Search NASA⌕ Search

SEARCH · Search NASA

Results for “High efficiency”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

High-efficiency electron ionizer for a mass spectrometer array

The present invention provides an improved electron ionizer for use in a quadrupole mass spectrometer. The improved electron ionizer includes a repeller plate that ejects sample atoms or molecules, an ionizer chamber, a cathode that emits an electron beam into the ionizer chamber, an exit opening for excess electrons to escape, at least one shim plate to collimate said electron beam, extraction apertures, and a plurality of lens elements for focusing the extracted ions onto entrance apertures.

Chutjian, Ara↗
NASA NTRS2007

Development of a High Efficiency UVR/IRR Coverglass for Triple Junction Solar Cells

Cover glasses have been a necessary and integral part of space solar arrays since their inception. The main function of the cover glass is to protect the underlying solar cell from the harsh radiation environment of space. They are formed either from fused silica or specially formulated ceria doped glass types that are resistant to radiation damage, for example Pilkington's CMX, CMG, CMO. Solar cells have steadily increased in performance over the past years, from Silicon cells through textured Silicon cells to GaAs cells and the multijunction cells of today. The optimum coverglass solution for each of these cells has been different. The glass itself has also evolved. In some cases it has had its expansion coefficient matched to the cell substrate material, and in addition, added value has been derived from the application of thin film optical coatings to the coverglass. In the majority of cases this has taken the form of a single layer of MgF2 which acts as an antireflection coating. There are also conductive coatings to address electrostatic discharge issues (ESD) and Ultra Violet Reflective (UVR) and Infrared Reflective (IRR) coatings designed for thermal enhancement. Each type of coating can be applied singly or in combination. This paper describes a new type of UVR/IRR (or blue red reflector BRR) specifically designed for triple junction solar cells. For space applications, where radiation is the principal mechanism for removing heat from the satellite, it is the emittance and solar absorptance that primarily determine the temperature of the array. It is therefore essential that any coatings designed to have an effect on the temperature by reducing the solar absorption have a minimal effect on the overall emittance.

Russell, John↗
NASA NTRS2009

High Efficiency Nuclear Power Plants using Liquid Fluoride Thorium Reactor Technology

An overall system analysis approach is used to propose potential conceptual designs of advanced terrestrial nuclear power plants based on Oak Ridge National Laboratory (ORNL) Molten Salt Reactor (MSR) experience and utilizing Closed Cycle Gas Turbine (CCGT) thermal-to-electric energy conversion technology. In particular conceptual designs for an advanced 1 GWe power plant with turbine reheat and compressor intercooling at a 950 K turbine inlet temperature (TIT), as well as near term 100 MWe demonstration plants with TITS of 950 K and 1200 K are presented. Power plant performance data were obtained for TITS ranging from 650 to 1300 K by use of a Closed Brayton Cycle (CBC) systems code which considered the interaction between major sub-systems, including the Liquid Fluoride Thorium Reactor (LFTR), heat source and heat sink heat exchangers, turbo -generator machinery, and an electric power generation and transmission system. Optional off-shore submarine installation of the power plant is a major consideration.

Juhasz, Albert J.↗
NASA NTRS2009

High Efficiency Nuclear Power Plants Using Liquid Fluoride Thorium Reactor Technology

An overall system analysis approach is used to propose potential conceptual designs of advanced terrestrial nuclear power plants based on Oak Ridge National Laboratory (ORNL) Molten Salt Reactor (MSR) experience and utilizing Closed Cycle Gas Turbine (CCGT) thermal-to-electric energy conversion technology. In particular conceptual designs for an advanced 1 GWe power plant with turbine reheat and compressor intercooling at a 950 K turbine inlet temperature (TIT), as well as near term 100 MWe demonstration plants with TITs of 950 and 1200 K are presented. Power plant performance data were obtained for TITs ranging from 650 to 1300 K by use of a Closed Brayton Cycle (CBC) systems code which considered the interaction between major sub-systems, including the Liquid Fluoride Thorium Reactor (LFTR), heat source and heat sink heat exchangers, turbo-generator machinery, and an electric power generation and transmission system. Optional off-shore submarine installation of the power plant is a major consideration.

Juhasz, Albert J.↗
NASA NTRS2007

High-Power, High-Efficiency Ka-Band Space Traveling-Wave Tube

The L-3 Communications Model 999H traveling-wave tube (TWT) has been demonstrated to generate an output power of 144 W at 60-percent overall efficiency in continuous-wave operation over the frequency band from 31.8 to 32.3 GHz. The best TWT heretofore commercially available for operation in the affected frequency band is characterized by an output power of only 35 W and an efficiency of 50 percent. Moreover, whereas prior TWTs are limited to single output power levels, it has been shown that the output power of the Model 999H can be varied from 54 to 144 W. A TWT is a vacuum electronic device used to amplify microwave signals. TWTs are typically used in free-space communication systems because they are capable of operating at power and efficiency levels significantly higher than those of solid-state devices. In a TWT, an electron beam is generated by an electron gun consisting of a cathode, focusing electrodes, and an anode. The electrons pass through a hole in the anode and are focused into a cylindrical beam by a stack of periodic permanent magnets and travel along the axis of an electrically conductive helix, along which propagates an electromagnetic wave that has been launched by an input signal that is to be amplified. The beam travels within the helix at a velocity close to the phase velocity of the electromagnetic wave. The electromagnetic field decelerates some of the electrons and accelerates others, causing the beam to become formed into electron bunches, which further interact with the electromagnetic wave in such a manner as to surrender kinetic energy to the wave, thereby amplifying the wave. The net result is to amplify the input signal by a factor of about 100,000. After the electrons have passed along the helix, they impinge on electrodes in a collector. The collector decelerates the electrons in such a manner as to recover most of the remaining kinetic energy and thereby significantly increase the power efficiency of the TWT.

Krawczyk, Richard↗
NASA NTRS2010

High efficiency thermoelectric power generation using Zintl-type materials

The invention disclosed herein relates to thermoelectrically-active p-type Zintl phase materials as well as devices utilizing such compounds. Such thermoelectric materials and devices may be used to convert thermal energy into electrical energy, or use electrical energy to produce heat or refrigeration. Embodiments of the invention relate to p-type thermoelectric materials related to the compound Yb.sub.14MnSb.sub.11.

Snyder, G. Jeffrey↗
NASA NTRS2011

High Efficiency Space Power Systems Project Advanced Space-Rated Batteries

Case Western Reserve University (CWRU) has an agreement with China National Offshore Oil Corporation New Energy Investment Company, Ltd. (CNOOC), under the United States-China EcoPartnerships Framework, to create a bi-national entity seeking to develop technically feasible and economically viable solutions to energy and environmental issues. Advanced batteries have been identified as one of the initial areas targeted for collaborations. CWRU invited NASA Glenn Research Center (GRC) personnel from the Electrochemistry Branch to CWRU to discuss various aspects of advanced battery development as they might apply to this partnership. Topics discussed included: the process for the selection of a battery chemistry; the establishment of an integrated development program; project management/technical interactions; new technology developments; and synergies between batteries for automotive and space operations. Additional collaborations between CWRU and NASA GRC's Electrochemistry Branch were also discussed.

Reid, Concha M.↗
NASA NTRS2005

High-Efficiency Solar Cells Using Photonic-Bandgap Materials

Solar photovoltaic cells would be designed to exploit photonic-bandgap (PBG) materials to enhance their energy-conversion efficiencies, according to a proposal. Whereas the energy-conversion efficiencies of currently available solar cells are typically less than 30 percent, it has been estimated that the energy-conversion efficiencies of the proposed cells could be about 50 percent or possibly even greater. The primary source of inefficiency of a currently available solar cell is the mismatch between the narrow wavelength band associated with the semiconductor energy gap (the bandgap) and the broad wavelength band of solar radiation. This mismatch results in loss of power from both (1) long-wavelength photons, defined here as photons that do not have enough energy to excite electron-hole pairs across the bandgap, and (2) short-wavelength photons, defined here as photons that excite electron- hole pairs with energies much above the bandgap. It follows that a large increase in efficiency could be obtained if a large portion of the incident solar energy could be funneled into a narrow wavelength band corresponding to the bandgap. In the proposed approach, such funneling would be effected by use of PBG materials as intermediaries between the Sun and photovoltaic cells.

Dowling, Jonathan↗
NASA NTRS2011

An Evaluation of Performance Metrics for High Efficiency Tube-and-Wing Aircraft Entering Service in 2030 to 2035

An analysis of basic vehicle characteristics required to meet the Fundamental Aeronautics Program s 70 percent energy consumption reduction goal for commercial airliners in the 2030 to 2035 timeframe was conducted. A total of 29 combinations of vehicle parasitic drag coefficient, vehicle induced drag coefficient, vehicle empty weight and engine Specific Fuel Consumption were used to create sized tube-and-wing vehicle models. The mission fuel burn for each of these sized vehicles was then compared to a baseline current technology vehicle. A response surface equation was generated of fuel burn reduction as a function of the four basic vehicle performance metrics, so that any values of the performance metrics up to a 50 percent reduction could be used to estimate fuel burn reduction of tube-and-wing aircraft for future studies.

Perkins, H. Douglas↗
NASA NTRS2009

Demonstration of a High-Efficiency Free-Space Optical Communications Link

In this paper we discuss recent progress on the implementation of a hardware free-space optical communications test-bed. The test-bed implements an end-to-end communications system comprising a data encoder, modulator, laser-transmitter, telescope, detector, receiver and error-correction-code decoder. Implementation of each of the component systems is discussed, with an emphasis on 'real-world' system performance degradation and limitations. We have demonstrated real-time data rates of 44 Mbps and photon efficiencies of approximately 1.8 bits/photon over a 100m free-space optical link.

pulse-position-modulation↗
NASA NTRS2008

High Efficiency Submillimeter-Wave Imaging Array

The period of a focal array is limited by the angular sampling and the f number of the system. This fact will limit the efficiency of imaging array systems to around 50%. Recently it been demonstrated that the use of a dielectric layer on top of an array of apertures can improve this efficiency limit. In this paper, we describe a similar structure that improves the efficiency in imaging applications and that it is easy to manufacture due to its compatibility with planar lithographic techniques.

Llombart, Nuria↗
NASA NTRS2015

Selenium Interlayer for High-Efficiency Multijunction Solar Cell

A multi junction solar cell is provided and includes multiple semiconducting layers and an interface layer disposed between the multiple semiconducting layers. The interface layer is made from an interface bonding material that has a refractive index such that a ratio of a refractive index of each of the multiple semiconducting layers to the refractive index of the interface bonding material is less than or equal to 1.5.

Landis, Geoffrey A↗
NASA NTRS2016

Planar Field Emitters and High Efficiency Photocathodes Based on Ultrananocrystalline Diamond

A method of forming a field emitter comprises disposing a first layer on a substrate. The first layer is seeded with nanodiamond particles. The substrate with the first layer disposed thereon is maintained at a first temperature and a first pressure in a mixture of gases which includes nitrogen. The first layer is exposed to a microwave plasma to form a nitrogen doped ultrananocrystalline diamond film on the first layer, which has a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %. The field emitter has about 10.sup.12 to about 10.sup.14 emitting sites per cm.sup.2. A photocathode can also be formed similarly by forming a nitrogen doped ultrananocrystalline diamond film on a substrate similar to the field emitter, and then hydrogen terminating the film. The photocathode is responsive to near ultraviolet light as well as to visible light.

Sumant, Anirudha V.↗
NASA NTRS2016

Selenium Interlayer for High-Efficiency Multijunction Solar Cell

A multi-junction solar cell is provided and includes multiple semiconducting layers and an interface layer disposed between the multiple semiconducting layers. The interface layer is made from an interface bonding material that has a refractive index such that a ratio of a refractive index of each of the multiple semiconducting layers to the refractive index of the interface bonding material is less than or equal to 1.5.

Landis, Geoffrey A.↗