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Gaidis, M. C.

Publications and source records attributed to Gaidis, M. C..

9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Transmission Properties of Zitex in the Infrared to Submillimeter

The results of measurements of the refractive index and power absorption coefficient of Zitex at 290 K, 77 K, and 4 K in the spectral region from 1 to 1000 microns are presented. Zitex is a porous Teflon sheet with a filling factor of approximately 50%, and is manufactured in several varieties as a filter paper. Zitex is found to be an effective infrared radiation block, with thin (200 micrometer) sheets transmitting less than 1% in the 1-50 micrometer range while absorbing <10% at wavelengths longer than 200 micrometers. Some variation in the cutoff wavelength is seen, tending to be a shorter wavelength cutoff for a smaller pore size. Additionally, the thermal conductivity of Zitex at cryogenic temperatures has been measured, and is found to be roughly one-half that of bulk Teflon.

Benford, D. J.↗
NASA NTRS2000

Space-based applications of far-infrared systems

This paper discusses the applications of space-based far-infrared/terahertz sensors and systems. It also covers the needs and desires of scientists, discusses what has been done to date, and what is planned for the future.

space-based sensors and systems↗
NASA NTRS1998

A2.5 THz Receiver Front-End for Spaceborne Application

The OH radical is an important player in known ozone depletion cycles; however, due to its location in the atmosphere, it must be studied from either a balloon or spaceborne platform.

receiver ozone destruction Earth Observing System ↗
NASA NTRS1997

Low Noise in a Diffusion-Cooled Hot-Electron Mixer at 2.5 THz

The noise performance of a Nb hot-electron bolometer mixer at 2.5 THz has been investigated. The devices are fabricated from a 12-nm-thick Nb film, and have a 0.30 micrometer x 0.15 micrometer in-plane size, thus exploiting diffusion as the electron cooling mechanism. The rf coupling was provided by a twin-slot planar antenna on an elliptical Si lens. The experimentally measured double sideband noise temperature of the receiver was as low as 2750 +/- 250 K with an estimated mixer noise temperature of approximately equal 900 K. The mixer bandwidth derived from both noise bandwidth and IF impedance measurements was approximately equal 1.4 GHz. These results demonstrate the low-noise operation of the diffusion-cooled bolometer mixer above 2 THz.

Karasik, B. S.↗
NASA NTRS1996

Modeling and Optimization of a High-Tc Hot-Electron Superconducting Mixer for Terahertz Applicaitons

The development of a YBa(sub 2)Cu(sub 3)O(sub 7-(kronecker delta))(YBCO) hot-electron bolometer (HEB) quasioptical mixer for a 2.5 heterodyne receiver is discussed. The modeled device is a submicron bridge made from a 10 nm thick film on a high thermal conductance substrate. The mixer performance expected for this device is analyzed in the framework of a two-temperature model which includes heating both of the electrons and the lattice. Also, the contribution of heat diffusion from the film through the substrate and from the film to the normal metal contacts is evaluated....a single sideband temperature of less than 2000k is predicted.

tetrahertz hot-electron bolometer quasioptical mix↗
NASA NTRS1993

Superconducting Al-trilayer tunnel junctions for use as X-ray detectors

Photolithographic techniques have been developed to fabricate high-quality Al-Al oxide-Al superconducting tunnel junctions for use in X-ray detectors. These devices are designed to incorporate about 1-micron-thick superconducting X-ray absorbers for the detection of less than 10-keV single photons. In an effort to increase energy resolution, superconductor bandgap engineering with lateral and vertical trapping has been used to shorten quasi-particle tunneling times and diffusion lengths and to prevent quasi-particle diffusion away from the tunnel junction. Methods that have been developed for overcoming materials imcompatibility and device degradation upon thermal cycling are reported. The authors also report on the use of a nonrectangular tunnel junction geometry which reduces the magnetic field needed to suppress the Josephson current for stable biasing. Work in progress to measure the energy resolution of these X-ray detectors at 0.35 K is also discussed.

Gaidis, M. C.↗