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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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At least 1,495 records · Page 83
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Design and commissioning of vertical test cryostats for XFEL superconducting cavities measurements

The European X-ray Free Electron Laser (XFEL), now under construction at DESY in Hamburg, will make an extensive use of 1.3 GHz superconducting cavities aimed at accelerating the electrons to the energy of 17.5 GeV. The cavities will be operated at 2 K with the use of saturated HeII. Prior to their assembly in accelerator cryomodules, the RF performance of the cavities will be cold-tested in two dedicated vertical cryostats. Each cryostat allows a simultaneous testing of 4 cavities mounted on a dedicated insert. The cryostats are equipped with external lines allowing their supply with liquid helium and further conversion of the helium into superfluid He II. The paper describes the test stand flow scheme, the technical key elements, including a recuperative heat exchanger, and the cold commissioning. The thermodynamic analysis of the cryostat cool down and steady-state operation is given. A Second Law of Thermodynamics based theoretical model of the heat exchanger performance, and the model experimental validation, is presented.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Optical characterization of the on-target OMEGA focal spot at high energy using the full-beam in-tank diagnostic

The full-beam in-tank (FBIT) diagnostic has been deployed to directly measure the target-plane beam fluence profile, when operated at high energy, of the OMEGA Laser System at the University of Rochester’s Laboratory for Laser Energetics. This article presents the results of early measurements taken with this diagnostic and discusses an improvement that has overcome performance limitations discovered during the initial testing. The diagnostic gives new insight into the ability of the OMEGA Laser System to provide uniform fluence profiles that are consistent across all 60 beams in the laser. Overall, the ultimate goal of the FBIT diagnostic is to allow accurate assessment of the fluence uniformity on a spherical target in 60-beam implosion experiments

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Effect of Low-Level Laser Irradiation on Proliferative Activity of Wharton’s Jelly Mesenchymal Stromal Cells

We studied the effect of low-level laser irradiation on proliferative activity of cultured human Wharton’s jelly mesenchymal stromal sells. Cells were irradiated with a solid-state laser emitting at 650 nm; irradiation doses were 0.04, 0.4, or 4 J/cm2. Laser irradiation was performed once at the start of the cell proliferation experiment or daily throughout the experiment. Cells were cultured for 7 days. The number of viable cells was assessed using the MTT test. An increase in cell proliferative activity was detected after daily laser irradiations; the maximum stimulating effect was achieved at a dose of 0.04 J/cm{sup 2}. These results substantiate medical use of lasers for expansion of cells intended for transplantation.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2012

Optical Measurements at the Combustor Exit of the HIFiRE 2 Ground Test Engine

The development of optical techniques capable of measuring in-stream flow properties of air breathing hypersonic engines is a goal of the Aerospace Propulsion Division at AFRL. Of particular interest are techniques such as tunable diode laser absorption spectroscopy that can be implemented in both ground and flight test efforts. We recently executed a measurement campaign at the exit of the combustor of the HIFiRE 2 ground test engine during Phase II operation of the engine. Data was collected in anticipation of similar data sets to be collected during the flight experiment. The ground test optical data provides a means to evaluate signal processing algorithms particularly those associated with limited line of sight tomography. Equally important, this in-stream data was collected to compliment data acquired with surface-mounted instrumentation and the accompanying flowpath modeling efforts-both CFD and lower order modeling. Here we discuss the specifics of hardware and data collection along with a coarse-grained look at the acquired data and our approach to processing and analyzing it.

Brown, Michael S.↗
NASA NTRS1985

NASA's communications programs for interconnectivity

The U.S. 'bent pipe' satellites will be joined in 1989 by the NASA ACTS satellite. The present paper provides a status report on the ACTS satellite program. The ACTS satellite and the mobile satellite systems will conduct flight tests with respect to onboard switching for both wide band and narrow band communications. The ACTS program, with the laser link, and the mobile satellite programs with the large antennas will contribute to the test of four new technologies. Attention is given to the ACTS communication systems, the ACTS spacecraft characteristics, the ACTS modes of operation, RF technologies, interconnectivity technologies, and large antenna technologies.

Lovell, R. R.↗
NASA NTRS1987

Feasibility of mapping velocity flowfields in an SSME powerhead using laser anemometry techniques

Nonintrusive anemometry measurement techniques are investigated for a NASA study of steady and unsteady aerothermal flow phenomena present in three engine component flow environments in the Space Shuttle Main Engine powerhead, the: (1) high-pressure fuel turbopump preburner; (2) turbine; and (3) turnaround duct. Issues considered include identification of feasible means of optical access to the high-pressure high-temperature measurement flow regions, and measurement system compatibility with the test environment. Descriptions of the two-component LDV and Laser Two Focus measurement systems are given whose capabilities include measurements of the time-averaged values of velocity magnitude and flow direction, turbulence intensity, and velocity component correlations.

Pelaccio, D. G.↗
NASA NTRS1991

Thermal design and test results for SUNLITE ultra-stable reference cavity

SUNLITE (Stanford University-NASA Laser In-Space Technology Experiment) is a space-based experiment which uses a reference cavity to provide a stable frequency reference for a terahertz laser oscillator. Thermal stability of the cavity is a key factor in attaining a stable narrow-linewidth laser beam. The mount which is used to support and align the cavity will provide thermal isolation from the environment. The baseline requirement for thermal stability of the cavity is 0.025 C/min, but the design is directed toward achieving stability well beyond this requirement to improve the science data gained. A prototype of the cavity mount was fabricated and tested to characterize the thermal performance. The thermal vacuum test involved stable high-resolution temperature measurements and stable baseplate temperature control over long durations. Based on test data, the cavity mount design satisfies the severe requirement for the cavity thermal stability.

Amundsen, Ruth M.↗
NASA NTRS2018

A Laser-Induced Fluorescence Diagnostic for HERMeS and High-Power Electric Propulsion

NASA is continuing the development of a 12.5-kW Hall thruster system, which is baselined in a phased exploration concept to expand human presence to cis-lunar space and eventually to Mars. The development team is transitioning knowledge gained from the testing of the government-built Technology Development Unit (TDU) to the contractor-built Engineering Development Unit (EDU). A new laser-induced fluorescence diagnostic that is compatible with the testing of engineering hardware was developed to obtain data for thruster model validation in the lowest background pressure achievable. Prior to performing the test on the EDU, the team performed a functional checkout test of this new diagnostic using the TDU. In addition to providing a checkout of the diagnostic, this test provided data that can be correlated to electron mobility for comparison to the EDU at a later date. A number of technical challenges related to large test facilities and interfacing with engineering hardware were overcome while implementing the new laser diagnostic system. The initial data set was in good agreement with prior optical and non-optical diagnostics data collected on the TDU thrusters. This data set also revealed the spatial origin of high angle ions that have been of concern for spacecraft integration.

Huang, Wensheng↗
NASA NTRS2018

A Laser-Induced Fluorescence Diagnostic for HERMeS and High-Power Electric Propulsion

NASA is continuing the development of a 12.5-kW Hall thruster system, which is baselined in a phased exploration concept to expand human presence to cis-lunar space and eventually to Mars. The development team is transitioning knowledge gained from the testing of the government-built Technology Development Unit (TDU) to the contractor-built Engineering Development Unit (EDU). A new laser-induced fluorescence diagnostic that is compatible with the testing of engineering hardware was developed to obtain data for thruster model validation in the lowest background pressure achievable. Prior to performing the test on the EDU, the team performed a functional checkout test of this new diagnostic using the TDU. In addition to providing a checkout of the diagnostic, this test provided data that can be correlated to electron mobility for comparison to the EDU at a later date. A number of technical challenges related to large test facilities and interfacing with engineering hardware were overcome while implementing the new laser diagnostic system. The initial data set was in good agreement with prior optical and non-optical diagnostics data collected on the TDU thrusters. This data set also revealed the spatial origin of high angle ions that have been of concern for spacecraft integration.

Huang, Wensheng↗
NASA NTRS1987

Monocrystalline silicon gradiometer for gravity experiments in space

A very important research effort has been made in the last decade in the field of high precision measurement with laser instrumentation. The development of a space borne gradiometer operating at a high sensitivity level using laser measurement of the distance between proof mass over a short base line of order one meter is discussed. Two aspects of laser technology make it a promising tool for gradiometry measurements: quantum limited accuracy and absolute distance measurements. The quantum limit associated with laser instrumentation was formulated. The relevant quantum and classical sources of errors in laser measurements were reviewed and corresponding laser performance requirements for gradient measurements were evaluated. Some mechanical quality factor measurements were made on simple resonant monocrystalline silicon suspensions. It was discovered that the use of zero derivative restoring forces to position the gradiometer test masses will dramatically reduce the gradiometer temperature control requirements. A laser beam side injection scheme was discovered which permits rejection of common mode accelerations. These concepts are briefly discussed.

Richard, Jean-Paul↗
NASA NTRSDate not supplied

One Million Newton-Second Duration Test of a 600 Watt Hall Effect Thruster Fueled By Xenon

A Hall Effect Thruster fueled by xenon was duration tested for7,198 hours at NASA’s Glenn Research Center.The thruster generated 1 million Newton-seconds of total impulse before the test was terminated voluntarily. Thrust, flow rate, and many other parameters were tracked continuously. Over 98.5% of the test was conducted at a single operating point, where the discharge power was 600 W, mean thrust was 39 mN and mean specific impulse was 1500 s. The shape of the discharge channel was measured via laser profilometery. The shape changed considerably over the course of the test, due to ion sputtering. However, the standard deviation of the thrust and specific impulse measurements at the nominal operating point was less than 1%. Evolution of the plasma plume was measured with a Faraday probe mounted upon a rotating arm. Plume divergence decreased over the course of the test

Electric Propulsion↗
NASA NTRS2021

Sensor Noise in LISA Pathfinder: In-Flight Performance of the Optical Test Mass Readout

We report on the first subpicometer interferometer flown in space. It was part of ESA’s Laser Interferometer Space Antenna (LISA) Pathfinder mission and performed the fundamental measurement of the positional and angular motion of two free-falling test masses. The interferometer worked immediately, stably, and reliably from switch on until the end of the mission with exceptionally low residual noise of 32.0 (+2.4, −1.7) fm/(√Hz), significantly better than required. We present an upper limit for the sensor performance at millihertz frequencies and a model for the measured sensitivity above 200 mHz.

Gravitational Waves,↗
NASA NTRS1974

Passively cooled glass CO2 laser tubes for severe environments

The objective of this effort was to design a glass CO2 laser tube that could survive the Titan 3 C launch environment and at the same time provide adequate thermal conductivity to maintain the wall of the laser tube below approximately equal to 50 C for efficient lasing. The approach that was taken to satisfy these requirements was to pot the tube in an aluminum heat sink using a space qualified polyurethane potting material. Two configurations of the laser tube successfully passed the complete Titan 3 C qualification level sine and random vibration specification and satisfied the thermal requirements. Fabrication details and test results are presented that indicate this could be a practical solution for laser tubes used in a severe environment and where flowing coolants are impractical or undesirable.

Walker, H. E.↗
NASA NTRS1999

Interplanetary Microlaser Transponders

The feasibility of an asynchronous (i.e. independently firing) interplanetary laser transponder, capable of ranging between Earth and Mars and using the automated SLR2000 Satellite Laser Ranging (SLR) system as an Earth base station, has been suggested. Since that time, we have received a small amount of discretionary funding to further explore the transponder concept and to develop and test an engineering breadboard. Candidate operational scenarios for acquiring and tracking the opposite laser terminal over interplanetary distances have been developed, and breadboard engineering parameters were chosen to reflect the requirements of an Earth-Mars link Laboratory tests have been devised to simulate the Earth- Mars link between two independent SLR2000 transceivers and to demonstrate the transfer of range and time in single photon mode. The present paper reviews the concept of the asynchronous microlaser transponder, the transponder breadboard design, an operational scenario recently developed for an asteroid rendezvous, and the laboratory test setup. The optical head of the transponder breadboard fits within a cylinder roughly 15 cm in diameter and 32 cm in length and is mounted in a commercial two axis gimbal driven by two computer-controlled stepper motors which allows the receiver optical axis to be centered on a simulated Earth image. The optical head is built around a small optical bench which supports a 14.7 cm diameter refractive telescope, a prototype 2 kHz SLR2000 microlaser transmitter, a quadrant microchannel plate photomultiplier (MCP/PMT), a CCD array camera, spatial and spectral filters, assorted lenses and mirrors, and protective covers and sun shields. The microlaser is end-pumped by a fiber-coupled diode laser array. An annular mirror is employed as a passive transmit/receive (T/R) switch in an aperture-sharing arrangement wherein the transmitted beam passes through the central hole and illuminates only the central 2.5 cm of the common telescope (adequate to achieve a 10 arcsecond full laser beam divergence) while the receiver uses the remainder of the 14.7 cm aperture. Additional electronic instrumentation includes the diode pump array and associated heat sink and current drivers, rubidium frequency standard, timing distribution module, range gate generator, a recently developed all-digital correlation range receiver, and system computer. Acquisition of the opposite transponder terminal requires a search within a three-dimensional volume determined by the initial pointing uncertainty and a maximum 500 microsecond uncertainty in the laser time of fire at the opposite terminal for totally uncorrelated Earth and spacecraft clocks. The angular search is aided by a sensitive CCD array capable of imaging the Earth, Moon, and surrounding stars within the nominal + 0.5 degree cone of uncertainty associated with the initial pointing of a spacecraft body or microwave communications dish.

Degnan, John J.↗
DOE OSTI2016

Development of a compact vertical-cavity surface-emitting laser end-pumped actively Q-switched laser for laser-induced breakdown spectroscopy

This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1997

Ultraviolet Molecular Rayleigh Scattering Used to Measure Velocity in High-Speed Flow

Molecular Rayleigh scattering offers a means to measure gas flow parameters including density, temperature, and velocity. No seeding of the flow is necessary. The Rayleigh scattered power is proportional to the gas density, the spectral width is related to the gas temperature, and the shift in the frequency of the spectral peak is proportional to one component of the fluid velocity. Velocity measurements based on Rayleigh scattering are more suitable for high-speed flow, where the bulk fluid velocity is on the order of, or larger than, the molecular thermal velocities. Use of ultraviolet wavelengths for Rayleigh scattering diagnostics is attractive for two reasons. First, the Rayleigh scattering cross section is proportional to the inverse 4th power of the wavelength. And second, the reflectivity of metallic surfaces is generally less than it is at longer wavelengths. This is of particular interest in confined flow situations, such as in small wind tunnels and aircraft engine components, where the stray laser light scattered from the windows and internal surfaces in the test facility limits the application of Rayleigh scattering diagnostics. In this work at the NASA Lewis Research Center, molecular Rayleigh scattering of the 266-nm fourth harmonic of a pulsed, injection seeded Nd:YAG (neodymium:yttriumaluminum- garnet) laser was used to measure velocity in a supersonic free air jet with a 9.3- mm exit diameter. The frequency of the Rayleigh scattered light was analyzed with a planar mirror Fabry-Perot interferometer used in a static imaging mode, with the images recorded on a cooled, high-quantum-efficiency charge-coupled discharge (CCD) camera. In addition, some unshifted light from the same laser pulse was imaged through the interferometer to generate a reference. Data were obtained with single laser pulses at velocities up to Mach 1.3. The measured velocities were in good agreement with velocities calculated from isentropic flow relations. Our conclusion from this study was that ultraviolet Rayleigh scattering is preferable in confined flow situations because of the increase in the ratio of Rayleigh scattering signal to stray laser light. On the other hand, in open flows, such as free jets and larger wind tunnels where stray laser light can be controlled, visible Rayleigh scattering is preferable.

Seasholtz, Richard G.↗