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Research Activities and Projects
The CSP has actively pursued the development of solar power from space as a non-conventional energy source for terrestrial application. In particular, the Center has fostered development of wireless power transmission by microwave beam and lasers as a enabling technology for the importation of electric energy from space. 
The Center for Space Power (CSP) is conducting commercially driven research programs for various advanced thermal management technologies. The Center, along with its Industry and Government partners are advancing the selected technologies through microgravity based research. Loop Heat Pipe: Loop Heat Pipes (LHP) are two-phase thermal control systems similar to regular heat pipes but can transport higher thermal loads over greater distances. These devices have many applications both in space and here on Earth. The Loop Heat Pipe flight experiment with Industry partner Thermacore flew aboard STS-87. The LHP flight experiment tested this advanced thermal technology and validated its readiness for space applications.These loop heat pipes are now in the BSS-702 geo spacecraft. 
Multi-Chip Module: Multi-chip modules (MCMs) are advanced thermal technologies that integrate the cooling system directly into the chip substrate. The integration allows improved cooling leading to lower power component temperatures. This technology will allow for greater heat fluxes for MCM boards and single chips. The CSP is working with The University of Cincinnati, Thermacore, and NASA GRC to develop this technology. Phase Separator: The use of two-phase thermal systems for spacecraft requires the separation of gas and liquid. The Phase Separator is a novel concept that utilizes the inherent momentum of the fluid to produce an artificial acceleration field. Liquid and gas separate under buoyancy forces and provide the thermal system with separate gas and liquid streams. This system will fly on a future shuttle mission as part of the Immobilized Microbe Microgravity Water Processing System (IMMWPS). 
Two-Phase Instrumentation: The Center for Space Power has also assisted organizations to test two-phase instrumentation used in microgravity. The CSP along with Creare , NASA Goddard Space Flight Center, and NASA Lewis Research Center tested a unique non-intrusive void fraction sensor developed by Creare aboard NASA's KC-135. Active Two-Phase Thermal Systems: The Center for Space Power also carries out basic microgravity two-phase research. Utilizing the Foster-Miller/Phillips Lab/ Johnson SpaceCenter/ Texas A&M test package, researchers are able to produce accurate two-phase flows to determine pressure drops and heat transfer parameters as well as flow regime mapping. The test bed is unique in that both the liquid and vapor velocities are known and adjustable. Energy storage projects include electrochemical and mechanical technologies. The current lithium-ion battery work which is closely coordinated with the battery group at NASA Glenn Research Center will support development of lithium-ion battery via fundamental understanding of the charge/discharge mechanism of the lithium-ion battery system and improved component development. Tasks will include synthesis of new/improved electrode materials, evaluation of solvent/electrolyte mixtures and half cell testing of electrode/electrolyte interactions. The result will be a battery design with greater energy density and longer life, resulting in reduced system mass and lower launch cost. Lithium-Ion batteries have become the battery o choice for consumer electronics and offer upto fourfold improvement in specific energy storage compared to state-of-the-art space batteries. The current Lithium-ion battery work is closely co-ordinated with the battery group at NASA Glenn Research Center. The effort to develop a lithium-ion polymer battery involves the fundamental understanding of materials as well as the solid-electrolyte interface. Magnetic Bearings for Flywheel Energy Storage: Flywheel energy storage aboard spacecraft presents the potential for a significant increase in system energy density and longevity when compared with batteries. A critical element of effective flywheel systems is the magnetic bearing subsystem that enables the very high rotational speeds needed to achieve an up to ten-fold performance improvement over batteries. The CSP is designing magnetic bearings, developing and implementing control algorithms, and building evaluation tools for ultra high-speed flywheels for space applications. Alkali Metal Thermal to Electric Conversion (AMTEC): The AMTEC is a high efficiency device for directly converting heat to electricity. AMTEC operates as a thermally regenerative electrochemical cell by expanding sodium through the pressure differential across a sodium beta alumina solid electrolyte (BASE) membrane. While AMTEC technology is still being developed, laboratory devices have achieved efficiencies as high as 19% and system design studies indicate that efficiencies as high as 30% are achievable in the near term and 35% or more may be possible. AMTEC can provide all the advantages of a static power system (low vibration, redundancy, no wear) at efficiencies normally achieved only in dynamic systems. Small system designs using AMTEC have shown 27% cell and 23% system efficiencies, while laboratory experiments with developmental ARPS type cells have achieved 16% efficiencies. Further, because AMTEC requires energy input at modest temperatures, and not at a specific wavelength, it is easily adapted to any heat source, including radioisotope, concentrated solar, external combustion, or reactor. This adaptability makes AMTEC very attractive for development because it has so many potential applications, both space and terrestrial, for a single basic design. The CSP supports AMTEC research in the following ways. We have a detailed model of AMTEC that allows better prediction of converter behavior and we are investigating material behavior in an AMTEC cell to better understand the interaction and degradation mechanisms that affect cell performance. Multi-Quantum Well Photovoltaic Conversion: Currently, photovoltaic devices operate with efficiencies up to about 28% in space. The CSP is investigating two approaches that should help increase that number to 40% or better. The first approach involves developing a new silicon based heterostructure material that allows control or engineering of the bandgap to effectively capture more of the solar spectrum. The second approach is to analyze ways to improve the collection efficiency of the carriers using modern heterostructure simulation tools. Insight into, as well as understanding, the key charge carrier dissipation mechanisms and charge extraction limits should help identify and focus on methods for reducing losses from mechanisms such as recombination, interface scattering, and impurity effects. |
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