the fluid from the first medium to the chamber and for decreasing the chamber volume to force the fluid from the chamber to the second medium, a first transducing material valve mounted in the conduit between the piston and the first medium and being transversely displaceable from a closed position to an open position to admit the fluid to the chamber, and control means for changing a first field applied to the piston to displace the piston for changing the chamber volume and for changing a second field applied to the first valve to change the position of the first valve.

  18. Optimization of Multilayer Laminated Film and Absorbent of Vacuum Insulation Panel for Use at High Temperature

    NASA Astrophysics Data System (ADS)

    Araki, Kuninari; Echigoya, Wataru; Tsuruga, Toshimitsu; Kamoto, Daigorou; Matsuoka, Shin-Ichi

    For the energy saving regulation and larger capacity, Vacuum Insulation Panel (VIP) has been used in refrigerators with urethane foam in recent years. VIP for low temperature is constructed by laminated plastic film, using heat welding of each neighboring part for keeping vacuum, so that the performance decrement is very large under high temperature. But recently high efficiency insulation material is desired for high temperature water holding devices (automatic vending machine, heat pump water heater, electric hot-water pot water, etc.), and we especially focused on cost and ability of the laminated plastic film and absorbent for high temperature VIP. We measured the heatproof temperature of plastic films and checked the amount of water vapor and out coming gas on temperature-programmed adsorption in absorbent. These results suggest the suitable laminated film and absorbent system for VIP use at high temperature, and the long-term reliability was evaluated by measuring thermal conductivity of high temperature. As a result it was found that high-retort pouch of CPP (cast polypropylene film) and adding of aluminum coating are the most suitable materials for use in the welded layers of high-temperature VIPs (105°C).

  19. Mechanical property determination of high conductivity metals and alloys

    NASA Technical Reports Server (NTRS)

    Harrod, D. L.; Vandergrift, E.; France, L.

    1973-01-01

    Pertinent mechanical properties of three high conductivity metals and alloys; namely, vacuum hot pressed grade S-200E beryllium, OFHC copper and beryllium-copper alloy no. 10 were determined. These materials were selected based on their possible use in rocket thrust chamber and nozzle hardware. They were procured in a form and condition similar to that which might be ordered for actual hardware fabrication. The mechanical properties measured include (1) tension and compression stress strain curves at constant strain rate (2) tensile and compressive creep, (3) tensile and compressive stress-relaxation behavior and (4) elastic properties. Tests were conducted over the temperature range of from 75 F to 1600 F. The resulting data is presented in both graphical and tabular form.

  20. A radiation hard vacuum switch

    DOEpatents

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  1. P-REx: The Piston Reconstruction Experiment for infrared interferometry

    NASA Astrophysics Data System (ADS)

    Widmann, Felix; Pott, Jörg-Uwe; Velasco, Sergio

    2018-03-01

    For sensitive infrared interferometry, it is crucial to control the differential piston evolution between the used telescopes. This is classically done by the use of a fringe tracker. In this work, we develop a new method to reconstruct the temporal piston variation from the atmosphere, by using real-time data from adaptive optics (AO) wavefront sensing: the Piston Reconstruction Experiment (P-REx). In order to understand the principle performance of the system in a realistic multilayer atmosphere, it is first extensively tested in simulations. The gained insights are then used to apply P-REx to real data, in order to demonstrate the benefit of using P-REx as an auxiliary system in a real interferometer. All tests show positive results, which encourages further research and eventually a real implementation. Especially, the tests on on-sky data showed that the atmosphere is, under decent observing conditions, sufficiently well structured and stable, in order to apply P-REx. It was possible to conveniently reconstruct the piston evolution in two-thirds of the data sets from good observing conditions (r0 ˜ 30 cm). The main conclusion is that applying the piston reconstruction in a real system would reduce the piston variation from around 10 μm down to 1-2 μm over time-scales of up to two seconds. This suggests an application for mid-infrared interferometry, for example for MATISSE at the very large telescope interferometer or the large binocular telescope interferometer. P-REx therefore provides the possibility to improve interferometric measurements without the need for more complex AO systems than already in regular use at 8-m-class telescopes.

  2. Radial-piston pump for drive of test machines

    NASA Astrophysics Data System (ADS)

    Nizhegorodov, A. I.; Gavrilin, A. N.; Moyzes, B. B.; Cherkasov, A. I.; Zharkevich, O. M.; Zhetessova, G. S.; Savelyeva, N. A.

    2018-01-01

    The article reviews the development of radial-piston pump with phase control and alternating-flow mode for seismic-testing platforms and other test machines. The prospects for use of the developed device are proved. It is noted that the method of frequency modulation with the detection of the natural frequencies is easily realized by using the radial-piston pump. The prospects of further research are given proof.

  3. Apollo Experiment Report: Lunar-Sample Processing in the Lunar Receiving Laboratory High-Vacuum Complex

    NASA Technical Reports Server (NTRS)

    White, D. R.

    1976-01-01

    A high-vacuum complex composed of an atmospheric decontamination system, sample-processing chambers, storage chambers, and a transfer system was built to process and examine lunar material while maintaining quarantine status. Problems identified, equipment modifications, and procedure changes made for Apollo 11 and 12 sample processing are presented. The sample processing experiences indicate that only a few operating personnel are required to process the sample efficiently, safely, and rapidly in the high-vacuum complex. The high-vacuum complex was designed to handle the many contingencies, both quarantine and scientific, associated with handling an unknown entity such as the lunar sample. Lunar sample handling necessitated a complex system that could not respond rapidly to changing scientific requirements as the characteristics of the lunar sample were better defined. Although the complex successfully handled the processing of Apollo 11 and 12 lunar samples, the scientific requirement for vacuum samples was deleted after the Apollo 12 mission just as the vacuum system was reaching its full potential.

  4. Mercury Conditions for the MESSENGER Mission Simulated in High- Solar-Radiation Vacuum Tests

    NASA Technical Reports Server (NTRS)

    Wong, Wayne A.

    2003-01-01

    The MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) spacecraft, planned for launch in March 2004, will perform two flybys of Mercury before entering a year-long orbit of the planet in September 2009. The mission will provide opportunities for detailed characterization of the surface, interior, atmosphere, and magnetosphere of the closest planet to the Sun. The NASA Glenn Research Center and the MESSENGER spacecraft integrator, the Johns Hopkins University Applied Physics Laboratory, have partnered under a Space Act Agreement to characterize a variety of critical components and materials under simulated conditions expected near Mercury. Glenn's Vacuum Facility 6, which is equipped with a solar simulator, can simulate the vacuum and high solar radiation anticipated in Mercury orbit. The MESSENGER test hardware includes a variety of materials and components that are being characterized during the Tank 6 vacuum tests, where the hardware will be exposed to up to 11 suns insolation, simulating conditions expected in Mercury orbit. In 2002, ten solar vacuum tests were conducted, including beginning of life, end of life, backside exposure, and solar panel thermal shock cycling tests. Components tested include candidate solar array panels, sensors, thermal shielding materials, and communication devices. As an example, for the solar panel thermal shock cycling test, two candidate solar array panels were suspended on a lift mechanism that lowered the panels into a liquid-nitrogen-cooled box. After reaching -140 C, the panels were then lifted out of the box and exposed to the equivalent of 6 suns (8.1 kilowatts per square meters). After five cold soak/heating cycles were completed successfully, there was no apparent degradation in panel performance. An anticipated 100-hr thermal shield life test is planned for autumn, followed by solar panel flight qualification tests in winter. Glenn's ongoing support to the MESSENGER program has been instrumental in

  5. Acoustic radiation efficiency of a periodically corrugated rigid piston

    NASA Astrophysics Data System (ADS)

    Estrada, Héctor; Uris, Antonio; Meseguer, Francisco

    2012-09-01

    The radiation of sound by a periodically corrugated rigid piston is explored using theoretical and numerical approaches and compared with the radiation of flat rigid piston. The depth and the period of the corrugation are considered to be comparable with the wavelength in the surrounding fluid. Radiation enhancement is predicted due to cavity resonances and coherent diffraction. In addition, broad regions of low radiation efficiency are observed. Both effects could have an impact in acoustic transducers technology, either to increase the piston radiated power or to create a source of evanescent acoustic waves. The possibilities offered by this strategy in the nonlinear acoustic regime are also briefly discussed.

  6. Thermal observations of gas pistoning at Kilauea Volcano

    USGS Publications Warehouse

    Johnson, J.B.; Harris, A.J.L.; Hoblitt, R.P.

    2005-01-01

    Data acquired by three continuously recording thermal infrared thermometers situated on the north rim of Pu'u'O' o Crater at Kilauea Volcano during 2002 revealed episodes of periodic thermal pulses originating from a degassing vent on the crater floor. These thermal pulses are interpreted as gas release (jetting events) associated with gas pistoning, a mechanism observed previously at both Mauna Ulu and Pu'u'O' o. During a 35-day-long period spanning June and July 2002, gas pistoning was frequently the dominant mode of gas release, with as many as several hundred pulses occurring in uninterrupted series. On other days, degassing alternated between periods of quasi-continuous gas jetting and intervals of gas pistoning that contained a few to a few dozen pulses. Characteristic time intervals between pistoning events ranged from 2 up to 7 min. We identify three types of pistoning. Type 1 involves emission of lava, followed by gas jetting and drain back; type 2 is the same but the elevated position of the vent does not allow postjet drain back; and type 3 involves gas jetting only with no precursory lava flow. To explain gas pistoning, we apply a model whereby a stagnant cap of degassed magma develops in the conduit below the vent. Gas bubbles rise through the magma column and collect under the cap. The collective buoyancy of these bubbles pushes the cap upward. When the cap reaches the surface, it erupts from the vent as a lava flow. Unloading of the conduit magma in this way results in an abrupt pressure drop (i.e., the overburden felt by the bubbles is reduced), causing explosive gas expansion in the form of gas jetting from the vent. This terminates the event and lava drains back into the conduit to start the cycle anew. In the case where there is no surface lava emission or drain back, the cap instead pushes into and spreads out within a subsurface cavity. Again, this unloads the conduit magma and terminates in explosive gas release. Once gas is expelled, lava in

  7. ULTRA HIGH VACUUM VALVE

    DOEpatents

    Fry, W.A.

    1962-05-29

    A valve for high vacuum applications such as the CStellarator where chamber pressures as low as 2 x 10/sup -10/ mm Hg are necessary is designed with a line-of-sight path through the valve for visual inspection of the contents of reactants in such chambers. The valve comprises a turnable resilient metal ball having an aperture therethrough, means for selectively turning the ball to rotate the axis of its line-of-sight path, and soft, deformable opposing orifices that are movable relatively toward said ball to seal with opposite ball surfaces upon said movement of said axis of said line-of-sight path. The valve also includes a bellows seal connected between said orifices and internal actuating means that eliminates the requirement for gasketed turnable valve closing stems. (AEC)

  8. Unsteady response of flow system around balance piston in a rocket pump

    NASA Astrophysics Data System (ADS)

    Kawasaki, S.; Shimura, T.; Uchiumi, M.; Hayashi, M.; Matsui, J.

    2013-03-01

    In the rocket engine turbopump, a self-balancing type of axial thrust balancing system using a balance piston is often applied. In this study, the balancing system in liquid-hydrogen (LH2) rocket pump was modeled combining the mechanical structure and the flow system, and the unsteady response of the balance piston was investigated. The axial vibration characteristics of the balance piston with a large amplitude were determined, sweeping the frequency of the pressure fluctuation on the inlet of the balance piston. This vibration was significantly affected by the compressibility of LH2.

  9. A CWT-based methodology for piston slap experimental characterization

    NASA Astrophysics Data System (ADS)

    Buzzoni, M.; Mucchi, E.; Dalpiaz, G.

    2017-03-01

    Noise and vibration control in mechanical systems has become ever more significant for automotive industry where the comfort of the passenger compartment represents a challenging issue for car manufacturers. The reduction of piston slap noise is pivotal for a good design of IC engines. In this scenario, a methodology has been developed for the vibro-acoustic assessment of IC diesel engines by means of design changes in piston to cylinder bore clearance. Vibration signals have been analysed by means of advanced signal processing techniques taking advantage of cyclostationarity theory. The procedure departs from the analysis of the Continuous Wavelet Transform (CWT) in order to identify a representative frequency band of piston slap phenomenon. Such a frequency band has been exploited as the input data in the further signal processing analysis that involves the envelope analysis of the second order cyclostationary component of the signal. The second order harmonic component has been used as the benchmark parameter of piston slap noise. An experimental procedure of vibrational benchmarking is proposed and verified at different operational conditions in real IC engines actually equipped on cars. This study clearly underlines the crucial role of the transducer positioning when differences among real piston-to-cylinder clearances are considered. In particular, the proposed methodology is effective for the sensors placed on the outer cylinder wall in all the tested conditions.

  10. Turbocharger with sliding piston, and having vanes and leakage dams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roberts, Quentin; Alnega, Ahmed

    2011-12-06

    A turbocharger having a sliding piston for regulating exhaust gas flow into the turbine wheel includes a set of first vanes mounted on a fixed first wall of the turbine nozzle and projecting axially toward an opposite second wall of the nozzle, and/or a set of second vanes mounted on the end of the piston and projecting in an opposite axial direction toward the first wall of the nozzle. For the/each set of vanes, there are leakage dams formed on the wall that is adjacent the vane tips when the piston is closed. The leakage dams are closely adjacent themore » vane tips and discourage exhaust gas from leaking in a generally radial direction past the vane tips as the piston just begins to open from its fully closed position.« less

  11. Structural design of Stirling engine with free pistons

    NASA Astrophysics Data System (ADS)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  12. Ultra high vacuum seal arrangement

    DOEpatents

    Flaherty, Robert

    1981-01-01

    Arrangement for demountably sealing two concentric metallic tubes in an ultra high vacuum system which facilitates remote actuation. A tubular seal includes integral spaced lips which circumferentially engage the metallic tubes. The lips plastically deform the metallic tubes by mechanical forces resulting from a martensite to austenite transformation of the tubular seal upon application of a predetermined temperature. The sealing force is released upon application of another temperature which causes a transformation from the stronger austenite to the weaker martensite. Use of a dual acting sealing ring and driving ring circumferentially contacting the sealing ring is particularly applicable to sealing larger diameter concentric metallic members.

  13. Natural vacuum electronics

    NASA Technical Reports Server (NTRS)

    Leggett, Nickolaus

    1990-01-01

    The ambient natural vacuum of space is proposed as a basis for electron valves. Each valve is an electron controlling structure similiar to a vacuum tube that is operated without a vacuum sustaining envelope. The natural vacuum electron valves discussed offer a viable substitute for solid state devices. The natural vacuum valve is highly resistant to ionizing radiation, system generated electromagnetic pulse, current transients, and direct exposure to space conditions.

  14. Vacuum mechatronics

    NASA Technical Reports Server (NTRS)

    Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

    1989-01-01

    The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

  15. High vacuum measurements and calibrations, molecular flow fluid transient effects

    DOE PAGES

    Leishear, Robert A.; Gavalas, Nickolas A.

    2015-04-29

    High vacuum pressure measurements and calibrations below 1 × 10 -8 Torr are problematic. Specifically, measurement accuracies change drastically for vacuum gauges when pressures are suddenly lowered in vacuum systems. How can gauges perform like this? A brief system description is first required to answer this question. Calibrations were performed using a vacuum calibration chamber with attached vacuum gauges. To control chamber pressures, vacuum pumps decreased the chamber pressure while nitrogen tanks increased the chamber pressure. By balancing these opposing pressures, equilibrium in the chamber was maintained at selected set point pressures to perform calibrations. When pressures were suddenly decreasedmore » during set point adjustments, a sudden rush of gas from the chamber also caused a surge of gas from the gauges to decrease the pressures in those gauges. Gauge pressures did not return to equilibrium as fast as chamber pressures due to the sparse distribution of gas molecules in the system. This disparity in the rate of pressure changes caused the pressures in different gauges to be different than expected. This discovery was experimentally proven to show that different gauge designs return to equilibrium at different rates, and that gauge accuracies vary for different gauge designs due to fluid transients in molecular flow.« less

  16. Computer controlled titration with piston burette or peristaltic pump - a comparison.

    PubMed

    Hoffmann, W

    1996-09-01

    The advantages and problems of the use of piston burettes and peristaltic pumps for dosage of titrant solutions in automatic titrations are shown. For comparison, only the dosing devices were exchanged and all other components and conditions remained unchanged. The results of continuous acid base titration show good agreement and comparable reproducibility. Potentiometric sensors (glass electrodes) with different equilibration behaviour influence the results. The capability of such electrodes was tested. Conductometric measurements allow a much faster detection because there is no equilibration of electrodes. Piston burettes should be used for titration with very high precision, titration with organic solvents and slow titrations. Peristaltic pumps seem to be more suitable for continuous titrations and long time operation without service.

  17. An Underappreciated Radiation Hazard from High Voltage Electrodes in Vacuum.

    PubMed

    West, Adam D; Lasner, Zack; DeMille, David; West, Elizabeth P; Panda, Cristian D; Doyle, John M; Gabrielse, Gerald; Kryskow, Adam; Mitchell, Corinne

    2017-01-01

    The use of high voltage (HV) electrodes in vacuum is commonplace in physics laboratories. In such systems, it has long been known that electron emission from an HV cathode can lead to bremsstrahlung x rays; indeed, this is the basic principle behind the operation of standard x-ray sources. However, in laboratory setups where x-ray production is not the goal and no electron source is deliberately introduced, field-emitted electrons accelerated by HV can produce x rays as an unintended hazardous byproduct. Both the level of hazard and the safe operating regimes for HV vacuum electrode systems are not widely appreciated, at least in university laboratories. A reinforced awareness of the radiation hazards associated with vacuum HV setups would be beneficial. The authors present a case study of a HV vacuum electrode device operated in a university atomic physics laboratory. They describe the characterization of the observed x-ray radiation, its relation to the observed leakage current in the device, the steps taken to contain and mitigate the radiation hazard, and suggested safety guidelines.

  18. Gas-lubricated seal for sealing between a piston and a cylinder wall

    DOEpatents

    Hoult, David P.

    1985-01-01

    A piston-cylinder seal uses gas for a lubricant and has a runner supported on a gapless structure and placed in the space between the piston and the cylinder wall. The runner is deformed elastically under the influence of the operating pressures to follow and compensate for variations in the piston-cylinder fit and maintain a seal.

  19. Gas-lubricated seal for sealing between a piston and a cylinder wall

    DOEpatents

    Hoult, D.P.

    1985-09-10

    A piston-cylinder seal uses gas for a lubricant and has a runner supported on a gapless structure and placed in the space between the piston and the cylinder wall. The runner is deformed elastically under the influence of the operating pressures to follow and compensate for variations in the piston-cylinder fit and maintain a seal. 4 figs.

  20. Free-piston Stirling engine/linear alternator 1000-hour endurance test

    NASA Technical Reports Server (NTRS)

    Rauch, J.; Dochat, G.

    1985-01-01

    The Free Piston Stirling Engine (FPSE) has the potential to be a long lived, highly reliable, power conversion device attractive for many product applications such as space, residential or remote site power. The purpose of endurance testing the FPSE was to demonstrate its potential for long life. The endurance program was directed at obtaining 1000 operational hours under various test conditions: low power, full stroke, duty cycle and stop/start. Critical performance parameters were measured to note any change and/or trend. Inspections were conducted to measure and compare critical seal/bearing clearances. The engine performed well throughout the program, completing more than 1100 hours. Hardware inspection, including the critical clearances, showed no significant change in hardware or clearance dimensions. The performance parameters did not exhibit any increasing or decreasing trends. The test program confirms the potential for long life FPSE applications.

  1. Symmetry of the Adiabatic Condition in the Piston Problem

    ERIC Educational Resources Information Center

    Anacleto, Joaquim; Ferreira, J. M.

    2011-01-01

    This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…

  2. Processing of extraterrestrial materials by high temperature vacuum vaporization

    NASA Technical Reports Server (NTRS)

    Grimley, R. T.; Lipschutz, M. E.

    1983-01-01

    It is noted that problems associated with the extraction and concentration of elements and commpounds important for the construction and operation of space habitats have received little attention. High temperature vacuum vaporization is considered a promising approach; this is a technique for which the space environment offers advantages in the form of low ambient pressures and temperatures and the possibility of sustained high temperatures via solar thermal energy. To establish and refine this new technology, experimental determinations must be made of the material release profiles as a function of temperature, of the release kinetics and chemical forms of material being transported, and of the various means of altering release kinetics. Trace element data determined by neutron activation analysis of meteorites heated to 1400 C in vacuum is summarized. The principal tool, high temperature spectrometry, is used to examine the vaporization thermodynamics and kinetics of major and minor elements from complex multicomponent extraterrestrial materials.

  3. Ethanol production from food waste at high solids content with vacuum recovery technology.

    PubMed

    Huang, Haibo; Qureshi, Nasib; Chen, Ming-Hsu; Liu, Wei; Singh, Vijay

    2015-03-18

    Ethanol production from food wastes does not only solve environmental issues but also provides renewable biofuels. This study investigated the feasibility of producing ethanol from food wastes at high solids content (35%, w/w). A vacuum recovery system was developed and applied to remove ethanol from fermentation broth to reduce yeast ethanol inhibition. A high concentration of ethanol (144 g/L) was produced by the conventional fermentation of food waste without a vacuum recovery system. When the vacuum recovery is applied to the fermentation process, the ethanol concentration in the fermentation broth was controlled below 100 g/L, thus reducing yeast ethanol inhibition. At the end of the conventional fermentation, the residual glucose in the fermentation broth was 5.7 g/L, indicating incomplete utilization of glucose, while the vacuum fermentation allowed for complete utilization of glucose. The ethanol yield for the vacuum fermentation was found to be 358 g/kg of food waste (dry basis), higher than that for the conventional fermentation at 327 g/kg of food waste (dry basis).

  4. Open Loop Heat Pipe Radiator Having a Free-Piston for Wiping Condensed Working Fluid

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M. (Inventor)

    2015-01-01

    An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

  5. Advances in high gradient normal conducting accelerator structures

    DOE PAGES

    Simakov, Evgenya Ivanovna; Dolgashev, Valery A.; Tantawi, Sami G.

    2018-03-09

    Here, this paper reviews the current state-of-the-art in understanding the phenomena of ultra-high vacuum radio-frequency (rf) breakdown in accelerating structures and the efforts to improve stable operation of the structures at accelerating gradients above 100 MV/m. Numerous studies have been conducted recently with the goal of understanding the dependence of the achievable accelerating gradients and breakdown rates on the frequency of operations, the geometry of the structure, material and method of fabrication, and operational temperature. Tests have been conducted with single standing wave accelerator cells as well as with the multi-cell traveling wave structures. Notable theoretical effort was directed atmore » understanding the physical mechanisms of the rf breakdown and its statistical behavior. Finally, the achievements presented in this paper are the result of the large continuous self-sustaining collaboration of multiple research institutions in the United States and worldwide.« less

  6. Advances in high gradient normal conducting accelerator structures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Simakov, Evgenya Ivanovna; Dolgashev, Valery A.; Tantawi, Sami G.

    Here, this paper reviews the current state-of-the-art in understanding the phenomena of ultra-high vacuum radio-frequency (rf) breakdown in accelerating structures and the efforts to improve stable operation of the structures at accelerating gradients above 100 MV/m. Numerous studies have been conducted recently with the goal of understanding the dependence of the achievable accelerating gradients and breakdown rates on the frequency of operations, the geometry of the structure, material and method of fabrication, and operational temperature. Tests have been conducted with single standing wave accelerator cells as well as with the multi-cell traveling wave structures. Notable theoretical effort was directed atmore » understanding the physical mechanisms of the rf breakdown and its statistical behavior. Finally, the achievements presented in this paper are the result of the large continuous self-sustaining collaboration of multiple research institutions in the United States and worldwide.« less

  7. Flow Visualization Proposed for Vacuum Cleaner Nozzle Designs

    NASA Technical Reports Server (NTRS)

    2005-01-01

    In 1995, the NASA Lewis Research Center and the Kirby Company (a major vacuum cleaner company) began negotiations for a Space Act Agreement to conduct research, technology development, and testing involving the flow behavior of airborne particulate flow behavior. Through these research efforts, we hope to identify ways to improve suction, flow rate, and surface agitation characteristics of nozzles used in vacuum cleaner nozzles. We plan to apply an advanced visualization technology, known as Stereoscopic Imaging Velocimetry (SIV), to a Kirby G-4 vacuum cleaner. Resultant data will be analyzed with a high-speed digital motion analysis system. We also plan to evaluate alternative vacuum cleaner nozzle designs. The overall goal of this project is to quantify both velocity fields and particle trajectories throughout the vacuum cleaner nozzle to optimize its "cleanability"--its ability to disturb and remove embedded dirt and other particulates from carpeting or hard surfaces. Reference

  8. Free-Standing Conducting Polymer Films for High-Performance Energy Devices.

    PubMed

    Li, Zaifang; Ma, Guoqiang; Ge, Ru; Qin, Fei; Dong, Xinyun; Meng, Wei; Liu, Tiefeng; Tong, Jinhui; Jiang, Fangyuan; Zhou, Yifeng; Li, Ke; Min, Xue; Huo, Kaifu; Zhou, Yinhua

    2016-01-18

    Thick, uniform, easily processed, highly conductive polymer films are desirable as electrodes for solar cells as well as polymer capacitors. Here, a novel scalable strategy is developed to prepare highly conductive thick poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (HCT-PEDOT:PSS) films with layered structure that display a conductivity of 1400 S cm(-1) and a low sheet resistance of 0.59 ohm sq(-1). Organic solar cells with laminated HCT-PEDOT:PSS exhibit a performance comparable to the reference devices with vacuum-deposited Ag top electrodes. More importantly, the HCT-PEDOT:PSS film delivers a specific capacitance of 120 F g(-1) at a current density of 0.4 A g(-1). All-solid-state flexible symmetric supercapacitors with the HCT-PEDOT:PSS films display a high volumetric energy density of 6.80 mWh cm(-3) at a power density of 100 mW cm(-3) and 3.15 mWh cm(-3) at a very high power density of 16160 mW cm(-3) that outperforms previous reported solid-state supercapacitors based on PEDOT materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Piston-assisted proton pumping in Complex I of mitochondria membranes

    NASA Astrophysics Data System (ADS)

    Mourokh, Lev; Filonenko, Ilan

    2014-03-01

    Proton-pumping mechanism of Complex I remains mysterious because its electron and proton paths are well separated and the direct Coulomb interaction seems to be negligible. The structure of this enzyme was resolved very recently and its functionality was connected the shift of the helix HL. We model the helix as a piston oscillating between the protons and electrons. We assume that positive charges are accumulated near the edges of the helix. In the oxidized state, the piston is attracted to electrons, so its distance to the proton sites increases, the energy of these sites decreases and the sites can be populated. When electrons proceed to the drain, elastic forces return the piston to the original position and the energies of populated proton sites increase, so the protons can be transferred to the positive site of the membrane. In this work, we explore a simplified model when the interaction of the piston with electrons is replaced by a periodic force. We derive quantum Heisenberg equations for the proton operators and solve them jointly with the Langevin equation for the piston position. We show that the proton pumping is possible in such structure with parameters closely resembling the real system. We also address the feasibility of using such mechanism in nanoelectronics.

  10. Vacuum chamber for containing particle beams

    DOEpatents

    Harvey, A.

    1985-11-26

    A vacuum chamber for containing a charged particle beam in a rapidly changing magnetic environment comprises a ceramic pipe with conducting strips oriented along the longitudinal axis of the pipe and with circumferential conducting bands oriented perpendicular to the longitudinal axis but joined with a single longitudinal electrical connection. When both strips and bands are on the outside of the ceramic pipe, insulated from each other, a high-resistance conductive layer such as nickel can be coated on the inside of the pipe.

  11. Oxygen fugacity control in piston-cylinder experiments: a re-evaluation

    NASA Astrophysics Data System (ADS)

    Jakobsson, Sigurdur; Blundy, Jon; Moore, Gordon

    2014-06-01

    Jakobsson (Contrib Miner Petrol 164(3):397-407, 2012) investigated a double capsule assembly for use in piston-cylinder experiments that would allow hydrous, high-temperature, and high-pressure experiments to be conducted under controlled oxygen fugacity conditions. Using a platinum outer capsule containing a metal oxide oxygen buffer (Ni-NiO or Co-CoO) and H2O, with an inner gold-palladium capsule containing hydrous melt, this study was able to compare the oxygen fugacity imposed by the outer capsule oxygen buffer with an oxygen fugacity estimated by the AuPdFe ternary system calibrated by Barr and Grove (Contrib Miner Petrol 160(5):631-643, 2010). H2O loss or gain, as well as iron loss to the capsule walls and carbon contamination, is often observed in piston-cylinder experiments and often go unexplained. Only a few have attempted to actually quantify various aspects of these changes (Brooker et al. in Am Miner 83(9-10):985-994, 1998; Truckenbrodt and Johannes in Am Miner 84:1333-1335, 1999). It was one of the goals of Jakobsson (Contrib Miner Petrol 164(3):397-407, 2012) to address these issues by using and testing the AuPdFe solution model of Barr and Grove (Contrib Miner Petrol 160(5):631-643, 2010), as well as to constrain the oxygen fugacity of the inner capsule. The oxygen fugacities of the analyzed melts were assumed to be equal to those of the solid Ni-NiO and Co-CoO buffers, which is incorrect since the melts are all undersaturated in H2O and the oxygen fugacities should therefore be lower than that of the buffer by 2 log.

  12. Dry piston coal feeder

    DOEpatents

    Hathaway, Thomas J.; Bell, Jr., Harold S.

    1979-01-01

    This invention provides a solids feeder for feeding dry coal to a pressurized gasifier at elevated temperatures substantially without losing gas from the gasifier by providing a lock having a double-acting piston that feeds the coals into the gasifier, traps the gas from escaping, and expels the trapped gas back into the gasifier.

  13. High energy density capacitors for vacuum operation with a pulsed plasma load

    NASA Technical Reports Server (NTRS)

    Guman, W. J.

    1976-01-01

    Results of the effort of designing, fabricating, and testing of a 40 joules/lb (88.2 joules/Kg) high voltage energy storage capacitor suitable for operating a pulsed plasma thruster in a vacuum environment for millions of pulses are presented. Using vacuum brazing and heli-arc welding techniques followed by vacuum and high pressure helium leak tests it was possible to produce a hermetically sealed relatively light weight enclosure for the dielectric system. An energy density of 40 joules/lb was realized with a KF-polyvinylidene fluoride dielectric system. One capacitor was D.C. life tested at 4 KV (107.8 joules/lb) for 2,000 hours before it failed. Another exceeded 2,670 hours without failure at 38.3 joules/lb. Pulse life testing in a vacuum exceeded 300,000 discharges with testing still in progress. The D.C. life test data shows a small decrease in capacitance and an increase in dissipation factor with time. Heat transfer from the load to the capacitor must also be considered besides the self-heat generated by the capacitor.

  14. Air-Bearing-Piston Suspension System

    NASA Technical Reports Server (NTRS)

    Mullen, Donald; Bishop, Stephen J.

    1992-01-01

    Suspension system based on air-bearing piston holds up steel ball against gravitation while allowing ball to translate vertically and rotate freely. System designed to simulate effect of microgravity on ball. Applicable to suppression of vibrations and delicate machining processes.

  15. Ultrasonic Spray Drying vs High Vacuum and Microwaves Technology for Blueberries

    NASA Astrophysics Data System (ADS)

    Candia-Muñoz, N.; Ramirez-Bunster, M.; Vargas-Hernández, Y.; Gaete-Garretón, L.

    Interest in high quality foods: good taste and a high content of nutrients with healthy beneficial effects are increasing. Fruits have good properties but, they are lost because the oxidation process, additionally, for different reasons a 40% of harvested fruit are lost. To conserve the fruit properties an ultrasonic assisted spray dryer was developed and tested, comparing its results with microwave-vacuum drying technology. Results did shown taste, color, smell, particle shape and size distribution better than the conventional one. The antioxidants conservation were quite good except in the anthocyanins, in which the microwave and vacuum technology shown best results.

  16. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leick, Michael T.; Moses, Ronald W.

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to chargemore » the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.« less

  17. Optimum step design for centering of pistons moving in an incompressible fluid

    NASA Technical Reports Server (NTRS)

    Etsion, I.; Hamrock, B. J.

    1976-01-01

    Hydrodynamic effects are analyzed for a stepped piston moving within a tight clearance tube filled with an incompressible fluid. Hydrostatic effects are analyzed and a complete solution is obtained and an optimum step design for centering of the piston is suggested. The axial speed resulting from an axial driving force is calculated, and some experimental results for pistons falling in a water-filled tube are presented.

  18. Vacuum Bloch-Siegert shift in Landau polaritons with ultra-high cooperativity

    NASA Astrophysics Data System (ADS)

    Li, Xinwei; Bamba, Motoaki; Zhang, Qi; Fallahi, Saeed; Gardner, Geoff C.; Gao, Weilu; Lou, Minhan; Yoshioka, Katsumasa; Manfra, Michael J.; Kono, Junichiro

    2018-06-01

    A two-level system resonantly interacting with an a.c. magnetic or electric field constitutes the physical basis of diverse phenomena and technologies. However, Schrödinger's equation for this seemingly simple system can be solved exactly only under the rotating-wave approximation, which neglects the counter-rotating field component. When the a.c. field is sufficiently strong, this approximation fails, leading to a resonance-frequency shift known as the Bloch-Siegert shift. Here, we report the vacuum Bloch-Siegert shift, which is induced by the ultra-strong coupling of matter with the counter-rotating component of the vacuum fluctuation field in a cavity. Specifically, an ultra-high-mobility two-dimensional electron gas inside a high-Q terahertz cavity in a quantizing magnetic field revealed ultra-narrow Landau polaritons, which exhibited a vacuum Bloch-Siegert shift up to 40 GHz. This shift, clearly distinguishable from the photon-field self-interaction effect, represents a unique manifestation of a strong-field phenomenon without a strong field.

  19. High-energy vacuum birefringence and dichroism in an ultrastrong laser field

    NASA Astrophysics Data System (ADS)

    Meuren, Sebastian; Bragin, Sergey; Keitel, Christoph H.; di Piazza, Antonino

    2017-10-01

    The interaction between real photons in vacuum is a long-standing prediction of quantum electrodynamics, which has never been observed experimentally. Upcoming 10 PW laser systems like the Extreme Light Infrastructure (ELI) will provide laser pulses with unprecedented intensities. If combined with highly energetic gamma photons - obtainable via Compton backscattering from laser-wakefield accelerated electron beams - the QED critical field becomes accessible. In we have derived how a generally polarized probe photon beam is influenced by both vacuum birefringence and dichroism in a strong linearly polarized plane-wave laser field. We put forward an experimental scheme to measure these effects in the nontrivial high-energy regime, where the QED critical field is reached and the Euler-Heisenberg approximation, valid for low-frequency electromagnetic fields, breaks down. Our results suggest the feasibility of verifying/rejecting the QED prediction for vacuum birefringence/dichroism at the 3 σ confidence level on the time scale of a few days at several upcoming laser facilities. Now at Princeton University, Princeton, NJ.

  20. Development of High Temperature Type Vacuum Insulation Panel using Soluble Polyimide and Characteristic Evaluation

    NASA Astrophysics Data System (ADS)

    Araki, Kuninari; Kamoto, Daigorou; Matsuoka, Shin-Ichi

    The utilization is expected from the high-insulated characteristic as a tool for energy saving also in the high temperature insulation fields as in vacuum insulation panels (VIP) in the future. For high temperature, the material composition and process of VIP were reviewed, the SUS foil was adopted as packaging material, and soluble polyimide was developed as the thermo compression bonding material for high temperature VIP at 150°C. To lower the glass-transition temperature (Tg) under 200°C, we elaborated the new soluble polyimide using aliphatic diamine copolymer, and controlled Tg to about 176°C. By making from trial VIP and evaluations, it was possible to be maintain high performance concerning the coefficient of thermal conductivity [λ<0.008 W/(m·K) at 150°C].

  1. Development of deep drawn aluminum piston tanks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Whitehead, J.C.; Bronder, R.L.; Kilgard, L.W.

    1990-06-08

    An aluminum piston tank has been developed for applications requiring lightweight, low cost, low pressure, positive-expulsion liquid storage. The 3 liter (183 in{sup 3}) vessel is made primarily from aluminum sheet, using production forming and joining operations. The development process relied mainly on pressurizing prototype parts and assemblies to failure, as the primary source of decision making information for driving the tank design toward its optimum minimum-mass configuration. Critical issues addressed by development testing included piston operation, strength of thin-walled formed shells, alloy choice, and joining the end cap to the seamless deep drawn can. 9 refs., 8 figs.

  2. Dynamically balanced, hydraulically driven compressor/pump apparatus for resonant free piston Stirling engines

    DOEpatents

    Corey, John A.

    1984-05-29

    A compressor, pump, or alternator apparatus is designed for use with a resonant free piston Stirling engine so as to isolate apparatus fluid from the periodically pressurized working fluid of the Stirling engine. The apparatus housing has a first side closed by a power coupling flexible diaphragm (the engine working member) and a second side closed by a flexible diaphragm gas spring. A reciprocally movable piston is disposed in a transverse cylinder in the housing and moves substantially at right angles relative to the flexible diaphragms. An incompressible fluid fills the housing which is divided into two separate chambers by suitable ports. One chamber provides fluid coupling between the power diaphragm of the RFPSE and the piston and the second chamber provides fluid coupling between the gas spring diaphragm and the opposite side of the piston. The working members of a gas compressor, pump, or alternator are driven by the piston. Sealing and wearing parts of the apparatus are mounted at the external ends of the transverse cylinder in a double acting arrangement for accessibility. An annular counterweight is mounted externally of the reciprocally movable piston and is driven by incompressible fluid coupling in a direction opposite to the piston so as to damp out transverse vibrations.

  3. Vacuum compatible, high-speed, 2-D mirror tilt stage

    DOEpatents

    Denham; Paul E.

    2007-09-25

    A compact and vacuum compatible magnetic-coil driven tiltable stage that is equipped with a high efficiency reflective coating can be employed as a scanner in EUV applications. The drive electronics for the scanner is fully in situ programmable and rapidly switchable.

  4. Overview of the 1985 NASA Lewis Research Center SP-100 free-piston Stirling engine activities

    NASA Technical Reports Server (NTRS)

    Slaby, J.

    1985-01-01

    This effort is keyed on the design, fabrication, assembly, and testing of a 25 kWe Stirling space-power technology-feasibility demonstrator engine. Another facet of the SP-100 project covers the status of a 9000-hr endurance test conducted on a 2 kWe free-piston Stirling/linear alternator system employing hydrostatic gas bearings. Dynamic balancing of the RE-1000 engine (a 1 kWe free-piston Stirling engine) using a passive dynamic absorber will be discussed along with the results of a parametric study showing the relationships of Stirling power converter specific weight and efficiency as functions of Stirling engine heater to cooler temperature ratio. Planned tests will be described covering a hydrodynamic gas bearing concept for potential SP-100 application.

  5. CFD Modeling of Free-Piston Stirling Engines

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir B.; Zhang, Zhi-Guo; Tew, Roy C., Jr.; Gedeon, David; Simon, Terrence W.

    2001-01-01

    NASA Glenn Research Center (GRC) is funding Cleveland State University (CSU) to develop a reliable Computational Fluid Dynamics (CFD) code that can predict engine performance with the goal of significant improvements in accuracy when compared to one-dimensional (1-D) design code predictions. The funding also includes conducting code validation experiments at both the University of Minnesota (UMN) and CSU. In this paper a brief description of the work-in-progress is provided in the two areas (CFD and Experiments). Also, previous test results are compared with computational data obtained using (1) a 2-D CFD code obtained from Dr. Georg Scheuerer and further developed at CSU and (2) a multidimensional commercial code CFD-ACE+. The test data and computational results are for (1) a gas spring and (2) a single piston/cylinder with attached annular heat exchanger. The comparisons among the codes are discussed. The paper also discusses plans for conducting code validation experiments at CSU and UMN.

  6. Vibration isolation in a free-piston driven expansion tube facility

    NASA Astrophysics Data System (ADS)

    Gildfind, D. E.; Jacobs, P. A.; Morgan, R. G.

    2013-09-01

    The stress waves produced by rapid piston deceleration are a fundamental feature of free-piston driven expansion tubes, and wave propagation has to be considered in the design process. For lower enthalpy test conditions, these waves can traverse the tube ahead of critical flow processes, severely interfering with static pressure measurements of the passing flow. This paper details a new device which decouples the driven tube from the free-piston driver, and thus prevents transmission of stress waves. Following successful incorporation of the concept in the smaller X2 facility, it has now been applied to the larger X3 facility, and results for both facilities are presented.

  7. High Current Density Cathodes for Future Vacuum Electronics Applications

    DTIC Science & Technology

    2008-05-30

    Tube - device for generating high levels of RF power DARPA Defense Advanced Research Agency PBG Photonic band gap W- Band 75-111 GHz dB Decibels GHz...Extended interaction klystron 1. Introduction All RF vacuum electron sources require a high quality electron beam for efficient operation. Research on...with long life. Pres- ently, only thermionic dispenser cathodes are practical for high power RF sources. Typical thermi- onic cathodes consists of a

  8. Tribological characteristics of perfluoropolyether liquid lubricants under sliding conditions in high vacuum

    NASA Technical Reports Server (NTRS)

    Masuko, Masabumi; Jones, William R., Jr.; Helmick, Larry S.

    1993-01-01

    Tribological characteristics of three PFPE's (Fomblin Z, Demnum, and Krytox) were studied under high vacuum using a four-ball apparatus with 440C steel specimens. Fomblin Z and Demnum exhibited initial scuffing-like high friction whereas Krytox did not. Steady state friction with Fomblin Z was the lowest among the three oils. Frictional values for Demnum and Krytox were almost the same. The lowest wear rate in air was provided by Krytox regardless of load, and low wear rates in vacuum at high load were achieved with Krytox and Demnum. Results are explained by reactivity and pressure-viscosity characteristics of the oils.

  9. Development of Subischial Prosthetic Sockets with Vacuum-Assisted Suspension for Highly Active Persons with Transfemoral Amputations

    DTIC Science & Technology

    2014-10-01

    Award Number: W81XWH-10-1-0744 TITLE: Development of Subischial Prosthetic Sockets with Vacuum...REPORT TYPE Annual 3. DATES COVERED 15 Sep 2013 – 14 Sep 2014 4. TITLE AND SUBTITLE Development of Subischial Prosthetic Sockets with Vacuum...to develop a highly flexible sub-ischial prosthetic socket with assisted-vacuum suspension for highly active persons with transfemoral amputation. The

  10. Nonevaporable getter coating chambers for extreme high vacuum

    DOE PAGES

    Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al; ...

    2018-03-01

    Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

  11. Nonevaporable getter coating chambers for extreme high vacuum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al

    Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

  12. Piston Bowl Optimization for RCCI Combustion in a Light-Duty Multi-Cylinder Engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hanson, Reed M; Curran, Scott; Wagner, Robert M

    2012-01-01

    Reactivity Controlled Compression Ignition (RCCI) is an engine combustion strategy that that produces low NO{sub x} and PM emissions with high thermal efficiency. Previous RCCI research has been investigated in single-cylinder heavy-duty engines. The current study investigates RCCI operation in a light-duty multi-cylinder engine at 3 operating points. These operating points were chosen to cover a range of conditions seen in the US EPA light-duty FTP test. The operating points were chosen by the Ad Hoc working group to simulate operation in the FTP test. The fueling strategy for the engine experiments consisted of in-cylinder fuel blending using port fuel-injectionmore » (PFI) of gasoline and early-cycle, direct-injection (DI) of diesel fuel. At these 3 points, the stock engine configuration is compared to operation with both the original equipment manufacturer (OEM) and custom machined pistons designed for RCCI operation. The pistons were designed with assistance from the KIVA 3V computational fluid dynamics (CFD) code. By using a genetic algorithm optimization, in conjunction with KIVA, the piston bowl profile was optimized for dedicated RCCI operation to reduce unburned fuel emissions and piston bowl surface area. By reducing these parameters, the thermal efficiency of the engine was improved while maintaining low NOx and PM emissions. Results show that with the new piston bowl profile and an optimized injection schedule, RCCI brake thermal efficiency was increased from 37%, with the stock EURO IV configuration, to 40% at the 2,600 rev/min, 6.9 bar BMEP condition, and NOx and PM emissions targets were met without the need for exhaust after-treatment.« less

  13. Simulation of cracking cores when molding piston components

    NASA Astrophysics Data System (ADS)

    Petrenko, Alena; Soukup, Josef

    2014-08-01

    The article deals with pistons casting made from aluminum alloy. Pistons are casting at steel mold with steel core. The casting is provided by gravity casting machine. The each machine is equipped by two metal molds, which are preheated above temperature 160 °C before use. The steel core is also preheated by flame. The metal molds and cores are heated up within the casting process. The temperature of the metal mold raise up to 200 °C and temperature of core is higher. The surface of the core is treated by nitration. The mold and core are cooled down by water during casting process. The core is overheated and its top part is finally cracked despite its intensive water-cooling. The life time cycle of the core is decreased to approximately 5 to 15 thousands casting, which is only 15 % of life time cycle of core for production of other pistons. The article presents the temperature analysis of the core.

  14. Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices

    NASA Astrophysics Data System (ADS)

    Gamzina, Diana

    Diana Gamzina March 2016 Mechanical and Aerospace Engineering Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices Abstract A methodology for performing thermo-mechanical design and analysis of high frequency and high average power vacuum electron devices is presented. This methodology results in a "first-pass" engineering design directly ready for manufacturing. The methodology includes establishment of thermal and mechanical boundary conditions, evaluation of convective film heat transfer coefficients, identification of material options, evaluation of temperature and stress field distributions, assessment of microscale effects on the stress state of the material, and fatigue analysis. The feature size of vacuum electron devices operating in the high frequency regime of 100 GHz to 1 THz is comparable to the microstructure of the materials employed for their fabrication. As a result, the thermo-mechanical performance of a device is affected by the local material microstructure. Such multiscale effects on the stress state are considered in the range of scales from about 10 microns up to a few millimeters. The design and analysis methodology is demonstrated on three separate microwave devices: a 95 GHz 10 kW cw sheet beam klystron, a 263 GHz 50 W long pulse wide-bandwidth sheet beam travelling wave tube, and a 346 GHz 1 W cw backward wave oscillator.

  15. Very high-vacuum heat treatment facility

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; Moody, M. V.; Richard, J.-P.

    1987-01-01

    A vacuum heat treatment facility, with hot zone dimensions of 12 x 19 x 19 cm, has been designed and constructed at a cost substantially below that of a commercial unit. The design incorporates efficient water cooling and a resistive heating element. A vacuum pressure of 1.5 x 10 to the -8th torr at room temperature has been obtained after baking. The temperature limit is approximately 1900 C. This limit results from the choice of niobium as the hot zone material.

  16. Extension of the shelf life of prawns (Penaeus japonicus) by vacuum packaging and high-pressure treatment.

    PubMed

    López-Caballero, M E; Pérez-Mateos, M; Borderías, J A; Montero, P

    2000-10-01

    The present study has investigated the application of high pressures (200 and 400 MPa) in chilled prawn tails, both conventionally stored (air) and vacuum packaged. Vacuum packaging and high-pressure treatment did extend the shelf life of the prawn samples, although it did affect muscle color very slightly, giving it a whiter appearance. The viable shelf life of 1 week for the air-stored samples was extended to 21 days in the vacuum-packed samples, 28 days in the samples treated at 200 MPa, and 35 days in the samples pressurized at 400 MPa. Vacuum packaging checked the onset of blackening, whereas high-pressure treatment aggravated the problem. From a microbiological point of view, batches conventionally stored reached about 6 log CFU/g or even higher at 14 days. Similar figures were reached in total number of bacteria in vacuum-packed samples and in pressurized at 200-MPa samples at 21 days. When samples were pressurized at 400 MPa, total numbers of bacteria were below 5.5 log CFU/g at 35 days of storage. Consequently, a combination of vacuum packaging and high-pressure treatment would appear to be beneficial in prolonging freshness and preventing spotting.

  17. Influence of Gap Distance on Vacuum Arc Characteristics of Cup Type AMF Electrode in Vacuum Interrupters

    NASA Astrophysics Data System (ADS)

    Cheng, Shaoyong; Xiu, Shixin; Wang, Jimei; Shen, Zhengchao

    2006-11-01

    The greenhouse effect of SF6 is a great concern today. The development of high voltage vacuum circuit breakers becomes more important. The vacuum circuit breaker has minimum pollution to the environment. The vacuum interrupter is the key part of a vacuum circuit breaker. The interrupting characteristics in vacuum and arc-controlling technique are the main problems to be solved for a longer gap distance in developing high voltage vacuum interrupters. To understand the vacuum arc characteristics and provide effective technique to control vacuum arc in a long gap distance, the arc mode transition of a cup-type axial magnetic field electrode is observed by a high-speed charge coupled device (CCD) video camera under different gap distances while the arc voltage and arc current are recorded. The controlling ability of the axial magnetic field on vacuum arc obviously decreases when the gap distance is longer than 40 mm. The noise components and mean value of the arc voltage significantly increase. The effective method for controlling the vacuum arc characteristics is provided by long gap distances based on the test results. The test results can be used as a reference to develop high voltage and large capacity vacuum interrupters.

  18. Lightweight piston-rod assembly for a reciprocating machine

    DOEpatents

    Corey, John A.; Walsh, Michael M.

    1986-01-01

    In a reciprocating machine, there is provided a hollow piston including a dome portion on one end and a base portion on the opposite end. The base portion includes a central bore into which a rod is hermetically fixed in radial and angular alignment. The extending end of the rod has a reduced diameter portion adapted to fit into the central bore of a second member such as a cross-head assembly, and to be secured thereto in radial and axial alignment with the piston.

  19. Mathematical modeling of bent-axis hydraulic piston motors

    NASA Technical Reports Server (NTRS)

    Bartos, R. D.

    1992-01-01

    Each of the DSN 70-m antennas uses 16 bent-axis hydraulic piston motors as part of the antenna drive system. On each of the two antenna axes, four motors are used to drive the antenna and four motors provide counter torque to remove the backlash in the antenna drive train. This article presents a mathematical model for bent-axis hydraulic piston motors. The model was developed to understand the influence of the hydraulic motors on the performance of the DSN 70-m antennas' servo control system.

  20. Ultra-high vacuum photoelectron linear accelerator

    DOEpatents

    Yu, David U.L.; Luo, Yan

    2013-07-16

    An rf linear accelerator for producing an electron beam. The outer wall of the rf cavity of said linear accelerator being perforated to allow gas inside said rf cavity to flow to a pressure chamber surrounding said rf cavity and having means of ultra high vacuum pumping of the cathode of said rf linear accelerator. Said rf linear accelerator is used to accelerate polarized or unpolarized electrons produced by a photocathode, or to accelerate thermally heated electrons produced by a thermionic cathode, or to accelerate rf heated field emission electrons produced by a field emission cathode.

  1. Numerical modelling of physical processes in a ballistic laboratory setup with a tapered adapter and plastic piston used for obtaining high muzzle velocities

    NASA Astrophysics Data System (ADS)

    Bykov, N. V.

    2014-12-01

    Numerical modelling of a ballistic setup with a tapered adapter and plastic piston is considered. The processes in the firing chamber are described within the framework of quasi- one-dimensional gas dynamics and a geometrical law of propellant burn by means of Lagrangian mass coordinates. The deformable piston is considered to be an ideal liquid with specific equations of state. The numerical solution is obtained by means of a modified explicit von Neumann scheme. The calculation results given show that the ballistic setup with a tapered adapter and plastic piston produces increased shell muzzle velocities by a factor of more than 1.5-2.

  2. Dynamics of vacuum-sealed, double-leaf partitions

    NASA Astrophysics Data System (ADS)

    Kavanaugh, Joshua Stephen

    The goal of this research is to investigate the feasibility and potential effectiveness of using vacuum-sealed, double-leaf partitions for applications in noise control. Substantial work has been done previously on double-leaf partitions where the acoustics of the inner chamber and mechanical vibrations of structural supports are passively and actively controlled. The work presented here is unique in that the proposed system aims to eliminate the need for active acoustic control of transmitted acoustic energy by removing all the air between the two panels of the double partition. Therefore, the only remaining energy paths would be along the boundary and at the points where there are intermediate structural supports connecting the two panels. The eventual goal of the research is to develop a high-loss double-leaf partition that simplifies active control by removing the need for control of the air cavity and channeling all the energy into discrete structural paths. The work presented here is a first step towards the goal of designing a high-loss, actively-controlled double-leaf partition with an air-evacuated inner chamber. One experiment is conducted to investigate the effects of various levels of vacuum on the response of a double-leaf partition whose panels are mechanically coupled only at the boundary. Another experiment is conducted which investigates the effect of changing the stiffness of an intermediate support coupling the two panels of a double-leaf partition in which a vacuum has been applied to the inner cavity. The available equipment was able to maintain a 99% vacuum between the panels. Both experiments are accompanied by analytical models used to investigate the importance of various dynamic parameters. Results show that the vacuum-sealed system shows some potential for increased transmission loss, primarily by the changing the natural frequencies of the double-leaf partition.

  3. Effect of osmotic dehydration and vacuum-frying parameters to produce high-quality mango chips.

    PubMed

    Nunes, Yolanda; Moreira, Rosana G

    2009-09-01

    Mango (Mangifera indica L.) is a fruit rich in flavor and nutritional values, which is an excellent candidate for producing chips. The objective of this study was to develop high-quality mango chips using vacuum frying. Mango ("Tommy Atkins") slices were pretreated with different maltodextrin concentrations (40, 50, and 65, w/v), osmotic dehydration times (45, 60, and 70 min), and solution temperatures (22 and 40 degrees C). Pretreated slices were vacuum fried at 120, 130, and 138 degrees C and product quality attributes (oil content, texture, color, carotenoid content) determined. The effect of frying temperatures at optimum osmotic dehydration times (65 [w/v] at 40 degrees C) was assessed. All samples were acceptable (scores > 5) to consumer panelists. The best mango chips were those pretreated with 65 (w/v) concentration for 60 min and vacuum fried at 120 degrees C. Mango chips under atmospheric frying had less carotenoid retention (32%) than those under vacuum frying (up to 65%). These results may help further optimize vacuum-frying processing of high-quality fruit-based snacks.

  4. 1987 overview of free-piston Stirling technology for space power application

    NASA Technical Reports Server (NTRS)

    Slaby, Jack G.; Alger, Donald L.

    1987-01-01

    The Lewis Research Center program concerned with the development of a free-piston Stirling engine for space-power applications is examined. The system mass of a Stirling system is compared to that of a Brayton system for the same peak temperature and output power; the advantages of the Stirling system are discussed. The predicted and experimental performances of the 25 kWe opposed-piston space power demonstrator engine are evaluated. It is determined that in order to enhance performance the regenerator needs to be modified, and the gas bearing flow between the displacer and power piston needs to be isolated in order to increase the operating stroke. Identification and correction of the energy losses, the design and operation of the linear alternator, and heat exchange concepts are considered. The design parameters and conceptual design characteristics for a 25 kWe single-cylinder free-piston Stirling space-power converter are described.

  5. First High-Convergence Cryogenic Implosion in a Near-Vacuum Hohlraum

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L. F.; Meezan, N. B.; Le Pape, S.; Divol, L.; Mackinnon, A. J.; Ho, D. D.; Hohenberger, M.; Jones, O. S.; Kyrala, G.; Milovich, J. L.; Pak, A.; Ralph, J. E.; Ross, J. S.; Benedetti, L. R.; Biener, J.; Bionta, R.; Bond, E.; Bradley, D.; Caggiano, J.; Callahan, D.; Cerjan, C.; Church, J.; Clark, D.; Döppner, T.; Dylla-Spears, R.; Eckart, M.; Edgell, D.; Field, J.; Fittinghoff, D. N.; Gatu Johnson, M.; Grim, G.; Guler, N.; Haan, S.; Hamza, A.; Hartouni, E. P.; Hatarik, R.; Herrmann, H. W.; Hinkel, D.; Hoover, D.; Huang, H.; Izumi, N.; Khan, S.; Kozioziemski, B.; Kroll, J.; Ma, T.; MacPhee, A.; McNaney, J.; Merrill, F.; Moody, J.; Nikroo, A.; Patel, P.; Robey, H. F.; Rygg, J. R.; Sater, J.; Sayre, D.; Schneider, M.; Sepke, S.; Stadermann, M.; Stoeffl, W.; Thomas, C.; Town, R. P. J.; Volegov, P. L.; Wild, C.; Wilde, C.; Woerner, E.; Yeamans, C.; Yoxall, B.; Kilkenny, J.; Landen, O. L.; Hsing, W.; Edwards, M. J.

    2015-05-01

    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ˜3.5 ) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 ×1015 neutrons, with 20% calculated alpha heating at convergence ˜27 × .

  6. First high-convergence cryogenic implosion in a near-vacuum hohlraum

    DOE PAGES

    Berzak Hopkins, L.  F.; Meezan, N.  B.; Le Pape, S.; ...

    2015-04-29

    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated inmore » a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ~ 3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 X 10¹⁵ neutrons, with 20% calculated alpha heating at convergence ~27X.« less

  7. Ultra-high speed visualization of the flashing instability under vacuum conditions

    NASA Astrophysics Data System (ADS)

    Hernández Sánchez, Jose Federico; Al-Ghamdi, Tariq; Thoroddsen, Sigurdur T.

    2017-11-01

    We investigated experimentally the flashing instability of a jet of perfluoro-n-hexane (PFnH) released into a low-pressure environment. Using a ultra-high speed camera we observed the jet fragmentation occurring close to the nozzle. Using a fixed total driving pressure, we decreased systematically the vacuum pressure, investigating the transition from a laminar jet to a fully flashing jet. Our high temporal resolution allowed to visualize the detailed dynamics of external flash-boiling for the first time. We identified different mechanisms of jet break-up. At chamber pressures lower than the vapor pressure the laminar jet evolves to a meandering stream. In this stage, bubbles start to nucleate and violently expand upstream the nozzle. At lower vacuum pressures the initially cylindrical jet elongates, forming a liquid sheet that breaks in branches and later in drops. At very low pressures both mechanisms are responsible for the jet breaking. We calculated the size distribution of the ejected droplets, their individual trajectories, velocities as well as the spray angle as a function of the dimensionless vacuum pressure.

  8. A High Vacuum High Speed Ion Pump

    DOE R&D Accomplishments Database

    Foster, J. S. Jr.; Lawrence, E. O.; Lofgren, E. J.

    1952-08-27

    A vacuum pump based on the properties of a magnetically collimated electric discharge is described. It has a speed in the range 3000 to 7000 liters a second and a base pressure in the order of 10{sup -6} mm. (auth)

  9. Vacuum die attach for integrated circuits

    DOEpatents

    Schmitt, Edward H.; Tuckerman, David B.

    1991-01-01

    A thin film eutectic bond for attaching an integrated circuit die to a circuit substrate is formed by coating at least one bonding surface on the die and substrate with an alloying metal, assembling the die and substrate under compression loading, and heating the assembly to an alloying temperature in a vacuum. A very thin bond, 10 microns or less, which is substantially void free, is produced. These bonds have high reliability, good heat and electrical conduction, and high temperature tolerance. The bonds are formed in a vacuum chamber, using a positioning and loading fixture to compression load the die, and an IR lamp or other heat source. For bonding a silicon die to a silicon substrate, a gold silicon alloy bond is used. Multiple dies can be bonded simultaneously. No scrubbing is required.

  10. Internal motion in high vacuum systems

    NASA Astrophysics Data System (ADS)

    Frank, J. M.

    Three transfer and positioning mechanisms have been developed for the non-air exposed, multistep processing of components in vacuum chambers. The functions to be performed in all of the systems include ultraviolet/ozone cleaning, vacuum baking, deposition of thin films, and thermocompression sealing of the enclosures. Precise positioning of the components is required during the evaporation and sealing processes. The three methods of transporting and positioning the components were developed to accommodate the design criteria and goals of each individual system. The design philosophy, goals, and operation of the three mechanisms are discussed.

  11. Assessment of 25 kW free-piston Stirling technology alternatives for solar applications

    NASA Technical Reports Server (NTRS)

    Erbeznik, Raymond M.; White, Maurice A.; Penswick, L. B.; Neely, Ronald E.; Ritter, Darren C.; Wallace, David A.

    1992-01-01

    The final design, construction, and testing of a 25-kW free-piston advanced Stirling conversion system (ASCS) are examined. The final design of the free-piston hydraulic ASCS consists of five subsystems: heat transport subsystem (solar receiver and pool boiler), free-piston hydraulic Stirling engine, hydraulic subsystem, cooling subsystem, and electrical and control subsystem. Advantages and disadvantages are identified for each technology alternative. Technology alternatives considered are gas bearings vs flexure bearings, stationary magnet linear alternator vs moving magnetic linear alternator, and seven different control options. Component designs are generated using available in-house procedures to meet the requirements of the free-piston Stirling convertor configurations.

  12. An assessment of the hardness of miniature vacuum tubes to high-voltage transients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Orvis, W.J.

    1990-03-01

    Miniature vacuum tubes are vacuum switching and control devices fabricated on a silicon wafer, using the same technology as is used to make integrated circuits. They operate in much the same manner as conventional vacuum tubes, but with two important differences: they are micron sized devices, and they employ field emission instead of thermionic emission as the electron source. As these devices have a vacuum as their active region, they will be extremely hard to nuclear radiation and relatively insensitive to temperature effects, they are also expected to be extremely fast devices. We have estimated here that their hardness tomore » high-voltage transients will be at least as good as existing semiconductor devices and possibly better. 5 figs.« less

  13. Non-technical skills for obstetricians conducting forceps and vacuum deliveries: qualitative analysis by interviews and video recordings.

    PubMed

    Bahl, Rachna; Murphy, Deirdre J; Strachan, Bryony

    2010-06-01

    Non-technical skills are cognitive and social skills required in an operational task. These skills have been identified and taught in the surgical domain but are of particular relevance to obstetrics where the patient is awake, the partner is present and the clinical circumstances are acute and often stressful. The aim of this study was to define the non-technical skills of an operative vaginal delivery (forceps or vacuum) to facilitate transfer of skills from expert obstetricians to trainee obstetricians. Qualitative study using interviews and video recordings. The study was conducted at two university teaching hospitals (St. Michael's Hospital, Bristol and Ninewells Hospital, Dundee). Participants included 10 obstetricians and eight midwives identified as experts in conducting or supporting operative vaginal deliveries. Semi-structured interviews were carried out using routine clinical scenarios. The experts were also video recorded conducting forceps and vacuum deliveries in a simulation setting. The interviews and video recordings were transcribed verbatim and analysed using thematic coding. The anonymised data were independently coded by the three researchers and then compared for consistency of interpretation. The experts reviewed the coded data for respondent validation and clarification. The themes that emerged were used to identify the non-technical skills required for conducting an operative vaginal delivery. The final skills list was classified into seven main categories. Four categories (situational awareness, decision making, task management, and team work and communication) were similar to the categories identified in surgery. Three further categories unique to obstetrics were also identified (professional relationship with the woman, maintaining professional behaviour and cross-monitoring of performance). This explicitly defined skills taxonomy could aid trainees' understanding of the non-technical skills to be considered when conducting an operative

  14. The spark-ignition aircraft piston engine of the future

    NASA Technical Reports Server (NTRS)

    Stuckas, K. J.

    1980-01-01

    Areas of advanced technology appropriate to the design of a spark-ignition aircraft piston engine for the late 1980 time period were investigated and defined. Results of the study show that significant improvements in fuel economy, weight and size, safety, reliability, durability and performance may be achieved with a high degree of success, predicated on the continued development of advances in combustion systems, electronics, materials and control systems.

  15. Gas-fired duplex free-piston Stirling refrigerator

    NASA Astrophysics Data System (ADS)

    Urieli, L.

    1984-03-01

    The duplex free-piston Stirling refrigerator is a potentially high efficiency, high reliability device which is ideally suited to the home appliance field, in particular as a gas-fired refrigerator. It has significant advantages over other equivalent devices including freedom from halogenated hydrocarbons, extremely low temperatures available at a high efficiency, integrated water heating, and simple burner system control. The design and development of a portable working demonstration gas-fired duplex Stirling refrigeration unit is described. A unique combination of computer aided development and experimental development was used, enabling a continued interaction between the theoretical analysis and practical testing and evaluation. A universal test rig was developed in order to separately test and evaluate major subunits, enabling a smooth system integration phase.

  16. Electron beam gun with kinematic coupling for high power RF vacuum devices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borchard, Philipp

    An electron beam gun for a high power RF vacuum device has components joined by a fixed kinematic coupling to provide both precise alignment and high voltage electrical insulation of the components. The kinematic coupling has high strength ceramic elements directly bonded to one or more non-ductile rigid metal components using a high temperature active metal brazing alloy. The ceramic elements have a convex surface that mates with concave grooves in another one of the components. The kinematic coupling, for example, may join a cathode assembly and/or a beam shaping focus electrode to a gun stem, which is preferably composedmore » of ceramic. The electron beam gun may be part of a high power RF vacuum device such as, for example, a gyrotron, klystron, or magnetron.« less

  17. Carbon nanotube vacuum gauges with wide-dynamic range and processes thereof

    NASA Technical Reports Server (NTRS)

    Manohara, Harish (Inventor); Kaul, Anupama B. (Inventor)

    2013-01-01

    A miniature thermal conductivity gauge employs a carbon single-walled-nanotube. The gauge operates on the principle of thermal exchange between the voltage-biased nanotube and the surrounding gas at low levels of power and low temperatures to measure vacuum across a wide dynamic range. The gauge includes two terminals, a source of constant voltage to the terminals, a single-walled carbon nanotube between the terminals, a calibration of measured conductance of the nanotube to magnitudes of surrounding vacuum and a current meter in electrical communication with the source of constant voltage. Employment of the nanotube for measuring vacuum includes calibrating the electrical conductance of the nanotube to magnitudes of vacuum, exposing the nanotube to a vacuum, applying a constant voltage across the nanotube, measuring the electrical conductance of the nanotube in the vacuum with the constant voltage applied and converting the measured electrical conductance to the corresponding calibrated magnitude of vacuum using the calibration. The nanotube may be suspended to minimize heat dissipation through the substrate, increasing sensitivity at even tower pressures.

  18. Comparison of free-piston Stirling engine model predictions with RE1000 engine test data

    NASA Technical Reports Server (NTRS)

    Tew, R. C., Jr.

    1984-01-01

    Predictions of a free-piston Stirling engine model are compared with RE1000 engine test data taken at NASA-Lewis Research Center. The model validation and the engine testing are being done under a joint interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA-Lewis. A kinematic code developed at Lewis was upgraded to permit simulation of free-piston engine performance; it was further upgraded and modified at Lewis and is currently being validated. The model predicts engine performance by numerical integration of equations for each control volume in the working space. Piston motions are determined by numerical integration of the force balance on each piston or can be specified as Fourier series. In addition, the model Fourier analyzes the various piston forces to permit the construction of phasor force diagrams. The paper compares predicted and experimental values of power and efficiency and shows phasor force diagrams for the RE1000 engine displacer and piston. Further development plans for the model are also discussed.

  19. Diffuser/ejector system for a very high vacuum environment

    NASA Technical Reports Server (NTRS)

    Riggs, K. E.; Wojciechowski, C. J. (Inventor)

    1984-01-01

    Turbo jet engines are used to furnish the necessary high temperature, high volume, medium pressure gas to provide a high vacuum test environment at comparatively low cost for space engines at sea level. Moreover, the invention provides a unique way by use of the variable area ratio ejectors with a pair of meshing cones are used. The outer cone is arranged to translate fore and aft, and the inner cone is interchangeable with other cones having varying angles of taper.

  20. Shallowly driven fluctuations in lava lake outgassing (gas pistoning), Kīlauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, Matthew R.; Orr, Tim; Sutton, A. J.; Lev, Einat; Thelen, Wes; Fee, David

    2016-01-01

    Lava lakes provide ideal venues for directly observing and understanding the nature of outgassing in basaltic magmatic systems. Kīlauea Volcano's summit lava lake has persisted for several years, during which seismic and infrasonic tremor amplitudes have exhibited episodic behavior associated with a rise and fall of the lava surface (;gas pistoning;). Since 2010, the outgassing regime of the lake has been tied to the presence or absence of gas pistoning. During normal behavior (no gas pistoning), the lake is in a ;spattering; regime, consisting of higher tremor amplitudes and gas emissions. In comparison, gas piston events are associated with an abrupt rise in lava level (up to 20 m), during which the lake enters a ;non-spattering; regime with greatly decreased tremor and gas emissions. We study this episodic behavior using long-term multidisciplinary monitoring of the lake, including seismicity, infrasound, gas emission and geochemistry, and time-lapse camera observations. The non-spattering regime (i.e. rise phase of a gas piston cycle) reflects gas bubbles accumulating near the top of the lake, perhaps as a shallow foam, while spattering regimes represent more efficient decoupling of gas from the lake. We speculate that the gas pistoning might be controlled by time-varying porosity and/or permeability in the upper portions of the lava lake, which may modulate foam formation and collapse. Competing models for gas pistoning, such as deeply sourced gas slugs, or dynamic pressure balances, are not consistent with our observations. Unlike other lava lakes which have cyclic behavior that is thought to be controlled by deeply sourced processes, external to the lake itself, we show an example of lava lake fluctuations driven by cycles of activity at shallow depth and close to the lake's surface. These observations highlight the complex and unsteady nature of outgassing from basaltic magmatic systems.

  1. Vacuum encapsulated, high temperature diamond amplified cathode capsule and method for making same

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rao, Triveni; Walsh, Josh; Gangone, Elizabeth

    2015-12-29

    A vacuum encapsulated, hermetically sealed cathode capsule for generating an electron beam of secondary electrons, which generally includes a cathode element having a primary emission surface adapted to emit primary electrons, an annular insulating spacer, a diamond window element comprising a diamond material and having a secondary emission surface adapted to emit secondary electrons in response to primary electrons impinging on the diamond window element, a first high-temperature solder weld disposed between the diamond window element and the annular insulating spacer and a second high-temperature solder weld disposed between the annular insulating spacer and the cathode element. The cathode capsulemore » is formed by a high temperature weld process under vacuum such that the first solder weld forms a hermetical seal between the diamond window element and the annular insulating spacer and the second solder weld forms a hermetical seal between the annular spacer and the cathode element whereby a vacuum encapsulated chamber is formed within the capsule.« less

  2. Non-adiabatic pumping in an oscillating-piston model

    NASA Astrophysics Data System (ADS)

    Chuchem, Maya; Dittrich, Thomas; Cohen, Doron

    2012-05-01

    We consider the prototypical "piston pump" operating on a ring, where a circulating current is induced by means of an AC driving. This can be regarded as a generalized Fermi-Ulam model, incorporating a finite-height moving wall (piston) and non-trivial topology (ring). The amount of particles transported per cycle is determined by a layered structure of phase space. Each layer is characterized by a different drift velocity. We discuss the differences compared with the adiabatic and Boltzmann pictures, and highlight the significance of the "diabatic" contribution that might lead to a counter-stirring effect.

  3. Microfabricated triggered vacuum switch

    DOEpatents

    Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  4. Vacuum die attach for integrated circuits

    DOEpatents

    Schmitt, E.H.; Tuckerman, D.B.

    1991-09-10

    A thin film eutectic bond for attaching an integrated circuit die to a circuit substrate is formed by coating at least one bonding surface on the die and substrate with an alloying metal, assembling the die and substrate under compression loading, and heating the assembly to an alloying temperature in a vacuum. A very thin bond, 10 microns or less, which is substantially void free, is produced. These bonds have high reliability, good heat and electrical conduction, and high temperature tolerance. The bonds are formed in a vacuum chamber, using a positioning and loading fixture to compression load the die, and an IR lamp or other heat source. For bonding a silicon die to a silicon substrate, a gold silicon alloy bond is used. Multiple dies can be bonded simultaneously. No scrubbing is required. 1 figure.

  5. The Adiabatic Piston and the Second Law of Thermodynamics

    NASA Astrophysics Data System (ADS)

    Crosignani, Bruno; Di Porto, Paolo; Conti, Claudio

    2002-11-01

    A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law when dealing with systems of mesoscopic dimensions.

  6. LINC-NIRVANA piston control elements

    NASA Astrophysics Data System (ADS)

    Brix, Mario; Pott, Jörg-Uwe; Bertram, Thomas; Rost, Steffen; Borelli, Jose Luis; Herbst, Thomas M.; Kuerster, Martin; Rohloff, Ralf-Rainer

    2010-07-01

    We review the status of hardware developments related to the Linc-Nirvana optical path difference (OPD) control. The status of our telescope vibration measurements is given. We present the design concept of a feed-forward loop to damp the impact of telescope mirror vibrations on the OPD seen by Linc-Nirvana. At the focus of the article is a description of the actuator of the OPD control loop. The weight and vibration optimized construction of this actuator (aka piston mirror) and its mount has a complex dynamical behavior, which prevents classical PI feedback control from delivering fast and precise motion of the mirror surface. Therefore, an H-; optimized control strategy will be applied, custom designed for the piston mirror. The effort of realizing a custom controller on a DSP to drive the piezo is balanced by the outlook of achieving more than 5x faster servo bandwidths. The laboratory set-up to identify the system, and verify the closed loop control performance is presented. Our goal is to achieve 30 Hz closed-loop control bandwidth at a precision of 30 nm.

  7. Semi-automated high-efficiency reflectivity chamber for vacuum UV measurements

    NASA Astrophysics Data System (ADS)

    Wiley, James; Fleming, Brian; Renninger, Nicholas; Egan, Arika

    2017-08-01

    This paper presents the design and theory of operation for a semi-automated reflectivity chamber for ultraviolet optimized optics. A graphical user interface designed in LabVIEW controls the stages, interfaces with the detector system, takes semi-autonomous measurements, and monitors the system in case of error. Samples and an optical photodiode sit on an optics plate mounted to a rotation stage in the middle of the vacuum chamber. The optics plate rotates the samples and diode between an incident and reflected position to measure the absolute reflectivity of the samples at wavelengths limited by the monochromator operational bandpass of 70 nm to 550 nm. A collimating parabolic mirror on a fine steering tip-tilt motor enables beam steering for detector peak-ups. This chamber is designed to take measurements rapidly and with minimal oversight, increasing lab efficiency for high cadence and high accuracy vacuum UV reflectivity measurements.

  8. Assessment of the Free-piston Stirling Convertor as a Long Life Power Convertor for Space

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    2001-01-01

    There is currently a renewed interest in the use of free-piston Stirling power convertors for space power applications. More specifically, the Stirling convertor is being developed to be part of the Stirling Radioisotope Power System to supply electric power to spacecraft for NASA deep space science missions. The current development effort involves the Department of Energy, Germantown, MD, the NASA Glenn Research Center, Cleveland, OH, and the Stirling Technology Company, Kennewick, WA. The Stirling convertor will absorb heat supplied from the decay of plutonium dioxide contained in the General Purpose Heat Source modules and convert it into electricity to power the spacecraft. For many years the "potentials" of the free-piston Stirling convertor have been publicized by it's developers. Among these "potentials" were long life and high reliability. This paper will present an overview of the critical areas that enable long life of the free-piston Stirling power convertor, and present some of the techniques that have been used when long life has been achieved.

  9. Pre-compression volume on flow ripple reduction of a piston pump

    NASA Astrophysics Data System (ADS)

    Xu, Bing; Song, Yuechao; Yang, Huayong

    2013-11-01

    Axial piston pump with pre-compression volume(PCV) has lower flow ripple in large scale of operating condition than the traditional one. However, there is lack of precise simulation model of the axial piston pump with PCV, so the parameters of PCV are difficult to be determined. A finite element simulation model for piston pump with PCV is built by considering the piston movement, the fluid characteristic(including fluid compressibility and viscosity) and the leakage flow rate. Then a test of the pump flow ripple called the secondary source method is implemented to validate the simulation model. Thirdly, by comparing results among the simulation results, test results and results from other publications at the same operating condition, the simulation model is validated and used in optimizing the axial piston pump with PCV. According to the pump flow ripples obtained by the simulation model with different PCV parameters, the flow ripple is the smallest when the PCV angle is 13°, the PCV volume is 1.3×10-4 m3 at such operating condition that the pump suction pressure is 2 MPa, the pump delivery pressure 15 MPa, the pump speed 1 000 r/min, the swash plate angle 13°. At the same time, the flow ripple can be reduced when the pump suction pressure is 2 MPa, the pump delivery pressure is 5 MPa,15 MPa, 22 MPa, pump speed is 400 r/min, 1 000 r/min, 1 500 r/min, the swash plate angle is 11°, 13°, 15° and 17°, respectively. The finite element simulation model proposed provides a method for optimizing the PCV structure and guiding for designing a quieter axial piston pump.

  10. High-efficiency solar cells fabricated by vacuum MO-CVD

    NASA Technical Reports Server (NTRS)

    Fraas, L. M.; Cape, J. A.; Partain, L. D.; Mcleod, P. S.

    1984-01-01

    High-efficiency, monolithic, two-color, three-terminal solar cells were fabricated by a novel growth technique, vacuum metal-organic chemical vapor deposition. The technique uses the expensive metal alkyls efficiently and toxic gases sparingly. The fact that the outer chamber is constructed of nonbreakable stainless steel is an attractive safety feature associated with this deposition system.

  11. High-speed pressure clamp.

    PubMed

    Besch, Stephen R; Suchyna, Thomas; Sachs, Frederick

    2002-10-01

    We built a high-speed, pneumatic pressure clamp to stimulate patch-clamped membranes mechanically. The key control element is a newly designed differential valve that uses a single, nickel-plated piezoelectric bending element to control both pressure and vacuum. To minimize response time, the valve body was designed with minimum dead volume. The result is improved response time and stability with a threefold decrease in actuation latency. Tight valve clearances minimize the steady-state air flow, permitting us to use small resonant-piston pumps to supply pressure and vacuum. To protect the valve from water contamination in the event of a broken pipette, an optical sensor detects water entering the valve and increases pressure rapidly to clear the system. The open-loop time constant for pressure is 2.5 ms for a 100-mmHg step, and the closed-loop settling time is 500-600 micros. Valve actuation latency is 120 micros. The system performance is illustrated for mechanically induced changes in patch capacitance.

  12. Progress in High Power Free-Piston Stirling Convertor Development

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-01-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  13. Progress in High Power Free-Piston Stirling Convertor Development

    NASA Astrophysics Data System (ADS)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-09-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  14. A high-performance, flexible and robust metal nanotrough-embedded transparent conducting film for wearable touch screen panels

    NASA Astrophysics Data System (ADS)

    Im, Hyeon-Gyun; An, Byeong Wan; Jin, Jungho; Jang, Junho; Park, Young-Geun; Park, Jang-Ung; Bae, Byeong-Soo

    2016-02-01

    We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband.We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07657a

  15. Diffraction-limited storage-ring vacuum technology

    PubMed Central

    Al-Dmour, Eshraq; Ahlback, Jonny; Einfeld, Dieter; Tavares, Pedro Fernandes; Grabski, Marek

    2014-01-01

    Some of the characteristics of recent ultralow-emittance storage-ring designs and possibly future diffraction-limited storage rings are a compact lattice combined with small magnet apertures. Such requirements present a challenge for the design and performance of the vacuum system. The vacuum system should provide the required vacuum pressure for machine operation and be able to handle the heat load from synchrotron radiation. Small magnet apertures result in the conductance of the chamber being low, and lumped pumps are ineffective. One way to provide the required vacuum level is by distributed pumping, which can be realised by the use of a non-evaporable getter (NEG) coating of the chamber walls. It may not be possible to use crotch absorbers to absorb the heat from the synchrotron radiation because an antechamber is difficult to realise with such a compact lattice. To solve this, the chamber walls can work as distributed absorbers if they are made of a material with good thermal conductivity, and distributed cooling is used at the location where the synchrotron radiation hits the wall. The vacuum system of the 3 GeV storage ring of MAX IV is used as an example of possible solutions for vacuum technologies for diffraction-limited storage rings. PMID:25177979

  16. The properties of an improvised piston pump for the rapid delivery of intravenous fluids.

    PubMed

    Smart, C M; Primrose, C W; Peters, A L; Speirits, E J

    2014-02-01

    To maximise the effect of a small fluid load, it is occasionally desirable to bolus manually with multiple depressions of a large-capacity syringe. This is usually achieved by placing the syringe on the side port of a three-way tap. We modified this technique by placing two-one-way valves in line with the three-way tap, effectively creating a piston pump, the infusion rates via which we compared with those achieved by an inflatable pressure-infuser in a simulated resuscitation. Fluid flow was faster using the piston pump than with the pressure-infuser (mean (SD) time to infuse 2000 ml saline 0.9% via a 16-G cannula 352 (10) s vs 495 (19) s, respectively, p < 0.0001). The piston pump appears to have potential for both tight control of fluid delivery and major high-volume resuscitation. The lightweight nature of the pump and its lack of reliance on gravity may also make it suitable for the pre-hospital setting. © 2014 The Association of Anaesthetists of Great Britain and Ireland.

  17. Overview of free-piston Stirling SP-100 activities at the NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Slaby, J. G.

    1986-01-01

    An overview of the National Aeronautics and Space Administration (NASA) Lewis Research Center (LeRC) SP-100 free-piston Stirling engine activities is presented. These activities are being conducted in support of the Department of Defense (DOD), Department of Energy (DOE), and NASA. The space-power technology effort, under SP-100, addresses the status of the 25 kWe Space Power Demonstrator Engine (SPDE). Another facet of the SP-100 project covers the status of an endurance test. Dynamic balancing of the SPDE engine is discussed along with a summary covering the parametric results of a study showing the relationship between power-converter specific weight and efficiency both as a function of Stirling engine heater to cooler temperature ratio. Design parameters and conceptual design features are presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter. And finally, a description of a hydrodynamic gas bearing concept is presented.

  18. Nonlinear Dynamics of a Spring-Supported Piston in a Vibrated Liquid-Filled Housing: II. Experiments

    NASA Astrophysics Data System (ADS)

    O'Hern, T. J.; Torczynski, J. R.; Clausen, J. R.

    2016-11-01

    The nonlinear dynamics of a piston supported by a spring in a vibrated liquid-filled housing is investigated experimentally. The housing containing the piston and the liquid is subjected to vibrations along its axis. A post fixed to the housing penetrates a hole through the piston and produces a flow resistance that depends on piston position. Flexible bellows attached to the housing ends enable the piston, liquid, and bellows to execute a collective motion that forces little liquid through the flow resistance. The low damping of this motion leads to a resonance, at which the flow-resistance nonlinearity produces a net force on the piston that can cause it to compress its spring. Experiments are performed to investigate the nonlinear dynamics of this system, and these results are compared to theoretical and numerical results. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. Comparison of vacuum and non-vacuum urine tubes for urinary sediment analysis.

    PubMed

    Topcuoglu, Canan; Sezer, Sevilay; Kosem, Arzu; Ercan, Mujgan; Turhan, Turan

    2017-12-01

    Urine collection systems with aspiration system for vacuum tubes are becoming increasingly common for urinalysis, especially for microscopic examination of the urine. In this study, we aimed to examine whether vacuum aspiration of the urine sample has any adverse effect on sediment analysis by comparing results from vacuum and non-vacuum urine tubes. The study included totally 213 urine samples obtained from inpatients and outpatients in our hospital. Urine samples were collected to containers with aspiration system for vacuum tubes. Each sample was aliquoted to both vacuum and non-vacuum urine tubes. Urinary sediment analysis was performed using manual microscope. Results were evaluated using chi-square test. Comparison of the sediment analysis results from vacuum and non-vacuum urine tubes showed that results were highly concordant for erythrocyte, leukocyte and epithelial cells (gamma values 1, 0.997, and 0.994, respectively; p < .001). Results were also concordant for urinary casts, crystals and yeast (kappa values 0.815, 0.945 and 1, respectively; p < .001). The results show that in urinary sediment analysis, vacuum aspiration has no adverse effect on the cellular components except on casts.

  20. EN AW-4032 T6 Piston Alloy After High-Temperature Exposure: Residual Strength and Microstructural Features

    NASA Astrophysics Data System (ADS)

    Balducci, Eleonora; Ceschini, Lorella; Morri, Alessandro; Morri, Andrea

    2017-08-01

    This study aims to evaluate the effects of prolonged thermal exposure on both microstructural evolution and mechanical properties of the EN AW-4032 T6 piston alloy. For the purpose, the experimental activities have been carried out on samples machined from forged and heat-treated automotive pistons. The effects of overaging have been investigated in the temperature range of 140-290 °C, firstly by evaluating the time-temperature-hardness curves and then by carrying out room-temperature tensile tests on overaged samples. The material softening was substantial and extremely rapid when the soaking temperature exceeded 250 °C. During overaging, both the tensile strength and the residual hardness considerably decreased, and a relationship between these parameters has been established. The alloy behavior in the plastic field has been modeled according to the Hollomon's equation, showing that both the strain hardening exponent and the strength coefficient are a function of the residual hardness. The results were finally related to the corresponding microstructural changes: OM and FEG-SEM metallographic and fractographic analyses on overaged samples gave evidence of coarsened precipitates along the grain boundaries.

  1. The performance simulation of single cylinder electric power confined piston engine

    NASA Astrophysics Data System (ADS)

    Gou, Yanan

    2017-04-01

    A new type of power plant. i.e, Electric Power Confined Piston Engine, is invented by combining the free piston engine and the crank connecting rod mechanism of the traditional internal combustion engine. Directly using the reciprocating movement of the piston, this new engine converts the heat energy produced by fuel to electrical energy and output it. The paper expounds the working mechanism of ECPE and establishes the kinematics and dynamics equations. Furthermore, by using the analytic method, the ECPE electromagnetic force is solved at load cases. Finally, in the simulation environment of MARLAB, the universal characteristic curve is obtained in the condition of rotational speed n between 1000 r/min and 2400 r/min, throttle opening α between 30% and 100%.

  2. Friction measurements in piston-cylinder apparatus using quartz-coesite reversible transition

    NASA Technical Reports Server (NTRS)

    Akella, J.

    1979-01-01

    The value of friction determined by monitoring piston displacement as a function of nominal pressure on compression and decompression cycles at 1273 K is compared with the friction value obtained by reversing the quartz-coesite transition at 1273 and 1073 K in a talc-glass-alsimag cell (Akella and Kennedy, 1971) and a low-friction salt cell (Mirwald et al., 1975). Quenching runs at 1273 K gave double values of friction of 0.25 GPa for the talc-glass-alsimag cell and 0.03 GPa for the salt cell. The piston-displacement technique gave somewhat higher values. Use of piston-displacement hysteresis loops in evaluating the actual pressure on a sample may lead to overestimates for decompression runs and underestimates for compression runs.

  3. Analysis of high vacuum systems using SINDA'85

    NASA Technical Reports Server (NTRS)

    Spivey, R. A.; Clanton, S. E.; Moore, J. D.

    1993-01-01

    The theory, algorithms, and test data correlation analysis of a math model developed to predict performance of the Space Station Freedom Vacuum Exhaust System are presented. The theory used to predict the flow characteristics of viscous, transition, and molecular flow is presented in detail. Development of user subroutines which predict the flow characteristics in conjunction with the SINDA'85/FLUINT analysis software are discussed. The resistance-capacitance network approach with application to vacuum system analysis is demonstrated and results from the model are correlated with test data. The model was developed to predict the performance of the Space Station Freedom Vacuum Exhaust System. However, the unique use of the user subroutines developed in this model and written into the SINDA'85/FLUINT thermal analysis model provides a powerful tool that can be used to predict the transient performance of vacuum systems and gas flow in tubes of virtually any geometry. This can be accomplished using a resistance-capacitance (R-C) method very similar to the methods used to perform thermal analyses.

  4. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    DOEpatents

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  5. Design of an interferometric system for piston measurements in segmented primary mirrors

    NASA Astrophysics Data System (ADS)

    Arasa, Josep; Laguarta, Ferran; Pizarro, Carlos; Tomas, Nuria; Pinto, Agusti

    2000-10-01

    Recently, telescopes with segmented primary mirrors are becoming increasingly popular due to their ability of achieving large apertures without the inconveniences caused by the fabrication and handling of monolithic surfaces with 8m (or over) in diameter. The difference in position of each pair of adjacent segments along the local normal of their interface (called piston hereafter), however, needs to be precisely measured in order to provide a diffraction- limited image. If a system yielding the nanometric accuracy required in piston measurements worked in daylight hours, the resultant saving in observation time would be an important advance on a majority of the state-of-the-art piston measurement systems. An interferometric piston measurement instrument accomplishing such objectives has been designed starting from the usual Michelson configuration at the CD6 (Terrassa, Spain), and its final test has been carried out in the test workbench of the Instituto de Astrofisica de Canarias (IAC, Canary Islands, Spain). Its optical layout relies on projecting the reference arm of the interferometer onto one of the segments of the pair considered, along the direction of the local normal to the surface while the measurement arm is projected onto the interface which divides the pair of segments considered. The field of view and its illumination are calculated to be equivalent in both segments. The lateral shift of the fringes in both interferograms determines the piston error present. A combination of monochromatic and white light is used, in order to remove the (lambda) /2 phase ambiguities present in piston measurements without losing the required resolution in the measurement. In this paper, the optical design of this interferometric piston measurement instrument will be presented. The particular configuration used in the interferometer, the implementation of an imaging system allowing to see both the interface of the segments and the interference fringes, the effect of the

  6. Advanced Small Free-Piston Stirling Convertors for Space Power Applications

    NASA Astrophysics Data System (ADS)

    Wood, J. Gary; Lane, Neill

    2004-02-01

    This paper reports on the current status of an advanced 35 We free-piston Stirling convertor currently being developed under NASA SBIR Phase II funding. Also described is a further advanced and higher performance ~80 watt free-piston convertor being developed by Sunpower and Boeing/Rocketdyne for NASA under NRA funding. Exceptional overall convertor (engine plus linear alternator) thermodynamic performance (greater than 50% of Carnot) with specific powers around 100 We /kg appear reasonable at these low power levels.

  7. High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-01-01

    Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal planeregion extending from 14 D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. TheVNC is a hybrid interferometriccoronagraphic approach for exoplanet science. It operates with high Lyot stopefficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential futureNASA flight telescopes. NASAGoddard Space Flight Center (GSFC) has a well-established effort to develop the VNCand its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and itsenabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry tounprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a W configurationto accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters.We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, criticaltechnologies and null sensing and control.

  8. Control scheme for power modulation of a free piston Stirling engine

    DOEpatents

    Dhar, Manmohan

    1989-01-01

    The present invention relates to a control scheme for power modulation of a free-piston Stirling engine-linear alternator power generator system. The present invention includes connecting an autotransformer in series with a tuning capacitance between a linear alternator and a utility grid to maintain a constant displacement to piston stroke ratio and their relative phase angle over a wide range of operating conditions.

  9. Translational velocity oscillations of piston generated vortex rings

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Arakeri, J. H.; Shankar, P. N.

    1995-11-01

    Experimental results are presented that show that the translational velocities of piston generated vortex rings often undergo oscillations, similar to those recently discovered for drop generated rings. An attempt has been made to minimize uncertainties by utilizing both dye and hydrogen bubbles for visualization and carefully repeating measurements on the same ring and on different realizations under the same nominal piston conditions. The results unambiguously show that under most conditions, both for laminar and turbulent rings and for rings generated from pipes and orifices, the oscillations are present. The present results, together with the earlier results on drop generated rings, give support to the view that translational velocity oscillations are probably an inherent feature of translating vortex ring fields.

  10. Apollo telescope mount thermal systems unit thermal vacuum test

    NASA Technical Reports Server (NTRS)

    Trucks, H. F.; Hueter, U.; Wise, J. H.; Bachtel, F. D.

    1971-01-01

    The Apollo Telescope Mount's thermal systems unit was utilized to conduct a full-scale thermal vacuum test to verify the thermal design and the analytical techniques used to develop the thermal mathematical models. Thermal vacuum test philosophy, test objectives configuration, test monitoring, environment simulation, vehicle test performance, and data correlation are discussed. Emphasis is placed on planning and execution of the thermal vacuum test with particular attention on problems encountered in conducting a test of this maguitude.

  11. Development of Subischial Prosthetic Sockets with Vacuum-Assisted Suspension for Highly Active Persons with Transfemoral Amputations

    DTIC Science & Technology

    2012-10-01

    materials to facilitate dissemination of this technique. 15. SUBJECT TERMS Transfemoral amputation, sub-ischial socket, prosthesis , vacuum-assisted...an appropriate mechanical pump to create suitable vacuum for suspension of the prosthesis ...sockets of highly active prosthesis users

  12. Maximum Work of Free-Piston Stirling Engine Generators

    NASA Astrophysics Data System (ADS)

    Kojima, Shinji

    2017-04-01

    Using the method of adjoint equations described in Ref. [1], we have calculated the maximum thermal efficiencies that are theoretically attainable by free-piston Stirling and Carnot engine generators by considering the work loss due to friction and Joule heat. The net work done by the Carnot cycle is negative even when the duration of heat addition is optimized to give the maximum amount of heat addition, which is the same situation for the Brayton cycle described in our previous paper. For the Stirling cycle, the net work done is positive, and the thermal efficiency is greater than that of the Otto cycle described in our previous paper by a factor of about 2.7-1.4 for compression ratios of 5-30. The Stirling cycle is much better than the Otto, Brayton, and Carnot cycles. We have found that the optimized piston trajectories of the isothermal, isobaric, and adiabatic processes are the same when the compression ratio and the maximum volume of the same working fluid of the three processes are the same, which has facilitated the present analysis because the optimized piston trajectories of the Carnot and Stirling cycles are the same as those of the Brayton and Otto cycles, respectively.

  13. Vacuum thermal evaporation of polyaniline doped with camphor sulfonic acid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boyne, Devon; Menegazzo, Nicola; Pupillo, Rachel C.

    2015-05-15

    Intrinsically conducting polymers belong to a class of organic polymers with intriguing electronic and physical properties specifically for electro-optical applications. Significant interest into doped polyaniline (PAni) can be attributed to its high conductivity and environmental stability. Poor dissolution in most solvents has thus far hindered the successful integration of PAni into commercial applications, which in turn, has led to the investigations of various deposition and acidic doping methods. Physical vapor deposition methods, including D.C. magnetron sputtering and vacuum thermal evaporation, have shown exceptional control over physical film properties (thickness and morphology). However, resulting films are less conductive than films depositedmore » by conventional methods (i.e., spin and drop casting) due to interruption of the hyperconjugation of polymer chains. Specifically, vacuum thermal evaporation requires a postdoping process, which results in incorporation of impurities and oxidation of surface moieties. In this contribution, thermally evaporated films, sequentially doped by vacuum evaporation of an organic acid (camphorsulfonic acid, CSA) is explored. Spectroscopic evidence confirms the successful doping of PAni with CSA while physical characterization (atomic force microscopy) suggests films retain good morphology and are not damaged by the doping process. The procedure presented herein also combines other postpreparation methods in an attempt to improve conductivity and/or substrate adhesion.« less

  14. Component improvement of free-piston Stirling engine key technology for space power

    NASA Technical Reports Server (NTRS)

    Alger, Donald L.

    1988-01-01

    The successful performance of the 25 kW Space Power Demonstrator (SPD) engine during an extensive testing period has provided a baseline of free piston Stirling engine technology from which future space Stirling engines may evolve. Much of the success of the engine was due to the initial careful selection of engine materials, fabrication and joining processes, and inspection procedures. Resolution of the few SPD engine problem areas that did occur has resulted in the technological advancement of certain key free piston Stirling engine components. Derivation of two half-SPD, single piston engines from the axially opposed piston SPD engine, designated as Space Power Research (SPR) engines, has made possible the continued improvement of these engine components. The two SPR engines serve as test bed engines for testing of engine components. Some important fabrication and joining processes are reviewed. Also, some component deficiencies that were discovered during SPD engine testing are described and approaches that were taken to correct these deficiencies are discussed. Potential component design modifications, based upon the SPD and SPR engine testing, are also reported.

  15. Robot design for a vacuum environment

    NASA Technical Reports Server (NTRS)

    Belinski, S.; Trento, W.; Imani-Shikhabadi, R.; Hackwood, S.

    1987-01-01

    The cleanliness requirements for many processing and manufacturing tasks are becoming ever stricter, resulting in a greater interest in the vacuum environment. Researchers discuss the importance of this special environment, and the development of robots which are physically and functionally suited to vacuum processing tasks. Work is in progress at the Center for robotic Systems in Microelectronics (CRSM) to provide a robot for the manufacture of a revolutionary new gyroscope in high vacuum. The need for vacuum in this and other processes is discussed as well as the requirements for a vacuum-compatible robot. Finally, researchers present details on work done at the CRSM to modify an existing clean-room compatible robot for use at high vacuum.

  16. Lightweight Vacuum Jacket for Cryogenic Insulation. Volume 1

    NASA Technical Reports Server (NTRS)

    Barclay, D. L.; Bell, J. E.; Brogren, E. W.; Straayer, J. W.

    1975-01-01

    The feasibility of producing a lightweight vacuum jacket using state-of-the-art technology and materials was examined. Design and analytical studies were made on a full-scale, orbital maneuvering system fuel tank. Preliminary design details were made for the tank assembly, including an optimized vacuum jacket and multilayer insulation system. A half-scale LH2 test model was designed and fabricated, and a force/stiffness proof test was conducted on the vacuum jacket. A vacuum leak rate of .000001 atmosphere ml of helium per second was measured, approximately 1500 hours of vacuum pressure were sustained, and 29 vacuum-pressure cycles were experienced prior to failure.

  17. Recent Advances in Design of Low Cost Film Concentrator and Low Pressure Free Piston Stirling Engines for Solar Power

    NASA Technical Reports Server (NTRS)

    Kleinwaechter, J.; Kleinwaechter, H.; Beale, W.

    1984-01-01

    The free piston Stirling-linear alternator was shown to be scalable to power levels of tens of kilowatts in a form which is simple, efficient, long lived and relatively inexpensive. It avoids entirely the vexing problem of high pressure shaft, and its control requirements are not severe nor do they represent a significant threat to durability. Linear alternators have demonstrated high efficiency and moderate weight, and are capable of delivering 3 phase power from single machines without great increases of cost or complexity. There remains no apparent impediments to the commercial exploitation of the free piston engine for solar electric power generation.

  18. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K.

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  19. Atomically Thin Graphene Windows That Enable High Contrast Electron Microscopy without a Specimen Vacuum Chamber.

    PubMed

    Han, Yimo; Nguyen, Kayla X; Ogawa, Yui; Park, Jiwoong; Muller, David A

    2016-12-14

    Scanning electron microscopes (SEMs) require a high vacuum environment to generate and shape an electron beam for imaging; however, the vacuum conditions greatly limit the nature of specimens that can be examined. From a purely scattering physics perspective, it is not necessary to place the specimen inside the vacuum chamber-the mean free paths (MFPs) for electron scattering in air at typical SEM beam voltages are 50-100 μm. This is the idea behind the airSEM, which removes the specimen vacuum chamber from the SEM and places the sample in air. The thickness of the gas layer is less than a MFP from an electron-transparent window to preserve the shape and resolution of the incident beam, resulting in comparable imaging quality to an all-vacuum SEM. Present silicon nitride windows scatter far more strongly than the air gap and are currently the contrast and resolution limiting factor in the airSEM. Graphene windows have been used previously to wrap or seal samples in vacuum for imaging. Here we demonstrate the use of a robust bilayer graphene window for sealing the electron optics from the room environment, providing an electron transparent window with only a 2% drop in contrast. There is a 5-fold-increase in signal/noise ratio for imaging compared to multi-MFP-thick silicon nitride windows, enabling high contrast in backscattered, transmission, and surface imaging modes for the new airSEM geometry.

  20. Advanced 35 W Free-Piston Stirling Engine for Space Power Applications

    NASA Astrophysics Data System (ADS)

    Wood, J. Gary; Lane, Neill

    2003-01-01

    This paper presents the projected performance and overall design characteristics of a high efficiency, low mass 35 W free-piston Stirling engine design. Overall (engine plus linear alternator) thermodynamic performance greater than 50% of Carnot, with a specific power close to 100 W/kg appears to be a reasonable goal at this small power level. Supporting test data and analysis results from exiting engines are presented. Design implications of high specific power in relatively low power engines is presented and discussed.

  1. One-Dimensional Shock Wave Formation by an Accelerating Piston. Ph.D. Thesis - Ohio State Univ.

    NASA Technical Reports Server (NTRS)

    Mann, M. J.

    1970-01-01

    The formation of a shock wave by a solid accelerating piston was studied. A theoretical solution using the method of characteristics for a perfect gas showed that a complex wave system exists, and that the compressed gas can have large gradients in temperature, density and entropy. Experiments were performed with a piston tube where piston speed, shock speed and pressure were measured. The comparison of theory and experiment was good.

  2. Fluid leakage detector for vacuum applications

    NASA Technical Reports Server (NTRS)

    Nguyen, Bich Ngoc (Inventor); Farkas, Tibor (Inventor); Kim, Brian Byungkyu (Inventor)

    2002-01-01

    A leak detection system for use with a fluid conducting system in a vacuum environment, such as space, is described. The system preferably includes a mesh-like member substantially disposed about the fluid conducting system, and at least one sensor disposed within the mesh-like member. The sensor is capable of detecting a decrease in temperature of the mesh-like member when a leak condition causes the fluid of the fluid conducting system to freeze when exposed to the vacuum environment. Additionally, a signal processor in preferably in communication with the sensor. The sensor transmits an electrical signal to the signal processor such that the signal processor is capable of indicating the location of the fluid leak in the fluid conducting system.

  3. Note: A simple sample transfer alignment for ultra-high vacuum systems.

    PubMed

    Tamtögl, A; Carter, E A; Ward, D J; Avidor, N; Kole, P R; Jardine, A P; Allison, W

    2016-06-01

    The alignment of ultra-high-vacuum sample transfer systems can be problematic when there is no direct line of sight to assist the user. We present the design of a simple and cheap system which greatly simplifies the alignment of sample transfer devices. Our method is based on the adaptation of a commercial digital camera which provides live views from within the vacuum chamber. The images of the camera are further processed using an image recognition and processing code which determines any misalignments and reports them to the user. Installation has proven to be extremely useful in order to align the sample with respect to the transfer mechanism. Furthermore, the alignment software can be easily adapted for other systems.

  4. In-Vacuum Dissociator for Atomic-Hydrogen Masers

    NASA Technical Reports Server (NTRS)

    Vessot, R. F.

    1987-01-01

    Thermal control and vacuum sealing achieved while contamination avoided. Simple, relatively inexpensive molecular-hydrogen dissociator for atomic-hydrogen masers used on Earth or in vacuum of space. No air cooling required, and absence of elastomeric O-ring seals prevents contamination. In-vacuum dissociator for atomic hydrogen masers, hydrogen gas in glass dissociator dissociated by radio-frequency signal transmitted from surrounding 3-turn coil. Heat in glass conducted away by contacting metal surfaces.

  5. Transient current interruption mechanism in a magnetically delayed vacuum switch

    NASA Technical Reports Server (NTRS)

    Morris, Gibson, Jr.; Dougal, Roger A.

    1993-01-01

    The capacity of a magnetically delayed vacuum switch to conduct current depends on the density of plasma injected into the switch. Exceeding the current capacity results in the switch entering a lossy mode of operation characterized by a transient interruption of the main current (opening behavior) and a rapid increase of voltage across the vacuum gap. Streak and framing photographs of the discharge indicate that a decrease of luminosity near the middle of the gap preceeds the transition to the opening phase. The zone of low luminosity propagates toward the cathode. This evidence suggests that the mechanism causing the opening phase is erosion of the background plasma in a manner similar to that in a plasma-opening switch. The resulting ion depletion forces a space-charge-limited conduction mode. The switch inductance maintains a high discharge current even during the space-charge-limited conduction phase, thus producing high internal fields. The high accelerating voltage, in turn, produces electron and ion beams that heat the electrode surfaces. As a result of the heating, jets of electrode vapor issue from the electrodes, either cathode or anode, depending on the selection of electrode materials.

  6. Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

    NASA Astrophysics Data System (ADS)

    Bhojwani, Virendra; Inamdar, Asif; Lele, Mandar; Tendolkar, Mandar; Atrey, Milind; Bapat, Shridhar; Narayankhedkar, Kisan

    2017-04-01

    A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2.

  7. Vacuum Outgassing Behavior of Carbon Nanotube Cathode with High-Intensity Pulsed Electron Emission

    NASA Astrophysics Data System (ADS)

    Shen, Yi; Zhang, Huang; Xia, Liansheng; Liu, Xingguang; Pan, Haifeng; Lv, Lu; Yang, Anmin; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun

    2015-02-01

    Experimental investigations on the vacuum outgassing of a carbon nanotube (CNT) cathode with high-intensity pulsed electron emission on a 2 MeV linear induction accelerator injector are presented. Under the 1.60 MV diode voltage, the CNT cathode could provide 1.67 kA electron beam with the amount of outgassing of about 0.51 Pa·L. It is found that the amount of outgassing, which determines the cathode emission current, depends on the diode voltage and the vacuum.

  8. Electrical Conductivity of Partially Molten Peridotite Analogue Under Shear: Supporting Evidence to the Partial Melting Hypothesis for the Oceanic Plate Motion

    NASA Astrophysics Data System (ADS)

    Manthilake, G.; Matsuzaki, T.; Yoshino, T.; Yamazaki, D.; Yoneda, A.; Ito, E.; Katsura, T.

    2008-12-01

    So far, two hypotheses have been proposed to explain softening of the oceanic asthenosphere allowing smooth motion of the oceanic lithosphere. One is partial melting, and the other is hydraulitic weakening. Although the hydraulitic weakening hypothesis is popular recently, Yoshino et al. [2006] suggested that this hypothesis cannot explain the high and anisotropic conductivity at the top of the asthenosphere near East Pacific Rise observed by Evans et al. [2005]. In order to explain the conductivity anisotropy over one order of magnitude by the partial melting hypothesis, we measured conductivity of partially molten peridotite analogue under shear conditions. The measured samples were mixtures of forsterite and chemically simplified basalt. The samples were pre- synthesized using a piston-cylinder apparatus at 1600 K and 2 GPa to obtain textural equilibrium. The pre- synthesized samples were formed to a disk with 3 mm in diameter and 1 mm in thickness. Conductivity measurement was carried out also at 1600 K and 2 GPa in a cubic-anvil apparatus with an additional uniaxial piston. The sample was sandwiched by two alumina pistons whose top was cut to 45 degree slope to generate shear. The shear strain rates of the sample were calibrated using a Mo strain marker in separate runs. The lower alumina piston was pushed by a tungsten carbide piston embedded in a bottom anvil with a constant speed. Conductivity was measured in the directions normal and parallel to the shear direction simultaneously. We mainly studied the sample with 1.6 volume percent of basaltic component. The shear strain rates were 0, 1.2x10(-6) and 5.2x10(-6) /s. The sample without shear did not show conductivity anisotropy. In contrast, the samples with shear showed one order of magnitude higher conductivity in the direction parallel to the shear than that normal to the shear. After the total strains reached 0.3, the magnitude of anisotropy became almost constant for both of the strain rates. The

  9. Piston rod seal for a Stirling engine

    DOEpatents

    Shapiro, Wilbur

    1984-01-01

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

  10. Experimental studies on twin PTCs driven by dual piston head linear compressor

    NASA Astrophysics Data System (ADS)

    Gour, Abhay S.; Joy, Joewin; Sagar, Pankaj; Sudharshan, H.; Mallappa, A.; Karunanithi, R.; Jacob, S.

    2017-02-01

    An experimental study on pulse tube cryocooler is presented with a twin pulse tube configuration. The study is conducted with a dual piston head linear compressor design which is developed indigenously. The two identical pulse tube cryocoolers are operated by a single linear motor which generates 1800 out of phase dual pressure waves. The advantages of the configuration being the reduction in fabrication cost and the increased cooling power. The compressor is driven at a frequency of 48 Hz using indigenously developed PWM based power supply. The CFD study of pulse tube cryocooler is discussed along with the experimental cool down results. A detailed experimental and FEM based studies on the fabrication procedure of heat exchangers is conducted to ensure better heat transfer in the same.

  11. Fatigue Analysis of the Piston Rod in a Kaplan Turbine Based on Crack Propagation under Unsteady Hydraulic Loads

    NASA Astrophysics Data System (ADS)

    Liu, X.; Y Luo, Y.; Wang, Z. W.

    2014-03-01

    As an important component of the blade-control system in Kaplan turbines, piston rods are subjected to fluctuating forces transferred by the turbines blades from hydraulic pressure oscillations. Damage due to unsteady hydraulic loads might generate unexpected down time and high repair cost. In one running hydropower plant, the fracture failure of the piston rod was found twice at the same location. With the transient dynamic analysis, the retainer ring structure of the piston rod existed a relative high stress concentration. This predicted position of the stress concentration agreed well with the actual fracture position in the plant. However, the local strain approach was not able to explain why this position broke frequently. Since traditional structural fatigue analyses use a local stress strain approach to assess structural integrity, do not consider the effect of flaws which can significantly degrade structural life. Using linear elastic fracture mechanism (LEFM) approaches that include the effect of flaws is becoming common practice in many industries. In this research, a case involving a small semi-ellipse crack was taken into account at the stress concentration area, crack growth progress was calculated by FEM. The relationship between crack length and remaining life was obtained. The crack propagation path approximately agreed with the actual fracture section. The results showed that presence of the crack had significantly changed the local stress and strain distributions of the piston rod compared with non-flaw assumption.

  12. Progress update of NASA's free-piston Stirling space power converter technology project

    NASA Technical Reports Server (NTRS)

    Dudenhoefer, James E.; Winter, Jerry M.; Alger, Donald

    1992-01-01

    A progress update is presented of the NASA LeRC Free-Piston Stirling Space Power Converter Technology Project. This work is being conducted under NASA's Civil Space Technology Initiative (CSTI). The goal of the CSTI High Capacity Power Element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space initiatives. Efforts are focused upon increasing system power output and system thermal and electric energy conversion efficiency at least five fold over current SP-100 technology, and on achieving systems that are compatible with space nuclear reactors. This paper will discuss progress toward 1050 K Stirling Space Power Converters. Fabrication is nearly completed for the 1050 K Component Test Power Converter (CTPC); results of motoring tests of the cold end (525 K), are presented. The success of these and future designs is dependent upon supporting research and technology efforts including heat pipes, bearings, superalloy joining technologies, high efficiency alternators, life and reliability testing, and predictive methodologies. This paper will compare progress in significant areas of component development from the start of the program with the Space Power Development Engine (SPDE) to the present work on CTPC.

  13. An autonomous single-piston engine with a quantum rotor

    NASA Astrophysics Data System (ADS)

    Roulet, Alexandre; Nimmrichter, Stefan; Taylor, Jacob M.

    2018-07-01

    Pistons are elementary components of a wide variety of thermal engines, allowing to convert input fuel into rotational motion. Here, we propose a single-piston engine where the rotational degree of freedom is effectively realized by the flux of a Josephson loop—a quantum rotor—while the working volume corresponds to the effective length of a superconducting resonator. Our autonomous design implements a Carnot cycle, relies solely on standard thermal baths and can be implemented with circuit quantum electrodynamics. We demonstrate how the engine is able to extract a net positive work via its built-in synchronicity using a filter cavity as an effective valve, eliminating the need for external control.

  14. Free-piston driver performance characterisation using experimental shock speeds through helium

    NASA Astrophysics Data System (ADS)

    Gildfind, D. E.; James, C. M.; Morgan, R. G.

    2015-03-01

    Tuned free-piston driver operation involves configuring the driver to produce a relatively steady blast of driver gas over the critical time scales of the experiment. For the purposes of flow condition development and parametric studies, it is useful to establish some average working values of the driver pressure and temperature for a given driver operating condition. However, in practise, these averaged values need to produce sufficiently accurate estimates of performance. In this study, two tuned driver conditions in the X2 expansion tube have been used to generate shock waves through a helium test gas. The measured shock speeds have then been used to calculate the effective driver gas pressure and temperature after diaphragm rupture. Since the driver gas is typically helium, or a mixture of helium and argon, and the test gas is also helium, ideal gas assumptions can be made without significant loss of accuracy. The technique is applicable to tuned free-piston drivers with a simple area change, as well as those using orifice plates. It is shown that this technique can be quickly used to establish average working driver gas properties which produce very good estimates of actual driven shock speed, across a wide range of operating conditions. The use of orifice plates to control piston dynamics at high driver gas sound speeds is also discussed in the paper, and a simple technique for calculating the restriction required to modify an established safe condition for use with lighter gases, such as pure helium, is presented.

  15. A high-performance, flexible and robust metal nanotrough-embedded transparent conducting film for wearable touch screen panels.

    PubMed

    Im, Hyeon-Gyun; An, Byeong Wan; Jin, Jungho; Jang, Junho; Park, Young-Geun; Park, Jang-Ung; Bae, Byeong-Soo

    2016-02-21

    We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband.

  16. Technical Trend of Environment-friendly High Voltage Vacuum Circuit Breaker (VCB)

    NASA Astrophysics Data System (ADS)

    Okubo, Hitoshi

    Vacuum Circuit Breakers (VCBs) have widely been used for low and medium voltage level, because of their high current interruption performance, maintenance free operations and environment-friendly characteristics. The VCB is now going to be applied to higher voltage systems for transmission and substation use. In this paper, the recent technical trend and future perspectives of high voltage VCBs are described, as well as their technical background.

  17. Evaporation in equilibrium, in vacuum, and in hydrogen gas

    NASA Technical Reports Server (NTRS)

    Nagahara, Hiroko

    1993-01-01

    Evaporation experiments were conducted for SiO2 in three different conditions: in equilibrium, in vacuum, and in hydrogen gas. Evaporation rate in vacuum is about two orders of magnitude smaller than that in equilibrium, which is consistent with previous works. The rate in hydrogen gas changes depending on hydrogen pressure. The rate at 10 exp -7 bar of hydrogen pressure is as small as that of free evaporation, but at 10 exp -5 bar of hydrogen pressure it is larger than that in equilibrium. In equilibrium and in vacuum, the evaporation rate is limited by decomposition of SiO2 on the crystal surface, but it is limited by a diffusion process for evaporation in hydrogen gas. Therefore, evaporation rate of minerals in the solar nebula can be shown neither by that in equilibrium nor by that in vacuum. The maximum temperature of the solar nebula at the midplane at 2-3 AU where chondrites are believed to have originated is calculated to be as low as 150 K, 1500 K, or in between them. The temperature is, in any case, not high enough for total evaporation of the interstellar materials. Therefore, evaporation of interstellar materials is one of the most important processes for the origin and fractionation of solid materials. The fundamental process of evaporation of minerals has been intensively studied for these several years. Those experiments were carried out either in equilibrium or in vacuum; however, evaporation in the solar nebula is in hydrogen (and much smaller amount of helium) gas. In order to investigate evaporation rate and compositional (including isotopic) fractionation during evaporation, vaporization experiments for various minerals in various conditions are conducted. At first, SiO2 was adopted for a starting material, because thermochemical data and its nature of congruent vaporization are well known. Experiments were carried out in a vacuum furnace system.

  18. Surface Effects and Challenges for Application of Piezoelectric Langasite Substrates in Surface Acoustic Wave Devices Caused by High Temperature Annealing under High Vacuum.

    PubMed

    Seifert, Marietta; Rane, Gayatri K; Kirbus, Benjamin; Menzel, Siegfried B; Gemming, Thomas

    2015-12-19

    Substrate materials that are high-temperature stable are essential for sensor devices which are applied at high temperatures. Although langasite is suggested as such a material, severe O and Ga diffusion into an O-affine deposited film was observed during annealing at high temperatures under vacuum conditions, leading to a damage of the metallization as well as a change of the properties of the substrate and finally to a failure of the device. Therefore, annealing of bare LGS (La 3 Ga 5 SiO 14 ) substrates at 800 ∘ C under high vacuum conditions is performed to analyze whether this pretreatment improves the suitability and stability of this material for high temperature applications in vacuum. To reveal the influence of the pretreatment on the subsequently deposited metallization, RuAl thin films are used as they are known to oxidize on LGS at high temperatures. A local study of the pretreated and metallized substrates using transmission electron microscopy reveals strong modification of the substrate surface. Micro cracks are visible. The composition of the substrate is strongly altered at those regions. Severe challenges for the application of LGS substrates under high-temperature vacuum conditions arise from these substrate damages, revealing that the pretreatment does not improve the applicability.

  19. Cooling the Motion of Diamond Nanocrystals in a Magneto-Gravitational Trap in High Vacuum.

    PubMed

    Hsu, Jen-Feng; Ji, Peng; Lewandowski, Charles W; D'Urso, Brian

    2016-07-22

    Levitated diamond nanocrystals with nitrogen-vacancy (NV) centres in high vacuum have been proposed as a unique system for experiments in fundamental quantum mechanics, including the generation of large quantum superposition states and tests of quantum gravity. This system promises extreme isolation from its environment while providing quantum control and sensing through the NV centre spin. While optical trapping has been the most explored method of levitation, recent results indicate that excessive optical heating of the nanodiamonds under vacuum may make the method impractical with currently available materials. Here, we study an alternative magneto-gravitational trap for diamagnetic particles, such as diamond nanocrystals, with stable levitation from atmospheric pressure to high vacuum. Magnetic field gradients from permanent magnets confine the particle in two dimensions, while confinement in the third dimension is gravitational. We demonstrate that feedback cooling of the centre-of-mass motion of a trapped nanodiamond cluster results in cooling of one degree of freedom to less than 1 K.

  20. Cooling the motion of diamond nanocrystals in a magneto-gravitational trap in high vacuum

    DOE PAGES

    Hsu, Jen -Feng; Ji, Peng; Lewandowski, Charles W.; ...

    2016-07-22

    Levitated diamond nanocrystals with nitrogen-vacancy (NV) centres in high vacuum have been proposed as a unique system for experiments in fundamental quantum mechanics, including the generation of large quantum superposition states and tests of quantum gravity. This system promises extreme isolation from its environment while providing quantum control and sensing through the NV centre spin. While optical trapping has been the most explored method of levitation, recent results indicate that excessive optical heating of the nanodiamonds under vacuum may make the method impractical with currently available materials. Here, we study an alternative magneto-gravitational trap for diamagnetic particles, such as diamondmore » nanocrystals, with stable levitation from atmospheric pressure to high vacuum. Magnetic field gradients from permanent magnets confine the particle in two dimensions, while confinement in the third dimension is gravitational. Furthermore, we demonstrate that feedback cooling of the centre-of-mass motion of a trapped nanodiamond cluster results in cooling of one degree of freedom to less than 1 K.« less

  1. Cooling the Motion of Diamond Nanocrystals in a Magneto-Gravitational Trap in High Vacuum

    PubMed Central

    Hsu, Jen-Feng; Ji, Peng; Lewandowski, Charles W.; D’Urso, Brian

    2016-01-01

    Levitated diamond nanocrystals with nitrogen-vacancy (NV) centres in high vacuum have been proposed as a unique system for experiments in fundamental quantum mechanics, including the generation of large quantum superposition states and tests of quantum gravity. This system promises extreme isolation from its environment while providing quantum control and sensing through the NV centre spin. While optical trapping has been the most explored method of levitation, recent results indicate that excessive optical heating of the nanodiamonds under vacuum may make the method impractical with currently available materials. Here, we study an alternative magneto-gravitational trap for diamagnetic particles, such as diamond nanocrystals, with stable levitation from atmospheric pressure to high vacuum. Magnetic field gradients from permanent magnets confine the particle in two dimensions, while confinement in the third dimension is gravitational. We demonstrate that feedback cooling of the centre-of-mass motion of a trapped nanodiamond cluster results in cooling of one degree of freedom to less than 1 K. PMID:27444654

  2. High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope.

    PubMed

    Fang, Yurui; Zhang, Zhenglong; Sun, Mengtao

    2016-03-01

    In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10(-7) Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 × 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.

  3. High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fang, Yurui; Bionanophotonics, Department of Applied Physics, Chalmers University of Technology, Göteborg, SE 41296; Zhang, Zhenglong

    2016-03-15

    In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10{sup −7} Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 ×more » 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.« less

  4. High specific surface area aerogel cryoadsorber for vacuum pumping applications

    DOEpatents

    Hill, Randal M.; Fought, Eric R.; Biltoft, Peter J.

    2000-01-01

    A cryogenic pumping system is provided, comprising a vacuum environment, an aerogel sorbent formed from a carbon aerogel disposed within the vacuum environment, and cooling means for cooling the aerogel sorbent sufficiently to adsorb molecules from the vacuum environment onto the aerogel sorbent. Embodiments of the invention include a liquid refrigerant cryosorption pump, a compressed helium cryogenic pump, a cryopanel and a Meissner coil, each of which uses carbon aerogel as a sorbent material.

  5. Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Man; Choi, Jang-Young; Lee, Kyu-Seok; Lee, Sung-Ho

    2017-05-01

    This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.

  6. GDP: A new source for shallow high-resolution seismic exploration

    NASA Astrophysics Data System (ADS)

    Rashed, Mohamed A.

    2009-06-01

    Gas-Driven Piston (GDP) is a new source for shallow seismic exploration. This source works by igniting a small amount of gas inside a closed chamber connected to a vertical steel cylinder. The gas explosion drives a steel piston, mounted inside the cylinder, downward so that the piston's thick head hits a steel base at the end of the cylinder generating a strong shock wave into the ground. Experimental field tests conducted near Ismailia, Egypt, prove that the portable, inexpensive and environmentally benign GDP generates stronger seismic waves than the sledgehammer that is commonly used in shallow seismic exploration. Tests also show that GDP is a highly repeatable and controllable and that its seismic waves contain a good amount of high frequencies which makes the GDP an excellent source for shallow seismic exploration.

  7. Gas-enabled resonance and rectified motion of a piston in a vibrated housing filled with a viscous liquid

    DOE PAGES

    Romero, Louis A.; Torczynski, John R.; Clausen, Jonathan R.; ...

    2015-11-16

    Herein, we show how introducing a small amount of gas can completely change the motion of a solid object in a viscous liquid during vibration. We analyze an idealized system exhibiting this behavior: a piston moving in a liquid-filled housing, where the gaps between the piston and the housing are narrow and depend on the piston position. Recent experiments have shown that vibration causes some gas to move below the piston and the piston to subsequently move downward and compress its supporting spring. Herein, we analyze the analogous but simpler situation in which the gas regions are replaced by bellowsmore » with similar pressure-volume relationships. We show that these bellows form a spring (analogous to the pneumatic spring formed by the gas regions) which enables the piston and the liquid to oscillate in a mode that does not exist without this spring. This mode is referred to here as the Couette mode because the liquid in the gaps moves essentially in Couette flow (i.e., with almost no component of Poiseuille flow). Since Couette flow by itself produces extremely low damping, the Couette mode has a strong resonance. We show that, near this resonance, the dependence of the gap geometry on the piston position produces a large rectified (net) force on the piston during vibration. As a result, this force can be much larger than the piston weight and the strength of its supporting spring and is in the direction that decreases the flow resistance of the gap geometry.« less

  8. Influence of pellet seating on the external ballistic parameters of spring-piston air guns.

    PubMed

    Werner, Ronald; Schultz, Benno; Frank, Matthias

    2016-09-01

    In firearm examiners' and forensic specialists' casework as well as in air gun proof testing, reliable measurement of the weapon's muzzle velocity is indispensable. While there are standardized and generally accepted procedures for testing the performance of air guns, the method of seating the diabolo pellets deeper into the breech of break barrel spring-piston air guns has not found its way into standardized test procedures. The influence of pellet seating on the external ballistic parameters was investigated using ten different break barrel spring-piston air guns. Test shots were performed with the diabolo pellets seated 2 mm deeper into the breech using a pellet seater. The results were then compared to reference shots with conventionally loaded diabolo pellets. Projectile velocity was measured with a high-precision redundant ballistic speed measurement system. In eight out of ten weapons, the muzzle energy increased significantly when the pellet seater was used. The average increase in kinetic energy was 31 % (range 9-96 %). To conclude, seating the pellet even slightly deeper into the breech of spring-piston air guns might significantly alter the muzzle energy. Therefore, it is strongly recommended that this effect is taken into account when accurate and reliable measurements of air gun muzzle velocity are necessary.

  9. Research on influence of different cover to the characteristic of FBG reflectance spectrum in vacuum thermal environment

    NASA Astrophysics Data System (ADS)

    Pei, Yifei; Zhang, Jingchuan; Zhang, Luosha; Liu, Yang; Zhang, Lina; Chen, Shiyu

    2018-01-01

    To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, two different kinds of sleeve compactly single model fiber covered by acrylate and polyimide are researched. Influence of the cover to the characteristic of FBG reflectance spectrum in high vacuum thermal environment is analyzed and verified. First, transmission characteristic of single model fiber in high vacuum thermal environment is analyzed by solve the equation of heat conduction. Then, experimental program of influence on FBG reflection spectrum characteristics is designed and a hardware-in-the-loop detection platform is set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG in different coating single-mode transmission fiber under high vacuum thermal environment is studied and verified. Experimental results indicate that: when vacuum varied from normal pressure to 10-4Pa level and then return to normal pressure, temperature of two different coating single-mode transmission fiber dropped to -196 ° from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provided the theoretical and experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4Pa level) and thermal environment (-196 ° 25 ° temperature cycle) .

  10. Aircraft Piston Engine Exhaust Emission Symposium

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A 2-day symposium on the reduction of exhaust emissions from aircraft piston engines was held on September 14 and 15, 1976, at the Lewis Research Center in Cleveland, Ohio. Papers were presented by both government organizations and the general aviation industry on the status of government contracts, emission measurement problems, data reduction procedures, flight testing, and emission reduction techniques.

  11. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces

    NASA Astrophysics Data System (ADS)

    Wilmsmeyer, Amanda R.; Gordon, Wesley O.; Davis, Erin Durke; Mantooth, Brent A.; Lalain, Teri A.; Morris, John R.

    2014-01-01

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry to study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications.

  12. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces.

    PubMed

    Wilmsmeyer, Amanda R; Gordon, Wesley O; Davis, Erin Durke; Mantooth, Brent A; Lalain, Teri A; Morris, John R

    2014-01-01

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry to study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications.

  13. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wilmsmeyer, Amanda R.; Morris, John R.; Gordon, Wesley O.

    2014-01-15

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry tomore » study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications.« less

  14. Development of Sub-Ischial Prosthetic Sockets with Vacuum-Assisted Suspension for Highly Active Persons with Transfemoral Amputations

    DTIC Science & Technology

    2013-10-01

    15. SUBJECT TERMS Transfemoral amputation, sub-ischial socket, prosthesis , vacuum-assisted suspension 16. SECURITY CLASSIFICATION OF: 17...vacuum for suspension of the prosthesis ...14 Task 6 Determine range of volumes to be evacuated from transfemoral sockets of highly active prosthesis users

  15. Laser-induced electron source in a vacuum diode

    NASA Astrophysics Data System (ADS)

    Ghera, U.; Boxman, R. L.; Kleinman, H.; Ruschin, S.

    1989-11-01

    Experiments were conducted in which a high-power CO2 TEA laser interacted with metallic cathode in a high-vacuum (10 to the -8th Torr) diode. For power densities lower than 5 x 10 to the 7th W/sq cm, no current was detected. For power densities in the range of 5 x 10 to the 7th to 5 x 10 to the 8th W/sq cm, the Cu cathode emitted a maximum current of 40 mA. At a higher power density level, a circuit-limited current of 8 A was detected. The jump of a few orders of magnitude in the current is attributed to breakdown of the diode gap. The experimental results are similar to those of a triggered vacuum gap, and a thorough comparison is presented in this paper. The influence of the pressure in the vacuum chamber on the current magnitude shows the active role that adsorbed gas molecules have in the initial breakdown. When the cathode material was changed from metal to metal oxide, much lower laser power densities were required to reach the breakdown current region.

  16. The adiabatic piston: a perpetuum mobile in the mesoscopic realm

    NASA Astrophysics Data System (ADS)

    Crosignani, Bruno; Porto, Paolo; Conti, Claudio

    2004-03-01

    A detailed analysis of the adiabatic-piston problem reveals, for a finely-tuned choice of the spatial dimensions of the system, peculiar dynamical features that challenge the statement that an isolated system necessarily reaches a time-independent equilibrium state. In particular, the piston behaves like a perpetuum mobile, i.e., it never comes to a stop but keeps wandering, undergoing sizeable oscillations around the position corresponding to maximum entropy; this has remarkable implications on the entropy changes of a mesoscopic isolated system and on the limits of validity of the second law of thermodynamics in the mesoscopic realm.

  17. The Friction of Piston Rings

    NASA Technical Reports Server (NTRS)

    Tischbein, Hans W

    1945-01-01

    The coefficient of friction between piston ring and cylinder liner was measured in relation to gliding acceleration, pressure, temperature, quantity of oil and quality of oil. Comparing former lubrication-technical tests, conclusions were drawn as to the state of friction. The coefficients of friction as figured out according to the hydrodynamic theory were compared with those measured by tests. Special tests were made on "oiliness." The highest permissible pressure was measured and the ratio of pressure discussed.

  18. Thermocouples of tantalum and rhenium alloys for more stable vacuum-high temperature performance

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1977-01-01

    Thermocouples of the present invention provide stability and performance reliability in systems involving high temperatures and vacuums by employing a bimetallic thermocouple sensor wherein each metal of the sensor is selected from a group of metals comprising tantalum and rhenium and alloys containing only those two metals. The tantalum, rhenium thermocouple sensor alloys provide bare metal thermocouple sensors having advantageous vapor pressure compatibilities and performance characteristics. The compatibility and physical characteristics of the thermocouple sensor alloys of the present invention result in improved emf, temperature properties and thermocouple hot junction performance. The thermocouples formed of the tantalum, rhenium alloys exhibit reliability and performance stability in systems involving high temperatures and vacuums and are adaptable to space propulsion and power systems and nuclear environments.

  19. Wide band cryogenic ultra-high vacuum microwave absorber

    DOEpatents

    Campisi, I.E.

    1992-05-12

    An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

  20. Wide band cryogenic ultra-high vacuum microwave absorber

    DOEpatents

    Campisi, Isidoro E.

    1992-01-01

    An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

  1. In-cylinder flows of a motored four-stroke engine with flat-crown and slightly concave-crown pistons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, R.F.; Yang, H.S.; Yeh, C.-N.

    2008-04-15

    The temporal and spatial evolution processes of the in-cylinder flow structures and turbulence intensities in the symmetry and offset planes of a motored four-valve, four-stroke engine during the intake and compression strokes are diagnosed by using a particle image velocimeter. Two pistons of different crown shapes (flat-crown and slightly concave-crown pistons) are studied. The inception, establishment, and evolution of the tumbling vortical flow structures during the intake and compression strokes are clearly depicted. Quantitative strengths of the rotating vortical flow motions are presented by a dimensionless parameter, the tumble ratio, which can represent the mean angular velocity of the vorticesmore » in the target plane. The turbulence intensity of the in-cylinder flow is also calculated by using the measured time-varying velocity data. The results show that the flat-crown piston induces higher bulk-averaged tumble ratio and turbulence intensity than the slightly concave-crown piston does because the tumble ratio and turbulence generated by the flat-crown piston in the offset planes during the compression stroke are particularly large. The engine with the flat-crown piston also presents larger torque and power outputs and lower hydrocarbon emission than that with the slightly concave-crown piston. This might be caused by the enhanced combustion in the engine cylinder due to the stronger tumble ratio and turbulence intensity. (author)« less

  2. Vacuum force

    NASA Astrophysics Data System (ADS)

    Han, Yongquan

    2015-03-01

    To study on vacuum force, we must clear what is vacuum, vacuum is a space do not have any air and also ray. There is not exist an absolute the vacuum of space. The vacuum of space is relative, so that the vacuum force is relative. There is a certain that vacuum vacuum space exists. In fact, the vacuum space is relative, if the two spaces compared to the existence of relative vacuum, there must exist a vacuum force, and the direction of the vacuum force point to the vacuum region. Any object rotates and radiates. Rotate bend radiate- centripetal, gravity produced, relative gravity; non gravity is the vacuum force. Gravity is centripetal, is a trend that the objects who attracted wants to Centripetal, or have been do Centripetal movement. Any object moves, so gravity makes the object curve movement, that is to say, the radiation range curve movement must be in the gravitational objects, gravity must be existed in non vacuum region, and make the object who is in the region of do curve movement (for example: The earth moves around the sun), or final attracted in the form gravitational objects, and keep relatively static with attract object. (for example: objects on the earth moves but can't reach the first cosmic speed).

  3. Air bearing vacuum seal assembly

    DOEpatents

    Booth, Rex

    1978-01-01

    An air bearing vacuum seal assembly capable of rotating at the speed of several thousand revolutions per minute using an air cushion to prevent the rotating and stationary parts from touching, and a two stage differential pumping arrangement to maintain the pressure gradient between the air cushion and the vacuum so that the leak rate into the vacuum is, for example, less than 1 .times. 10.sup.-4 Pa m.sup.3 /s. The air bearing vacuum seal has particular application for mounting rotating targets to an evacuated accelerator beam tube for bombardment of the targets with high-power charged particle beams in vacuum.

  4. Investigation of high-voltage pulse trigger generator based on photo-conductive semiconductor switch

    NASA Astrophysics Data System (ADS)

    Chu, Xu; Liu, Jin-Liang; Wang, Lang-Ning; Qiu, Yong-Feng

    2018-06-01

    The trigger to generate high-voltage pulse is one of the most important parts in a pulsed-power system, especially for the conduction characteristics of the main switch. However, traditional triggers usually have the drawbacks of large structure and worse long-term working stability, which goes against the demands of pulsed-power system miniaturization and stability. In the paper, a pulse trigger using photo-conductive semiconductor switch was developed, which is of small size, stable performance and steep leading edge of the output pulse rise. It is found that the output trigger pulse rise time is 14 ns, and the jitter of 20 shots is 330 ps. Applying the designed pulsed trigger in a field distortion switch and a triggered vacuum switch, experiments show that the switches could be triggered stably with reduced jitter.

  5. Enhanced Photocatalytic Activity of Vacuum-activated TiO2 Induced by Oxygen Vacancies.

    PubMed

    Dong, Guoyan; Wang, Xin; Chen, Zhiwu; Lu, Zhenya

    2018-05-01

    TiO 2 (Degussa P25) photocatalysts harboring abundant oxygen vacancies (Vacuum P25) were manufactured using a simple and economic Vacuum deoxidation process. Control experiments showed that temperature and time of vacuum deoxidation had a significant effect on Vacuum P25 photocatalytic activity. After 240 min of visible light illumination, the optimal Vacuum P25 photocatalysts (vacuum deoxidation treated at 330 °C for 3 h) reach as high as 94% and 88% of photodegradation efficiency for rhodamine B (RhB) and tetracycline, respectively, which are around 4.5 and 4.9 times as that of pristine P25. The XPS, PL and EPR analyses indicated that the oxygen vacancies were produced in the Vacuum P25 during the vacuum deoxidation process. The oxygen vacancy states can produce vacancy energy level located below the conduction band minimum, which resulting in the bandgap narrowing, thus extending the photoresponse wavelength range of Vacuum P25. The positron annihilation analysis indicated that the concentrations ratio of bulk and surface oxygen vacancies could be adjusted by changing the vacuum deoxidation temperature and time. Decreasing the ratio of bulk and surface oxygen vacancies was shown to improve photogenerated electron-hole pair separation efficiency, which leads to an obvious enhancement of the visible photocatalytic activities of Vacuum P25. © 2017 The American Society of Photobiology.

  6. Vacuum-Induction, Vacuum-Arc, and Air-Induction Melting of a Complex Heat-Resistant Alloy

    NASA Technical Reports Server (NTRS)

    Decker, R. F.; Rowe, John P.; Freeman, J. W.

    1959-01-01

    The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and/or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking and improve surface during hot-rolling. It also resulted in more uniform properties within heats. The creep-rupture properties were slightly superior in vacuum heats at low boron plus zirconium or in heats with zirconium. There was little advantage at high boron levels and air heats were superior at high levels of boron plus zirconium. Vacuum heats also had fewer oxide and carbonitride inclusions although this was a function of the opportunity for separation of the inclusions from high oxygen plus nitrogen heats. The removal of phosphorous by vacuum melting was not found to be related to properties. Oxygen plus nitrogen appeared to increase ductility in creep-rupture tests suggesting that vacuum melting removes unidentified elements detrimental to ductility. Oxides and carbonitrides in themselves did not initiate microcracks. Carbonitrides in the grain boundaries of air heats did initiate microcracks. The role of microcracking from this source and as a function of oxygen and nitrogen content was not clear. Oxygen and nitrogen did intensify corner cracking during hot-rolling but were not responsible for poor surface which resulted from rolling heats melted in air.

  7. Thermophysical Properties of Cold- and Vacuum Plasma-Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings I: Electrical and Thermal Conductivity, Thermal Diffusivity, and Total Hemispherical Emissivity

    NASA Astrophysics Data System (ADS)

    Raj, S. V.

    2017-11-01

    This two-part paper reports the thermophysical properties of several cold- and vacuum plasma-sprayed monolithic Cu- and Ni-based alloy coatings. Part I presents the electrical and thermal conductivity, thermal diffusivity, and total hemispherical emissivity data, while Part II reports the specific heat capacity data for these coatings. Metallic copper alloys and stoichiometric NiAl and NiCrAlY coatings were fabricated by either the cold spray or the vacuum plasma spray deposition processes for thermal property measurements between 77 and 1223 K. The temperature dependencies of the thermal conductivities, thermal diffusivities, electrical conductivities, and total hemispherical emissivities of these cold- and vacuum-sprayed monolithic coatings are reported in this paper. The electrical and thermal conductivity data correlate reasonably well for Cu-8%Cr-1%Al, Cu-23%Cr-5%Al, and NiAl in accordance with the Wiedemann-Franz (WF) law although a better fit is obtained using the Smith-Palmer relationship. The Lorentz numbers determined from the WF law are close to the theoretical value.

  8. High Performance Variable Emittance Devices for Spacecraft Application Based on Conducting Polymers Coupled with Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, Prasanna; Zay, Brian J.; Barbolt, Scott; Werner, Robert; Birur, Gajanana C.; Paris, Anthony

    2009-03-01

    This contribution describes the fabrication, function and performance of thin-film variable emittance electrochromic skins fabricated using poly(aniline) as the conducting polymer (CP), a long-chain polymeric dopant, and an ionic liquid as electrolyte. The ionic electrolyte allows operation in space vacuum without any seals. A unique, space-durable coating applied to the external surface of the skins drastically lowers the solar absorptance of the skins, such that in their dark (highly emissive) electrochromic state, it is no more than 0.44, whilst in their light electrochromic state, it is ca. 0.3. Data presented show tailorable, variations from 0.19 to 0.90, ∀(s)<0.3, and nearly indefinite cyclability. Extended thermal vacuum, atomic-O, micrometeoroid, VUV and other studies show excellent space durability. Performance of a doughnut-shaped skin designed for a specific micro-spacecraft is also described.

  9. A thin polymer membrane, nano-suit, enhancing survival across the continuum between air and high vacuum

    PubMed Central

    Takaku, Yasuharu; Suzuki, Hiroshi; Ohta, Isao; Ishii, Daisuke; Muranaka, Yoshinori; Shimomura, Masatsugu; Hariyama, Takahiko

    2013-01-01

    Most multicellular organisms can only survive under atmospheric pressure. The reduced pressure of a high vacuum usually leads to rapid dehydration and death. Here we show that a simple surface modification can render multicellular organisms strongly tolerant to high vacuum. Animals that collapsed under high vacuum continued to move following exposure of their natural extracellular surface layer (or that of an artificial coat-like polysorbitan monolaurate) to an electron beam or plasma ionization (i.e., conditions known to enhance polymer formation). Transmission electron microscopic observations revealed the existence of a thin polymerized extra layer on the surface of the animal. The layer acts as a flexible “nano-suit” barrier to the passage of gases and liquids and thus protects the organism. Furthermore, the biocompatible molecule, the component of the nano-suit, was fabricated into a “biomimetic” free-standing membrane. This concept will allow biology-related fields especially to use these membranes for several applications. PMID:23589878

  10. Tilt/Tip/Piston Manipulator with Base-Mounted Actuators

    NASA Technical Reports Server (NTRS)

    Tahmasebi, Farhad

    2006-01-01

    A proposed three-degree-of-freedom (tilt/tip/piston) manipulator, suitable for aligning an optical or mechanical component, would offer several advantages over prior such manipulators: Unlike in some other manipulators, no actuator would support the weight of another actuator: All of the actuators would be mounted on a base. Hence, there would be less manipulated weight. The basic geometry of the manipulator would afford mechanical advantage: that is, actuator motions would be larger than the motions they produce in the manipulated object. Mechanical advantage inherently increases the accuracy and resolution of manipulation. Unlike in some other manipulators, it would not be necessary to route power and/or data lines through manipulator joints. The proposed manipulator (see figure) would include three prismatic actuators (T1N1, T2N2, and T3N3) mounted on the base and operating in the same plane. Examples of suitable prismatic actuators include lead-screw mechanisms, linear hydraulic motors, piezoelectric linear drives, inchworm-movement linear stepping motors, and linear flexure drives. The actuators would control the lengths of links R1T1, R2T2, and R3T3. Three spherical joints (P1, P2, and P3) would be located at the corners of an equilateral triangle of side length q on the platform holding the object to be manipulated. Three inextensible limbs (R1P1, R2P2, and R3P3) having length r would connect the spherical joints on the platform to revolute joints (R1, R2, and R3) at the ends of the actuator-controlled links R1T1, R2T2, and R3T3. By varying the lengths of these links, one could control the tilt, tip, and piston coordinates of the platform. Closed-form equations for direct or forward kinematics of the manipulator (given the lengths of the variable links, find the tilt, tip, and piston coordinates) have been derived. The equations of inverse kinematics (find the variable link lengths needed to obtain the desired tilt, tip, and piston coordinates) have also

  11. Development of Electronic Load Controllers for Free-Piston Stirling Convertors Aided by Stirling Simulation Model

    NASA Technical Reports Server (NTRS)

    Regan, Timothy F.

    2004-01-01

    The free-piston Stirling convertor end-to-end modeling effort at the NASA Glenn Research Center has produced a software-based test bed in which free-piston Stirling convertors can be simulated and evaluated. The simulation model includes all the components of the convertor: the Stirling cycle engine, heat source, linear alternator, controller, and load. So far, it has been used in evaluating the performance of electronic controller designs. Three different controller design concepts were simulated using the model: 1) Controllers with parasitic direct current loading. 2) Controllers with parasitic alternating current loading. 3) Controllers that maintain a reference current. The free-piston Stirling convertor is an electromechanical device that operates at resonance. It is the function of the electronic load controller to ensure that the electrical load seen by the machine is always great enough to keep the amplitude of the piston and alternator oscillation at the rated value. This is done by regulating the load on the output bus. The controller monitors the instantaneous voltage, regulating it by switching loads called parasitic loads onto the bus whenever the bus voltage is too high and removing them whenever the voltage is too low. In the first type of controller, the monitor-ing and switching are done on the direct-current (dc) bus. In the second type, the alternating current bus is used. The model allows designers to test a controller concept before investing time in hardware. The simulation code used to develop the model also offers detailed models of digital and analog electronic components so that the resulting designs are realistic enough to translate directly into hardware circuits.

  12. High Vacuum Creep Facility in the Materials Processing Laboratory

    NASA Image and Video Library

    1973-01-21

    Technicians at work in the Materials Processing Laboratory’s Creep Facility at the National Aeronautics and Space Administration (NASA) Lewis Research Center. The technicians supported the engineers’ studies of refractory materials, metals, and advanced superalloys. The Materials Processing Laboratory contained laboratories and test areas equipped to prepare and develop these metals and materials. The ultra-high vacuum lab, seen in this photograph, contained creep and tensile test equipment. Creep testing is used to study a material’s ability to withstand long durations under constant pressure and temperatures. The equipment measured the strain over a long period of time. Tensile test equipment subjects the test material to strain until the material fails. The two tests were used to determine the strength and durability of different materials. The Materials Processing Laboratory also housed arc and electron beam melting furnaces, a hydraulic vertical extrusion press, compaction and forging equipment, and rolling mills and swagers. There were cryogenic and gas storage facilities and mechanical and oil diffusion vacuum pumps. The facility contained both instrumental and analytical chemistry laboratories for work on radioactive or toxic materials and the only shop to machine toxic materials in the Midwest.

  13. Carbon nanotube vacuum gauges utilizing long, dissipative tubes

    NASA Astrophysics Data System (ADS)

    Kaul, Anupama B.; Manohara, Harish M.

    2008-04-01

    A carbon nanotube-based thermal conductivity vacuum gauge is described which utilizes 5-10 μm long diffusively contacted SWNTs for vacuum sensing. By etching the thermal SiO II beneath the tubes and minimizing heat conduction through the substrate, pressure sensitivity was extended toward higher vacuums. The pressure response of unannealed and annealed devices was compared to that of released devices. The released devices showed sensitivity to pressure as low as 1 x 10 -6 Torr. The sensitivity increased more dramatically with power for the released device compared to that of the unreleased device. Low temperature electronic transport measurements of the tubes were suggestive of a thermally activated hopping mechanism where the activation energy for hopping was calculated to be ~ 39 meV.

  14. Spherical-wave expansions of piston-radiator fields.

    PubMed

    Wittmann, R C; Yaghjian, A D

    1991-09-01

    Simple spherical-wave expansions of the continuous-wave fields of a circular piston radiator in a rigid baffle are derived. These expansions are valid throughout the illuminated half-space and are useful for efficient numerical computation in the near-field region. Multipole coefficients are given by closed-form expressions which can be evaluated recursively.

  15. Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum

    PubMed Central

    Lee, Ho Nyung; Ambrose Seo, Sung S.; Choi, Woo Seok; Rouleau, Christopher M.

    2016-01-01

    In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on single crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Therefore, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but expands the utility of pulsed laser epitaxy of other materials as well. PMID:26823119

  16. Mask-free, vacuum-free fabrication of high-conductivity metallic nanowire by spatially shaped ultrafast laser (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wang, Andong; Li, Xiaowei; Qu, Lianti; Lu, Yongfeng; Jiang, Lan

    2017-03-01

    Metal nanowire fabrication has drawn tremendous attention in recent years due to its wide application in electronics, optoelectronics, and plasmonics. However, conventional laser fabrication technologies are limited by diffraction limit thus the fabrication resolution cannot meet the increasingly high demand of modern devices. Herein we report on a novel method for high-resolution high-quality metal nanowire fabrication by using Hermite-Gaussian beam to ablate metal thin film. The nanowire is formed due to the intensity valley in the center of the laser beam while the surrounding film is ablated. Arbitrary nanowire can be generated on the substrate by dynamically adjusting the orientation of the intensity valley. This method shows obvious advantages compared to conventional methods. First, the minimum nanowire has a width of 60 nm (≍1/13 of the laser wavelength), which is much smaller than the diffraction limit. The high resolution is achieved by combining the ultrashort nature of the femtosecond laser and the low thermal conductivity of the thin film. In addition, the fabricated nanowires have good inside qualities. No inner nanopores and particle intervals are generated inside the nanowire, thus endowing the nanowire with good electronic characteristics: the conductivity of the nanowires is as high as 1.2×107 S/m (≍1/4 of buck material), and the maximum current density is up to 1.66×108 A/m2. Last, the nanowire has a good adhesion to the substrates, which can withstand ultrasonic bath for a long time. These advantages make our method a good approach for high-resolution high-quality nanowire fabrication as a complementary method to conventional lithography methods.

  17. Preparation of High-Grade Powders from Tomato Paste Using a Vacuum Foam Drying Method.

    PubMed

    Sramek, Martin; Schweiggert, Ralf Martin; van Kampen, Andreas; Carle, Reinhold; Kohlus, Reinhard

    2015-08-01

    We present a rapid and gentle drying method for the production of high-grade tomato powders from double concentrated tomato paste, comparing results with powders obtained by foam mat air drying and freeze dried powders. The principle of this method consists of drying tomato paste in foamed state at low temperatures in vacuum. The formulations were dried at temperatures of 50, 60, and 70 °C and vacuum of 200 mbar. Foam stability was affected by low serum viscosity and the presence of solid particles in tomato paste. Consequently, serum viscosity was increased by maltodextrin addition, yielding optimum stability at tomato paste:maltodextrin ratio of 2.4:1 (w/w) in dry matter. Material foamability was improved by addition of 0.5% (w/w, fresh weight) egg white. Because of solid particles in tomato paste, foam air filling had to be limited to critical air volume fraction of Φ = 0.7. The paste was first pre-foamed to Φ = 0.2 and subsequently expanded in vacuo. After drying to a moisture content of 5.6% to 7.5% wet base (w.b.), the materials obtained were in glassy state. Qualities of the resulting powders were compared with those produced by freeze and air drying. Total color changes were the least after vacuum drying, whereas air drying resulted in noticeable color changes. Vacuum foam drying at 50 °C led to insignificant carotenoid losses, being equivalent to the time-consuming freeze drying method. In contrast, air drying caused lycopene and β-carotene losses of 18% to 33% and 14% to 19% respectively. Thus, vacuum foam drying enables production of high-grade tomato powders being qualitatively similar to powders obtained by freeze drying. © 2015 Institute of Food Technologists®

  18. Teflon-wire piston or stainless-steel bucket stapes prosthesis: does it make a difference?

    PubMed

    Farrior, J B; Temple, A E

    1999-04-01

    The goal of this study was to determine whether postoperative (implantation of a stapes prosthesis) hearing gain and the amount of air-bone gap overclosure are more improved with the Teflon-wire piston or with the stainless-steel bucket prosthesis. We retrospectively reviewed the outcomes of 82 surgeries that had been performed by the primary author; 41 of these patients had received a Fisch Teflon-wire piston, and 41 had received a Bailey-modified Robinson stainless-steel bucket prosthesis. The mean hearing gain for the patients who received the Teflon-wire piston was 23.3 dB after primary stapes surgery and 20.5 dB after revision surgery. Patients who received the stainless-steel bucket prosthesis experienced a mean hearing gain of 20.7 and 20.3 dB, respectively. Following primary stapes surgery, the air-bone gap overclosure was 4.4 dB with the Teflon-wire piston and 5.2 dB with the stainless-steel bucket prosthesis. There was no statistically significant difference in either hearing gain or air-bone gap overclosure between the two prostheses.

  19. Development of free-piston Stirling engine performance and optimization codes based on Martini simulation technique

    NASA Technical Reports Server (NTRS)

    Martini, William R.

    1989-01-01

    A FORTRAN computer code is described that could be used to design and optimize a free-displacer, free-piston Stirling engine similar to the RE-1000 engine made by Sunpower. The code contains options for specifying displacer and power piston motion or for allowing these motions to be calculated by a force balance. The engine load may be a dashpot, inertial compressor, hydraulic pump or linear alternator. Cycle analysis may be done by isothermal analysis or adiabatic analysis. Adiabatic analysis may be done using the Martini moving gas node analysis or the Rios second-order Runge-Kutta analysis. Flow loss and heat loss equations are included. Graphical display of engine motions and pressures and temperatures are included. Programming for optimizing up to 15 independent dimensions is included. Sample performance results are shown for both specified and unconstrained piston motions; these results are shown as generated by each of the two Martini analyses. Two sample optimization searches are shown using specified piston motion isothermal analysis. One is for three adjustable input and one is for four. Also, two optimization searches for calculated piston motion are presented for three and for four adjustable inputs. The effect of leakage is evaluated. Suggestions for further work are given.

  20. Stabilizing gas bearing in free piston machines

    NASA Technical Reports Server (NTRS)

    Dhar, Manmohan (Inventor)

    1992-01-01

    In a free piston engine, to reduce dynamic loads on the reciprocating elements caused by a time varying pressure gradient across the gas bearing and close clearance seals provided therein, drain galleries are incorporated at the ends of the gas bearings to isolate the same, and circumferentially spaced grooves are incorporated in the close clearance seal region.

  1. Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings. Part 1; Electrical and Thermal Conductivity, Thermal Diffusivity, and Total Hemispherical Emissivity

    NASA Technical Reports Server (NTRS)

    Raj, S. V.

    2017-01-01

    This two-part paper reports the thermophysical properties of several cold and vacuum plasma sprayed monolithic Cu and Ni-based alloy coatings. Part I presents the electrical and thermal conductivity, thermal diffusivity, and total hemispherical emissivity data while Part II reports the specific heat capacity data for these coatings. Metallic copper alloys, stoichiometric NiAl and NiCrAlY coatings were fabricated by either the cold sprayed or the vacuum plasma spray deposition processes for thermal property measurements between 77 and 1223 K. The temperature dependencies of the thermal conductivities, thermal diffusivities, electrical conductivities and total hemispherical emissivities of these cold and vacuum sprayed monolithic coatings are reported in this paper. The electrical and thermal conductivity data correlate reasonably well for Cu-8%Cr-1%Al, Cu-23%Cr-5%Al and NiAl in accordance with the Wiedemann-Franz (WF) law although a better fit is obtained using the Smith-Palmer relationship. The Lorentz numbers determined from the WF law are close to the theoretical value.

  2. Open loop, auto reversing liquid nitrogen circulation thermal system for thermo vacuum chamber

    NASA Astrophysics Data System (ADS)

    Naidu, M. C. A.; Nolakha, Dinesh; Saharkar, B. S.; Kavani, K. M.; Patel, D. R.

    2012-11-01

    In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of "Open loop, auto reversing liquid nitrogen based thermal system". System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.

  3. Working in a Vacuum

    ERIC Educational Resources Information Center

    Rathey, Allen

    2005-01-01

    In this article, the author discusses several myths about vacuum cleaners and offers tips on evaluating and purchasing this essential maintenance tool. These myths are: (1) Amps mean performance; (2) Everyone needs high-efficiency particulate air (HEPA): (3) Picking up a "bowling ball" shows cleaning power; (4) All vacuum bags are the same; (5)…

  4. Integrated two-cylinder liquid piston Stirling engine

    NASA Astrophysics Data System (ADS)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-10-01

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  5. Ultra-high speed vacuum pump system with first stage turbofan and second stage turbomolecular pump

    DOEpatents

    Jostlein, Hans

    2006-04-04

    An ultra-high speed vacuum pump evacuation system includes a first stage ultra-high speed turbofan and a second stage conventional turbomolecular pump. The turbofan is either connected in series to a chamber to be evacuated, or is optionally disposed entirely within the chamber. The turbofan employs large diameter rotor blades operating at high linear blade velocity to impart an ultra-high pumping speed to a fluid. The second stage turbomolecular pump is fluidly connected downstream from the first stage turbofan. In operation, the first stage turbofan operates in a pre-existing vacuum, with the fluid asserting only small axial forces upon the rotor blades. The turbofan imparts a velocity to fluid particles towards an outlet at a high volume rate, but moderate compression ratio. The second stage conventional turbomolecular pump then compresses the fluid to pressures for evacuation by a roughing pump.

  6. Thermal design and validation of radiation detector for the ChubuSat-2 micro-satellite with high-thermal-conductive graphite sheets

    NASA Astrophysics Data System (ADS)

    Park, Daeil; Miyata, Kikuko; Nagano, Hosei

    2017-07-01

    This paper describes thermal design of the radiation detector (RD) for the ChubuSat-2 with the use of high-thermal-conductive materials. ChubuSat-2 satellite is a 50-kg-class micro-satellite joint development with Nagoya University and aerospace companies. The main mission equipment of ChubuSat-2 is a RD to observe neutrons and gamma rays. However, the thermal design of the RD encounters a serious problem, such as no heater for RD and electric circuit alignment constrain. To solve this issue, the RD needs a new thermal design and thermal control for successful space missions. This paper proposes high-thermal-conductive graphite sheets to be used as a flexible radiator fin for the RD. Before the fabrication of the device, the optimal thickness and surface area for the flexible radiator fin were determined by thermal analysis. Consequently, the surface area of flexible radiator fin was determined to be 8.6×104 mm2. To verify the effects of the flexible radiator fin, we constructed a verification model and analyzed the temperature distributions in the RD. Also, the thermal vacuum test was performed using a thermal vacuum chamber, which was evacuated at a pressure of around 10-4 Pa, and its internal temperature was cooled at -80 °C by using a refrigerant. As a result, it has been demonstrated that the flexible radiator fin is effective. And the thermal vacuum test results are presented good correlation with the analysis results.

  7. The HAMP Signal Relay Domain Adopts Multiple Conformational States through Collective Piston and Tilt Motions

    PubMed Central

    Zhu, Lizhe; Bolhuis, Peter G.; Vreede, Jocelyne

    2013-01-01

    The HAMP domain is a linker region in prokaryotic sensor proteins and relays input signals to the transmitter domain and vice versa. Functional as a dimer, the structure of HAMP shows a parallel coiled-coil motif comprising four helices. To date, it is unclear how HAMP can relay signals from one domain to another, although several models exist. In this work, we use molecular simulation to test the hypothesis that HAMP adopts different conformations, one of which represents an active, signal-relaying configuration, and another an inactive, resting state. We first performed molecular dynamics simulation on the prototype HAMP domain Af1503 from Archaeoglobus fulgidus. We explored its conformational space by taking the structure of the A291F mutant disabling HAMP activity as a starting point. These simulations revealed additional conformational states that differ in the tilt angles between the helices as well as the relative piston shifts of the helices relative to each other. By enhancing the sampling in a metadynamics set up, we investigated three mechanistic models for HAMP signal transduction. Our results indicate that HAMP can access additional conformational states characterized by piston motion. Furthermore, the piston motion of the N-terminal helix of one monomer is directly correlated with the opposite piston motion of the C-terminal helix of the other monomer. The change in piston motion is accompanied by a change in tilt angle between the monomers, thus revealing that HAMP exhibits a collective motion, i.e. a combination of changes in tilt angles and a piston-like displacement. Our results provide insights into the conformational changes that underlie the signaling mechanism involving HAMP. PMID:23468603

  8. Mathematical Modelling of Liner Piston Maintenance Activity using Field Data to Minimize Overhauling Time and Human Energy Consumption

    NASA Astrophysics Data System (ADS)

    Belkhode, Pramod Namdeorao

    2017-06-01

    Field data based model is proposed to reduce the overhauling time and human energy consumed in liner piston maintenance activity so as to increase the productivity of liner piston maintenance activity. The independent variables affecting the phenomenon such as anthropometric parameters of workers (Eastman Kodak Co. Ltd in Section VIA Appendix-A: Anthropometric Data. Ergonomic Design for People at Work, Van Nostrans Reinhold, New York, 1), workers parameters, specification of liner piston data, specification of tools used in liner piston maintenance activity, specification of solvents, axial clearance of big end bearing and bolt elongation, workstation data (Eastman Kodak Co. Ltd in Work Place Ergonomic Design for People at Work, Van Nostrans Reinhold, New York, 2) and extraneous variables, namely, temperature, humidity at workplace, illumination at workplace and noise at workplace (Eastman Kodak Co. Ltd in Chapter V Environment Ergonomic Design for People at Work, Van Nostrans Reinhold, New York, 3) are taken into account. The model is formulated for dependent variables of liner piston maintenance activity to minimize the overhauling time and human energy consumption so as to improve the productivity of liner piston maintenance activity. The developed model can predict the performance of liner piston maintenance activity which involves man and machine system (Schenck in Theories of Engineering Experimentation, Mc-Graw Hill, New York 4). The model is then optimized by optimization technique and the sensitivity analysis of the model has also been estimated.

  9. Design and construction of the X-2 two-stage free piston driven expansion tube

    NASA Technical Reports Server (NTRS)

    Doolan, Con

    1995-01-01

    This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

  10. Analysis of a system modelling the motion of a piston in a viscous gas

    NASA Astrophysics Data System (ADS)

    Maity, Debayan; Takahashi, Takéo; Tucsnak, Marius

    2017-09-01

    We study a free boundary problem modelling the motion of a piston in a viscous gas. The gas-piston system fills a cylinder with fixed extremities, which possibly allow gas from the exterior to penetrate inside the cylinder. The gas is modeled by the 1D compressible Navier-Stokes system and the piston motion is described by the second Newton's law. We prove the existence and uniqueness of global in time strong solutions. The main novelty brought in by our results is that they include the case of nonhomogeneous boundary conditions which, as far as we know, have not been studied in this context. Moreover, even for homogeneous boundary conditions, our results require less regularity of the initial data than those obtained in previous works.

  11. Extreme-UV lithography vacuum chamber zone seal

    DOEpatents

    Haney, Steven J.; Herron, Donald Joe; Klebanoff, Leonard E.; Replogle, William C.

    2001-01-01

    Control of particle contamination on the reticle and carbon contamination of optical surfaces in photolithography systems can be achieved by the establishment of multiple pressure zones in the photolithography systems. The different zones will enclose the reticle, projection optics, wafer, and other components of system. The system includes a vacuum apparatus that includes: a housing defining a vacuum chamber; one or more metrology trays situated within the vacuum chamber each of which is supported by at least one support member, wherein the tray separates the vacuum chamber into a various compartments that are maintained at different pressures; and conductance seal devices for adjoining the perimeter of each tray to an inner surface of the housing wherein the tray is decoupled from vibrations emanating from the inner surface of the housing.

  12. Extreme-UV lithography vacuum chamber zone seal

    DOEpatents

    Haney, Steven J.; Herron, Donald Joe; Klebanoff, Leonard E.; Replogle, William C.

    2003-04-08

    Control of particle contamination on the reticle and carbon contamination of optical surfaces in photolithography systems can be achieved by the establishment of multiple pressure zones in the photolithography systems. The different zones will enclose the reticle, projection optics, wafer, and other components of system. The system includes a vacuum apparatus that includes: a housing defining a vacuum chamber; one or more metrology trays situated within the vacuum chamber each of which is supported by at least one support member, wherein the tray separates the vacuum chamber into a various compartments that are maintained at different pressures; and conductance seal devices for adjoining the perimeter of each tray to an inner surface of the housing wherein the tray is decoupled from vibrations emanating from the inner surface of the housing.

  13. Extreme-UV lithography vacuum chamber zone seal

    DOEpatents

    Haney, Steven J.; Herron, Donald Joe; Klebanoff, Leonard E.; Replogle, William C.

    2003-04-15

    Control of particle contamination on the reticle and carbon contamination of optical surfaces in photolithography systems can be achieved by the establishment of multiple pressure zones in the photolithography systems. The different zones will enclose the reticle, projection optics, wafer, and other components of system. The system includes a vacuum apparatus that includes: a housing defining a vacuum chamber; one or more metrology trays situated within the vacuum chamber each of which is supported by at least one support member, wherein the tray separates the vacuum chamber into a various compartments that are maintained at different pressures; and conductance seal devices for adjoining the perimeter of each tray to an inner surface of the housing wherein the tray is decoupled from vibrations emanating from the inner surface of the housing.

  14. Growth control of oxygen stoichiometry in homoepitaxial SrTiO 3 films by pulsed laser epitaxy in high vacuum

    DOE PAGES

    Lee, Ho Nyung; Ambrose Seo, Sung S.; Choi, Woo Seok; ...

    2016-01-29

    In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO 3 (STO) thin films onmore » single crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Thus, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but it expands the utility of pulsed laser epitaxy of other materials as well.₃« less

  15. How Hot Can a Fire Piston Get?

    ERIC Educational Resources Information Center

    Scott-Brown, J. A.; Cunningham, O. A.; Goad, B. C.

    2010-01-01

    The fire piston is just a sealed syringe containing a small amount of tinder. When the plunger is forced downwards, the air inside is compressed and heats up, setting fire to the tinder. It has been used as a convenient and portable way of starting fires "over a wide area from northern Burma and Siam through the Malay Peninsula and the Malayan…

  16. On the radiation impedance of a rectangular piston

    NASA Technical Reports Server (NTRS)

    Levine, H.

    1982-01-01

    Single integral representations for the resistive and reactive components of the radiation impedance appropriate to a rectangular piston are established, thereby enabling a systematic refinement of estimates at both short and long wave lengths. Comparisons with previous analyses are made explicit as well as extensions and corrections thereto.

  17. An ultra-high vacuum chamber for scattering experiments featuring in-vacuum continuous in-plane variation of the angle between entrance and exit vacuum ports

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Englund, Carl-Johan; Agåker, Marcus, E-mail: marcus.agaker@physics.uu.se; Fredriksson, Pierre

    2015-09-15

    A concept that enables in-vacuum continuous variation of the angle between two ports in one plane has been developed and implemented. The vacuum chamber allows for measuring scattering cross sections as a function of scattering angle and is intended for resonant inelastic X-ray scattering experiments. The angle between the ports can be varied in the range of 30°-150°, while the pressure change is less than 2 × 10{sup −10} mbars.

  18. Vacuum distillation/vapor filtration water recovery

    NASA Technical Reports Server (NTRS)

    Honegger, R. J.; Neveril, R. B.; Remus, G. A.

    1974-01-01

    The development and evaluation of a vacuum distillation/vapor filtration (VD/VF) water recovery system are considered. As a functional model, the system converts urine and condensates waste water from six men to potable water on a steady-state basis. The system is designed for 180-day operating durations and for function on the ground, on zero-g aircraft, and in orbit. Preparatory tasks are summarized for conducting low gravity tests of a vacuum distillation/vapor filtration system for recovering water from urine.

  19. O-Ring sealing arrangements for ultra-high vacuum systems

    DOEpatents

    Kim, Chang-Kyo; Flaherty, Robert

    1981-01-01

    An all metal reusable O-ring sealing arrangement for sealing two concentric tubes in an ultra-high vacuum system. An O-ring of a heat recoverable alloy such as Nitinol is concentrically positioned between protruding sealing rings of the concentric tubes. The O-ring is installed between the tubes while in a stressed martensitic state and is made to undergo a thermally induced transformation to an austenitic state. During the transformation the O-ring expands outwardly and contracts inwardly toward a previously sized austenitic configuration, thereby sealing against the protruding sealing rings of the concentric tubes.

  20. Ultra-high vacuum surface analysis study of rhodopsin incorporation into supported lipid bilayers.

    PubMed

    Michel, Roger; Subramaniam, Varuni; McArthur, Sally L; Bondurant, Bruce; D'Ambruoso, Gemma D; Hall, Henry K; Brown, Michael F; Ross, Eric E; Saavedra, S Scott; Castner, David G

    2008-05-06

    Planar supported lipid bilayers that are stable under ambient atmospheric and ultra-high-vacuum conditions were prepared by cross-linking polymerization of bis-sorbylphosphatidylcholine (bis-SorbPC). X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to investigate bilayers that were cross-linked using either redox-initiated radical polymerization or ultraviolet photopolymerization. The redox method yields a more structurally intact bilayer; however, the UV method is more compatible with incorporation of transmembrane proteins. UV polymerization was therefore used to prepare cross-linked bilayers with incorporated bovine rhodopsin, a light-activated, G-protein-coupled receptor (GPCR). A previous study (Subramaniam, V.; Alves, I. D.; Salgado, G. F. J.; Lau, P. W.; Wysocki, R. J.; Salamon, Z.; Tollin, G.; Hruby, V. J.; Brown, M. F.; Saavedra, S. S. J. Am. Chem. Soc. 2005, 127, 5320-5321) showed that rhodopsin retains photoactivity after incorporation into UV-polymerized bis-SorbPC, but did not address how the protein is associated with the bilayer. In this study, we show that rhodopsin is retained in supported bilayers of poly(bis-SorbPC) under ultra-high-vacuum conditions, on the basis of the increase in the XPS nitrogen concentration and the presence of characteristic amino acid peaks in the ToF-SIMS data. Angle-resolved XPS data show that the protein is inserted into the bilayer, rather than adsorbed on the bilayer surface. This is the first study to demonstrate the use of ultra-high-vacuum techniques for structural studies of supported proteolipid bilayers.

  1. Overview of NASA Lewis Research Center free-piston Stirling engine technology activities applicable to space power systems

    NASA Technical Reports Server (NTRS)

    Slaby, Jack G.

    1987-01-01

    A brief overview is presented of the development and technological activities of the free-piston Stirling engine. The engine started as a small scale fractional horsepower engine which demonstrated basic engine operating principles and the advantages of being hermetically sealed, highly efficient, and simple. It eventually developed into the free piston Stirling engine driven heat pump, and then into the SP-100 Space Reactor Power Program from which came the Space Power Demonstrator Engine (SPDE). The SPDE successfully operated for over 300 hr and delivered 20 kW of PV power to an alternator plunger. The SPDE demonstrated that a dynamic power conversion system can, with proper design, be balanced; and the engine performed well with externally pumped hydrostatic gas bearings.

  2. [Lubricant-free piston compressors for mechanized medical instruments].

    PubMed

    Sabitov, V Kh; Repin, V A; Kil'kinov, A A

    1988-01-01

    Piston compressor without lubrication with air blow to packing rings by plunger, disposed in subpiston space, is recommended as the basic scheme of construction of a power supply unit for medical pneumatic tooling. The construction reduces a leak of the compressive medium, increasing the efficiency of a compressor and seal reliability.

  3. High Thermal Conductivity Polymer Matrix Composites (PMC) for Advanced Space Radiators

    NASA Technical Reports Server (NTRS)

    Shin, E. Eugene; Bowman, Cheryl; Beach, Duane

    2007-01-01

    High temperature polymer matrix composites (PMC) reinforced with high thermal conductivity (approx. 1000 W/mK) pitch-based carbon fibers are evaluated for a facesheet/fin structure of large space radiator systems. Significant weight reductions along with improved thermal performance, structural integrity and space durability toward its metallic counterparts were envisioned. Candidate commercial resin systems including Cyanate Esters, BMIs, and polyimide were selected based on thermal capabilities and processability. PMC laminates were designed to match the thermal expansion coefficient of various metal heat pipes or tubes. Large, but thin composite panels were successfully fabricated after optimizing cure conditions. Space durability of PMC with potential degradation mechanisms was assessed by simulated thermal aging tests in high vacuum, 1-3 x 10(exp -6) torr, at three temperatures, 227 C, 277 C, and 316 C for up to one year. Nanocomposites with vapor-grown carbon nano-fibers and exfoliated graphite flakes were attempted to improve thermal conductivity (TC) and microcracking resistance. Good quality nanocomposites were fabricated and evaluated for TC and durability including radiation resistance. TC was measured in both in-plan and thru-the-thickness directions, and the effects of microcracks on TC are also being evaluated. This paper will discuss the systematic experimental approaches, various performance-durability evaluations, and current subcomponent design and fabrication/manufacturing efforts.

  4. Ultrahigh vacuum, high temperature, low cycle fatigue of coated and uncoated Rene 80

    NASA Technical Reports Server (NTRS)

    Kortovich, C. S.

    1976-01-01

    A study was conducted on the ultrahigh vacuum strain controlled by low cycle fatigue behavior of uncoated and CODEP B-1 aluminide coated Rene' 80 nickel-base superalloy at 1000 C (1832 F) and 871 C (1600 F). The results indicated little effect of coating or temperature on the fatigue properties. There was, however, a significant effect on fatigue life when creep was introduced into the strain cycles. The effect of this creep component was analyzed in terms of the method of strainrange partitioning.

  5. Calorimetric thermal-vacuum performance characterization of the BAe 80 K space cryocooler

    NASA Technical Reports Server (NTRS)

    Kotsubo, V. Y.; Johnson, D. L.; Ross, R. G., Jr.

    1992-01-01

    A comprehensive characterization program is underway at JPL to generate test data on long-life, miniature Stirling-cycle cryocoolers for space application. The key focus of this paper is on the thermal performance of the British Aerospace (BAe) 80 K split-Stirling-cycle cryocooler as measured in a unique calorimetric thermal-vacuum test chamber that accurately simulates the heat-transfer interfaces of space. Two separate cooling fluid loops provide precise individual control of the compressor and displacer heatsink temperatures. In addition, heatflow transducers enable calorimetric measurements of the heat rejected separately by the compressor and displacer. Cooler thermal performance has been mapped for coldtip temperatures ranging from below 45 K to above 150 K, for heatsink temperatures ranging from 280 K to 320 K, and for a wide variety of operational variables including compressor-displacer phase, compressor-displacer stroke, drive frequency, and piston-displacer dc offset.

  6. Effect of piston profile on performance and emission characteristics of a GDI engine with split injection strategy - A CFD study

    NASA Astrophysics Data System (ADS)

    Karaya, Y.; Mallikarjuna, J. M.

    2017-09-01

    Gasoline direct injection (GDI) engines have gained popularity in the recent times because of lower fuel consumption and exhaust emissions. But in these engines, the mixture preparation plays an important role which affects combustion, performance and emission characteristics. The mixture preparation in turn depends mainly upon combustion chamber geometry. Therefore, in this study, an attempt has been made to understand the effect of piston profile on the performance and emission characteristics in a GDI engine. The analysis is carried out on a four-stroke wall guided GDI engine using computational fluid dynamics (CFD). The spray breakup model used is validated with the available experimental results from the literature to the extent possible. The analysis is carried out for four piston profiles viz., offset pentroof with offset bowl (OPOB), flat piston with offset bowl (FPOB), offset pentroof with offset scoop (OPOS) and inclined piston with offset bowl (IPOB) fitted in an engine equipped with a six-hole injector with the split injection ratio of 30:70. All the CFD simulations are carried out at the engine speed of 2000 rev/min., with the overall equivalence ratio of about 0.65±0.05. The performance and emission characteristics of the engine are compared while using the above piston profiles. It is found that, the OPOB piston is preferred compared to that of the other pistons because it has better in-cylinder flow, IMEP and lower HC emissions compared to that of other pistons.

  7. Performance analysis on free-piston Stirling cryocooler based on an idealized mathematical model

    NASA Astrophysics Data System (ADS)

    Guo, Y. X.; Chao, Y. J.; Gan, Z. H.; Li, S. Z.; Wang, B.

    2017-12-01

    Free-piston Stirling cryocoolers have extensive applications for its simplicity in structure and decrease in mass. However, the elimination of the motor and the crankshaft has made its thermodynamic characteristic different from that of Stirling cryocoolers with displacer driving mechanism. Therefore, an idealized mathematical model has been established, and with this model, an attempt has been made to analyse the thermodynamic characteristic and the performance of free-piston Stirling cryocooler. To certify this mathematical model, a comparison has been made between the model and a numerical model. This study reveals that due to the displacer damping force necessary for the production of cooling capacity, the free-piston Stirling cryocooler is inherently less efficient than Stirling cryocooler with displacer driving mechanism. Viscous flow resistance and incomplete heat transfer in the regenerator are the two major causes of the discrepancy between the results of the idealized mathematical model and the numerical model.

  8. Near-vacuum hohlraums for driving fusion implosions with high density carbon ablatorsa)

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N. B.; Mackinnon, A. J.; Ho, D. D.; Jones, O. S.; Khan, S.; Milovich, J. L.; Ross, J. S.; Amendt, P.; Casey, D.; Celliers, P. M.; Pak, A.; Peterson, J. L.; Ralph, J.; Rygg, J. R.

    2015-05-01

    Recent experiments at the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] have explored driving high-density carbon ablators with near-vacuum hohlraums, which use a minimal amount of helium gas fill. These hohlraums show improved efficiency relative to conventional gas-filled hohlraums in terms of minimal backscatter, minimal generation of suprathermal electrons, and increased hohlraum-capsule coupling. Given these advantages, near-vacuum hohlraums are a promising choice for pursuing high neutron yield implosions. Long pulse symmetry control, though, remains a challenge, as the hohlraum volume fills with material. Two mitigation methodologies have been explored, dynamic beam phasing and increased case-to-capsule ratio (larger hohlraum size relative to capsule). Unexpectedly, experiments have demonstrated that the inner laser beam propagation is better than predicted by nominal simulations, and an enhanced beam propagation model is required to match measured hot spot symmetry. Ongoing work is focused on developing a physical model which captures this enhanced propagation and on utilizing the enhanced propagation to drive longer laser pulses than originally predicted in order to reach alpha-heating dominated neutron yields.

  9. Development of the Sunpower 35 We Free-Piston Stirling Convertor

    NASA Astrophysics Data System (ADS)

    Wood, J. Gary; Lane, Neill

    2005-02-01

    This paper describes the development and performance of the Sunpower 35 We free-piston Stirling convertor. Exceptional thermodynamic performance has been achieved in a small lightweight machine. Efficiency of over 30 percent, at a temperature ratio of 2.6 has been achieved. Specific power of the convertor in final low mass hermetically-sealed form is projected to exceed 90 watts/Kg. This convertor was developed under NASA SBIR funding. Potential applications for this convertor include highly efficient and low mass radioisotope fueled space power systems, as well as terrestrial use as a fuel fired battery replacement.

  10. Ethanol production from food waste at high solid contents with vacuum recovery technology

    USDA-ARS?s Scientific Manuscript database

    Ethanol production from food wastes does not only solve the environmental issues but also provide renewable biofuel to partially substitute fossil fuels. This study investigated the feasibility of utilization of food wastes for producing ethanol at high solid contents (35%, w/w). Vacuum recovery sys...

  11. Integrated two-cylinder liquid piston Stirling engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin

    2014-10-06

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harnessmore » useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.« less

  12. Free-piston Stirling component test power converter

    NASA Technical Reports Server (NTRS)

    Dochat, George; Dhar, Manmohan

    1991-01-01

    The National Aeronautics and Space Administration (NASA) has been evaluating free-piston Stirling power converters (FPSPCs) for use on a wide variety of space missions. They provide high reliability, long life, and efficient operation and can be coupled with all potential heat sources, various heat input and heat rejection systems, and various power management and distribution systems. FPSPCs can compete favorably with alternative power conversion systems over a range of hundreds of watts to megawatts. Mechanical Technology Incorporated (MTI) is developing FPSPC technology under contract to NASA Lewis Research Center and will demonstrate this technology in two full-scale power converters operating at space temperature conditions. The testing of the first of these, the component test power converter (CTPC), was initiated in Spring 1991 to evaluate mechanical operation at space operating temperatures. The CTPC design, hardware fabrication, and initial test results are reviewed.

  13. Ultra-high vacuum compatible preparation chain for intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Benka, G.; Regnat, A.; Franz, C.; Pfleiderer, C.

    2016-11-01

    We report the development of a versatile material preparation chain for intermetallic compounds, which focuses on the realization of a high-purity growth environment. The preparation chain comprises an argon glovebox, an inductively heated horizontal cold boat furnace, an arc melting furnace, an inductively heated rod casting furnace, an optically heated floating-zone furnace, a resistively heated annealing furnace, and an inductively heated annealing furnace. The cold boat furnace and the arc melting furnace may be loaded from the glovebox by means of a load-lock permitting to synthesize compounds starting with air-sensitive elements while handling the constituents exclusively in an inert gas atmosphere. All furnaces are all-metal sealed, bakeable, and may be pumped to ultra-high vacuum. We find that the latter represents an important prerequisite for handling compounds with high vapor pressure under high-purity argon atmosphere. We illustrate the operational aspects of the preparation chain in terms of the single-crystal growth of the heavy-fermion compound CeNi2Ge2.

  14. Free piston variable-stroke linear-alternator generator

    DOEpatents

    Haaland, Carsten M.

    1998-01-01

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.

  15. Heat Flow Measurement and Analysis of Thermal Vacuum Insulation

    NASA Astrophysics Data System (ADS)

    Laa, C.; Hirschl, C.; Stipsitz, J.

    2008-03-01

    A new kind of calorimeter has been developed at Austrian Aerospace to measure specific material parameters needed for the analysis of thermal vacuum insulation. A detailed description of the measuring device and the measurement results will be given in this paper. This calorimeter facility allows to measure the heat flow through the insulation under vacuum conditions in a wide temperature range from liquid nitrogen to ambient. Both boundary temperatures can be chosen within this range. Furthermore the insulation can be characterized at high vacuum or under degraded vacuum, the latter is simulated by using helium or nitrogen gas. The mechanisms of heat transfer have been investigated, namely infrared radiation between the reflective layers of the insulation and conduction through the interleaving spacer material. A mathematical description of the heat flow through the insulation has been derived. Based on this, the heat flow for a typical insulation material has been calculated by finite element analysis by use of the sotware tool Ansys®. Such a transient calculation is needed to determine the time to reach thermal equilibrium, which is mandatory for a proper interpretation and evaluation of the measurement. The new insulation measurement results combined with the proposed type of analysis can be applied to better understand the thermal behavior of any kind of cryogenic system.

  16. A high-vacuum wound drainage system reduces pain and length of treatment for pediatric soft tissue abscesses.

    PubMed

    Yang, Chao; Wang, Shan; Li, Chang-Chun; Kong, Xiang-Ru; Zhao, Zhenzhen; Deng, Xiao-Bin; Peng, Liang; Zhang, Jun

    2017-02-01

    Open incision and drainage (I&D) and wound packing is accepted as the standard treatment for soft tissue abscesses. However, conventional I&D has a number of problems in practice which prompt us to improve the I&D methods that would minimize the pain associated with packing during dressing changes. In order to compare the pain associated with dressing changes in the conventional I&D group to the vacuum system group and the treatment time of both groups, we performed a randomized trial in pediatric patients between 0 and 18 years of age who are undergoing abscess drainage in the operating room from April 2011 to April 2015. Patients treated with open I&D (n = 648) were compared to those treated with placement of high-vacuum wound drainage system (n = 776) through the abscess cavities. Both groups received equivalent antibiotic treatment, and all patients were followed up in the outpatient clinics until the infection has been resolved. The mean FACES scale pain scores were significantly higher in the open I&D group than in the vacuum system group. The vacuum system group had a shorter length of stay and less need for community doctor or outpatient dressing changes than the open I&D group (p < 0.001). No recurrent abscesses were observed in the vacuum system group, and 10 patients in the open I&D group required another drainage at the exact same location. High-vacuum wound drainage system was an efficient and safe alternative to the traditional I&D for community-acquired soft tissue abscesses with few complications in short term. What is Known: • Open incision and drainage (I&D) followed by irrigation and wound packing is the standard treatment for soft tissue abscesses. • The painful daily packing may cause emotional trauma to the child and lead to an unwelcoming challenge to the caretakers and health care providers. What is New: • We modified the method of I&D by adding primary suturing of the wound and placement of a high-vacuum wound drainage system

  17. Analysis of thermal stress of the piston during non-stationary heat flow in a turbocharged Diesel engine

    NASA Astrophysics Data System (ADS)

    Gustof, P.; Hornik, A.

    2016-09-01

    In the paper, numeric calculations of thermal stresses of the piston in a turbocharged Diesel engine in the initial phase of its work were carried out based on experimental studies and the data resulting from them. The calculations were made using a geometrical model of the piston in a five-cylinder turbocharged Diesel engine with a capacity of about 2300 cm3, with a direct fuel injection to the combustion chamber and a power rating of 85 kW. In order to determine the thermal stress, application of own mathematical models of the heat flow in characteristic surfaces of the piston was required to show real processes occurring on the surface of the analysed component. The calculations were performed using a Geostar COSMOS/M program module. A three-dimensional geometric model of the piston was created in this program based on a real component, in order to enable the calculations and analysis of thermal stresses during non-stationary heat flow. Modelling of the thermal stresses of the piston for the engine speed n=4250 min-1 and engine load λ=1.69 was carried out.

  18. Propagation of Intra-Seasonal Tropical Oscillations (PISTON)

    NASA Astrophysics Data System (ADS)

    Moum, J. N.

    2017-12-01

    During monsoon season over the South China Sea and Philippines, weather varies on the subseasonal time scale. Disturbances of the "boreal summer intraseasonal oscillation" (BSISO) move north and east across the region over periods of weeks. These disturbances are strongly conditioned by the complex geography of the region. The diurnal cycle in convection over islands and adjacent coastal seas is strong. Air-sea interaction is modulated by ocean stratification and local circulation patterns that are themselves complex and diurnally varying. The multiple pathways and space-time scales in the regional ocean-atmosphere-land system make prediction on subseasonal to seasonal time scales challenging. The PISTON field campaign targets the west coast of Luzon in August/September 2018. It includes ship-based, moored and land-based measurements, a significant modeling effort and coordinates with the Philippine SALICA program (Sea Air Land Interactions in the Context of Archipelagos) and the aircraft-based, NASA-funded CAMP2EX campaign (Cloud and Aerosol Monsoonal Processes-Philippines Experiment). The diurnal cycle and its interaction with the BSISO are primary targets for PISTON. Key questions are: how heat is stored and released in the upper ocean on intraseasonal time scales; how that heat storage interacts with atmospheric convection; and what role it plays in BSISO maintenance and propagation. Key processes include land-sea breezes, orographic influence on convection, river discharge to coastal oceans, gravity waves, diurnal warm layers, internal tides, and a buoyancy-driven northward coastal current. As intraseasonal disturbances approach the region, the presence of islands, with their low surface heat capacity, mountains, inhomogeneous distribution of urban/vegetation/soil, and strong diurnal cycle disrupts the air-sea heat exchange that sustains the BSISO over the ocean, confounding prediction models in which these processes are inadequately represented. Along with

  19. Effects of vacuum exposure on stress and spectral shift of high reflective coatings

    NASA Astrophysics Data System (ADS)

    Stolz, C. J.; Taylor, J. R.; Eickelberg, W. K.; Lindh, J. D.

    1992-06-01

    The Atomic Vapor Laser Isotope Laser Separation (AVLIS) program operates the world's largest average power dye laser; the dye laser beams are combined, formatted, and transported in vacuum. The optical system is aligned at atmosphere, while the system must meet requirements in vacuum. Therefore, coating performance must be characterized in both atmosphere and vacuum. Changes in stress and spectral shift in ambient and vacuum environments are reported for conventional and dense multilayer dielectric coatings.

  20. Highly efficient and bendable organic solar cells using a three-dimensional transparent conducting electrode

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Bae, Tae-Sung; Park, Yeon Hyun; Kim, Dong Ho; Lee, Sunghun; Min, Guanghui; Lee, Gun-Hwan; Song, Myungkwan; Yun, Jungheum

    2014-05-01

    A three-dimensional (3D) transparent conducting electrode, consisting of a quasi-periodic array of discrete indium-tin-oxide (ITO) nanoparticles superimposed on a highly conducting oxide-metal-oxide multilayer using ITO and silver oxide (AgOx) as oxide and metal layers, respectively, is synthesized on a polymer substrate and used as an anode in highly flexible organic solar cells (OSCs). The 3D electrode is fabricated using vacuum sputtering sequences to achieve self-assembly of distinct ITO nanoparticles on a continuous ITO-AgOx-ITO multilayer at room-temperature without applying conventional high-temperature vapour-liquid-solid growth, solution-based nanoparticle coating, or complicated nanopatterning techniques. Since the 3D electrode enhances the hole-extraction rate in OSCs owing to its high surface area and low effective series resistance for hole transport, OSCs based on this 3D electrode exhibit a power conversion efficiency that is 11-22% higher than that achievable in OSCs by means of conventional planar ITO film-type electrodes. A record high efficiency of 6.74% can be achieved in a bendable OSC fabricated on a poly(ethylene terephthalate) substrate.A three-dimensional (3D) transparent conducting electrode, consisting of a quasi-periodic array of discrete indium-tin-oxide (ITO) nanoparticles superimposed on a highly conducting oxide-metal-oxide multilayer using ITO and silver oxide (AgOx) as oxide and metal layers, respectively, is synthesized on a polymer substrate and used as an anode in highly flexible organic solar cells (OSCs). The 3D electrode is fabricated using vacuum sputtering sequences to achieve self-assembly of distinct ITO nanoparticles on a continuous ITO-AgOx-ITO multilayer at room-temperature without applying conventional high-temperature vapour-liquid-solid growth, solution-based nanoparticle coating, or complicated nanopatterning techniques. Since the 3D electrode enhances the hole-extraction rate in OSCs owing to its high surface area

  1. Fundamental Materials Studies for Advanced High Power Microwave and Terahertz Vacuum Electronic Radiation Sources

    DTIC Science & Technology

    2014-12-10

    AFRL-OSR-VA-TR-2014-0359 Fundamental Materials Studies for Advanced High Power Microwave and Terahertz John Booske UNIVERSITY OF WISCONSIN SYSTEM...12-2014 Final Technical Performance Report October 1, 2011 - September 30, 2014 Fundamental Materials Studies for Advanced High Power Microwave and...emission-barrier scandate cathodes and identify related, alternative cathode materials systems for advanced vacuum electronic cathodes for high power THz

  2. High-Reflectivity Coatings for a Vacuum Ultraviolet Spectropolarimeter

    NASA Astrophysics Data System (ADS)

    Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko; Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono, Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère, Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen, Jianrong; Choi, Joanne

    2017-03-01

    Precise polarization measurements in the vacuum ultraviolet (VUV) region are expected to be a new tool for inferring the magnetic fields in the upper atmosphere of the Sun. High-reflectivity coatings are key elements to achieving high-throughput optics for precise polarization measurements. We fabricated three types of high-reflectivity coatings for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα; 121.567 nm) region and evaluated their performance. The first high-reflectivity mirror coating offers a reflectivity of more than 80 % in Lyα optics. The second is a reflective narrow-band filter coating that has a peak reflectivity of 57 % in Lyα, whereas its reflectivity in the visible light range is lower than 1/10 of the peak reflectivity (˜ 5 % on average). This coating can be used to easily realize a visible light rejection system, which is indispensable for a solar telescope, while maintaining high throughput in the Lyα line. The third is a high-efficiency reflective polarizing coating that almost exclusively reflects an s-polarized beam at its Brewster angle of 68° with a reflectivity of 55 %. This coating achieves both high polarizing power and high throughput. These coatings contributed to the high-throughput solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.

  3. Technical specification for vacuum systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Khaw, J.

    The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing andmore » designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)« less

  4. Gas propagation in a liquid helium cooled vacuum tube following a sudden vacuum loss

    NASA Astrophysics Data System (ADS)

    Dhuley, Ram C.

    This dissertation describes the propagation of near atmospheric nitrogen gas that rushes into a liquid helium cooled vacuum tube after the tube suddenly loses vacuum. The loss-of-vacuum scenario resembles accidental venting of atmospheric air to the beam-line of a superconducting radio frequency particle accelerator and is investigated to understand how in the presence of condensation, the in-flowing air will propagate in such geometry. In a series of controlled experiments, room temperature nitrogen gas (a substitute for air) at a variety of mass flow rates was vented to a high vacuum tube immersed in a bath of liquid helium. Pressure probes and thermometers installed on the tube along its length measured respectively the tube pressure and tube wall temperature rise due to gas flooding and condensation. At high mass in-flow rates a gas front propagated down the vacuum tube but with a continuously decreasing speed. Regression analysis of the measured front arrival times indicates that the speed decreases nearly exponentially with the travel length. At low enough mass in-flow rates, no front propagated in the vacuum tube. Instead, the in-flowing gas steadily condensed over a short section of the tube near its entrance and the front appeared to `freeze-out'. An analytical expression is derived for gas front propagation speed in a vacuum tube in the presence of condensation. The analytical model qualitatively explains the front deceleration and flow freeze-out. The model is then simplified and supplemented with condensation heat/mass transfer data to again find the front to decelerate exponentially while going away from the tube entrance. Within the experimental and procedural uncertainty, the exponential decay length-scales obtained from the front arrival time regression and from the simplified model agree.

  5. Cold cathode vacuum gauging system

    DOEpatents

    Denny, Edward C.

    2004-03-09

    A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

  6. Latest Progress In Novel High Conductivity And Highly Stable Composite Structure Developments For Satellite Applications

    NASA Astrophysics Data System (ADS)

    Klebor, Maximillian; Reichmann, Olaf; Pfeiffer, Ernst K.; Ihle, Alexander; Linke, Stefan; Tschepe, Christoph; Roddecke, Susanne; Richter, Ines; Berrill, Mark; Santiago-Prowald, Julian

    2012-07-01

    Materials such as aluminium, titanium and carbon fibre based composites are indispensable in space business. However, special demands on spaceborne applications require both new ideas and new concepts but also powerful novel materials. These days the trend is to substitute aluminium for CFRP basically in order to safe mass or to decrease thermal expansions. Nevertheless there are upcoming requirements that cannot be met using standard CFRP materials. In this connection innovative composites have to be introduced. In the frame of this paper three major applications for such material requests are considered, i.e.: • antennas • satellite platform structural panels • radiators. The new composites need to cope with the following challenges and demands: high operational temperature range, high stiffness, high strength, high thermal conductivity, vacuum compatibility, low mass, high in- orbit stability, compatibility with metallic parts and many more. Some of these demands have to be fulfilled in conjunction. Herein the innovative composites cover new raw materials and their combination, manufacturing process enhancement as well as new inspection and test methods. It has been observed that by using the developed CFRPs it is possible to satisfy and excel the needs. However, these materials feature a different behaviour than conventional composites which has to be taken into account during future design.

  7. Rotary piston blood pumps: past developments and future potential of a unique pump type.

    PubMed

    Wappenschmidt, Johannes; Autschbach, Rüdiger; Steinseifer, Ulrich; Schmitz-Rode, Thomas; Margreiter, Raimund; Klima, Günter; Goetzenich, Andreas

    2016-08-01

    The design of implantable blood pumps is either based on displacement pumps with membranes or rotary pumps. Both pump types have limitations to meet the clinical requirements. Rotary piston blood pumps have the potential to overcome these limitations and to merge the benefits. Compared to membrane pumps, they are smaller and with no need for wear-affected membranes and valves. Compared to rotary pumps, the blood flow is pulsatile instead of a non-physiological continuous flow. Furthermore, the risk of flow-induced blood damage and platelet activation may be reduced due to low shear stress to the blood. The past developments of rotary piston blood pumps are summarized and the main problem for long-term application is identified: insufficient seals. A new approach with seal-less drives is proposed and current research on a simplified rotary piston design is presented. Expert commentary: The development of blood pumps focuses mainly on the improvement of rotary pumps. However, medical complications indicate that inherent limitations of this pump type remain and restrict the next substantial step forward in the therapy of heart failure patients. Thus, research on different pump types is reasonable. If the development of reliable drives and bearings succeeds, rotary piston blood pumps become a promising alternative.

  8. A free-piston Stirling cryocooler using metal diaphragms

    NASA Astrophysics Data System (ADS)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-12-01

    A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

  9. Carrier Conduction and Light Emission by Modification of Poly(alkylfluorene) Interface under Vacuum Ultraviolet Light Irradiation

    NASA Astrophysics Data System (ADS)

    Ohmori, Yutaka; Kajii, Hirotake; Terashima, Daiki; Kusumoto, Yusuke

    2013-03-01

    Organic field effect transistors (OFETs) have been extensively studied for flexible electronics. The characteristics of poly(9,9-dioctylfluorenyl-2,7-dyl) (F8) modified by thermal or light are strongly dependent on the carrier transport and optical characteristics. We investigate all solution-processed OFETs with Ag nano-ink as gate electrodes patterned by Vacuum Ultraviolet (VUV) (172 nm). Bi-layer gate insulators of amorphous fluoro-polymer CYTOP (Asahi Glass Corp.) and poly(methylmethacrylate) (PMMA) were used. Top-gate-type OFETs with ITO source/drain electrode utilizing F8 or poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as an active layer were fabricated, and investigated the carrier conduction and emission characteristic. Without VUV irradiation, both OFETs showed the ambipolar and light-emitting characteristics. On the other hand, F8 devices with VUV exhibited only p-type conduction. The quenching centers were generated in F8 layer by VUV irradiation, which are related to the electron trap sites at the interface. OFETs with F8BT showed both p- and n-type conduction even after VUV. F8BT suffers less damage by VUV and maintain light emission. Light emitting transistors were realized utilizing F8BT patterned by VUV irradiation. This research was partially supported financially by MEXT. The authors thank Harima Chemicals Inc. for providing Ag nano-ink.

  10. Conceptual design and cost analysis of hydraulic output unit for 15 kW free-piston Stirling engine

    NASA Technical Reports Server (NTRS)

    White, M. A.

    1982-01-01

    A long-life hydraulic converter with unique features was conceptually designed to interface with a specified 15 kW(e) free-piston Stirling engine in a solar thermal dish application. Hydraulic fluid at 34.5 MPa (5000 psi) is produced to drive a conventional hydraulic motor and rotary alternator. Efficiency of the low-maintenance converter design was calculated at 93.5% for a counterbalanced version and 97.0% without the counterbalance feature. If the converter were coupled to a Stirling engine with design parameters more typcial of high-technology Stirling engines, counterbalanced converter efficiency could be increased to 99.6%. Dynamic computer simulation studies were conducted to evaluate performance and system sensitivities. Production costs of the complete Stirling hydraulic/electric power system were evaluated at $6506 which compared with $8746 for an alternative Stirling engine/linear alternator system.

  11. D0 Solenoid Upgrade Project: Vacuum Pumping Calculations for the D0 Solenoid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rucinski, R.; /Fermilab

    1993-08-02

    This engineering note documents the calculations done to determine the vacuum pumping speed for the D-Zero solenoid. The raw calculations are attached. A summary of the results are listed. The vacuum pumping speed of the solenoid is determined by the conductance of the pumping path. At higher pressure ranges during initial pumpdown, the conductances will be rather high. Calculations were not done for the transient pumpdown period, only the steady state type pumping situation. The pressure is assumed to be on the order of 10E-7 torr. This is the free molecular flow regime based on Knudsen number. This pressure regimemore » is also where the pumping speed would be least. The conductances were calculated based on pumping helium gas at a temperature of 300 Kelvin. The total conductance of the pumping path from the solenoid to the inlet of the turbomolecular pump is 11.8 L/s. The effective pumping speed of a 1000 L/s turbo pump attached to this pumping path is 11.7 L/s. The minimum required pumping speed for design purposes was set at 4.3 L/s. This value was arrived at by assuming a warm leak size (10E-8 atm-cc/sec) was not detected during fabrication of the solenoid. It is then assumed that the leak leaks cold liquid helium into the vacuum space. With this leak rate, a 4.3 L/s pumping speed would be able to maintain a 2 x 10E-7 torr pressure in the solenoid vacuum jacket. The solenoid would be able to be operated with this small leak with continuous pumping.« less

  12. Free piston variable-stroke linear-alternator generator

    DOEpatents

    Haaland, C.M.

    1998-12-15

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine is described. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod. 8 figs.

  13. Calibration and comparison of the NASA Lewis free-piston Stirling engine model predictions with RE-1000 test data

    NASA Technical Reports Server (NTRS)

    Geng, Steven M.

    1987-01-01

    A free-piston Stirling engine performance code is being upgraded and validated at the NASA Lewis Research Center under an interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA Lewis. Many modifications were made to the free-piston code in an attempt to decrease the calibration effort. A procedure was developed that made the code calibration process more systematic. Engine-specific calibration parameters are often used to bring predictions and experimental data into better agreement. The code was calibrated to a matrix of six experimental data points. Predictions of the calibrated free-piston code are compared with RE-1000 free-piston Stirling engine sensitivity test data taken at NASA Lewis. Reasonable agreement was obtained between the code prediction and the experimental data over a wide range of engine operating conditions.

  14. Calibration and comparison of the NASA Lewis free-piston Stirling engine model predictions with RE-1000 test data

    NASA Technical Reports Server (NTRS)

    Geng, Steven M.

    1987-01-01

    A free-piston Stirling engine performance code is being upgraded and validated at the NASA Lewis Research Center under an interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA Lewis. Many modifications were made to the free-piston code in an attempt to decrease the calibration effort. A procedure was developed that made the code calibration process more systematic. Engine-specific calibration parameters are often used to bring predictions and experimental data into better agreement. The code was calibrated to a matrix of six experimental data points. Predictions of the calibrated free-piston code are compared with RE-1000 free-piston Stirling engine sensitivity test data taken at NASA Lewis. Resonable agreement was obtained between the code predictions and the experimental data over a wide range of engine operating conditions.

  15. Investigations of Heat Transfer in Vacuum between Room Temperature and 80 K

    NASA Astrophysics Data System (ADS)

    Hooks, J.; Demko, J. A.; E Fesmire, J.; Matsumoto, T.

    2017-12-01

    The heat transfer between room temperature and 80 K is controlled using various insulating material combinations. The modes of heat transfer are well established to be conduction and thermal radiation when in a vacuum. Multi-Layer Insulation (MLI) in a vacuum has long been the best approach. Typically this layered system is applied to the cold surface. This paper investigates the application of MLI to both the cold and warm surface to see whether there is a significant difference. In addition if MLI is on the warm surface, the cold side of the MLI may be below the critical temperature of some high temperature superconducting (HTS) materials. It has been proposed that HTS materials can serve to block thermal radiation. An experiment is conducted to measure this effect. Boil-off calorimetry is the method of measuring the heat transfer.

  16. Gas injected vacuum switch

    DOEpatents

    Hardin, K. Dan

    1977-01-01

    The disclosure relates to a gas injected vacuum switch comprising a housing having an interior chamber, a conduit for evacuating the interior chamber, within the chamber an anode and a cathode spaced from the anode, and a detonator for injecting electrically conductive gas into the chamber between the anode and the cathode to provide a current path therebetween.

  17. The influence of titanium adhesion layer oxygen stoichiometry on thermal boundary conductance at gold contacts

    NASA Astrophysics Data System (ADS)

    Olson, David H.; Freedy, Keren M.; McDonnell, Stephen J.; Hopkins, Patrick E.

    2018-04-01

    We experimentally demonstrate the role of oxygen stoichiometry on the thermal boundary conductance across Au/TiOx/substrate interfaces. By evaporating two different sets of Au/TiOx/substrate samples under both high vacuum and ultrahigh vacuum conditions, we vary the oxygen composition in the TiOx layer from 0 ≤ x ≤ 2.85. We measure the thermal boundary conductance across the Au/TiOx/substrate interfaces with time-domain thermoreflectance and characterize the interfacial chemistry with x-ray photoemission spectroscopy. Under high vacuum conditions, we speculate that the environment provides a sufficient flux of oxidizing species to the sample surface such that one essentially co-deposits Ti and these oxidizing species. We show that slower deposition rates correspond to a higher oxygen content in the TiOx layer, which results in a lower thermal boundary conductance across the Au/TiOx/substrate interfacial region. Under the ultrahigh vacuum evaporation conditions, pure metallic Ti is deposited on the substrate surface. In the case of quartz substrates, the metallic Ti reacts with the substrate and getters oxygen, leading to a TiOx layer. Our results suggest that Ti layers with relatively low oxygen compositions are best suited to maximize the thermal boundary conductance.

  18. Observation of Live Ticks (Haemaphysalis flava) by Scanning Electron Microscopy under High Vacuum Pressure

    PubMed Central

    Ishigaki, Yasuhito; Nakamura, Yuka; Oikawa, Yosaburo; Yano, Yasuhiro; Kuwabata, Susumu; Nakagawa, Hideaki; Tomosugi, Naohisa; Takegami, Tsutomu

    2012-01-01

    Scanning electron microscopes (SEM), which image sample surfaces by scanning with an electron beam, are widely used for steric observations of resting samples in basic and applied biology. Various conventional methods exist for SEM sample preparation. However, conventional SEM is not a good tool to observe living organisms because of the associated exposure to high vacuum pressure and electron beam radiation. Here we attempted SEM observations of live ticks. During 1.5×10−3 Pa vacuum pressure and electron beam irradiation with accelerated voltages (2–5 kV), many ticks remained alive and moved their legs. After 30-min observation, we removed the ticks from the SEM stage; they could walk actively under atmospheric pressure. When we tested 20 ticks (8 female adults and 12 nymphs), they survived for two days after SEM observation. These results indicate the resistance of ticks against SEM observation. Our second survival test showed that the electron beam, not vacuum conditions, results in tick death. Moreover, we describe the reaction of their legs to electron beam exposure. These findings open the new possibility of SEM observation of living organisms and showed the resistance of living ticks to vacuum condition in SEM. These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition. PMID:22431980

  19. Advanced Controller Developed for the Free-Piston Stirling Convertor

    NASA Technical Reports Server (NTRS)

    Gerber, Scott S.

    2005-01-01

    A free-piston Stirling power convertor is being considered as an advanced power-conversion technology for future NASA deep-space missions requiring long-life radioisotope power systems. The NASA Glenn Research Center has identified key areas where advanced technologies can enhance the capability of Stirling energy-conversion systems. One of these is power electronic controls. Current power-conversion technology for Glenn-tested Stirling systems consists of an engine-driven linear alternator generating an alternating-current voltage controlled by a tuning-capacitor-based alternating-current peak voltage load controller. The tuning capacitor keeps the internal alternator electromotive force (EMF) in phase with its respective current (i.e., passive power factor correction). The alternator EMF is related to the piston velocity, which must be kept in phase with the alternator current in order to achieve stable operation. This tuning capacitor, which adds volume and mass to the overall Stirling convertor, can be eliminated if the controller can actively drive the magnitude and phase of the alternator current.

  20. Modelling of crater formation on anode surface by high-current vacuum arcs

    NASA Astrophysics Data System (ADS)

    Tian, Yunbo; Wang, Zhenxing; Jiang, Yanjun; Ma, Hui; Liu, Zhiyuan; Geng, Yingsan; Wang, Jianhua; Nordlund, Kai; Djurabekova, Flyura

    2016-11-01

    Anode melting and crater formation significantly affect interruption of high-current vacuum arcs. The primary objective of this paper is to theoretically investigate the mechanism of anode surface crater formation, caused by the combined effect of surface heating during the vacuum arc and pressure exerted on the molten surface by ions and electrons from the arc plasma. A model of fluid flow and heat transfer in the arc anode is developed and combined with a magnetohydrodynamics model of the vacuum arc plasma. Crater formation is observed in simulation for a peak arcing current higher than 15 kA on 40 mm diam. Cu electrodes spaced 10 mm apart. The flow of liquid metal starts after 4 or 5 ms of arcing, and the maximum velocities are 0.95 m/s and 1.39 m/s for 20 kA and 25 kA arcs, respectively. This flow redistributes thermal energy, and the maximum temperature of the anode surface does not remain in the center. Moreover, the condition for the liquid droplet formation on the anode surfaces is developed. The solidification process after current zero is also analyzed. The solidification time has been found to be more than 3 ms after 25 kA arcing. The long solidification time and sharp features on crater rims induce Taylor cone formation.

  1. Tribological properties of polymer films and solid bodies in a vacuum environment

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1988-01-01

    The tribological properties of ten different polymer based materials were evaluated in a vacuum environment to determine their suitability for possible lubrication applications in a space environment, such as might be encountered on the proposed Space Station. A pin-on-disk tribometer was used and the polymer materials were evaluated either as solid body disks or as films applied to 440C HT stainless steel disks. A 440C HT stainless steel hemispherically tipped pin was slid against the polymer materials. For comparison, similar tests were conducted in a controlled air atmosphere of 50 percent relative humidity air. In most instances, the polymer materials lubricated much better under vacuum conditions than in air. Thus, several of the materials show promise as lubricants for vacuum applications. Friction coefficients of 0.05 or less and polymer material wear rates of up to 2 orders of magnitude less than in air were obtained. One material showed considerable promise as a traction drive material. Relative high friction coefficients (0.36 to 0.52) and reasonably low wear rates were obtained in vacuum.

  2. Tribological properties of polymer films and solid bodies in a vacuum environment

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1987-01-01

    The tribological properties of ten different polymer based materials were evaluated in a vacuum environment to determine their suitability for possible lubrication applications in a space environment, such as might be encountered on the proposed space station. A pin-on-disk tribometer was used and the polymer materials were evaluated either as solid body disks or as films applied to 440C HT stainless steel disks. A 440C HT stainless steel hemispherically tipped pin was slid against the polymer materials. For comparison, similar tests were conducted in a controlled air atmosphere of 50 percent relative humidity air. In most instances, the polymer materials lubricated much better under vacuum conditions than in air. Thus, several of the materials show promise as lubricants for vacuum applications. Friction coefficients of 0.05 or less and polymer material wear rates of up to 2 orders of magnitude less than in air were obtained. One material showed considerable promise as a traction drive material. Relatively high friction coefficients (0.36 to 0.52) and reasonably low wear rates were obtained in vacuum.

  3. 58. Detail of steam pistons and gears for driving winches ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    58. Detail of steam pistons and gears for driving winches to Marine Railways #1 and #2, Marine Railway Headhouse, ground floor, looking north. - Thames Tow Boat Company, Foot of Farnsworth Street, New London, New London County, CT

  4. Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

    PubMed

    Fang, Yurui; Zhang, Zhenglong; Chen, Li; Sun, Mengtao

    2015-01-14

    Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

  5. Multipurpose Vacuum Induction Processing System

    NASA Astrophysics Data System (ADS)

    Govindaraju, M.; Kulkarni, Deepak; Balasubramanian, K.

    2012-11-01

    Multipurpose vacuum processing systems are cost effective; occupy less space, multiple functional under one roof and user friendly. A multipurpose vacuum induction system was designed, fabricated and installed in a record time of 6 months time at NFTDC Hyderabad. It was designed to function as a) vacuum induction melting/refining of oxygen free electronic copper/pure metals, b) vacuum induction melting furnace for ferrous materials c) vacuum induction melting for non ferrous materials d) large vacuum heat treatment chamber by resistance heating (by detachable coil and hot zone) e) bottom discharge vacuum induction melting system for non ferrous materials f) Induction heat treatment system and g) directional solidification /investment casting. It contains provision for future capacity addition. The attachments require to manufacture multiple shaped castings and continuous rod casting can be added whenever need arises. Present capacity is decided on the requirement for 10years of development path; presently it has 1.2 ton liquid copper handling capacity. It is equipped with provision for capacity addition up to 2 ton liquid copper handling capacity in future. Provision is made to carry out the capacity addition in easy steps quickly. For easy operational maintenance and troubleshooting, design was made in easily detachable sections. High vacuum system is also is detachable, independent and easily movable which is first of its kind in the country. Detailed design parameters, advantages and development history are presented in this paper.

  6. Ballistic piston fissioning plasma experiment.

    NASA Technical Reports Server (NTRS)

    Miller, B. E.; Schneider, R. T.; Thom, K.; Lalos, G. T.

    1971-01-01

    The production of fissioning uranium plasma samples such that the fission fragment stopping distance is less than the dimensions of the plasma is approached by using a ballistic piston device for the compression of uranium hexafluoride. The experimental apparatus is described. At room temperature the gun can be loaded up to 100 torr UF6 partial pressure, but at compression a thousand fold increase of pressure can be obtained at a particle density on the order of 10 to the 19th power per cu cm. Limited spectral studies of UF6 were performed while obtaining the pressure-volume data. The results obtained and their implications are discussed.

  7. 75 FR 76019 - Compliance Policy Guide Sec. 390.500 Definition of “High-Voltage Vacuum Switch”-21 CFR 1002.61(a...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ...] Compliance Policy Guide Sec. 390.500 Definition of ``High-Voltage Vacuum Switch''--21 CFR 1002.61(a)(3) and... Sec. 390.500 Definition of ``High-Voltage Vacuum Switch''--21 CFR 1002.61(a)(3) and (b)(2) (CPG Sec.... 2010-30677 Filed 12-6-10; 8:45 am] BILLING CODE 4160-01-P ...

  8. Method Of Making A Vacuum-Tight Continuous Cable Feedthrough Device

    DOEpatents

    Bazizi, Kamel Abdel; Haelen, Thomas Eugene; Lobkowicz, Frederick; Slattery, Paul Francis

    2001-07-17

    A vacuum-tight cable feedthrough device includes a metallic first flange that is penetrated by a slot. Passing through the slot is a flat stripline cable that includes a plurality of conductive signal channels encompassed by a dielectric material on whose upper and lower surfaces is disposed a conductive material includes a ground. The stripline cable is sealed within the slot to provide a substantially vacuum-tight seal between the cable and the first flange. In a preferred embodiment, the cable feedthrough device includes a plurality, at least 16, of stripline cables. In a further preferred embodiment, the device includes a second flange and a bellows sealably connecting the first and second flanges, thereby providing a substantially vacuum-tight, flexible housing for the plurality of cables.

  9. Lightweight Vacuum Jacket for Cryogenic Insulation - Appendices to Final Report. Volume 2

    NASA Technical Reports Server (NTRS)

    Barclay, D. L.; Bell, J. E.; Brogren, E. W.; Straayer, J. W.

    1975-01-01

    The feasibility is demonstrated of producing a lightweight vacuum jacket using state-of-the-art technology and materials. Design and analytical studies were made on an orbital maneuvering system fuel tank. Preliminary design details were completed for the tank assembly which included an optimized vacuum jacket and multilayered insulation system. A half-scale LH2 test model was designed and fabricated and a force/stiffness proof test was conducted on the vacuum jacket. A vacuum leak rate of 0.00001 was measured, approximately 1500 hours of vacuum pressure was sustained, and 29 vacuum pressure cycles were experienced prior to failure. For vol. 1, see N75-26192.

  10. Measurement of liquid film thickness by optical fluorescence and its application to an oscillating piston positive displacement flowmeter

    NASA Astrophysics Data System (ADS)

    Morton, Charlotte E.; Baker, Roger C.; Hutchings, Ian M.

    2011-12-01

    The movement of the circular piston in an oscillating piston positive displacement flowmeter is important in understanding the operation of the flowmeter, and the leakage of liquid past the piston plays a key role in the performance of the meter. The clearances between the piston and the chamber are small, typically less than 60 µm. In order to measure this film thickness a fluorescent dye was added to the water passing through the meter, which was illuminated with UV light. Visible light images were captured with a digital camera and analysed to give a measure of the film thickness with an uncertainty of less than 7%. It is known that this method lacks precision unless careful calibration is undertaken. Methods to achieve this are discussed in the paper. The grey level values for a range of film thicknesses were calibrated in situ with six dye concentrations to select the most appropriate one for the range of liquid film thickness. Data obtained for the oscillating piston flowmeter demonstrate the value of the fluorescence technique. The method is useful, inexpensive and straightforward and can be extended to other applications where measurement of liquid film thickness is required.

  11. A fixed collector employing reversible vee-trough concentrator and a vacuum tube receiver for high temperature solar energy systems

    NASA Technical Reports Server (NTRS)

    Selcuk, M. K.

    1976-01-01

    A solar heat collection system employing non-tracking reflectors integrated with a fixed vacuum tube receiver which achieves modest year-round concentration (about 2) of the sunlight at low capital costs is discussed. The axis of the vee-trough reflector lies in a east-west direction and requires reversal of the reflector surfaces only twice a year without disturbing the receiver tubes and associated plumbing. It collects most of the diffuse flux. The vacuum tube receiver with selective absorber has no convection losses while radiation and conduction losses are minimal. Significant cost reductions are offered since the vee-trough can be fabricated from inexpensive polished or plastic reflector laminated sheet metal covering 2/3 of the collection area, and only about 1/3 of the area is covered with the more expensive vacuum tube receivers. Thermal and economic performance of the vee-trough vacuum tube system, year-round variation of the concentration factor, incident flux, useful heat per unit area at various operation temperatures and energy cost estimates are presented. The electrical energy cost is estimated to be 77 mills/kWh, and the system construction cost is estimated to be $1140/kWe.

  12. A near-wearless and extremely long lifetime amorphous carbon film under high vacuum

    PubMed Central

    Wang, Liping; Zhang, Renhui; Jansson, Ulf; Nedfors, Nils

    2015-01-01

    Prolonging wear life of amorphous carbon films under vacuum was an enormous challenge. In this work, we firstly reported that amorphous carbon film as a lubricant layer containing hydrogen, oxygen, fluorine and silicon (a-C:H:O:F:Si) exhibited low friction (~0.1), ultra-low wear rate (9.0 × 10–13 mm3 N–1 mm–1) and ultra-long wear life (>2 × 106 cycles) under high vacuum. We systematically examined microstructure and composition of transfer film for understanding of the underlying frictional mechanism, which suggested that the extraordinarily excellent tribological properties were attributed to the thermodynamically and structurally stable FeF2 nanocrystallites corroborated using first-principles calculations, which were induced by the tribochemical reaction. PMID:26059254

  13. Venturi air-jet vacuum ejectors for high-volume atmospheric sampling on aircraft platforms

    NASA Technical Reports Server (NTRS)

    Hill, Gerald F.; Sachse, Glen W.; Young, Douglas C.; Wade, Larry O.; Burney, Lewis G.

    1992-01-01

    Documentation of the installation and use of venturi air-jet vacuum ejectors for high-volume atmospheric sampling on aircraft platforms is presented. Information on the types of venturis that are useful for meeting the pumping requirements of atmospheric-sampling experiments is also presented. A description of the configuration and installation of the venturi system vacuum line is included with details on the modifications that were made to adapt a venturi to the NASA Electra aircraft at GSFC, Wallops Flight Facility. Flight test results are given for several venturis with emphasis on applications to the Differential Absorption Carbon Monoxide Measurement (DACOM) system at LaRC. This is a source document for atmospheric scientists interested in using the venturi systems installed on the NASA Electra or adapting the technology to other aircraft.

  14. 26. Detail showing piston which is one of two steam ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. Detail showing piston which is one of two steam powered drive units for winches for Marine Railways #1. and #2, Marine Railway Headhouse. - Thames Tow Boat Company, Foot of Farnsworth Street, New London, New London County, CT

  15. Nearly Seamless Vacuum-Insulated Boxes

    NASA Technical Reports Server (NTRS)

    Stepanian, Christopher J.; Ou, Danny; Hu, Xiangjun

    2010-01-01

    A design concept, and a fabrication process that would implement the design concept, have been proposed for nearly seamless vacuum-insulated boxes that could be the main structural components of a variety of controlled-temperature containers, including common household refrigerators and insulating containers for shipping foods. In a typical case, a vacuum-insulated box would be shaped like a rectangular parallelepiped conventional refrigerator box having five fully closed sides and a hinged door on the sixth side. Although it is possible to construct the five-closed-side portion of the box as an assembly of five unitary vacuum-insulated panels, it is not desirable to do so because the relatively high thermal conductances of the seams between the panels would contribute significant amounts of heat leakage, relative to the leakage through the panels themselves. In contrast, the proposal would make it possible to reduce heat leakage by constructing the five-closed-side portion of the box plus the stationary portion (if any) of the sixth side as a single, seamless unit; the only remaining seam would be the edge seal around the door. The basic cross-sectional configuration of each side of a vacuum-insulated box according to the proposal would be that of a conventional vacuum-insulated panel: a low-density, porous core material filling a partially evacuated space between face sheets. However, neither the face sheets nor the core would be conventional. The face sheets would be opposite sides of a vacuum bag. The core material would be a flexible polymer-modified silica aerogel of the type described in Silica/Polymer and Silica/Polymer/Fiber Composite Aero - gels (MSC-23736) in this issue of NASA Tech Briefs. As noted in that article, the stiffness of this core material against compression is greater than that of prior aerogels. This is an important advantage because it translates to greater retention of thickness and, hence, of insulation performance when pressure is

  16. HIGH PRESSURE GAS REGULATOR

    DOEpatents

    Ramage, R.W.

    1962-05-01

    A gas regulator operating on the piston and feedback principle is described. The device is particularly suitable for the delicate regulation of high pressure, i.e., 10,000 psi and above, gas sources, as well as being perfectly adaptable for use on gas supplies as low as 50 psi. The piston is adjustably connected to a needle valve and the movement of the piston regulates the flow of gas from the needle valve. The gas output is obtained from the needle valve. Output pressure is sampled by a piston feedback means which, in turn, regulates the movement of the main piston. When the output is other than the desired value, the feedback system initiates movement of the main piston to allow the output pressure to be corrected or to remain constant. (AEC)

  17. Development of an optical time-resolved measurement system under high-pressure and low-temperature with a piston-cylinder pressure cell

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Satoshi; Kino, Yohei; Nakagawa, Koichi; Nakagawa, Daisuke; Yamada, Jun-ichi; Toda, Yasunori

    2016-04-01

    To perform the femtosecond pump-probe spectroscopy under high pressure and low temperature, we constructed a measurement system with a piston cylinder type pressure cell installing an optical fiber bundle. The applied pressure was achieved to 6 kbar and the cell was cooled down to 15 K. Several demonstrations revealed that broadening and change of polarization of pulse (duration of ˜120 fs) owing to the dispersions in the fiber bundle are much small indicating that those have little influence on the measurement of carrier relaxation dynamics. In the measurements of κ-(BEDT-TTF)2Cu(NCS)2 under 1.3 kbar at 43 K, we have successfully detected the polarization anisotropy of the carrier relaxation dynamics and estimated the decay time in the same way as the normal measurement.

  18. Development of an optical time-resolved measurement system under high-pressure and low-temperature with a piston-cylinder pressure cell.

    PubMed

    Tsuchiya, Satoshi; Kino, Yohei; Nakagawa, Koichi; Nakagawa, Daisuke; Yamada, Jun-Ichi; Toda, Yasunori

    2016-04-01

    To perform the femtosecond pump-probe spectroscopy under high pressure and low temperature, we constructed a measurement system with a piston cylinder type pressure cell installing an optical fiber bundle. The applied pressure was achieved to 6 kbar and the cell was cooled down to 15 K. Several demonstrations revealed that broadening and change of polarization of pulse (duration of ∼120 fs) owing to the dispersions in the fiber bundle are much small indicating that those have little influence on the measurement of carrier relaxation dynamics. In the measurements of κ-(BEDT-TTF)2Cu(NCS)2 under 1.3 kbar at 43 K, we have successfully detected the polarization anisotropy of the carrier relaxation dynamics and estimated the decay time in the same way as the normal measurement.

  19. Pistons and Cylinders Made of Carbon-Carbon Composite Materials

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon-carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.

  20. Propellant Expulsion in Unmanned Spacecraft

    DTIC Science & Technology

    1966-07-01

    29 19. Experimental WAC Corporal piston tank .. ......... . 33 20. Three piston tank designs used in the Corporal program ..... 34 21...propellant. The only universal F. Filling seal at this writing is a metal bellows. Usually, piston tank assemblies are filled by a vacuum technique...externally gener- Piston tank assemblies are subjected to essentially the ated loads due to shock and vibration may be the sever- same tests as bladders. 31