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Results for “performance gain”

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.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

MIT Participation in the Data Analysis of the XRS and XIS Instruments on the Astro-E2 Mission

Since the inception of this grant six weeks ago, we have completed the initial activation of the Suzaku X-ray Imaging Spectrometer (XIS) (on 13 August) and we have supported initial calibration observations. The instrument is performing very well in all respects. We have characterized the spectral resolution and effective area of each XIS sensor. We are especially excited about the scientific opportunities provided by the XIS'S back- illuminated sensor, which exhibits spectral resolution in the sub-keV band unmatched by any X-ray CCD currently in orbit. As specified in our proposal, we have established a web site (http://space.mit.edu/XIS) on which we maintain an up-to-date summary of instrument performance characteristics. Gain, spectral resolution and system noise, as well as residual background rates, are currently available on this site. Although the particle background level is low compared with Chandra and XMM, we are currently evaluating methods to reduce it still further. Techniques under study include use of 5x5 mode information and alternative grade selection methods. Although the primary responsibility for development of instrument response functions rests with our Japanese colleagues, we are incorporating our latest measurements of spectral resolution into some temporary response functions which we hope to make available to the Suzaku General Observer Facility and the Science Working Group(SWG). We are also preparing proposals for use of SWG observing time.

Bautz, Mark↗
NASA NTRS2006

Real Time Phase Noise Meter Based on a Digital Signal Processor

A digital signal-processing meter for phase noise measurement on sinusoidal signals is dealt with. It enlists a special hardware architecture, made up of a core digital signal processor connected to a data acquisition board, and takes advantage of a quadrature demodulation-based measurement scheme, already proposed by the authors. Thanks to an efficient measurement process and an optimized implementation of its fundamental stages, the proposed meter succeeds in exploiting all hardware resources in such an effective way as to gain high performance and real-time operation. For input frequencies up to some hundreds of kilohertz, the meter is capable both of updating phase noise power spectrum while seamlessly capturing the analyzed signal into its memory, and granting as good frequency resolution as few units of hertz.

phase noise↗
NASA NTRS2007

Design of an Integrated-System FARAD Thruster

Pulsed inductive plasma accelerators are spacecraft propulsion devices in which energy is stored in a capacitor and then discharged through an inductive coil. The device is electrodeless, inducing a current s heet in a plasma located near the face of the coil. The propellant is accelerated and expelled at a high exhaust velocity (order of 10 km/s) through the interaction of the plasma current and the induced magne tic field, The Faraday Accelerator with RF-Assisted Discharge (FARAD) thruster is a type of pulsed inductive plasma accelerator in which t he plasma is preionized by a mechanism separate from that used to for m the current sheet and accelerate the gas. Employing a separate preionization mechanism allows for the formation of an inductive current s heet at much lower discharge energies and voltages than those used in previous pulsed inductive accelerators like the Pulsed Inductive Thr uster (PIT). In this paper, we present the design of a benchtop FARAD thruster with all the subsystems (mass injection, preionization, and acceleration) integrated into a single unit. Design of the thruster follows the guidelines and similarity performance parameters presented elsewhere. The system is designed to use the ringing, RF-frequency s ignal produced by a discharging Vector Inversion Generator (VIG) to p reionize the gas. The acceleration stage operates on the order of 100 J/pulse and can be driven by several different pulsed powertrains. These include a simple capacitor coupled to the system, a Bernardes and Merryman configuration, and a pulsecompression circuit that takes a temporally broad, low current pulse and transforms it into a short, h igh current pulse. A set of applied magnetic field coils are integrated into the system to guide the preionized propellant as it spreads ov er the face of the inductive acceleration coil. The coils are operate d in a pulsed mode, and the thruster can be operated without using the coils to determine if there is a performance improvement gain realiz ed when an applied field is present.

Polzin, K.A.↗
NASA NTRS2011

Fission Power System Technology for NASA Exploration Missions

Under the NASA Exploration Technology Development Program, and in partnership with the Department of Energy (DOE), NASA is conducting a project to mature Fission Power System (FPS) technology. A primary project goal is to develop viable system options to support future NASA mission needs for nuclear power. The main FPS project objectives are as follows: 1) Develop FPS concepts that meet expected NASA mission power requirements at reasonable cost with added benefits over other options. 2) Establish a hardware-based technical foundation for FPS design concepts and reduce overall development risk. 3) Reduce the cost uncertainties for FPS and establish greater credibility for flight system cost estimates. 4) Generate the key products to allow NASA decisionmakers to consider FPS as a preferred option for flight development. In order to achieve these goals, the FPS project has two main thrusts: concept definition and risk reduction. Under concept definition, NASA and DOE are performing trade studies, defining requirements, developing analytical tools, and formulating system concepts. A typical FPS consists of the reactor, shield, power conversion, heat rejection, and power management and distribution (PMAD). Studies are performed to identify the desired design parameters for each subsystem that allow the system to meet the requirements with reasonable cost and development risk. Risk reduction provides the means to evaluate technologies in a laboratory test environment. Non-nuclear hardware prototypes are built and tested to verify performance expectations, gain operating experience, and resolve design uncertainties.

Mason, Lee↗
NASA NTRS2013

Orion Boiler Plate Airdrop Test System

On the 29th of February 2012 the Orion Capsule Parachute Assembly System (CPAS) project attempted to perform an airdrop test of a boilerplate test article for the second time. The first attempt (Cluster Development Test 2, July 2008) to deliver a similar boilerplate from a C-17 using the Low Velocity Air Drop (LVAD) technique resulted in the programmer parachute failing to properly inflate, the test article failing to achieve the desired test initiation conditions, and the test article a total loss. This paper will pick up where the CDT-2 failure investigation left off, describing the test technique that was adopted, and outline the modeling that was performed to gain confidence that the second attempt would be successful. The second boiler plate test (Cluster Development Test 3-3) was indeed a complete success and has subsequently been repeated several times, allowing the CPAS project to proceed with the full scale system level development testing required to integrate the hardware to the first Entry Flight Test vehicle as well as go into the Critical Design Review with minimum risk and a mature design.

Machin, Ricardo A.↗
NASA NTRS2014

Superconducting Quantum Arrays for Wideband Antennas and Low Noise Amplifiers

Superconducting Quantum Iinetference Filters (SQIF) consist of a two-dimensional array of niobium Josephson Junctions formed into N loops of incommensurate area. This structure forms a magnetic field (B) to voltage transducer with an impulse like response at B0. In principle, the signal-to-noise ratio scales as the square root of N and the noise can be made arbitrarily small (i.e. The SQIF chips are expected to exhibit quantum limited noise performance). A gain of about 20 dB was recently demonstrated at 10 GHz.

SQUID Detectors↗
NASA NTRS2015

Propulsion System Development for the Iodine Satellite (iSAT) Demonstration Mission

The development and testing of a 200-W iodine-fed Hall thruster propulsion system that will be flown on a 12-U CubeSat is described. The switch in propellant from more traditional xenon gas to solid iodine yields the advantage of high density, low pressure propellant storage but introduces new requirements that must be addressed in the design and operation of the propulsion system. The thruster materials have been modified from a previously-flown xenon Hall thruster to make it compatible with iodine vapor. The cathode incorporated into this design additionally requires little or no heating to initiate the discharge, reducing the power needed to start the thruster. The feed system produces iodine vapor in the propellant reservoir through sublimation and then controls the flow to the anode and cathode of the thruster using a pair of proportional flow control valves. The propellant feeding process is controlled by the power processing unit, with feedback control on the anode flow rate provided through a measure of the thruster discharge current. Thermal modeling indicates that it may be difficult to sufficiently heat the iodine if it loses contact with the propellant reservoir walls, serving to motivate future testing of that scenario to verify the modeling result and develop potential mitigation strategies. Preliminary, short-duration materials testing has thus-far indicated that several materials may be acceptable for prolonged contact with iodine vapor, motivating longer-duration testing. A propellant loading procedure is presented that aims to minimize the contaminants in the feed system and propellant reservoir. Finally, an 80-hour duration test being performed to gain experience operating the thruster over long durations and multiple restarts is discussed.

Polzin, Kurt A.↗
NASA NTRS2016

Electron-Beam Deposition of Superconducting Molybdenum Thin Films for the Development of Mo/Au TES X-Ray Microcalorimeter

We are exploring the properties of electron-beam evaporated molybdenum thin films on silicon nitride coated silicon wafers at substrate temperatures between room temperature and 650 C. The temperature dependence of film stress, transition temperature, and electrical properties are presented. X-ray diffraction measurements are performed to gain information on molybdenum crystallite size and growth. Results show the dominant influence of the crystallite size on the intrinsic properties of our films. Wafer-scale uniformity, wafer yield, and optimal thermal bias regime for TES fabrication are discussed.

Microcalorimeter↗
NASA NTRS2017

Parametric Evaluation of Interstellar Exploration Mission Concepts

One persistent difficulty in evaluating the myriad advanced propulsion concepts proposed over the last 60 years is a true apples to apples comparison of the expected gain in performance. This analysis is complicated by numerous factors including, multiple missions of interest to the advanced propulsion community, the lack of a credible closed form solution to 'medium thrust' trajectories, and lack of detailed design data for most proposed concepts that lend credibility to engine performance estimates. This paper describes a process on how to make fair comparisons of different propulsion concepts for multiple missions over a wide range of performance values. The figure below illustrates this process. This paper describes in detail the process and outlines the status so far in compiling the required data. Parametric data for several missions are calculated and plotted against specific power-specific impulse scatter plots of expected propulsion system performance. The overlay between required performance as defined by the trajectory parametrics and expected performance as defined in the literature for major categories of propulsion systems clearly defines which propulsion systems are the most apt for a given mission. The application of the Buckingham Pi theorem to general parameters for interstellar exploration ( mission time, mass, specific impulse, specific power, distance, propulsion source energy/mass, etc.) yields a number of dimensionless variables. The relationships of these variables can then be explored before application to a particular mission. Like in the fields of fluid mechanics and heat transfer, the use of the Buckingham Pi theorem results in new variables to make apples to apples comparisons.

Adams, Robert B.↗
NASA NTRS2018

Investigation of a Verification and Validation Tool with a Turbofan Aircraft Engine Application

The development of more advanced control architectures for turbofan aircraft engines can yield gains in performance and efficiency over the lifetime of an engine. However, the implementation of these increasingly complex controllers is contingent on their ability to provide safe, reliable engine operation. Therefore, having the means to verify the safety of new control algorithms is crucial. As a step towards this goal, CoCoSim, a publicly available verification tool for Simulink, is used to analyze C-MAPSS40k, a 40,000 lbf class turbo-fan engine model developed at NASA for testing new control algorithms. Due to current limitations of the verification software, several modifications are made to C-MAPSS40k to achieve compatibility with CoCoSim. Some of these modifications sacrifice fidelity to the original model. Several safety and performance requirements typical for turbofan engines are identified and constructed into a verification framework. Preliminary results using an industry standard baseline controller for these requirements are presented. While verification capabilities are demonstrated, a truly comprehensive analysis will require further development of the verification tool.

V&↗
NASA NTRS2019

Results of the Micro-12 Flight Experiment: Effects of Microgravity on Shewanella oneidensis MR-1

The Micro-12 flight experiment was launched on SpaceX-15 and completed during berthing on the International Space Station. The goal of this experiment was to understand the effects of spaceflight and microgravity on the physiology of the model exoelectrogen Shewanella oneidensis MR-1. BioServe Fluid Processing Apparatus (FPA) and Group Activation Pack (GAP) hardware systems were used for both flight and ground control tests. Under spaceflight conditions, extracellular electron transfer (EET) rates were found to be significantly increased on insoluble substrates, while biofilm development appeared to be unchanged under the conditions tested; these processes are critical for microbial-assisted bioelectrochemical systems. Additionally, RNAseq analysis, proteomic profiling, and competitive mutant fitness profiling were performed to gain further understanding of microbial physiology under EET-respiring conditions during spaceflight. Overall, the results of the Micro-12 project support the idea that Shewanella oneidensis MR-1, in particular, and exoelectrogens in general could be useful chassis organisms for synthetic biology applications using microbial bioelectrochemical systems. These findings will assist bioengineering and synthetic biology development efforts harnessing the unique capabilities of exoelectrogens for life support and in situ resource utilization.

Dougherty, Michael↗
NASA NTRSDate not supplied

Time-Resolved OH-PLIF Assessment of Deflagrations Levels in a CH4-O2 Rotating Detonation Rocket Combustor

The parasitic loss incurred by deflagrative pre-burning is considered to be one of the key challenges to the effective implementation of rotating detonation engine (RDE) systems. Thus far, there have been relatively limited high fidelity, spatio-temporally resolved measurements of the pre-burning process as a function of the reactant conditions and composition within an RDE. In this work, simultaneous high-repetition-rate broadband OH* chemiluminescence and OH planar laser-induced fluorescence (PLIF) imaging are employed to investigate deflagrative burning dynamics in a fully optically accessible CH4-O2 RDE as compared to a H2-air systems under the same conditions. A custom-built optical parametric oscillator (OPO) is coupled with a high-repetition-rate burst-mode laser to generate the 284 nm source for the excitation of the Q1(9) transition of the OH radical. Significant deflagrative burning is observed throughout the chamber as a consequence of the oxygen-rich environment. Trailing wave systems that consume unburned reactants in the region immediately following the primary detonation wave are observed. The formation of a product gas recirculation zone that entrains and combusts incoming reactants is observed, and quantitative analysis is performed to gain valuable insight into deflagration characteristics. At an oxidizer mass flux of Gox ≈ 350kg/m2/s, it is found that the levels of pre-wave burning in CH4-O2 are a factor of ∼2-3 times higher than in H2-air in the region directly ahead of the detonation wave at a global equivalence ratio Φ ≈ 1.0. This study highlights the key roles of ignition delay and turbulent mixing of the combustion product and reactant fields on the levels of pre-burning and establishes a methodology for further investigation, such as for the effects of various RDE inlet configurations.

Propulsion↗
NASA NTRSDate not supplied

Earth-Independent Medical Operations (EIMO) Concept of Operations

In contrast to the current crew health paradigm for low-Earth orbit and Lunar missions, which depends on real-time communication with Mission Control, deep-space exploration missions will require a significant shift in medical operations. This shift is driven by the constraints of operating at a considerable distance from Earth, such as resource limitations—lack of resupply, restricted mass, power, volume, and data—as well as communication delays and the inability to evacuate back to Earth during emergencies. To move toward a more self-reliant medical model, a strategy is needed to gradually increase space-based crew autonomy and reduce risks to mission success in the challenging environment of deep space. This transformative change, known as "Earth-Independent Medical Operations" (EIMO), explores the gradual transfer of medical care and decision-making from Earth-based support to space-based systems. The goal of this transition is to enhance astronaut health and performance while minimizing mission risks. EIMO requires the development of a medical system that integrates seamlessly with mission planning, vehicle and spacesuit design, and data architecture. This integration is crucial for building a robust medical infrastructure that not only safeguards astronaut well-being but also ensures overall mission success. The Human Research Program (HRP) Exploration Medical Capability (ExMC) Element has revised the EIMO model-based Concept of Operations (ConOps) which outlines an initial vision for EIMO. The ConOps, which is built on the stakeholders’ need, system goals, and objectives (NGOs), presents an array of in-mission scenarios that span a wide range of medical conditions demonstrating the system’s capabilities from basic to complex events. Developed by a multidisciplinary team of systems engineers, scientists, and clinicians within ExMC, the ConOps revision includes two new scenarios(Barotrauma and Self-Medical Management and Behavioral Health and Chronic Medical Care), and implementation of findings from EIMO technical interchange meetings that focused on data and training. The envisioned EIMO Medical System (MS) operates as a system of systems, gathering data from various sources such as reference databases, real-time wearable sensors, point-of-care diagnostics, and environmental controls. The MS also incorporates advanced training tools to support autonomous medical care, assisting the Crew Medical Officer (CMO) during medical events where Ground Support is either unavailable or communication-delayed beyond practicality. Furthermore, MS functions and capabilities were decomposed from the scenarios to establish foundational requirements for EIMO and traced to the NASA Spaceflight Human-System Standard(NASA-STD-3001, Volumes 1 and 2). These traces were performed to gain insights on the alignment of EIMO requirements with the NASA standard. This work serves as an initial recommendation to increase crew autonomy gradually and safely for Mars missions and future deep-space exploration.

medical system↗
DOE OSTI2025

Development of Transformative Preparation Methods to Push up High Q&G Performance of FRIB Spare HWR Cryomodule Cavities

The FRIB accelerator project construction, a top priority of US nuclear science, was completed in January 2022, and is now moving to user operation. The stable and reliable operation of the accelerating cryomodules is essential in achieving/fulfilling DOE and user expectations. So far, FRIB cryomodules meet all FRIB specifications for cavity performance. However, during the lifetime of machine operation, degradation of cryomodule performance is possible, as reported in similar operating facilities (CEBAF, SNS). If cryomodule degradation is observed at FRIB, the under-performing cryomodule will require replacement/maintenance. In effort to manage operational reliability, FRIB plans to construct a 0.53 half-wave cryomodule to serve as an active spare. In a parallel effort, FRIB will also work toward increasing operational Q and gradient of spare cryomodule cavities to gain an overall performance margin to support future operational reliability. The current FRIB cavity designs have a potential to operate at gradients higher than 8 MV/m, but are currently limited by field emission (FE) and/or high field Q slope (HFQS); known issue in buffered chemical polished (BCP) treated cavities. The proposal looks to develop transformative surface preparation treatments to improve the operational gradient of spare cryomodules higher than 10 MV/m while maintaining high Q. Thus, increasing operational margin by 30 - 50%. With the goal to improve operational reliability set, the proposal will investigate multiple objectives as possible paths forward to achieve an overall increase in cavity performance and gain a better understanding of SRF limiting mechanisms. The proposal will study the application of different chemical surface treatments to 0.53 half-wave cavities, with the addition of low temperature bakes (LTB), and measure their effects on accelerating performance. Proposed chemical treatments to be explored in this proposal include conventional EP acid mixtures, as well as innovated EP and BCP acid mixtures designed to simplify processing paths in migrating FE and HFQS. The proposed transformative treatment wet N-doping also has the potential to replicate recent advancements in SRF technology relating to nitrogen doping and high Q operation without the requirement for an ultra-high vacuum annealing furnace; currently being developed at FNAL and JLAB. In parallel, high Q performance relating to flux trapping will be investigated with the installation of a second layer of magnetic shielding in the vertical test Dewar. The research objectives presented in the proposal, and their corresponding effects on cavity performance, will provide essential knowledge and future guidance to the SRF community and provide possible paths for future SRF based projects and applications.

43 PARTICLE ACCELERATORS↗
NASA NTRS1977

Monopulse receiver

A time division multiplexing and a quadraphase combining dual channel system were analyzed, designed, and tested. Analyses performed include the following: (1) boresight error as a function of the error channel bandwidth; (2) error channel interference with the sum channel functions; (3) threshold performance; and (4) error channel crosstalk, linearity, and drift as a function of signal level, Doppler, and environment. Test results indicate that the time division multiplexing system meets the design goals of the program. However, careful selection and alignment of all gain controlled amplifiers are required along with temperature compensation of the angle channel gain. The quadraphase system crosstalk performance is comparatively poor (-15 dB) with respect to the -30 dB requirements and this consequently affects gain tracking performance. Gain tracking was found to be + or - 20 percent rather than the + or - 5 percent specification. Data for the two systems is compared and recommendations are presented.

Source record↗
DOE OSTI2021

Comparative Study for Pressure Gain Combustion-Gas Turbine System Performance in NGCC Configurations

The Department of Energy (DOE) has a goal to increase natural gas combined cycle (NGCC) plant efficiency to greater than 70 percent on a lower heating value (LHV) basis. Improvement in gas turbine (GT) efficiency is key achieving this goal. While many of the traditional improvement methods (higher firing temperature, advanced materials, improved cooling methods, etc.) may increase current GT and NGCC efficiencies incrementally, combining these traditional advancements with breakthrough technologies such as pressure gain combustion (PGC) may provide significant system efficiency gains. PGC is a combustion process that results in a net pressure increase across the combustor (up to pressure ratio of 2.2) rather than the traditional (<5%) pressure drop. There are multiple PGC technologies being developed that create the pressure rise phenomena, including resonant pulse combustors (RPCs), pulse detonation engines (PDEs), wave rotor combustor (WRC) engines and rotating detonation engines (RDEs). In this study, scoping analyses of PGC concepts applied to NGCC power plants were performed by combining simplified analytical models for the RPC, PDE, WRC, and RDE types of pressure gain processes with a GT model to evaluate impacts of using each of the PGC technologies on key GT performance parameters. Sensitivity analyses were also performed. Ultimately, the PGC technologies were found to have the potential to increase simple cycle efficiency by 4–6 percent (absolute) and NGCC efficiency by 2–3 percent (absolute) based on the results of the current study.

03 NATURAL GAS↗
NASA NTRS1994

Defocussing characteristics of the ACTS, T1-VSAT Earth terminal antennas

This report describes a study, the purpose of which was to determine the characteristics of two reflector antennas, as the reflector feed is moved away from the focus. The antennas are a 1.2 meter and a 2.44 meter reflector that will be used in the T1-VSAT earth terminals for the Advanced Communications Technology Satellite (ACTS). These terminals have been constructed in such a way that is inconvenient to use attenuators to control the gain of the signal that is directed toward the satellite. Feed defocusing was proposed as a simple, convenient way to achieve the required gain control. The study was performed in two parts. In order to determine the feasibility of the technique, a theoretical analysis was performed to obtain the gain, beamwidth and far-field pattern of the antennas, as a function of feed displacement. An experimental investigation followed in which patterns of the 1.2 meter antenna were obtained through measurement in the NASA Lewis Research Center, Near-Field Antenna Test Facility. Results of the theoretical and experimental investigation are presented for both uplink (30 GHz) and downlink (20 GHz) frequencies.

Lambert, Kevin M.↗