Agency: National Aeronautics and Space Administration | Branch: | Program: STTR | Phase: Phase II | Award Amount: 599.24K | Year: 2011
Advances in high power, photovoltaic technology has enabled the possibility of reasonably sized, high specific power, high power, solar arrays. At high specific powers, power levels ranging from 50 to several hundred kW are feasible. Coupled with gridded ion thruster technology, this power technology can be mission enabling for a wide range of missions ranging from ambitious near Earth NASA missions to those missions involving other customers as well such as DOD and commercial satellite interests. Indeed the HEFT clearly identified the need for high power electric. The appeal of the ion thrusters for such applications stems from their overall high efficiency, typically>70% and long life. In response to the need for a single, high powered engine to fill the gulf between the 7 kW NEXT system and a notional 25 kW engine, a Phase I activity to build a 25 kW, 50 cm ion thruster discharge chamber was completed with a laboratory model fabricated. The proposed Phase II effort aims to mature the laboratory model into a proto-engineering model ion thruster. The proposed effort involves the evolution of the discharge chamber to a high performance thruster by performance testing and characterization via simulated and full beam extraction testing. Through such testing the design will be optimized leading ultimately to the proposed design, build and preliminary checkout of a proto-engineering model thruster, thereby advancing the TRL level to 4-5 range. Deliverables include the thruster, a design package, and a performance data document.
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2012
ABSTRACT: The next generation of hypersonic and reentry vehicles being designed for the Department of Defense (DoD) applications will require advanced Thermal Protection System (TPS). While new TPS shields are under development, a key difficulty is the ability to predict and diagnose TPS performance. ElectroDynamic Applications (EDA) has been developing an optical diagnosticfor use during testing and in flightthat will help address this need for experimental data. During an initial SBIR effort, we began the development of a low intrusive fiber optic plug insert for TPS materials that will enable spectrographic measurements of the reentry environment surrounding a TPS. This proposal seeks to modify the fiber optic plug to also permit interferometric measurement of surface recession rates for an ablative TPS. As the ablative surface recedes, light reflected from the fiber end alternates between constructive and destructive interference with light reflected from a similar (but unablated) fiber. The resulting fringe pattern permits sub-micron resolution of changes in the fiber length, and thus the TPS thickness. In addition, the optical fiber can simultaneously provide benchmark data for fundamental flow, radiation, and materials modeling as well as provide operational correlations between vehicle reentry drag and radiation. BENEFIT: EDA"s plan to pursue this technology beyond Phase-I is to develop production of flight hardware for DoD, NASA, and privately funded vehicles. Boeing has also expressed significant interest in transitioning the technology into their thermal protection systems as part of an integrated vehicle health monitoring system. As private sector space ventures continue to blossom, there will be significant opportunities for commercialization. This technology may also have derivative terrestrial applications in high power plasma processing and energy creation systems.
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.65K | Year: 2012
ABSTRACT: The proposed Phase I efforts seek to develop a dual-mode Hybrid ChemicalElectric Propulsion thruster concept design based on the extensive microwave torch/arcjet experience of PSU and Hall and ion experience of EDA. The primary focus of the Phase I effort will be demonstrate the operation of an ionic liquid microwave thruster in the high-T/P regime and the basic operation of a Hall and/or ion thruster on an ionic liquid simulant. Microwave-generated plasmas have been used in a variety of propulsion systems. They can be used to ignite and accelerate the combustion of a chemical propellant, to add heat to a propellant gas in an electrothermal thruster concept, or to provide propellant ionization for an ion or Hall thruster. High power microwave generation using vacuum electron devices such as magnetrons or klystrons are highly efficient, approaching 90% electrical efficiency. What is proposed is a new spacecraft electric propulsion concept that, through the use of a microwave-generated plasma, can operate as a chemical thruster, a low ISP electric thruster or a high ISP electric thruster, using the same propellant for all three regimes. The propellant would be an energetic ionic liquid, an example being HAN-based monopropellants, along with other energetic ionic liquids under development. BENEFIT: The successful completion of the Phase II portion of this program will result in an electric thruster that can operate at specific impulses ranging from chemical to 3000 seconds with advanced low toxicity monopropellants that can be incorporated for use on spacecraft and satellites, resulting in higher performance over a broad range of operating conditions with more environmentally friendly propellants. EDA will be able to offer energetic ionic liquid spacecraft electric thruster systems that will give higher performance with more environmentally friendly propellants, products that will have high commercial value. The reduced toxicity of the propellants directly translates into a reduction of the propellant handling and spacecraft fueling costs, whereas the increased density Isp allows for a significant reduction in spacecraft volume and mass. The Hybrid Chemical-Electric Propulsion thruster can provide the means to move away, for the first time after more than fifty years of their use, from all the negatives associated with current storable mono- and bipropellants. EDA is committed to developing spacecraft propulsion related systems such as a Hybrid ChemicalElectric Propulsion thruster. EDA is uniquely qualified to advance this technology rapidly through initial prototype development and qualification due to its experience in flight hardware. The PIs of this proposed project have first-hand experience with commercial EP devices having assisted three major aerospace engineering firms with thruster (and associated electronics) qualification. Additionally, the HCEP team has experience with the development of flight hardware that has been flown in space.
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 399.93K | Year: 2010
The objective of this program is to build upon many decades of experience with magnetic flowmeters to develop a next-generation system to measure the burning surface admittance of high-energy-density solid propellants at high frequencies and pressures. Using the results of research on solid propellant rocket motor combustion instability from the past fifty years, one can directly measure the acoustic admittance of the atomization/vaporization/mixing/combustion processes associated with liquid propellant rocket engine injection. Such a measurement would provide a quantitative value for the acoustic sources or sinks caused by these processes. This would enable an a priori prediction of the combustion stability for a particular liquid rocket engine design, something that has not been possible to date. BENEFIT: If successful, this research will provide a commercially available apparatus that would be able to characterize the dynamic behavior of a wide number of high-energy-density propellants. This would provide faster prototyping, and allow for more mass and fuel efficient design of rocket engines in general. This diagnostic technology would obviously be very attractive to any commercial market working in solid and liquid rocket design in both military and commercial applications.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.79K | Year: 2014
The proposed work investigates an approach that would allow an annular ion engine geometry to achieve ion beam currents approaching the Child-Langmuir limit. In this respect, the annular engine, whose design inherently allows for significant increases in perveance by resolving the span-to-gap problem, can achieve the projected high current densities necessary for high thrust, high power applications. The case for high power gridded ion thrusters is compelling if not only for risk reduction in contrast to lower TRL Hall thruster variants such as the nested channel systems. This point cannot be over emphasized as there is now significant effort and resources applied to Hall engine development. Yet there still remains some uncertainty as to how high power variants or magnetically insulated variants will actually perform in space. Interpretation of high power Hall engine operation in ground test facilities is also not completely well understood. This is in contrast with gridded ion technology whose facility corrections are well understood. The current investment in high power gridded ion thruster technology is minimal. This effort seeks to address this gap in technology development and in the process continue the advancement of a credible risk reducing technology for high power mission applications.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 599.97K | Year: 2011
EDA, Inc., in partnership with Penn State, has shown previously that the concept of embedding fiber optics within ablative TPS material has merit and should yield a successful implementation of a spectrometer "window" during a Phase-II development program.Optical instrumentation, such as optical spectrometers would provide benchmark data for fundamental flow, radiation, and materials modeling as well as provide operational correlations between vehicle reentry drag and radiation if implemented in a TPS flight test program. Without flight spectral data, and the appropriate modeling efforts, the power of prediction to assist in new heat shield design does not exist for reentry into other planetary atmospheres. This is a severe limitation for future space exploration missions which FiberPlug helps address.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.48K | Year: 2011
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 199.72K | Year: 2013
The presence of energetic ions, that appear under high cathode current operation, stand as a showstopper to the realization of high power electric propulsion. Physical barriers such as the use of carbon electrodes (e.g. NEXT) are no longer sufficient as ion energies measured greatly exceed the sputter threshold of even carbon. Unless this problem is addressed, the prospect of inadequate life looms. The benefits of high power electric propulsion missions supporting human operations in particular would be left unfulfilled.This effort aims to fully characterize the conditions under which energy ions occur by documenting ion energy spectra over a range of representative operating conditions. At these conditions, the effort will implement two novel methods of essentially defeating the energetic ion production mechanism: 1) magnetic shorting and 2) gas injection. While the concept of injecting gas to quench energetic ion production has been demonstrated in the past, we take the approach a step further by 1) elucidating the mechanism by which gas injection actually quenches energetic ion production and 2) implementing a novel gas applicator that would conserve propellant thereby allowing for gas implementation without a significant efficiency sacrifice. Past studies have shown that energetic ions form under conditions of high current. No satisfactory understanding of how these are formed or how to mitigate has been communicated. This effort aims to address both issues. The focus of the proposed effort directly addresses a problem that stands in the critical path for the development of high power electric propulsion. Without a solution to the energetic ion lifetime issue, it is difficult to imagine the actual implementation of high power electric propulsion for actual missions. This proposed effort aims to generate a methodology and apparatus for the elimination of energy ions in high current cathodes.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.94K | Year: 2013
Surface temperatures in atmospheric reentry simulations range from 1500-2300 K, while stagnation temperature on the leading edge of a Mach 6 flight vehicle at 25 km altitude is 1817 K. Sensors that can operate at temperatures well above 1273 K are needed to provide reliable validation data for TPS modeling and design tools.We propose to develop a low-intrusive fiber-optical pyrometer capable of measuring temperature profiles within an ablating thermal protection system (TPS). In this concept a bundle of parallel sapphire fibers is embedded in a step-wise manner into a multilayered "plug" of TPS material. The sensing tip of each fiber consists of a metallic coating, forming an isothermal cavity; graybody emission from this cavity is transmitted through the fiber to a fiber-optic multiplexer, and thence to a compact near-infrared (NIR) spectrometer. By fitting the thermal spectrum from the shortest fiber to a Planck distribution (adjusted to account for spectral absorption in the sapphire fiber), a cold-side temperature can be inferred first. The next longest fiber can use this temperature to estimate the distorting effects of self-emission in the heated fiber. Sequential evaluation of fiber tip temperatures at known locations along the bundle will allow effective estimation of temperature gradient and subsequent calculation of heat flux.The proposed fiber-optic sensors are thermally and physically robust, lightweight, electrically passive, and immune to electromagnetic and radio-frequency interference. Additionally, our proposed fiber-optic pyrometer is optimized for high temperatures. As the TPS-embedded sensing tip temperature increases, the wavelength peak for the thermal emission spectrum moves from 2634 nm (at 1000 K) to 1260 nm (at the sapphire melting point of 2300 K), while the integrated spectral intensity increases as the 4th power of the temperature. Both effects improve the pyrometer signal-to-noise ratio.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.98K | Year: 2015
The innovation proposed is a hollow cathode that integrates mitigation methods to suppress wear to the keeper. Recent advances in the magnetic topology in Hall thrusters has eliminated erosion of the thruster walls. As such the life limiting component of Hall thrusters has shifted to the cathode lifetime. Under a previous investigation aimed at understanding the impact of high energy ions in high current hollow cathodes, we mapped the energy spectra of cathode derived ions for both a barium oxide hollow cathode and a LaB6 hollow cathode. Energetic ions were clearly present and their intensity and peak energy tended to increase with increasing discharge current. Preliminary mitigations experiments showed promise in the use of an externally applied magnetic field as a way to reduce the peak energy of the emitted ion flux. The overall goal of this proposal is to produce a hollow cathode with integrated energetic ion mitigation technology. This cathode will be tested in magnetic field environments characteristic of Hall and gridded ion engines. It will provide a good body of experimental evidence of how to successfully mitigate cathode erosion for the high powered thrusters currently under development. Additionally, an energetic ion mitigation method could be directly integrated into the cathode design for the recently proposed Asteroid Retrieval Mission (ARM) which is currently baselined to use 4-5 10 kW class magnetically shielded Hall thrusters.