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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Ion beam sputter etching of orthopedic implanted alloy MP35N and resulting effects on fatigue

The effects of two types of argon ion sputter etched surface structures on the tensile stress fatigue properties of orthopedic implant alloy MP35N were investigated. One surface structure was a natural texture resulting from direct bombardment by 1 keV argon ions. The other structure was a pattern of square holes milled into the surface by a 1 keV argon ion beam through a Ni screen mask. The etched surfaces were subjected to tensile stress only in fatigue tests designed to simulate the cyclic load conditions experienced by the stems of artificial hip joint implants. Both types of sputter etched surface structures were found to reduce the fatigue strength below that of smooth surface MP35N.

Wintucky, E. G.↗
NASA NTRS1982

Study on application of aerospace technology to improve surgical implants

The areas where aerospace technology could be used to improve the reliability and performance of metallic, orthopedic implants was assessed. Specifically, comparisons were made of material controls, design approaches, analytical methods and inspection approaches being used in the implant industry with hardware for the aerospace industries. Several areas for possible improvement were noted such as increased use of finite element stress analysis and fracture control programs on devices where the needs exist for maximum reliability and high structural performance.

Johnson, R. E.↗
NASA NTRS1982

Development of a new, completely implantable intraventricular pressure meter and preliminary report of its clinical experience

A completely implantable intracranial pressure sensor designed for long-term measurement of intraventricular pressure in hydrocephalic patients is described. The measurement principal of the device is discussed along with the electronic and component structure and sources of instrument error. Clinical tests of this implanted pressure device involving both humans and animals showed it to be comparable to other methods of intracranial pressure measurement.

Osaka, K.↗
NASA NTRS1982

Non-mass-analyzed ion implantation equipment for high volume solar cell production

Equipment designed for junction formation in silicon solar cells is described. The equipment, designed for a production level of approximately one megawatt per year, consists of an ion implanter and annealer. Low cost is achieved by foregoing the use of mass analysis during the implantation, and by the use of a belt furnace for annealing. Results of process development, machine design and cost analysis are presented.

Armini, A. J.↗
NASA NTRS1983

Ion implanted junctions for silicon space solar cells

This paper reviews the application of ion implantation to emitter and back surface field formation in silicon space solar cells. Experiments based on 2 ohm-cm boron-doped silicon are presented. It is shown that the implantation process is particularly compatible with formation of a high-quality back surface reflector. Large area solar cells with AM0 efficiency greater than 14 percent are reported.

Spitzer, M. B.↗
NASA NTRS1985

Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

Fonash, S. J.↗
NASA NTRS1985

Far-infrared transmittance of boron-implanted germanium at liquid-helium temperatures

The transmission of far-infrared radiation of 100-microns-wavelength through Ge wafers ion implanted with B was measured at a temperature of approximately 4 K. Transmittance ranged from approximately 0.5 to 0.08 for doses from 3 x 10 to the 12th to 3 x 10 to the 15th/sq cm. The resistivity at temperatures between 4 and 1 K, and the impurity profiles of the implanted layers were also measured and correlated with the infrared transmittance.

Hadek, V.↗
NASA NTRS1986

Four-micron period ion-implanted bubble test circuits

Packaged magnetic bubble test circuits made with 4-micron period ion-implanted circuits were operated over -55 to +110 C. The circuits used bidirectional transfer and nondestructive detection and were made on bismuth-containing magnetic garnet films. Passivated circuits that incorporated an improved transfer conductor design were operated on films with higher Gilbert damping parameters. Potential advantages to using films with lower bubble aspect ratios for ion-implanted circuits are discussed. However nondestructive read-out detection was not realized with these 'flat' bubbles.

Nelson, T. J.↗
NASA NTRS1987

Implantable, Ingestible Electronic Thermometer

Small quartz-crystal-controlled oscillator swallowed or surgically implanted provides continuous monitoring of patient's internal temperature. Receiver placed near patient measures oscillator frequency, and temperature inferred from previously determined variation of frequency with temperature. Frequency of crystal-controlled oscillator varies with temperature. Circuit made very small and implanted or ingested to measure internal body temperature.

Kleinberg, Leonard↗
NASA NTRS1986

Characterization of NTD germanium and ion-implanted Si bolometers at 0.3K and 0.1K

Bolometer elements were built and tested using NTD germanium and ion-implanted Si thermometer elements. The thermal links were made using aluminum wires and NbC(x)N(y) coated carbon fibers. The temperature dependence of the detector resistance, lead thermal conductivity, and heat capacity were measured. The dependence of the detector resistance on applied electric field was also measured. This, combined with the current-voltage curve for the detector, allowed the calculation of the detector responsivity. Known amounts of energy were deposited into the detector by allowing X-rays from the decay of Fe-55 to be thermalized in the detector. In the best-measured case, the predicted pulse height/measured height was 1.04 + or - .05. The noise at frequencies above 25 Hz in the NTD Ge was near that predicted by thermodynamics. The noise below 25 Hz has a 1/f character and may be in the carbon fiber/bolometer junction. The implanted detectors show some 1/f noise which depends on the total thermometer volume. Comparison between noise measurements and theory will be presented.

Moseley, H.↗
NASA NTRS1986

Stoichiometric disturbances in compound semiconductors due to ion implantation

A method is developed to calculate the depth distribution of the local stoichiometric disturbance (SD) resulting from ion implantation in binary-compound substrates. The calculation includes first-order recoils considering projected range straggle of projectiles and recoils and lateral straggle of recoils. The method uses tabulated final-range statistics to infer the projectile range distributions at intermediate energies. This approach greatly simplifies the calculation with little compromise on accuracy as compared to existing procedures. As an illustration, the SD profile is calculated for implantation of boron, silicon, and aluminum in silicon carbide. The results for the latter case suggest that the SD may be responsible for otherwise unexplained distortions in the annealed aluminum profile. A comparison with calculations by other investigators using the Boltzmann transport equation shows good agreement.

Avila, R. E.↗
NASA NTRS1988

Biofeedback With Implanted Blood-Pressure Device

Additional uses found for equipment described in "Implanted Blood-Pressure-Measuring Device" (GSC-13042). Implanted with device electronic circuitry that measures, interprets, and transmits data via inductive link through patient's skin to external receiver. Receiver includes audible alarm generator activated when patient's blood pressure exceeds predetermined threshold. Also included in receiver a blood-pressure display, recorder, or both, for use by patient or physician.

Rischell, Robert E.↗
NASA NTRS1988

GaAs/GaAlAs distributed Bragg reflector laser with a focused ion beam, low dose dopant implanted grating

The performance of a GaAs/GaAlAs distributed Bragg reflector (DBR) laser using a focused ion beam implanted grating (FIB-DBR) is reported for the first time. Stripes of Si(2+) with a period of 2300 A and a dose about 10 to the 14th/sq cm are directly implanted into the passive large optical cavity layer to provide the distributed feedback. Surface-emitting light from the second-order grating is observed. Threshold current of 110 mA and single DBR mode operation from 20 to 40 C are obtained. The wavelength tuning rate with temperature is 0.8 A/C. The coupling coefficient is estimated to be 15/cm. The results show that FIB technology is practical for distributed feedback and DBR lasers and optoelectronic integrated circuits.

Wu, M. C.↗
NASA NTRS1989

Mandrels For Microtextured Small-Vessel Implants

Research shows artificial blood-vessel and heart-valve implants made more compatible with their biological environments by use of regularly microtextured surfaces. In new manufacturing process, ion beam etches patterned array of small pillars on mandrel used to mold tubular plastic implant. Pillars create tiny regularly spaced holes in inner surface of tube. Holes expected to provide sites for attachment of healthy lining. Polytetrafluoroethylene (PTFE) used as mandrel material because it can be etched by ion beam.

Deininger, William D.↗
NASA NTRS1988

Photoreflectance Study of Boron Ion-Implanted (100) Cadmium Telluride

Ion implanted (100) cadmium telluride was studied using the contactless technique of photoreflectance. The implantations were performed using 50- to 400-keV boron ions to a maximum dosage of 1.5 x 10(16)/sq cm, and the annealing was accomplished at 500 C under vacuum. The spectral measurements were made at 77 K near the E(0) and E(1) critical points; all the spectra were computer-fitted to Aspnes' theory. The spectral line shapes from the ion damaged, partially recovered and undamaged, or fully recovered regions could be identified, and the respective volume fraction of each phase was estimated.

Amirtharaj, P. M.↗
NASA NTRS1991

Ion-implanted extrinsic Ge photodetectors with extended cutoff wavelength

Far-IR Ge detectors fabricated using boron ion implantation are shown to exhibit operating characteristics compatible with requirements for low background applications. Device parameters such as low dark currents, reasonably good sensitivity, and extended wavelength threshold demonstrate that ion-implanted Ge far-IR detectors offer promise for use in astrophysics instrumentation.

Wu, I. C.↗
NASA NTRS1992

Oxygen isotopes implanted in the LDEF spacecraft

Depth profiles of O-16 and O-18/O-16 were measured on stainless steel nuts and copper sheet (from a grounding strap) recovered from the leading edge of LDEF (Tray E10). The measurements were obtained by dynamic SIMS (secondary ion mass spectrometry) using a VG Isolab 54 ion microprobe. Plots of O-18/O-16 against time, show large depletions of up to a factor of 2 compared to the O-18/O-16 value at sea level. The O-16 current decreases by 2 orders of magnitude in the interior of the metal, and the corresponding profile of anomalous O-16 is strongly peaked in the outer few tens of nanometers of the surface. This depth scale is a tentative one based on estimated sputtering rates. Plots of O-18/O-16 against 1/O-16 should be linear if two isotopically distinct components, one of variable concentration (orbital component) and one of fixed concentration (normal oxygen), are mixed. Data to be presented at the meeting show departures from linearity which result from variability in the concentration of normal oxygen, but may also arise from the implantation of oxygen with a range of fractionation due to the decaying orbit of the LDEF, sputtering of the surface by atomic oxygen, and the different momenta of the two isotopes due to their equal velocities. The potential for using this method as a means of identifying exposure to low-Earth orbit, de-convoluting the effects of space exposure from terrestrial contamination, and using the implanted anomolous oxygen as a means of studying the atomic oxygen density and upper atmosphere temperature height profile will be discussed at the meeting.

Saxton, J. M.↗