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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Advances in Non-contact Measurement of Creep Properties

Our team has developed a novel approach to measuring creep at extremely high temperatures using electrostatic levitation (ESL). This method has been demonstrated on niobium up to 2300 C, while ESL has melted tungsten (3400 C). High-precision machined spheres of the sample are levitated in the NASA MSFC ESL, a national user facility, and heated with a laser. The laser is aligned off-center so that the absorbed photons transfer their momentum to the sample, causing it to rotate at up to 250,000+ RPM. The rapid rotation loads the sample through centripetal acceleration, causing it to deform. The deformation of the sample is captured on high-speed video, which is analyzed by machine-vision software from the University of Massachusetts. The deformations are compared to finite element models to determine the constitutive constants in the creep relation. Furthermore, the noncontact method exploits stress gradients within the sample to determine the stress exponent in a single test. This method was validated in collaboration with the University of Tennessee for niobium at 1985 C, with agreement within the uncertainty of the conventional measurements. A similar method is being employed on Ultra-High-Temperature ZrB2- SiC composites, which may see application in rocket nozzles and sharp leading edges for hypersonic vehicles.

Hyers, Robert W.↗
NASA NTRS2003

MEMS-Based Piezoelectric/Electrostatic Inchworm Actuator

A proposed inchworm actuator, to be designed and fabricated according to the principles of microelectromechanical systems (MEMS), would effect linear motion characterized by steps as small as nanometers and an overall range of travel of hundreds of microns. Potential applications for actuators like this one include precise positioning of optical components and active suppression of noise and vibration in scientific instruments, conveyance of wafers in the semiconductor industry, precise positioning for machine tools, and positioning and actuation of micro-surgical instruments. The inchworm motion would be generated by a combination of piezoelectric driving and electrostatic clamping. The actuator (see figure), would include a pair of holders (used for electrostatic clamping), a slider (the part that would engage in the desired linear motion), a driver, a piezoelectric stack under the driver, and a pair of polymer beams centrally clamped to the flexure beam via a T bar. The holders would be held stationary. One end of the piezoelectric stack would be held stationary; the other end would be connected to the bottom of the driver, which would be free to move up and down. All of these components except the piezoelectric stack and the polymer beams would be micromachined from a 500- m-thick silicon wafer by deep reactive-ion etching. The inchworm motion would be perpendicular to the broad faces of the wafer (perpendicular to the plane of the figure). The combination of the polymer beams and the centrally clamped flexure beam would spring-bias the slider into a position such that, in the absence of electrostatic clamping, the gap between the slider on the one hand and both the driver and the holder on the other hand would be no more than a few microns. This arrangement would make it possible to electrostatically pull the slider into contact with either the holders or the driver at a clamping force of the order of 1 N by applying a reasonably small voltage (of the order of 100 V).

Yang, Eui-Hyeok↗
NASA NTRS2004

Electrostatically clean solar array

Provided are methods of manufacturing an electrostatically clean solar array panel and the products resulting from the practice of these methods. The preferred method uses an array of solar cells, each with a coverglass where the method includes machining apertures into a flat, electrically conductive sheet so that each aperture is aligned with and undersized with respect to its matched coverglass sheet and thereby fashion a front side shield with apertures (FSA). The undersized portion about each aperture of the bottom side of the FSA shield is bonded to the topside portions nearest the edges of each aperture's matched coverglass. Edge clips are attached to the front side aperture shield edges with the edge clips electrically and mechanically connecting the tops of the coverglasses to the solar panel substrate. The FSA shield, edge clips and substrate edges are bonded so as to produce a conductively grounded electrostatically clean solar array panel.

Stern, Theodore Garry↗
NASA NTRS1995

Surface Micro-Machining: Progress Towards Micro-Electro Mechanical Systems

Surface micromachining is a technique for building electromechanical systems in silicon. A number of electromechanical systems have been implemented in miniature using the fundamental structural building blocks of tensile and non-tensile springs, differential capacitance sensing cells, and electrostatic drive. The integration of complicated mechanical structures and electrical circuits onto a single chip is expected to improve reliability and testability of systems. Reduction in interconnect wiring, the increased use of automation, and the inherent reliability of integrated circuits will all contribute to increased reliability of systems.

Doscher, James↗
NASA NTRS2004

Microsystem Cooler Development

A patented microsystem Stirling cooler is under development with potential application to electronics, sensors, optical and radio frequency (RF) systems, microarrays, and other microsystems. The microsystem Stirling cooler is most suited to volume-limited applications that require cooling below the ambient or sink temperature. Primary components of the planar device include: two diaphragm actuators that replace the pistons found in traditional-scale Stirling machines; and a micro-regenerator that stores and releases thermal energy to the working gas during the Stirling cycle. The use of diaphragms eliminates frictional losses and bypass leakage concerns associated with pistons, while permitting reversal of the hot and cold sides of the device during operation to allow precise temperature control. Three candidate microregenerators were custom fabricated for initial evaluation: two constructed of porous ceramic, and one made of multiple layers of nickel and photoresist in an offset grating pattern. An additional regenerator was prepared with a random stainless steel fiber matrix commonly used in existing Stirling machines for comparison to the custom fabricated regenerators. The candidate regenerators were tested in a piezoelectric-actuated test apparatus designed to simulate the Stirling refrigeration cycle. In parallel with the regenerator testing, electrostatically-driven comb-drive diaphragm actuators for the prototype device have been designed for deep reactive ion etching (DRIE) fabrication.

Moran, Matthew E.↗
NASA NTRS1978

Alternative approaches to plasma confinement

The paper discusses 20 plasma confinement schemes each representing an alternative to the tokamak fusion reactor. Attention is given to: (1) tokamak-like devices (TORMAC, Topolotron, and the Extrap concept), (2) stellarator-like devices (Torsatron and twisted-coil stellarators), (3) mirror machines (Astron and reversed-field devices, the 2XII B experiment, laser-heated solenoids, the LITE experiment, the Kaktus-Surmac concept), (4) bumpy tori (hot electron bumpy torus, toroidal minimum-B configurations), (5) electrostatically assisted confinement (electrostatically stuffed cusps and mirrors, electrostatically assisted toroidal confinement), (6) the Migma concept, and (7) wall-confined plasmas. The plasma parameters of the devices are presented and the advantages and disadvantages of each are listed.

Roth, J. R.↗
NASA NTRS2000

Development of Individually Addressable Micro-Mirror-Arrays for Space Applications

We have been developing a 32 x 32 prototype array of individually addressable Micro-Mirrors capable of operating at cryogenic temperature for Earth and Space Science applications. Micro-Mirror-Array technology has the potential to revolutionize imaging and spectroscopy systems for NASA's missions of the 21st century. They can be used as programmable slits for the Next Generation Space Telescope, as smart sensors for a steerable spectrometer, as neutral density filters for bright scene attenuation etc. The, entire fabrication process is carried out in the Detector Development Laboratory at NASA, GSFC. The fabrication process is low temperature compatible and involves integration of conventional CMOS technology and surface micro-machining used in MEMS. Aluminum is used as the mirror material and is built on a silicon substrate containing the CMOS address circuit. The mirrors are 100 microns x l00 microns in area and deflect by +/- 10 deg induced by electrostatic actuation between two parallel plate capacitors. A pair of thin aluminum torsion straps allow the mirrors to tilt. Finite-element-analysis and closed form solutions using electrostatic and mechanical torque for mirror operation were developed and the results were compared with laboratory performance. The results agree well both at room temperature and at cryogenic temperature. The development demonstrates the first cryogenic operation of two-dimensional Micro-Mirrors with bi-state operation. Larger arrays will be developed meeting requirements for different science applications. Theoretical analysis, fabrication process, laboratory test results and different science applications will be described in detail.

Dutta, Sanghamitra B.↗
NASA NTRS2009

NASA Workmanship Hot Topics: Water Soluble Flux and ESD Charge Device Model

This slide presentation reviews two topics of interest to NASA Workmanship: (1) Water Soluble Flux (WSF) and Electrostatic Discharge (ESD) safety. In the first topic, WSF, the presentation reviews voiding and the importance of cleanliness in using WSF for welding and soldering operations. The second topic reviews the NASA-HDBK-8739.21 for Human Body Model, and Machine Model safety methods, and challenges associated with the Charged Device Model (CDM)

Plante, Jeannette F.↗
NASA NTRS2001

IEC Research Status at MSFC

This viewgraph presentation gives an overview of the Inertial Electrostatic Confinement (IEC) research status at Marshall Space Flight Center. Details are given on the experiment setup (hardware characteristics, diagnostic equipment, propellant feed system, and planned pulse mode operation), grid manufacturing (identified manufacturing techniques, such as metal deposition, negative template mold, and machining), and grid for IEC operation (negative template technique and electrochemical technique).

Hrbud, Ivana↗
NASA NTRS1978

Production technology for high efficiency ion implanted solar cells

Ion implantation is being developed for high volume automated production of silicon solar cells. An implanter designed for solar cell processing and able to properly implant up to 300 4-inch wafers per hour is now operational. A machine to implant 180 sq m/hr of solar cell material has been designed. Implanted silicon solar cells with efficiencies exceeding 16% AM1 are now being produced and higher efficiencies are expected. Ion implantation and transient processing by pulsed electron beams are being integrated with electrostatic bonding to accomplish a simple method for large scale, low cost production of high efficiency solar cell arrays.

Kirkpatrick, A. R.↗
NASA NTRS2010

Improved Creep Measurements for Ultra-High Temperature Materials

Our team has developed a novel approach to measuring creep at extremely high temperatures using electrostatic levitation (ESL). This method has been demonstrated on niobium up to 2300 C, while ESL has melted tungsten (3400 C). This method has been extended to lower temperatures and higher stresses and applied to new materials, including a niobium-based superalloy, MASC. High-precision machined spheres of the sample are levitated in the NASA MSFC ESL, a national user facility and heated with a laser. The samples are rotated with an induction motor at up to 30,000 revolutions per second. The rapid rotation loads the sample through centripetal acceleration, producing a shear stress of about 60 MPa at the center, causing the sample to deform. The deformation of the sample is captured on high-speed video, which is analyzed by machine-vision software from the University of Massachusetts. The deformations are compared to finite element models to determine the constitutive constants in the creep relation. Furthermore, the non-contact method exploits stress gradients within the sample to determine the stress exponent in a single test.

Hyers, Robert W.↗
NASA NTRS1996

Array of micro-machined mass energy micro-filters for charged particles

An energy filter for charged particles includes a stack of micro-machined wafers including plural apertures passing through the stack of wafers, focusing electrodes bounding charged particle paths through the apertures, an entrance orifice to each of the plural apertures and an exit orifice from each of the plural apertures and apparatus for biasing the focusing electrodes with an electrostatic potential corresponding to an energy pass band of the filter.

Stalder, Roland E.↗
NASA NTRS1976

Evaluation of a method to shield a welding electron beam from magnetic interference

It is known that electron beams are easily deflected by magnetic and electrostatic fields. Therefore, to prevent weld defects, stray electromagnetic fields are avoided in electron beam welding chambers if at all possible. The successful results of tests conducted at MSFC to evaluate a simple magnetic shield made from steel tubing are reported. Tests indicate that this shield was up to 85 percent effective in reducing magnetic effects on the electron beam of a welding machine. In addition, residual magnetic fields within the shield were so nearly uniform that the net effect on the beam alignment was negligible. It is concluded that the shield, with the addition of a tungsten liner, could be used in production welding.

Wall, W. A.↗
NASA NTRS1994

NASA Ultra-Sensitive Miniature Accelerometer

Using micro-machined silicon technology, an ultra-sensitive miniature acce.,rometer can be constructed which meets the requirements for microgravity experiments in the space environment.Such an accelerometer will have a full scale sensitivity of 1C2 g a resolution of lC8 g, low cross axis sensitivity, and low temperature sensitivity. Mass of the device is approximately five grams and its footprint is 2 cm x 2 cm. Innovative features of the accelerometer, which are patented, are: electrostatic caging to withstand handling shock up to 150 g, in-situ calibration, in situ performance characterization, and both static and dynamic compensation. The transducer operates on a force balance principle wherein the displacement of the proof mass is monitored by measuring tunneling electron current flow between a conductive tip, and a fixed platen. The four major parts of the accelerometer are tip die, incorporating the tunneling tip and four field plates for controlling pitch and roll of the proof mass; two proof mass dies, attached to the surrounding frame by sets of four leg" springs; and a force plate die. The four parts are fuse-bonded into a complete assembly. External electrical connections are made at bond pads on the front surface of the force plate die. Materials and processes used in the construction of the transducer are compatible with volume production.

Zavracky, Paul M.↗
NASA NTRS1998

3-D capaciflector

A capacitive type proximity sensor having improved range and sensitivity between a surface of arbitrary shape and an intruding object in the vicinity of the surface having one or more outer conductors on the surface which serve as capacitive sensing elements shaped to conform to the underlying surface of a machine. Each sensing element is backed by a reflector driven at the same voltage and in phase with the corresponding capacitive sensing element. Each reflector, in turn, serves to reflect the electric field lines of the capacitive sensing element away from the surface of the machine on which the sensor is mounted so as to enhance the component constituted by the capacitance between the sensing element and an intruding object as a fraction of the total capacitance between the sensing element and ground. Each sensing element and corresponding reflecting element are electrically driven in phase, and the capacitance between the sensing elements individually and the sensed object is determined using circuitry known to the art. The reflector may be shaped to shield the sensor and to shape its field of view, in effect providing an electrostatic lensing effect. Sensors and reflectors may be fabricated using a variety of known techniques such as vapor deposition, sputtering, painting, plating, or deformation of flexible films, to provide conformal coverage of surfaces of arbitrary shape.

Vranish, John M.↗
NASA NTRS1977

Mass-driver reaction engine as Shuttle upper-stage

Optimization has been carried out on the design of a mass-driver intended for upgrading the Shuttle to geosynchronous and lunar-orbit capability. The machine accelerates 2,100 tons/yr of external tankage, in 14-gram segments, to exhaust velocities of 8,000-10,000 m/s. The resulting reaction force raises 1,700 tons/yr. of Shuttle payloads to high orbit, in two round trips. Exhaust velocity and thrust can be optimized for each mission segment. For a mission requiring an exhaust velocity of 8,000 m/sec, thrust is 560 newtons, power is 2.9 megawatts, and efficiency is 75%. Total electrical component mass including power supplies and waste-heat radiators is 89 tons. To insure that reaction mass does not constitute a hazard, segments may be in the form of powder, electrostatically dispersed after acceleration, and/or thrust may be vectored.

Oneill, G. K.↗
NASA NTRS2019

MISSE-11 Ground Experiment Control

Back during the Apollo missions, when astronauts were being sent to the moon to explore and further scientific knowledge by conducting experiments and collecting samples for scientists back on Earth, they were faced with a surprising problem. It was discovered that the moon’s surface is covered with dust that has electrostatic properties, which would stick to suit and equipment. This hindered the functionality of the astronauts’ space suits, solar panels, optical instruments, among other exposed surfaces due to the jagged geometry of the dust which would damage said equipment. To resolve this issue, the Electrostatics and Surface Physics Laboratory (ESPL) came up with the solution of using an Electrodynamic Dust Shield (EDS)1 that uses electrostatic forces to move particles across a surface. Varieties of this dust shield have been developed for different applications. The purpose of the Materials International Space Station Experiments 11 (MISSE-11) is to experiment a payload that contains the dust mitigation technology to be flown to space for one year and an identical payload will be on earth, under vacuum, in the Electrostatics and Surface Physics Laboratory. The space payload was prepared prior to our arrival and shipped to fly on the International Space Station (ISS). The payload staying on the ground is going to act as a control for the experiment so that we may compare it to the payload that was flown in space. During our time at Kennedy Space Center, we were tasked with building and start testing the ground control unit of the MISSE-11 payload. To complete our task for the ground control unit, we constructed a new vacuum chamber setup and added automated aspects, procured the necessary flight electronics, designed and communicated for the machining of the payload frame, and performed functional and thermal testing on the electronics to the same original operational standards. Some modifications were made where possible, without affecting the performance of the samples, to be efficient with the production of the control unit while keeping important aspects identical. The experiment is now nearly complete, and testing will be starting within the next few weeks.

MISSE↗
NASA NTRS1995

Implementation and Characterization of Three-Dimensional Particle-in-Cell Codes on Multiple-Instruction-Multiple-Data Massively Parallel Supercomputers

A three-dimensional electrostatic particle-in-cell (PIC) plasma simulation code has been developed on coarse-grain distributed-memory massively parallel computers with message passing communications. Our implementation is the generalization to three-dimensions of the general concurrent particle-in-cell (GCPIC) algorithm. In the GCPIC algorithm, the particle computation is divided among the processors using a domain decomposition of the simulation domain. In a three-dimensional simulation, the domain can be partitioned into one-, two-, or three-dimensional subdomains ("slabs," "rods," or "cubes") and we investigate the efficiency of the parallel implementation of the push for all three choices. The present implementation runs on the Intel Touchstone Delta machine at Caltech; a multiple-instruction-multiple-data (MIMD) parallel computer with 512 nodes. We find that the parallel efficiency of the push is very high, with the ratio of communication to computation time in the range 0.3%-10.0%. The highest efficiency (> 99%) occurs for a large, scaled problem with 64(sup 3) particles per processing node (approximately 134 million particles of 512 nodes) which has a push time of about 250 ns per particle per time step. We have also developed expressions for the timing of the code which are a function of both code parameters (number of grid points, particles, etc.) and machine-dependent parameters (effective FLOP rate, and the effective interprocessor bandwidths for the communication of particles and grid points). These expressions can be used to estimate the performance of scaled problems--including those with inhomogeneous plasmas--to other parallel machines once the machine-dependent parameters are known.

Lyster, P. M.↗