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Results for “emittance measurement”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

The emittance of space radiator materials measured at elevated temperatures

The spectral emittances of textured space radiator materials between 1.7 and 14.7 micrometer have been evaluated at room temperature and elevated temperature (630 C) in air. Heating in air caused a permanent increase in spectral emittance for all materials tested: HCl/ion beam textured 304 stainless steel, untextured Ti (6 percent Al, 4 percent V), and sandblasted Ti (6 percent Al, 4 percent V). Changes in the surface chemistry and/or surface morphology of these materials were also observed. Elevated temperature spectral emittance was measured in an argon atmosphere and compared to the measurements in air. Similarity between the room temperature and elevated temperature spectral emittance measurements was also investigated, and limited agreement was found.

Mirtich, Michael J.↗
NASA NTRS1975

Apparatus description and data analysis of a radiometric technique for measurements of spectral and total normal emittance

The development of a radiometric technique for determining the spectral and total normal emittance of materials heated to temperatures of 800, 1100, and 1300 K by direct comparison with National Bureau of Standards (NBS) reference specimens is discussed. Emittances are measured over the spectral range of 1 to 15 microns and are statistically compared with NBS reference specimens. Results are included for NBS reference specimens, Rene 41, alundum, zirconia, AISI type 321 stainless steel, nickel 201, and a space-shuttle reusable surface insulation.

Edwards, S. F.↗
NASA NTRS1960

Spectral Emittance and Reflectance Measurements at the Jet Propulsion Laboratory

In late 1959 a spectrophotometer laboratory was established at JPL to be used as a support for temperature-control programs. The immediate task was spectroradiometric measurements of light sources to be used in a simulated-deep-space environment chamber. It was also necessary to have permanent provisions for measuring reflectances of surfaces for the calculation of solar absorptance alpha, and thermal emittance epsilon. The spectral distribution of an unknown source, in this case a Ventarc carbon-arc lamp, was derived from the ratio of detector outputs (with monochromatic light) of the arc lamp and a tungsten lamp, and the spectral intensity of the tungsten lamp. The tungsten lamp is a ribbonfilament lamp calibrated from 0.25 to 2.6 microns. A recording of pen deflection (linearly proportional to detector output) of each source over the visible and near infrared range is made with all parameters (slit width, amplifier gain, and source focusing) identical; then the ratios are computed at discrete wavelengths from these recordings. Because the spectral intensities of the tungsten lamp and a solar simulator are very different in most of the range, an adjustable slit is placed immediately in front of the detector to obtain comparable pen deflections for the two sources. This slit is set by means of a feeler gage, and the attenuation coefficient is evaluated by a transmission measurement.

Maclay, James E.↗
DOE OSTI2025

Measurements of source emittance and beam coherence properties of the upgraded Advanced Photon Source

The Advanced Photon Source (APS) has been upgraded with a multi-bend achromat lattice, achieving significantly reduced electron beam emittance and enhanced X-ray coherence. Precise characterization of these properties is essential for optimizing beamline performance and enabling new experiments that take full advantage of the upgraded source. We report on measurements of source size and transverse coherence properties using grating interferometry at two beamlines: the APS 3-ID-B undulator beamline and the 1-BM-B bending magnet beamline. The results confirm the world-record horizontal emittance of the upgraded APS below 30 pm rad and validate the theoretical design parameters. We further investigate the impact of optical aberrations and mechanical vibrations at the 12-ID-C beamline on coherence preservation. These measurements establish a benchmark for future beamline enhancements and demonstrate the effectiveness of grating interferometry for high-precision beam characterization. Our findings provide critical insights into synchrotron beam dynamics, coherence degradation mechanisms, and strategies for optimizing beamline X-ray optics at next-generation light sources.

Advanced Photon Source↗
DOE OSTI2026

Measurement of the Emittance for the CeC Project

Coherent Electron Cooling (CeC) experiment was carried out at RHIC [1]. It required small emi ance of 10-15 MeV electron beam with high peak current. In most cases the emi ance was measured by either quadrupole or solenoid scan. For a low-energy beam with high peak current the measurements are affected by space charge forces. To overcome these difficul es the pepper-pot [2,3] or slit scan [4] can be used.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

New precise half-life measurement for the superallowed β+ emitter Ar34

We have measured the half-life of 34 Ar, the parent of a superallowed 0 + → 0 + β transition, to be 0.84646(35) s. With a precision of 0.04%, this result is an essential ingredient needed to complete a third pair of mirror superallowed transitions, 34 Ar → 34 Cl and 34 Cl → 34 S, the ratio of whose ft values would provide the most sensitive test yet of the isospin-symmetry-breaking corrections used to obtain V ud . In a sequence repeated thousands of times, we implanted a very pure 34 Ar beam into tape for 0.7 s, and then rapidly transported the collected source to a shielded 4π proportional gas counter, which detected the decay positrons from the combined decays of 34 Ar and its daughter 34 Cl. The data were analyzed as a linked parent-daughter pair. Our new result replaces one we published 13 years ago.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1962

A Method for Measuring the Spectral Normal Emittance in Air of A Variety of Materials Having Stable Emittance Characteristics

A method and apparatus is described for the measurement of spectral normal emittance in air of a variety of materials. The system permits measurements to be performed over a wavelength region of 1.0 through 15.0 microns and over a temperature range of 600F to 1,8000F with an accuracy of 5.0 percent. The advantages of this system are described. Results obtained by this system are compared with results reported by another observer using a different technique.

COATING↗
DOE OSTI2020

Source size measurement options for low-emittance light sources

Radiation-based techniques for measuring electron source sizes are widely used as emittance diagnostics at existing synchrotron sources. Three of these techniques, namely, pinhole imaging, double-slit interferometry, and a K-edge filter-based beam position and size monitor system (ps-BPM), are evaluated for measuring source sizes at low-emittance storage rings. Each technique is reviewed with a detailed system description, design optimization, and practical considerations targeted for small source sizes. Pinhole imaging has the simplest setup and gives the beam profile in both transverse dimensions but with limited resolution. Double-slit interferometry has the highest resolution but with a limited detectable size range. The ps-BPM system shows reasonable resolution for monitoring small source sizes and divergence and can give real-time information of the source position and angle. New facilities may consider an integrated system that combines some or all of these techniques.

43 PARTICLE ACCELERATORS↗
NASA NTRS1992

Separation of temperature and emittance in remotely sensed radiance measurements

The remote determination of surface temperature and surface spectral emittance by use of airborne or satellite-borne thermal infrared instruments is not straightforward. The radiance measured is a function of surface temperature, the unknown surface spectral emittance, and absorption and emission in the intervening atmosphere. With a single measurement, the solution for temperature and spectral emittance is undedetermined. This article reviews two of the early approximate methods which have been fairly widely used to approach this problem.

Kahle, Anne B.↗
NASA NTRS2008

The Global Sweep of Pollution: How You Think About a Problem Determines How You Will Respond

NASA is the preeminent source of data with synoptic coverage of the globe. NASA's budget for measuring attributes of the Earth is far larger than any other single organization. Satellites provide geophysical measurements such as radiance or emittance. These measurements can be used directly or can be used as input to numeric models, which in turn produce estimates of other parameters. In general the emphasis in NASA has been to use this capability to address basic science questions. The Agency is also required to apply these data and models to help improve lives and the economy. NASA's Applied Science Program has the mandate for directing and funding such applied work. The managers of the program have recognized the disciplines of air quality, pollution, atmospheric composition and public health are aspects of a single topic with local, regional, national and global implications. Significant effort is being made to bridge the disparate disciplines and deal with the multiple scales at NASA's Marshall Space Flight Center. A central portion of our strategic approach is to integrate our personnel with short-term (proposal) colleagues and with long-term, essentially permanent, partners. We consider such broad and inclusive viewpoints as important to making real, substantive differences in people's lives.

Rickman, D. L.↗
NASA NTRS1978

Investigations of negative and positive cesium ion species

A direct test is provided of the hypothesis of negative ion creation at the anode or collector of a diode operating under conditions simulating a cesium thermionic converter. The experimental technique involves using direct ion sampling through the collector electrode with mass analysis using a quadrupole mass analyzer. Similar measurements are undertaken on positive ions extracted through the emitter electrode. Measurements were made on a variety of gases including pure cesium, helium-cesium mixtures and cesium-hydrogen as well as cesium-xenon mixtures. The gas additive was used primarily to aid in understanding the negative ion formation processes. Measurements were conducted using emitter (cathode) temperatures up to about 1000 F. The major negative ion identified through the collector was Cs(-) with minor negative ion peaks tentatively identified as H(-), H2(-), H3(-), He(-) and a mass 66. Positive ions detected were believed to be Cs(+), Cs2(+) and Cs3(+).

Chanin, L. M.↗