NASA Scientific and Technical Aerospace Reports

International Thermal Detectors Workshop (TDW 2003); February 2004, pp. P2; In English; See also 20040068186; No
Copyright; Abstract Only; Available from CASI only as part of the entire parent document
Thermoelectric refrigerators operating at cryogenic temperatures will considerably simplify and facilitate the problem of
obtaining temperatures below 4.2 K, which is required for different types of sensitive photon detectors. The results of
investigation of the cooling on the basis of the Peltier effect in a single crystal of CeB6 grown by the floating zone method
are presented. The temperature dependencies of thermopower S(T), resistivity rho(T), and thermal conductivity k(T) have been
measured, and the parameter ZT=TS(exp 2)/rho k has been calculated in the temperature range 3.5 K-300 K. The value of 0.2
at 4.5 K has been obtained for ZT, which allows one to expect noticeable Peltier cooling in this material at that temperature.
Initial measurements of thermoelectric cooling vs. electric current value were made at temperatures 3.5 K, 4.5 K, 5.5 K, 9.5
K. A single-stage prototype solid-state micro-refrigerator demonstrated a temperature drop of 0.2 K at the temperature 4.5 K.
Author
Thermoelectric Cooling; Single Crystals; Cryogenic Temperature; Cerium Compounds; Boron Compounds
20040068218 Pennsylvania State Univ., PA, USA
Epitaxial Superconducting MgB2 Thin Films by HPCVD
Xi, Xiao-Xing; International Thermal Detectors Workshop (TDW 2003); February 2004, pp. 4-6; In English; See also
20040068186; No Copyright; Abstract Only; Available from CASI only as part of the entire parent document
The recently discovered superconductor MgB2 with Tc at 39 K has great potential in superconducting electronics. In this
paper, we present results of in situ epitaxial MgB2 thin films grown by Hybrid Physical-Chemical Vapor Deposition (HPCVD)
technique which successfully achieves a high Mg pressure necessary for in situ growth of MgB2 thin films. Excellent
superconducting properties have been abtained in these films.
Author
Thin Films; Vapor Deposition; Magnesium Compounds; Superconductors (Materials); Epitaxy
20040068219 Hypres, Inc., Elmsford, NY, USA
Superconducting Digital Multiplexers for Sensor Arrays
Kadin, Alan M.; Brock, Darren K.; Gupta, Deepnarayan; International Thermal Detectors Workshop (TDW 2003); February
2004, pp. 4-7 - 4-10; In English; See also 20040068186
Contract(s)/Grant(s): NAS3-03044; No Copyright; Avail: CASI; A01, Hardcopy
Arrays of cryogenic microbolometers and other cryogenic detectors are being developed for infrared imaging. If the signal
from each sensor is amplified, multiplexed, and digitized using superconducting electronics, then this data can be efficiently
read out to ambient temperature with a minimum of noise and thermal load. HYPRES is developing an integrated system
based on SQUID amplifiers, a high-resolution analog-to-digital converter (ADC) based on RSFQ (rapid single flux quantum)
logic, and a clocked RSFQ multiplexer. The ADC and SQUIDs have already been demonstrated for other projects, so this
paper will focus on new results of a digital multiplexer. Several test circuits have been fabricated using Nb Josephson
technology and are about to be tested at T = 4.2 K, with a more complete prototype in preparation.
Author
Multiplexing; Squid (Detectors); Superconductivity; Digital Electronics; Arrays; Fabrication
20040068220 Wales Univ. Inst. of Science and Technology, Cardiff, UK
Far-infrared and Submillimeter Filters
Haynes, C. V.; Ade, P. A. R.; Budd, J.; Lee, C.; Tucker, C. E.; International Thermal Detectors Workshop (TDW 2003);
February 2004, pp. 5-1 - 5-5; In English; See also 20040068186; No Copyright; Avail: CASI; A01, Hardcopy
Filters are critical for thermal detector systems, which are responsive to a wide frequency range. Without spectral
limitation the detectors respond to frequencies outside those of interest with the consequence of increased photon noise and
detector loading. For cooled systems it is also important to filter out high frequency radiation, minimising the thermal load
and cooling power necessary. At Cardiff University we are developing far-infrared and submillimeter bandpass, high-pass, and
low-pass blocking filters using a metal mesh technology. We have been able to maintain high in-band transmission with good
out of band rejection to UV wavelengths. This technology is space qualified and has been used in a number of Astronomical
and Earth Observation projects. Here we present our latest advancements.
Author
Submillimeter Waves; Far Infrared Radiation; Low Pass Filters; Bandpass Filters; Fabrication
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