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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Multimode Bolometer Development for the Primordial Inflation Explorer (PIXIE) Instrument

The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission concept designed to measure the polarization and absolute intensity of the cosmic microwave background [1]. In this work, we report on the design, fabrication, and performance of the multimode polarization-sensitive bolometers for PIXIE, which are based on silicon thermistors. In particular we focus on several recent advances in the detector design, including the implementation of a tensioning scheme to greatly raise the frequencies of the internal vibrational modes of the large-area, low-mass optical absorber structure consisting of a grid of micromachined, ion-implanted silicon wires. With 30 times the absorbing area of the spider-web bolometers used by Planck, the tensioning scheme enables the PIXIE bolometers to be robust in the vibrational and acoustic environment at launch of the space mission. More generally, it could be used to reduce microphonic sensitivity in other types of low temperature detectors. We also report on the performance of the PIXIE bolometers in a dark cryogenic environment.

PIXIE↗
NASA NTRS2016

Multimode Bolometer Development for the PIXIE Instrument

The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission concept designed to measure the polarization and absolute intensity of the cosmic microwave background. In the following, we report on the design, fabrication, and performance of the multimode polarization-sensitive bolometers for PIXIE, which are based on silicon thermistors. In particular we focus on several recent advances in the detector design, including the implementation of a scheme to greatly raise the frequencies of the internal vibrational modes of the large-area, low-mass optical absorber structure consisting of a grid of micromachined, ion-implanted silicon wires. With approximately 30 times the absorbing area of the spider-web bolometers used by Planck, the tensioning scheme enables the PIXIE bolometers to be robust in the vibrational and acoustic environment at launch of the space mission. More generally, it could be used to reduce microphonic sensitivity in other types of low temperature detectors. We also report on the performance of the PIXIE bolometers in a dark cryogenic environment.

PIXIE↗
DOE OSTI2020

Self-absorption and Phonon Pulse Shape Discrimination in Scintillating Bolometers

In this work, we show that self-absorption of photons in scintillating bolometers can differentiate phonon pulse shapes between α (or nuclear recoil) and β/γ signals. This enables phonon pulse shape discrimination for particle identification. We establish a detector signal model that includes self-absorption and compare the simulated phonon pulse shapes with previously reported experimental results. The model predicts increase in pulse shape difference at higher self-absorption. Based on this result, we propose a new design of scintillating bolometers using 4π light reflectors for maximized self-absorption and only a single phonon readout, instead of light detectors that are typically employed for particle discrimination in scintillating bolometers.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

The infrared imaging video bolometer at Wendelstein 7-X

The radiated power distribution is a crucial aspect of heat transport, heat load mitigation, and plasma exhaust performance. An imaging video bolometer camera has been installed to measure the plasma radiated power in the divertor region of the Wendelstein 7-X (W7-X) stellarator. This diagnostic offers a wide-angle (40° × 68°) sampling of the plasma volume in both the poloidal and toroidal directions. The field-of-view is covered with a large number (> 500) of bolometer channels, providing imaging capability. The diagnostic design is introduced here together with its data analysis procedure. A set of laboratory experiments is performed to assess the thermal properties of the gold absorber foil and their spatial uniformity. Following installation, a heat source originating from the inertially cooled front of the diagnostic is identified and filtered out. The discharge data indicate a satisfactory signal-to-noise ratio as well as spatiotemporal resolution. These represent the first toroidally resolved images of the line-integrated radiated power in the W7-X island divertor. The diagnostic was then upgraded with a thinner platinum absorber and adjusted mirrors. Early data from the most recent experimental campaign employing the upgraded design show a considerable improvement in the diagnostic performance with more bolometer channels (> 1400), extended coverage, and increased spatial resolution.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Twelve-crystal prototype of Li 2 MoO 4 scintillating bolometers for CUPID and CROSS experiments

An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers equipped with 16 bolometric Ge light detectors, aiming at optimization of detector structure for CROSS and CUPID double-beta decay experiments, was constructed and tested in a low-background pulse-tube-based cryostat at the Canfranc underground laboratory in Spain. Performance of the scintillating bolometers was studied depending on the size of phonon NTD-Ge sensors glued to both LMO and Ge absorbers, shape of the Ge light detectors (circular vs. square, from two suppliers), in different light collection conditions (with and without reflector, with aluminum coated LMO crystal surface). The scintillating bolometer array was operated over 8 months in the low-background conditions that allowed to probe a very low, μBq/kg, level of the LMO crystals radioactive contamination by 228 Th and 226 Ra.

47 OTHER INSTRUMENTATION↗
NASA NTRS1964

Wedge immersed thermistor bolometers

An immersed thermistor bolometer for the detection of ultraviolet, visible, and infrared radiation is described. Two types of immersed bolometers are discussed. The immersion of thermistor flakes in a lens, or half immersed by optical contact on a lens, is examined. Lens materials are evaluated for optimum immersion including fused aluminum oxide, beryllium oxide, and germanium. The application of the bolometer to instruments in which the entrance pupil of the immersion optics has a high aspect ratio is considered.

Dreyfus, M. G.↗
NASA NTRS1980

Investigation of electrical noise in selenium-immersed thermistor bolometers

The selenium immersed, thermistor bolometer, IR detector failed due to spurious and escalating electrical noise outburst as a function of time at elevated temperatures during routine ground based testing in a space simulated environment. Spectrographic analysis of failed bolometers revealed selenium pure zones in the insulating selenium arsenic (Se-As) glass film which surrounds the active sintered Mn, Ni, Co oxide flake. The selenium pure film was identified as a potentially serious failure mechanism. Significant changes were instituted in the manufacturing techniques along with more stringent process controls which eliminated the selenium pure film and successfully produced 22study bolometers.

Tarpley, J. L.↗
NASA NTRS1984

Bolometers - Ultimate sensitivity, optimization, and amplifier coupling

Theoretical expressions for Johnson noise and thermal noise in bolometers are considered, and optimization with respect to thermal conductivity and bias power is performed. Numerical approximations are given for the ultimate NEP of bolometers as a function of material parameters and compared with photon noise including photon correlations. A resonating capacitor is shown to improve the coupling to an amplifier, so that the amplifier need not limit performance even for very low temperature bolometers.

Mather, J. C.↗
NASA NTRS1984

Bolometers operated at 0.1 K and 0.2 K cooled by adiabatic demagnetization

The construction of bolometers operating at temperatures of 0.1 K and 0.2 K and cooled by adiabatic demagnetization is reported. The electrical noise-equivalent power (NEP) of the bolometers was found to be 1.8 and 6.6 x 10 to the -16th W/sq rt Hz, respectively. These values are within a factor of two of the expected performance based upon bolometer theory. The thermistor material used was gallium-doped single-crystal germanium, for which a resistivity temperature dependence is found.

Lesyna, L.↗
NASA NTRS1985

Physics and design of advanced IR bolometers and photoconductors

The state-of-the-art in photoconductors and bolometers is reviewed, centering on the materials development and concepts of extrinsic Si and Ge devices. It is suggested that in the field of 2-D detector arrays the hybrid circuits containing a photoconductor or a photodiode array, bonded with In solder to a switched MOS readout device with up to 60 x 60 elements, will produce superior performance. Other systems discussed include charge-coupled devices, developed for visible-light imaging and adapted to IR imaging, and charge-injection devices, a monolithic combination of a standard photoconductor and a metal-insulator-semiconductor capacitor. Finally, it is pointed out that a nonequilibrium theory of bolometer noise demonstrates the possibility of reducing the traditionally accepted noise limits by 60 percent for Johnson noise and 30 percent for the noise from phonons in the thermal link of the bolometer.

Haller, E. E.↗
NASA NTRS1986

A progress report on bolometers operating at 0.1 K using adiabatic demagnetization refrigeration

Bolometers are still the detectors of choice for low background infrared observations at wavelengths longer than 200 microns. In the low background limit, bolometers become more sensitive as their operating temperature decreases, due to fundamental thermodynamic laws. The adiabatic demagnetization technique was evaluated by building a bolometer detection system operating at a wavelength of 1 millimeter for use at a ground based telescope. The system was fit checked at the telescope and is expected to take its first data in November, 1985.

Roellig, T.↗
NASA NTRS1988

An adiabatic demagnetization cooled bolometer system

An adiabatic demagnetization refrigeration (ADR) system suitable for cooling bolometers for use at infrared and submillimeter wavelengths is constructed. Because it does not rely on a gravitational field for operation, this refrigeration method has been proposed to cool bolometers intended for NASA's Space Infrared Telescope Facility. To explore the use of ADR in this manner, a portable instrument that has been used successfully for ground-based astronomical observations was constructed. By employing chromic potassium sulfate as a paramagnetic cooling material, bolometers were cooled to temperatures of 0.1 K with a cryogenic hold time of greater than nine hours.

Lesyna, L.↗
NASA NTRS1990

Thermal response of large area high temperature superconducting YBaCuO infrared bolometer

Thermal analysis of large area high temperature superconducting infrared detector operating in the equilibrium mode (bolometer) was performed. An expression for the temperature coefficient beta=1/R(dR/dT) in terms of the thermal conductance and the thermal time constant of the detector were derived. A superconducting transition edge bolometer is a thermistor consisting of a thin film superconducting YBaCuO evaporated into a suitable thermally isolated substrate. The operating temperature of the bolometer is maintained close to the midpoint of the superconducting transition region where the resistance R has a maximum dynamic range. A detector with a strip configuration was analyzed and an expression for the temperature rise (delta T) above the ambient due to a uniform illumination with a source of power density P(sub i) was calculated. An expression for the thermal responsivity of the detector was derived using the thermal diffusion analysis with appropriate boundary conditions. It was found that the thermal responsibility depends upon the spatial modulation frequency and the angular frequency of the incoming radiation. The problem of the thermal cross talk between different detector elements was addressed. In the case of monolithic HTS detector array with a row of square elements of dimensions 2a and CCD or CID readout electronics the thermal spread function was derived for different spacing between elements. This analysis can be critical for future design and applications of large area focal plane arrays as broad band optical detectors made of granular thin films HTS YBaCuO.

Khalil, Ali E.↗
NASA NTRS1989

Flight worthy infrared bolometers with high throughput and low NEP

This paper describes the features of flight-worthy IR bolometers that were developed to meet the requirements of the Far Infrared Absolute Spectrometer (FIRAS) and the Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer of a short time constant, high throughput, and low noise equivalent power (NEP). The new bolometers use small chips of doped and compensated silicon as sensing elements, and diamond wafers coated with thin layers of Cr and Au as the absorbing substrate. The throughput values for the FIRAS bolometers and for DIRBE are 1.28 sr-sq cm, and 0.21 sr-sq cm, respectively. At 1.6, the time constants range from 3 to 40 ms, and their NEP range from 4 x 10 to the -15th to 1 x 10 to the -14th W/sq rt of Hz.

Serlemitsos, Aristides T.↗
NASA NTRS1991

Thermal response of large area high temperature superconducting YBaCuO infrared bolometers

Thermal analysis of large area high temperature superconducting infrared detector operating in the equilibrium mode (bolometer) was performed. An expression for the temperature coefficient beta = 1/R(dR/dT) in terms of the thermal conductance and the thermal time constant of the detector were derived. A superconducting transition edge bolometer is a thermistor consisting of a thin film superconducting YBaCuO evaporated into a suitable thermally isolated substrate. The operating temperature of the bolometer is maintained close to the midpoint of the superconducting transition region where the resistance R has a maximum dynamic range. A detector with a strip configuration was analyzed and an expression for the temperature rise (delta T) above the ambient due to a uniform illumination with a source of power density was calculated. An expression for the thermal responsibility depends upon the spatial modulation frequency and the angular frequency of the incoming radiation. The problem of the thermal cross talk between different detector elements was addressed. In the case of monolithic HTS detector array with a row of square elements of dimensions 2a and CCD or CID readout electronics the thermal spread function was derived for different spacing between elements.

Khalil, Ali E.↗
NASA NTRS1983

The 0.1K bolometers cooled by adiabatic demagnetization

The most straightforward way of reducing the noise equivalent power of bolometers is to lower their operating temperature. We have been exploring the possibility of using conventionally constructed bolometers at ultra-low temperatures to achieve NEP's suitable to the background environment of cooled space telescopes. We have chosen the technique of adiabatic demagnetization of a paramagnetic salt as a gravity independent, compact, and low power way to achieve temperatures below pumped He-3 (0.3 K). The demagnetization cryostat we used was capable of reaching temperatures below 0.08 K using Chromium Potassium Alum as a salt from a starting temperature of 1.5 K and a starting magnetic field of 30,000 gauss. Computer control of the magnetic field decay allowed a temperature of 0.2 K to be maintained to within 0.5 mK over a time period exceeding 14 hours. The refrigerator duty cycle was over 90 percent at this temperature. The success of these tests has motivated us to construct a more compact portable adiabatic demagnetization cryostat capable of bolometer optical tests and use at the 5m Hale telescope at 1mm wavelengths.

Roellig, T.↗
NASA NTRS1994

A monolithic Si bolometer array for the Caltech Submillimeter Observatory

We are developing a submillimeter continuum camera for the Caltech Submillimeter Observatory (CSO) located on Mauna Kea. The camera will employ a monolithic Si bolometer array which was developed by Moseley et al. at the NASA Goddard Space Flight Center (GSFC). The camera will be cooled to a temperature of about 300 mK in a He-3 cryostat, and will operate primarily at wavelengths of 350 and 450 micrometers. We plan to use a bolometer array with 1x24 directly illuminated pixels, each pixel of dimension 1x2 sq mm, which is about half of the F/4 beam size at these wavelengths. Each pixel is 10 to 12 micrometers thick and is supported only by four thin Si legs formed by wet chemical etch. The pixels are doped n-type by phosphorus implantation, compensated by boron implantation. Signals from the bolometer pixels are first amplified by cryogenically cooled FET's. The signals are further amplified by room-temperature amplifiers and then separately digitized by 16 bit A/D converters with differential inputs. The outputs of the A/D converters are fed into a digital signal processing board via fiber-optic cables. The electronics and data acquisition system were designed by the Goddard group. We will report the status of this effort.

Wang, Ning↗
NASA NTRS2001

Multiplexed Readout of Thermal Bolometers with Superconducting Transition Edge Thermometers

History shows that in astronomy, more is better. In the near future, direct detector arrays for the far-infrared and submillimeter will contain hundreds to thousands of elements. A multiplexed readout is necessary for practical implementation of such arrays, and has been developed using SQUIDs. The technology permits a 32 x 32 array of bolometers to be read out using approximately 100 wires rather than the >2000 needed with direct wiring. These bolometer arrays are made by micromachining techniques, using superconducting transition edge sensors as the thermistors. We describe the development of this multiplexed superconducting bolometer array architecture as a step toward bringing about the first astronomically useful arrays of this design. This technology will be used in the Submillimeter and Far Infrared Experiment (SAFIRE) instrument on Stratospheric Observatory for Infrared Astronomy (SOFIA), and is a candidate for a wide variety of other spectroscopic and photometric instruments.

Benford, Dominic J.↗