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Electron beam energy is absorbed by deflectors which allow beam distribution over an absorber located between the deflectors and workpiece. The undeflected beam passes through a hole in the absorber when the deflection is de-energized, when energized, the beam is kept to a minimum power level by deflection rate change.
The electric power system is a crucial element of any mission for the human exploration of the Martian surface. The bulk of the power generated will be delivered to crew life support systems, extravehicular activity suits, robotic vehicles, and predeployed in situ resource utilization (ISRU) equipment. In one mission scenario, before the crew departs for Mars, the ISRU plant operates for 435 days producing liquefied methane and oxygen for ascent-stage propellants and water for crew life support. About 200 days after ISRU production is completed, the crew arrives for a 500-day surface stay. In this scenario, the power system must operate for a total of 1130 days (equivalent to 1100 Martian "sols"), providing 400 MW-hr of energy to the ISRU plant and up to 18 kW of daytime user power. A photovoltaic power-generation system with regenerative fuel cell (RFC) energy storage has been under study at the NASA Glenn Research Center at Lewis Field. The conceptual power system is dominated by the 4000- m2 class photovoltaic array that is deployed orthogonally as four tent structures, each approximately 5 m on a side and 100-m long. The structures are composed of composite members deployed by an articulating mast, an inflatable boom, or rover vehicles, and are subsequently anchored to the ground. Array panels consist of thin polymer membranes with thin-film solar cells. The array is divided into eight independent electrical sections with solar cell strings operating at 600 V. Energy storage is provided by regenerative fuel cells based on hydrogen-oxygen proton exchange membrane technology. Hydrogen and oxygen reactants are stored in gaseous form at 3000 psi, and the water produced is stored at 14.7 psi. The fuel cell operating temperature is maintained by a 40-m2 deployable pumped-fluid loop radiator that uses water as the working fluid. The power management and distribution (PMAD) architecture features eight independent, regulated 600-Vdc channels. Power management and distribution power cables use various gauges of copper conductors with ethylene tetrafluoroethylene insulation. To assess power system design options and sizing, we developed a dedicated Fortran code to predict detailed power system performance and estimate system mass. This code also modeled the requisite Mars surface environments: solar insolation, Sun angles, dust storms, dust deposition, and thermal and ultraviolet radiation. Using this code, trade studies were performed to assess performance and mass sensitivities to power system design parameters (photovoltaic array geometry and orientation) and mission parameters (landing date and landing site latitude, terrain slope, and dust storm activity). Mission analysis cases were also run. Power results are shown in this graph for an analysis case with a September 1, 2012, landing date; 18.95 North latitude landing site; two seasonal dusts storms; and tent arrays. To meet user load requirements and the ISRU energy requirement, an 8-metric ton (MT) power system and 4000-m2 photovoltaic array area were required for the assumed advanced CuInS2 thin-film solar cell technology. In this figure, the top curve is the average daytime photovoltaic array power, the middle curve is average daytime user load power, and the bottom curve is nighttime power. At mission day 1, daytime user power exceeds 120 kW before falling off to 80 kW at the end of the mission. Throughout the mission, nighttime user power is set to the nighttime power requirement. In this analysis, "nighttime" is defined as the 13- to 15-hr period when array power output is below the daytime power requirement. During dust storms, power system capability falls off dramatically so that by mission day 900, a daily energy balance cannot be maintained. Under these conditions, the ISRU plant is placed in standby mode, and the regenerative fuel cell energy storage is gradually discharged to meet user loads.
Cell-bypass control system senses low capacity cells before they overcharge or discharge. Relay automatically removes defective cell (when it is detected) from battery circuit. System shows promise for improving batteries in computer standby power systems, electric vehicles, and energy storage systems.
A transponder that may be used as an RFID tag includes a passive circuit to eliminate the need for an "always on" active RF receiving element to anticipate a wake-up signal for the balance of the transponder electronics. This solution allows the entire active transponder to have all circuit elements in a sleep (standby) state, thus drastically extending battery life or other charge storage device life. Also, a wake-up solution that reduces total energy consumption of an active transponder system by allowing all non-addressed transponders to remain in a sleep (standby) state, thereby reducing total system or collection energy. Also, the transponder and wake-up solution are employed in an asset tracking system.
A transponder that may be used as an RFID tag includes a passive circuit to eliminate the need for an "always on" active RF receiving element to anticipate a wake-up signal for the balance of the transponder electronics. This solution allows the entire active transponder to have all circuit elements in a sleep (standby) state, thus drastically extending battery life or other charge storage device life. Also, a wake-up solution that reduces total energy consumption of an active transponder system by allowing all non-addressed transponders to remain in a sleep (standby) state, thereby reducing total system or collection energy. Also, the transponder and wake-up solution are employed in an asset tracking system.
A transponder that may be used as an RFID tag includes a passive circuit to eliminate the need for an "always on" active RF receiving element to anticipate a wake-up signal for the balance of the transponder electronics. This solution allows the entire active transponder to have all circuit elements in a sleep (standby) state, thus drastically extending battery life or other charge storage device life. Also, a wake-up solution that reduces total energy consumption of an active transponder system by allowing all non-addressed transponders to remain in a sleep (standby) state, thereby reducing total system or collection energy. Also, the transponder and wake-up solution are employed in an asset tracking system.
This paper describes how commercial pump technology was modified for rocket engine application by trading long life for low weight. The component life of typical turbopump components is presented, and the modes of failure will be discussed. A comparison of the basic commercial and rocket engine pump requirements such as flow, pressure, etc. is made. It is concluded that rocket engine pump technology can be applied directly only if similar basic requirements exist in emergency or stand-by equipment. The specific design requirements for rocket engine turbopumps are presented and the need for high speeds is explained by the weight-speed relationship and the optimum NPSH of the tank and pump system. The trend of required rocket engine pump discharge pressure and future operational requirements is predicted. The need for inducers and boost pumps in rocket engines is explained, and the results of the flat-plate-inducer cavitation therein are briefly presented. Design solutions and material selections for high-pressure pump housings, ultra-high tip speed impellers, and pump packaging are demonstrated. As a typical example of utilizing rocket engine technology for commercial application, a helicopter stand-by engine i shown. This standby engine is designed from existing rocket engine components, using JATO rockets as the prime energy source.
Composite-material cathodes that enable Li-ion electrochemical cells and batteries to function at both high energy densities and high discharge rates are undergoing development. Until now, using commercially available cathode materials, it has been possible to construct cells that have either capability for high-rate discharge or capability to store energy at average or high density, but not both capabilities. However, both capabilities are needed in robotic, standby-power, and other applications that involve duty cycles that include long-duration, low-power portions and short-duration, high-power portions. The electrochemically active ingredients of the present developmental composite cathode materials are: carbon-coated LiFePO4, which has a specific charge capacity of about 160 mA h/g and has been used as a high-discharge-rate cathode material and Li[Li(0.17)Mn(0.58)Ni(0.25)]O2, which has a specific charge capacity of about 240 mA h/g and has been used as a high-energy-density cathode material. In preparation for fabricating the composite material cathode described, these electrochemically active ingredients are incorporated into two sub-composites: a mixture comprising 10 weight percent of poly(vinylidine fluoride); 10 weight percent of carbon and 80 weight percent of carbon coated LiFePO4; and, a mixture comprising 10 weight percent of PVDF, and 80 weight percent of Li[Li(0.17)Mn(0.58)Ni(0.25)]O2. In the fabrication process, these mixtures are spray-deposited onto an aluminum current collector. Electrochemical tests performed thus far have shown that better charge/discharge performance is obtained when either 1) each mixture is sprayed on a separate area of the current collector or (2) the mixtures are deposited sequentially (in contradistinction to simultaneously) on the same current-collector area so that the resulting composite cathode material consists of two different sub-composite layers.
Rotating standby power system compensates for brief interruptions in commercial power supply. System furnishes few cycles of alternating current from its stored rotational energy. Protects equipment vulnerable to brief losses of power; for example, prevents computers from erroneously suppressing or adding bits to data being handled at moment of power failure.
NASA analyzes, tests, packages, and fabricates electrical, electronic, and electromechanical (EEE) parts used in space vehicles. One area that NASA wishes to advance is energy storage and delivery. Currently, space vehicles use rechargeable batteries that utilize silver zinc or lithium ion electrochemical processes. These current state-of-the-art rechargeable batteries cannot be rapidly charged, contain harmful chemicals, and suffer from early wear-out mechanisms. A solid state ultracapacitor is an EEE part that offers significant advantages over current electrochemical and electrolytic devices. The objective of this research is to develop an internal barrier layer ultracapacitor (IBLC) using novel dielectric materials as a battery replacement with a focus on these advantages: longer life, lower mass-toweight ratio, rapid charging, on-demand pulse power, improved on-pad standby time without maintenance, and environmental friendliness. The approach is unique in two areas. A deposition technique is used that has been shown to produce a more uniformly coated nanoparticle than sol-gel, which has resulted in colossal permittivities. These particles are then distributed in an ink formulation developed at NASA Marshall Space Flight Center (MSFC) and deposited utilizing a 3D aerosol jet technique. This additive manufacturing technique controls layer thickness, resulting in extremely large capacitance and energy density.
The Enhanced Thematic Mapper Plus (ETM+) Main Electronics Module (MEM) power supply heat sink temperature is critical to the Landsat-7 mission. It is strongly dependent on the thermal louver design. A lower power supply heat sink temperature increases the reliability of the MEM, and reduces the risk of over heating and thermal shut-down. After the power supply failures in ETM+ instrument thermal vacuum tests #1 and #2, the author performed detailed thermal analyses of the MEM, and proposed to reduce the louver set-points by 7C. At the 1998 Intersociety Energy Conversion Engineering Conference (IECEC), the author presented a paper that included results of thermal analysis of the MEM. It showed that a 70C reduction of the louver set points could reduce the maximum power supply heat sink temperature in thermal vacuum test and in flight to below 20"C in the cooler outgas mode and in the nominal imaging mode, and has no significant impact on the standby heater duty cycle. It also showed that the effect of Earth infrared and albedo on the power supply heat sink temperature is small. The louver set point reduction was implemented in June 1998, just prior to ETM+ thermal vacuum test #3. Results of the thermal vacuum tests, and temperature data in flight validate the MEM thermal performance improvement due to the 70C reduction of the louver set points.