排序方式: 共有42条查询结果,搜索用时 15 毫秒
31.
E. J. Wollack D. J. Fixsen R. Henry A. Kogut M. Limon P. Mirel 《Journal of Infrared, Millimeter and Terahertz Waves》2008,29(1):51-61
We discuss the mechanical, thermal, and electromagnetic properties of a castable microwave absorber consisting of a mixture of stainless steel powder suspended in a commercially available epoxy. The resulting mixture is well suited for cryogenic applications. Its coefficient of thermal expansion closely matches most metals to reduce mechanical strain during cool down. The absorption can be tuned by varying the volume filling fraction of the stainless steel powder in the mixture and exhibits little change from room temperature to 4 K. We provide simple expressions for the real and imaginary parts of the dielectric permittivity as a function of frequency and the stainless steel filling fraction. 相似文献
32.
U-yen K. Wollack E. J. Horst S. Doiron T. Papapolymerou J. Laskar J. 《Microwave and Wireless Components Letters, IEEE》2007,17(2):100-102
We propose a low-loss slotline (SL) stepped circular ring termination for use in a microstrip-to-slotline (MS-to-SL) transition. Not only does this termination achieve broadband characteristics, but it also reduces SL radiation. The experimental results show that, using the proposed technique, the radiation loss around the pass-band frequency is lower than that of the conventional transitions using radial or circular pad terminations 相似文献
33.
34.
E. M. Barrentine P. T. Timbie T. R. Stevenson S. Ali J. A. Chervenak E. Wollack S. H. Moseley C. A. Allen W. T. Hseih T. M. Miller D. J. Benford A. D. Brown 《Journal of Low Temperature Physics》2008,151(1-2):173-179
Future experiments to probe the Cosmic Microwave Background (CMB) polarization will need arrays of 1000s of sensitive bolometers.
We are developing a Transition-edge Hot-electron Microbolometer (THM) to fill this need. This small-volume bolometer consists
of a superconducting bilayer Transition-Edge Sensor (TES) with a thin-film absorber. Unlike traditional monolithic bolometers
which make use of micromachined structures, the THM employs the decoupling between electrons and phonons at milliKelvin temperatures
to provide thermal isolation. The devices are fabricated photolithographically and are easily integrated with antennas via
microstrip transmission lines, and with SQUID readouts. We present the results of noise, responsivity, and thermal conductance
measurements in which electrical power is dissipated in the absorber, and confirm a thermal model for a test THM with a Mo/Au
TES and Bi/Au absorber.
相似文献
35.
C. A. Allen D. J. Benford T. M. Miller S. H. Moseley J. G. Staguhn E. J. Wollack 《Journal of Low Temperature Physics》2008,151(1-2):266-270
The Backshort-Under-Grid (BUG) superconducting bolometer array architecture is intended to be highly versatile, operating
over a large range of wavelengths and background conditions. To validate the basic array design and to demonstrate its applicability
for future kilopixel arrays, we will demonstrate a 128-element bolometer array optimized for 2 mm wavelength using a new Goddard
Space Flight Center instrument, GISMO (Goddard IRAM Superconducting 2-Millimeter Observer). The design considerations unique
to GISMO and laboratory experimental results will be discussed.
相似文献
36.
Chuss DT Wollack EJ Henry R Hui H Juarez AJ Krejny M Moseley SH Novak G 《Applied optics》2012,51(2):197-208
We investigate the polarization modulation properties of a variable-delay polarization modulator (VPM). The VPM modulates polarization via a variable separation between a polarizing grid and a parallel mirror. We find that in the limit where the wavelength is much larger than the diameter of the metal wires that comprise the grid, the phase delay derived from the geometric separation between the mirror and the grid is sufficient to characterize the device. However, outside of this range, additional parameters describing the polarizing grid geometry must be included to fully characterize the modulator response. In this paper, we report test results of a VPM at wavelengths of 350 μm and 3 mm. Electromagnetic simulations of wire grid polarizers were performed and are summarized using a simple circuit model that incorporates the loss and polarization properties of the device. 相似文献
37.
D. T. Chuss A. Ali M. Amiri J. Appel C. L. Bennett F. Colazo K. L. Denis R. Dünner T. Essinger-Hileman J. Eimer P. Fluxa D. Gothe M. Halpern K. Harrington G. Hilton G. Hinshaw J. Hubmayr J. Iuliano T. A. Marriage N. Miller S. H. Moseley G. Mumby M. Petroff C. Reintsema K. Rostem K. U-Yen D. Watts E. Wagner E. J. Wollack Z. Xu L. Zeng 《Journal of Low Temperature Physics》2016,184(3-4):759-764
38.
S. W. Henderson R. Allison J. Austermann T. Baildon N. Battaglia J. A. Beall D. Becker F. De Bernardis J. R. Bond E. Calabrese S. K. Choi K. P. Coughlin K. T. Crowley R. Datta M. J. Devlin S. M. Duff J. Dunkley R. Dünner A. van Engelen P. A. Gallardo E. Grace M. Hasselfield F. Hills G. C. Hilton A. D. Hincks R. Hloẑek S. P. Ho J. Hubmayr K. Huffenberger J. P. Hughes K. D. Irwin B. J. Koopman A. B. Kosowsky D. Li J. McMahon C. Munson F. Nati L. Newburgh M. D. Niemack P. Niraula L. A. Page C. G. Pappas M. Salatino A. Schillaci B. L. Schmitt N. Sehgal B. D. Sherwin J. L. Sievers S. M. Simon D. N. Spergel S. T. Staggs J. R. Stevens R. Thornton J. Van Lanen E. M. Vavagiakis J. T. Ward E. J. Wollack 《Journal of Low Temperature Physics》2016,184(3-4):772-779
39.
Increasing the coercive force of a magnetic recording medium normally improves high density digital performance. However, in rigid disk systems, the head is not in intimate contact with the disk. In addition, the ferrites employed as head materials have much lower saturation magnetization than the metals normally used in other types of heads. Under these conditions, the head field may be inadequate to fully saturate recording media of higher than normal coercive force. In the development of the latest disk products, increasing the coercive force has not improved performance but has increased overwrite modulation. This situation has not been improved by increasing write current amplitude. Pole tip and core saturation of the record head has been suspected as the cause of these observations. This paper describes a method of characterizing saturation effects in low inductance heads such as those used with rigid disks. Evidence of the deterioration of performance due to pole tip and core saturation is shown from isolated pulse measurements on a rigid disk with NiZn and MnZn ferrite heads. 相似文献
40.
Wollack Stephen; Wijting Jan P.; Goodale James G.; Smith Patricia C. 《Canadian Metallurgical Quarterly》1970,54(2):174
Investigated the idea that attitude measures should include 2 components: an evaluative component and a measure of the strength of agreement. A number of scoring methods were analyzed for a newly developed measure of worker attitude, the Survey of Work Values. Multipoint and dichotomous scoring of agreement responses were highly correlated with scores based upon a more elaborate multiplicative technique which used both evaluative and agreement weights. Results suggest that the unweighted methods of scoring be used, but that additional research is warranted. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献