Engineering Papers⌕ Search

Engineering topics

Shimada, K.

Publications and source records attributed to Shimada, K..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

The development of a charge-coupled device tracker for spacecraft

Charge-coupled device (CCD) optical sensors have made it possible to construct high performance star and target trackers for spacecraft. The Advanced Star and Target Reference Orbital Sensor (ASTROS) trackers have been developed by JPL for the Shuttle-based astronomical flight Astro-1 and the Mariner Mark II (MMII) spacecraft. For the Shuttle application the tracker will provide the data for high precision instrument pointing and for the MMII application the tracker will provide stellar and extended target tracking data for flyby and rendezvous navigation. The specifications, architecture, and testing program for these trackers will be described. Laboratory measurements have demonstrated that these trackers can be very effective. The versatility and flexibility of the ASTROS type trackers will permit adaptation to a variety of navigation and guidance applications. These trackers represent one of the technologically advanced components that will be used in the development of the next generation of spacecraft.

Dennison, E. W.↗
NASA NTRS1986

ASTROS - High-performance CCD tracker for spacecraft

The architecture, capabilities, and testing of the Advanced Star and Target Reference Optical Sensor (ASTROS) I and II are described. The ASTROS I tracker is to be utilized for a UV telescope experiment on a Shuttle flight and is capable of measuring pointing errors of 1.5 microrad, and the ASTROS II tracker is being developed for the Mariner Mark II spacecraft to perform tracking, guiding, and optical navigation functions. The requirements for the two trackers are compared. Consideration is given to star and target tracking, optical navigation, and mass and power constraints. The compositions of the trackers, in particular the sensor, electrode drives, amplifiers and signal clamp, video signal processor, control and timing generator, memories, microprocessor, and interface, are examined.

Dennison, E. W.↗
NASA NTRS1985

Photovoltaics in Japan

Report surveys status of research and development on photovoltaics in Japan. Report based on literature searches, private communications, and visits by author to Japanese facilities. Included in survey are Sunshine Project, national program to develop energy sources; industrial development at private firms; and work at academic institutions.

Shimada, K.↗
NASA NTRS1985

Determining Thermal Diffusivities of Radiating Specimens

Two heat-pulse techniques eliminate uncertainties due to radiation losses. Flashlamp supplies pulse of heat to one side of specimen. Temperatures of illumninated surface and of opposite surface monitored photometrically. In second method, pulse of electrons supplies heat to one side of specimen. Temperature of opposite side monitored by photon detector. Techniques needed because radiation heat losses in this temperature range introduce uncertainties into conventional heat-flux measurements.

Wood, C.↗
NASA NTRS1985

Potential of thin-film solar cell module technology

During the past five years, thin-film cell technology has made remarkable progress as a potential alternative to crystalline silicon cell technology. The efficiency of a single-junction thin-film cell, which is the most promising for use in flat-plate modules, is now in the range of 11 percent with 1-sq cm cells consisting of amorphous silicon, CuInSe2 or CdTe materials. Cell efficiencies higher than 18 percent, suitable for 15 percent-efficient flat plate modules, would require a multijunction configuration such as the CdTe/CuInSe2 and tandem amorphous-silicon (a-Si) alloy cells. Assessments are presented of the technology status of thin-film-cell module research and the potential of achieving the higher efficiencies required for large-scale penetration into the photovoltaic (PV) energy market.

Shimada, K.↗
NASA NTRS1984

Silicon-sheet and thin-film cell and module technology potential: Issue study

The development of high-efficiency low-cost crystalline silicon ribbon and thih-film solar cells for the energy national photovoltaics program was examined. The findings of an issue study conducted are presented. The collected data identified the status of the technology, future research needs, and problems experienced. The potentials of present research activities to meet the Federal/industry long-term technical goal of achieving 15 cents per kilowatt-hour levelized PV energy cost are assessed. Recommendations for future research needs related to crystalline silicon ribbon and thin-film technologies for flat-plate collectors are also included.

Shimada, K.↗
NASA NTRS1984

The U.S. and Japanese amorphous silicon technology programs A comparison

The U.S. Department of Energy/Solar Energy Research Institute Amorphous Silicon (a-Si) Solar Cell Program performs R&D on thin-film hydrogenated amorphous silicon for eventual development of stable amorphous silicon cells with 12 percent efficiency by 1988. The Amorphous Silicon Solar Cell Program in Japan is sponsored by the Sunshine Project to develop an alternate energy technology. While the objectives of both programs are to eventually develop a-Si photovoltaic modules and arrays that would produce electricity to compete with utility electricity cost, the U.S. program approach is research oriented and the Japanese is development oriented.

Shimada, K.↗
NASA NTRS1984

Multijunction cells for concentrators: Technology prospects

Development of high-efficiency multijunction solar cells for concentrator applications is a key step in achieving the goals of the U.S. Department of Energy National Photovoltaics Program. This report summarizes findings of an issue study conducted by the Jet Propulsion Laboratory Photovoltaic Analysis and Integration Center, with the assistance of the Solar Energy Research Institute and Sandia National laboratoies, which surveyed multijunction cell research for concentrators undertaken by federal agencies and by private industry. The team evaluated the potentials of research activities sponsored by DOE and by corporate funding to achieve projected high-efficiency goals and developed summary statements regarding industry expectations. Recommendations are made for the direction of future work to address specific unresolved aspects of multijunction cell technology.

Ferber, R. R.↗
NASA NTRS1984

Terrestrial photovoltaic collector technology trends

Following the path of space PV collector development in its early stages, terrestrial PV technologies based upon single-crystal silicon have matured rapidly. Currently, terrestrial PV cells with efficiencies approaching space cell efficiencies are being fabricated into modules at a fraction of the space PV module cost. New materials, including CuInSe2 and amorphous silicon, are being developed for lowering the cost, and multijunction materials for achieving higher efficiency. Large grid-interactive, tracking flat-plate power systems and concentrator PV systems totaling about 10 MW, are already in operation. Collector technology development both flat-plate and concentrator, will continue under an extensive government and private industry partnership.

Shimada, K.↗
NASA NTRS1983

Simplified Heat-Source/Thermionic Converter

Radiation coupling of heat from heat-source cylinder to converter cylinder through vacuum gap eliminates need for high-temperature electrical insulators between reactor heat pipes and thermionic converters. In addition no radiatior heat pipe is necessary because collectors of thermionic converters from which excess heat must be removed radiate directly to space. New design concept is also applicable to terrestrial and non-nuclear thermionic power supplies.

Shimada, K.↗
NASA NTRS1983

Photovoltaic research and development in Japan

The status of the Japanese photovoltaic (PV) R&D activities was surveyed through literature searches, private communications, and site visits in 1982. The results show that the Japanese photovoltaic technology is maturing rapidly, consistent with the steady government funding under the Sunshine Project. Two main thrusts of the Project are: (1) completion of the solar panel production pilot plants using cast ingot and sheet silicon materials, and (2) development of large area amorphous silicon solar cells with acceptable efficiency (10 to 12%). An experimental automated solar panel production plant rated at 500 kW/yr is currently under construction for the Sunshine Project for completion in March 1983. Efficiencies demonstrated by experimental large are amorphous silicon solar cells are approaching 8%. Small area amorphous silicon solar cells are, however, currently being mass produced and marketed by several companies at an equivalent annual rate of 2 MW/yr for consumer electronic applications. There is no evidence of an immediate move by the Japanese PV industry to enter extensively into the photovoltaic power market, domestic or otherwise. However, the photovoltaic technology itself could become ready for such an entry in the very near future, especially by making use of advanced process automation technologies.

Shimada, K.↗
NASA NTRS1982

Removing Defects From Silicon Ribbon

Proposal for removing impurities from silicon ribbon and sheet could be developed into an automated production-line process. New technique which combines ion-cluster bombardment, electron-gun heating, and plasma etching, could be key step in fabricating inexpensive solar-cell arrays. Silicon sheets and ribbons treated this way could have enhanced carrier lifetimes necessary for satisfactory solar-cell performance.

Shimada, K.↗
NASA NTRS1982

Cost estimates for flat plate and concentrator collector arrays

The current module and installation costs for the U.S. National Photovoltaic Program's grid-connected systems are significantly higher than required for economic viability of this alternative. Attention is accordingly given to the prospects for installed module cost reductions in flat plate, linear focus Fresnel concentrator, and point focus Fresnel concentrator candidate systems. Cost projections indicate that all three systems would meet near-term and midterm goals, provided that module costs of $2.80/W(p) and $0.70/W(p), respectively, are met. The point focus Fresnel system emerges as the most viable for the near term.

Shimada, K.↗
NASA NTRS1981

Radiatively coupled thermionic power system concept

It is shown that thermionic converters at moderate emitter temperatures of about 1600 K can be designed for a radiatively coupled 100 kWe device. A nuclear reactor is a primary heat source, with heat pipes extracting heat from the reactor and distributing it over a large surface opposite an array of thermionic energy converters. The radiative heat transfer across the vacuum gap heats up the thermionic emitters, and excess heat from the converters is radiated from the collector electrodes to the vacuum of space; the heat transfer is controlled by the energy density to be transferred, and by the temperature differential between the heat source and the heat receiver. It is concluded that this system achieves isolation of power converter modules from the heat source, elimination of additional radiators, and reduction of converter dimensions.

Shimada, K.↗
NASA NTRS1981

Radiatively coupled thermionic and thermoelectric power system concept

The study presented showed that the large power systems (about 100 kW) utilizing radiatively coupled thermionic or thermoelectric converters could be designed so that the power subsystem could be contained in a Space Shuttle bay as a part of an electrically propelled spacecraft. The radiatively coupled system requires a large number of individual converters since the transferred heat is smaller than with the conductively coupled system, but the advantages of the new system indicates merit for further study. The advantages are (1) good electrical isolation between converters and the heat source, (2) physical separation of converters from the heat source (making the system fabrication manageable), and (3) elimination of radiator heat pipes, which are required in an all-heat-pipe power system. In addition, the specific weight of the radiatively coupled power systems favorably compares with that of the all-heat-pipe systems.

Shimada, K.↗
NASA NTRS1981

A photovoltaic industry overview - The results of a survey on photovoltaic technology industrialization

The National Photovoltaics Program of the United States Department of Energy has the objective of bringing photovoltaic power systems to a point where they can supply a significant portion of the United States energy requirements by the year 2000. This is planned to be accomplished through substantial research and technology development activities aimed at achieving major cost reductions and market penetration. This paper presents information derived from a limited survey performed to obtain photovoltaic industry attitudes concerning industrialization, and to determine current industry plans to meet the DOE program goals. Silicon material production, a key photovoltaic manufacturing industry, is highlighted with regards to implementation of technology improvement and silicon material supply outlook.

Ferber, R. R.↗
NASA NTRS1980

Heat flux at the thermionic collector

Heat flux arriving at the thermionic collector is theoretically considered to be composed of an electron heating term, proportional to the output current, plus the radiation and conduction terms. However, the measured electron heating term is always larger than what one would expect from the accepted theory. In this paper, the electron heating term at the collector is theoretically calculated as a sum of the conventional electron heating term and the heat flux which is carried into the collector by the random plasma current. The arriving random electrons and ions are considered to recombine nonradiatively at the collector surface after imparting their kinetic energies to the collector, in addition to the ionization potential energy. In this process, random electrons do not lose their potential energy equal to the collector work function, since they do not contribute to the output current.

Shimada, K.↗