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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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70 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

High efficiency normal conducting linac for environmental water remediation

A continuous wave (CW) electron accelerator for the treatment of industrial streams including an electron beam source, a modified high efficiency slot coupled cavity, at least one focusing magnet positioned surrounding the accelerator to contain the beam in the accelerator, an efficient radio frequency power supply means for supplying power of a radio frequency to the cavity to induce a TM01 accelerating mode in the cavity, an electron beam spreader or raster, a fixed magnet array or two-dimensional scanning magnet for deflecting the accelerated beam into a desired shape, and an exit window for extracting the deflected electron beam. The accelerator includes a graded-beta cavity to enable use with a low-power pulsed electron source. The accelerator benefits from a low wall-power loss accelerating cavity that is energized with efficient RF sources, enabling it to be operated in continuous wave mode.

Hannon, Fay↗
DOE OSTI2022

Simulating single-particle dynamics in magnetized plasmas: The RMF code

The RMF (Rotating Magnetic Field) code is designed to calculate the motion of a charged particle in a given electromagnetic field. It integrates Hamilton’s equations in cylindrical coordinates using an adaptive predictor-corrector double-precision variable-coefficient ordinary differential equation solver for speed and accuracy. RMF has multiple capabilities for the field. Particle motion is initialized by specifying the position and velocity vectors. Here, the six-dimensional state vector and derived quantities are saved as functions of time. A post-processing graphics code, XDRAW, is used on the stored output to plot up to 12 windows of any two quantities using different colors to denote successive time intervals. Multiple cases of RMF may be run in parallel and perform data mining on the results. Recent features are a synthetic diagnostic for simulating the observations of charge-exchange-neutral energy distributions and RF grids to explore a Fermi acceleration parallel to static magnetic fields.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1990

CO2 lasers and applications II; Proceedings of the Third European Congress on Optics, The Hague, Netherlands, Mar. 12-14, 1990

Recent advances in CO2 laser technology and its applications are examined. Topics discussed include the excitation of CO2 lasers by microwave discharge, a compact RF-excited 12-kW CO2 laser, a robotic laser for three-dimensional cutting and welding, three-dimensional CO2-laser material processing with gantry machine systems, and a comparison of hollow metallic waveguides and optical fibers for transmitting CO2-laser radiation. Consideration is given to an aerodynamic window with a pump cavity and a supersonic jet, cutting and welding Al using a high-repetition-rate pulsed CO2 laser, speckle reduction in CO2 heterodyne laser radar systems, high-power-laser float-zone crystal growth, melt dynamics in surface processing with laser radiation, laser hardfacing, surface melting of AlSi10Mg with CO2 laser radiation, material processing with Cu-vapor lasers, light-induced flow at a metal surface, and absorption measurements in high-power CW CO2-laser processing of materials.

Opower, Hans↗
NASA NTRS1990

The effects of the space environment on two aramid materials

Two aramid fibers having closely related chemical structures were chosen for important roles in the first tether to be used to connect pairs of orbiting vehicles. The protective outer jackets of the tethers will consist of woven fibers of poly(m-phenylene isophthalamide), commercially available from du Pont as Nomex. A cylindrical sheath of woven Kevlar 29, whose principal constituent is poly(p-phenylene terephthalamide), will be the load-bearing component for the tethers. Orbiting tethers will be in a hostile environment in which short wavelength electromagnetic radiation and energetic charged particles degrade exposed organic materials. At lower orbiting altitudes atomic oxygen is an especially serious hazard. Studies on the effects of ultraviolet radiation and atomic oxygen on fibers and films of Kevlar and Nomex are in progress. In an experiment to simulate the effects of atomic oxygen in space, small tows of Kevlar and Nomex were mounted in a commercial ashing device filled with oxygen at low pressure. An RF discharge in the instrument dissociated the molecular oxygen producing a strongly oxidizing atmosphere containing O(3P)(sup 4). Erosion was measured in terms of mass loss. Kevlar films were exposed to UV radiation in an apparatus consisting of a small vacuum chamber, 23 cm in diameter, into which a mass spectrometer and a quartz window were incorporated. Samples were exposed under vacuum with a 1000 watt xenon-arc lamp. Volatile products could be monitored with the mass spectrometer during the exposures. Transmission infrared spectra were taken before and after exposure to monitor chemical changes in the films.

Kiefer, Richard L.↗
NASA NTRS1970

Thermal performance and radio-frequency transmissivity of candidate ablation materials for S-band antenna window application on manned spacecraft

A test program was conducted in the MSC 1.5 MW arc-heated facility to evaluate the thermal performance of ablation materials having potential application as radio frequency windows. These tests were conducted for the improvement of omnidirectional antenna operating characteristics during atmospheric reentry. Since a full scale model of the Apollo command service module was available for antenna tests, this mockup was used as a basic for the tests. Test models were subjected to heating conditions simulating the nominal lunar return trajectory (AS-501) and the design trajectories, high heat load and high heating rate. RF measurements were made before and after the arc jet tests to measure attenuation effects due to the thermal degradation of the materials under consideration. The test program demonstrated that additional development is required in materials technology to achieve an ablative system with both good RF transmission characteristics and thermal-structural integrity.

Tillian, D. J.↗
NASA NTRS1988

Ion beam and plasma methods of producing diamondlike carbon films

A variety of plasma and ion beam techniques was employed to generate diamondlike carbon films. These methods included the use of RF sputtering, dc glow discharge, vacuum arc, plasma gun, ion beam sputtering, and both single and dual ion beam deposition. Since films were generated using a wide variety of techniques, the physico-chemical properties of these films varied considerably. In general, these films had characteristics that were desirable in a number of applications. For example, the films generated using both single and dual ion beam systems were evaluated for applications including power electronics as insulated gates and protective coatings on transmitting windows. These films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Nuclear reaction and combustion analysis indicated hydrogen to carbon ratios to be 1.00, which allowed the films to have good transmittance not only in the infrared, but also in the visible. Other evaluated properties of these films include band gap, resistivity, adherence, density, microhardness, and intrinsic stress. The results of these studies and those of the other techniques for depositing diamondlike carbon films are presented.

Swec, Diane M.↗
NASA NTRS1987

Nonuniform sampling techniques for antenna applications

A two-dimensional sampling technique, which can employ irregularly spaced samples (amplitude and phase) in order to generate the complete far-field patterns is presented. The technique implements a matrix inversion algorithm, which depends only on the nonuniform sampled data point locations and with no dependence on the actual field values at these points. A powerful simulation algorithm is presented to allow a real-life simulation of many reflector/feed configurations and to determine the usefulness of the nonuniform sampling technique for the copolar and cross-polar patterns. Additionally, an overlapped window concept and a generalized error simulation model are discussed to identify the stability of the technique for recovering the field data among the nonuniform sampled data. Numerical results are tailored for the pattern reconstruction of a 20-m offset reflector antenna operating at L-band. This reflector is planned to be used in a proposed measurement concept of large antenna aboard the Space Shuttle, whereby it would be almost impractical to accurately control the movement of the Shuttle with respect to the RF source in prescribed directions in order to generate uniform sampled points. Also, application of the nonuniform sampling technique to patterns obtained using near-field measured data is demonstrated. Finally, results of an actual far-field measurement are presented for the construction of patterns of a reflector antenna from a set of nonuniformly distributed measured amplitude and phase data.

Rahmat-Samii, Yahya↗
DOE OSTI2023

Testing of PIP-II pre-production 650 MHz couplers in warm test stand and in cryomodule

650 MHz fundamental power couplers were developed for PIP-II project to deliver RF power for low-beta and high-beta elliptical cavities. Few prototypes were built and tested and after some modification we built 8 pre-production couplers (with few spares for vacuum side) for HB650 cryomodule. All couplers were successfully tested in pulse mode (up to 100kW) and in CW mode (up to 50kW) in test stand at full reflection at 8 phases. In baseline configuration with DC bias we do not see any multipactoring activity after short processing. We also tested power processing without bias for uncoated and TiN coated ceramic window. Results of these studies presented in this paper. One of the coupler was assembled on LB650 cavity and tested at cryogenic environment in STC cryostat at ~20kW power with full reflection at different reflection phase. We also demonstrated good result from power processing without bias for warm and cold cavity. Six couplers were assembled on HB650 cavities in pre-production cryomodule. Test results from cryomodule qualification is discussing in this paper.

43 PARTICLE ACCELERATORS↗
NASA NTRS2007

Compact Microwave Mercury Ion Clock for Deep-Space Applications

We have recently completed a breadboard ion-dock physics package based on Kg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability -1-2xl0-13 at 1 second, averaging to 10-15 at 1 day. This development shows that 8- maser quality stabilities can be produced in a small clock package, comparable in size to an oItra-stable quartz oscillator required for holding 1-2xl0-13 at 1 second. This performance was obtained in a sealed vacuum configuration where only agetter pump was used to maintain vacuum. The vacuum tube containing the traps has now been onder sealed vacuum conditions for nearly two years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow a - 400 C tube bake-out to prepare for tube sealoff. This approach to the vacuum follows the methods used in mght vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved. We use neon as a buffer gas with 2-3 times less pressure induced frequency pulling than helium and, being heavier, negligable diffusion losses will occur over the operation lifetime.

space clock↗
NASA NTRS2009

Progress on Small Mercury Ion Clock for Space Applications

We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approx.1-2x10-(sup 1)(sup 3) at 1 second, averaging to 10-(sup 1)? at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2x10-(sup 1)(sup 3) at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for over three years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow approx. 400 deg C bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved.

positioning↗
NASA NTRS2008

Compact Microwave Mercury Ion Clock for Space Applications

We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approximately 1 - 2 x 10(exp -13) at 1 second, averaging to 10(exp -15) at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1 - 2 x 10(exp -13) at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly three years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow an approximately 400 C bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved.

Atomic Clock↗
NASA NTRS2019

Rising Above the Cloud - Toward High-Rate Delay-Tolerant Networking in Low-Earth Orbit

The High Data Rate Architecture (HiDRA) project is implementing a High-rate Delay Tolerant Networking (HDTN) capability that can support Low Earth Orbit (LEO) applications and environments. The present state of the effort, future work, and other elements of the work to date are described in this paper. This implementation is intended to support applications that run at 1+ Gbps, per the requirements of modern optical and high-frequency RF links. Uniquely, this implementation is also tuned to support relay and data trunking applications, which might require support for large numbers of small bundles per second. The design for this platform is based entirely on commercial-off-the-shelf (COTS) components, and possesses buffering capabilities in the 5 TB range. This document takes results from previous individual tests and integrates them to demonstrate results in the presence of a coherent use-case: consider a network aboard the ISS which intends to utilize an upcoming optical communications capability. For this use-case, orbital analysis software is used to analyze orbital dynamics, from which a list of access times are generated that might take in to account weather, schedule competition, etc. A variant of Contact Graph Routing (CGR) is applied to these windows to determine an optimal schedule. This schedule is then loaded into the HDTN prototype and, in conjunction with various measurement tools, a complete end-to-end analysis of HDTN's performance is conducted. Various bottlenecks (including storage) are identified: these bottlenecks are expected to help us focus our future work on the elements of the system that are most likely to present issues moving forward. Finally, we discuss possible paths for evolution beyond the present rates supported by the system, including (but not limited to) hardware acceleration.

Hylton, Alan↗
NASA NTRS2011

Development of a 150-GHz MMIC Module Prototype for Large-Scale CMB Radiation

HEMT-based receiver arrays with excellent noise and scalability are already starting to be manufactured at 100 GHz, but the advances in technology should make it possible to develop receiver modules with even greater operation frequency up to 200 GHz. A prototype heterodyne amplifier module has been developed for operation from 140 to 170 GHz using monolithic millimeter-wave integrated circuit (MMIC) low-noise InP high electron mobility transistor (HEMT) amplifiers. The compact, scalable module is centered on the 150-GHz atmospheric window using components known to operate well at these frequencies. Arrays equipped with hundreds of these modules can be optimized for many different astrophysical measurement techniques, including spectroscopy and interferometry. This module is a heterodyne receiver module that is extremely compact, and makes use of 35-nm InP HEMT technology, and which has been shown to have excellent noise temperatures when cooled cryogenically to 30 K. This reduction in system noise over prior art has been demonstrated in commercial mixers (uncooled) at frequencies of 160-180 GHz. The module is expected to achieve a system noise temperature of 60 K when cooled. An MMIC amplifier module has been designed to demonstrate the feasibility of expanding heterodyne amplifier technology to the 140 to 170-GHz frequency range for astronomical observations. The miniaturization of many standard components and the refinement of RF interconnect technology have cleared the way to mass-production of heterodyne amplifier receivers, making it a feasible technology for many large-population arrays. This work furthers the recent research efforts in compact coherent receiver modules, including the development of the Q/U Imaging ExperimenT (QUIET) modules centered at 40 and 90 GHz, and the production of heterodyne module prototypes at 90 GHz.

Kangaslahti, Pekka P.↗
DOE OSTI2024

Conceptual design of a high reactive-power ferroelectric fast reactive tuner

We present a novel design of a ferroelectric fast reactive tuner (FE-FRT) capable of modulating mega-VAR reactive power on a submicrosecond timescale. The high reactive power capability of our design extends the range of applications of reactive tuners to numerous applications. We present a detailed analytical model of the performance of a megawatt-class reactive power device and benchmark it against finite-element method eigenmode and frequency domain electromagnetic simulations. We introduce new features, including an annulus design for the ferroelectric capacitors and capacitive window coupling to the cavity. We consider thermal design issues and nonlinear effects in the ferroelectric. The model covers several configurations, allowing control of the frequency of superconducting and normal-conducting cavities in a variety of applications and frequencies. We calculate that the FE-FRT designed should be capable of handling around 0.45 MVAR of reactive power with around 3 kW of resistive losses, providing a frequency tuning range of 8 kHz in an example of 400 MHz cavity geometry. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
NASA NTRS1966

Postflight Evaluation of Atlas-Centaur AC-6 (Launched August 11, 1965)

The sixth Atlas Centaur vehicle (AC-6) was successfully launched from the Eastern T e s t Range, Complex 36B, on August 11, 1965, at 0931:04.430 EST. A 2084-pound dynamic model of the Surveyor payload was placed in a simulated lunar transfer trajectory. Vehicle systems operated satisfactorily and all the flight objectives were accomplished. Lift-off within 4 seconds of the window opening demonstrated the launch-on-time capability of the vehicle were accurately compensated for by the Centaur guidance system. the Surveyor model into a near-perfect lunar transfer trajectory would have resulted in an impact of the moon without a midcourse correction. To hit the precise target area on the lunar surface, the required correction would have been 4.25 meters per second, which is well within the spacecraft capability. Normal thrust and impulse levels were obtained with both the A t l a s and Centaur propulsion systems. However, a sizeable thrust overshoot on startup of the Centaur engines has not been resolved. A propellant-utilization system used for the first time on the Centaur, accurately controlled the fuel and oxidant consumption. The turnaround and retrothrust maneuver were performed without incident. Relatively high longitudinal modal excitations and lateral payload excitations were obtained at lift-off; these high perturbations are believed t o be related t o the launcher holddown arms. Nominal temperatures were recorded for both the external vehicle skin and the payload compartment; however, abnormally low temperatures were measured in the forward equipment area, which may have resulted from leakage of cold helium purge gas. All vehicle electrical systems performed satisfactorily; the only difficulty with the RF systems was obtained with the C-band transponder. of the vehicle instrumentation yielded valid data. The AC-6 vehicle was constructed with several new lightweight designs including the forward bulkhead, thrust barrel, interstage adapter and tank skin thickness reduction from 0.016 t o 0.014 inch. No deficiencies were observed in any of these new structural elements.

Source record↗
NASA NTRS2013

Soft Decision Analyzer

The Soft Decision Analyzer (SDA) is an instrument that combines hardware, firmware, and software to perform realtime closed-loop end-to-end statistical analysis of single- or dual- channel serial digital RF communications systems operating in very low signal-to-noise conditions. As an innovation, the unique SDA capabilities allow it to perform analysis of situations where the receiving communication system slips bits due to low signal-to-noise conditions or experiences constellation rotations resulting in channel polarity in versions or channel assignment swaps. SDA s closed-loop detection allows it to instrument a live system and correlate observations with frame, codeword, and packet losses, as well as Quality of Service (QoS) and Quality of Experience (QoE) events. The SDA s abilities are not confined to performing analysis in low signal-to-noise conditions. Its analysis provides in-depth insight of a communication system s receiver performance in a variety of operating conditions. The SDA incorporates two techniques for identifying slips. The first is an examination of content of the received data stream s relation to the transmitted data content and the second is a direct examination of the receiver s recovered clock signals relative to a reference. Both techniques provide benefits in different ways and allow the communication engineer evaluating test results increased confidence and understanding of receiver performance. Direct examination of data contents is performed by two different data techniques, power correlation or a modified Massey correlation, and can be applied to soft decision data widths 1 to 12 bits wide over a correlation depth ranging from 16 to 512 samples. The SDA detects receiver bit slips within a 4 bits window and can handle systems with up to four quadrants (QPSK, SQPSK, and BPSK systems). The SDA continuously monitors correlation results to characterize slips and quadrant change and is capable of performing analysis even when the receiver under test is subjected to conditions where its performance degrades to high error rates (30 percent or beyond). The design incorporates a number of features, such as watchdog triggers that permit the SDA system to recover from large receiver upsets automatically and continue accumulating performance analysis unaided by operator intervention. This accommodates tests that can last in the order of days in order to gain statistical confidence in results and is also useful for capturing snapshots of rare events.

Steele, Glen↗