Axial fatigue testing of sheet materials down to -423 f.
Cryostat fatigue testing of sheet materials by fully reversed axial loading down to minus 423 degrees f
AXIAL LOAD↗
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Test system accurately determines tensile properties of irradiated metals at cryogenic temperatures
Modified testing system determines tensile properties of irradiated brittle-type metals at cryogenic temperatures. The system includes a lightweight cryostat, split-screw grips, a universal joint, and a special temperature control system.
Levine, P. J.↗
Measurements of Magnetization in Superconductive Molybdenum
Magnetization in superconducting Mo measured in He 3 cryostat, noting transition temperatures and critical field
TEMPERATURE EFFECT↗
Problems with dielectric measurements at cryogenic temperatures.
Dielectric measurements at cryogenic temperatures, noting dielectric losses and leads reaching cryostat bottom
Mathes, K. N.↗
Calibration of a resistance thermometer down to 0.04 degrees K
Method for calibrating germanium-resistance thermometers in cryostats between 0.4 degrees K and 4 degrees K involves extrapolating the specific heat of a simple metal to low temperatures. This method is used when a magnetic thermometer is not available.
Culbert, H. V.↗
Proximity effect between superconductivity and normal metals
The SNS junctions were limited to having gold (n) layers of less than 3000 A in order to avoid having the tin (S) films become normal under the influence of the signal current in the gold. The gold layer was alloyed with 10 wt% copper to shorten its electronic mean free path, increasing the tin layer critical current while decreasing the Josephson critical current. It was also found that a previously reported anomalous voltage shift in the presence of I2 is caused by the tin being driven normal. After deposition, the samples were transferred to a conventional cryostat to provide better thermal contact to the films. This reduction of heating in the films produced more linear I-V characteristics and a change in the constant voltage current gain. In order to achieve power gain the SNS device must be operated at lower temperatures were the effects of fluctuations are less and be constructed such that the input resistance is much reduced and the dynamic output resistance increased. A geometry is proposed using a more sophisticated evaporator.
Meissner, H.↗
Electromagnetic position sensor for a magnetically supported model in a wind tunnel
An investigation was undertaken to determine the feasibility of using superconducting force-producing coils for positioning a model in a wind tunnel. The cryostat containing the forcing coils surrounded the test section of the tunnel, thus favoring an electromagnetic position sensor. Another reason favoring this choice was the fact that the performance of an electromagnetic sensor is essentially unaffected by the shape of the model.
Towler, W. R.↗
The possibility of using superconductive systems in the analysis of the composition of cosmic rays
The experimental results on the use of superconductive systems onboard of spacecraft are described. To ensure low temperatures in the cryostat under weightlessness, helium was used at a pressure above the critical pressure. In flight, the temperature was controlled at six points, while the pressure and intensity of the magnetic field were controlled in the solenoids. The methodical test proved it possible to mount special installations on satellites, with extensive magnetic fields based on superconductive alloys, and particularly, low weights and low power consumption magnetic analyzers.
Anashkin, O. P.↗
A balloon-borne Ge/Li/ spectrometer for gamma-ray astronomy
On June 10, 1974, a new high-resolution gamma ray spectrometer operating in the energy range of 0.05 to 10 MeV was successfully balloon-flight tested. This system uses four 40 cu cm Ge(Li) crystals in a single cryostat as prime sensors. A 6.35 cm thick CsI (Na) shield provides background rejection and collimation, defining a solid angle of 0.095 sr. Cooling is provided by a liquid-nitrogen dewar. The system was highly stable with spectral resolution of better than 2.5 keV at 1 MeV for the flight duration. The background total count rate was about 20 counts/sec. Numerous lines were observed, most of which originated from secondary neutron interactions in the spectrometer. The sensitivity of the system to line emissions originating in cosmic point sources is 0.0001 to 0.001 photons per sq cm s over the energy range.
Jacobson, A. S.↗
Thermal control systems for low temperature Shuttle payloads
Greater sensitivity and longer life for future space sensor systems place more stringent demands on cooling system technology. Results are presented for a study designed to determine and evaluate low-temperature thermal control system concepts for various cooling categories in the range 3-200 K and to generate hardware development plans for undeveloped viable system concepts. The study considered Shuttle launched payloads in the 1980-1991 time frame, with 1-5 yr of life. Cooling concepts are categorized as open-cycle (expendable), closed-cycle (mechanical), solid-state, and radiative. Particular attention is given to the concepts of multistage heat pipe radiator, diode heat pipe radiator, and radiator guarded cryostat. Results are given for parametric analyses of the Vuilleumier refrigerator, the rotary reciprocating refrigerator, the solid hydrogen refrigerator, the solid hydrogen/multistage radiator hybrid cooler, and the magneto-Peltier hybrid cooler.
Wright, J. P.↗
Measurement of the time-temperature dependent dynamic mechanical properties of boron/aluminum composites
A flexural vibration test and associated equipment were developed to accurately measure the low strain dynamic modulus and damping of composite materials from -200 C to over 500 C. The basic test method involves the forced vibration of composite bars at their resonant free-free flexural modes in a high vacuum cryostat furnace. The accuracy of these expressions and the flexural test was verified by dynamic moduli and damping capacity measurements on 50 fiber volume percent boron/aluminum (B/Al) composites vibrating near 2000 Hz. The phase results were summarized to permit predictions of the B/Al dynamic behavior as a function of frequency, temperature, and fiber volume fraction.
Dicarlo, J. A.↗
Experiment definition and integration study for the accommodation of magnetic spectrometer payload on Spacelab/shuttle missions
A super-cooled magnetic spectrometer for a cosmic-ray experiment is considered for application in the high energy astronomical observatory which may be used on a space shuttle spacelab mission. New cryostat parameters are reported which are appropriate to shuttle mission weight and mission duration constraints. Since a super-conducting magnetic spectrometer has a magnetic fringe field, methods for shielding sensitive electronic and mechanical components on nearby experiments are described.
Buffington, A.↗
Measurement of the time-temperature dependent dynamic mechanical properties of boron/aluminum composites
A relatively simple flexural vibration test is developed for accurate measurement of the low-strain dynamic modulus and damping capacity of B/Al composite bar specimens from -200 C to over 500 C. The specimens are prepared from 8-ply unidirectional panels containing 50 volume percent fibers composed of 203-micron commercial boron-on-tungsten fibers. The basic test technique consists of the forced flexural vibration of the composite bar specimens at their two lowest free-free symmetrical resonant modes in a high-vacuum cryostat furnace. Specimen damping is determined from oscilloscope photographs of the free decay obtained after simultaneously removing the resonant drive signal and grounding the vibration-drive electrode. The availability of time-temperature dynamic data coupled with the predictive accuracy of composite theory suggests a future potential for using such data in examining environmental effects on composite macrostructure and microstructure.
Dicarlo, J. A.↗
Solid state crystal physics at very low temperatures
The properties of nearly perfect crystals was studied at cryogenic temperatures. A large Helium 3 and Helium 4 dilution refrigerator has been assembled, and is described. A cryostat suitable for cooling a 35 liter volume to .020 Kelvin was designed and constructed, together with instrumentation to observe the properties of nearly perfect crystals.
Davis, W.↗
Superfluid helium film in zero gravity
The behaviour of nearly-saturated superfluid helium films several hundred Angstroms thick was investigated under zero gravity conditions in a small cryostat carried on a 0.3 m diameter, 3 m long sounding rocket, using a quartz microbalance technique. The flight provided 30 s of high acceleration, about 5 min. of zero gravity, and 90 s of mg acceleration. The temperature of the experiment ranged from 1.67 to 2.15 K. In contrast to ground test results, thick films uniformly distributed on all surfaces were observed in zero gravity.
Yang, L. C.↗
Thermal conductivity of Rene 41 honeycomb panels
Effective thermal conductivities of Rene 41 panels suitable for advanced space transportation vehicle structures were determined analytically and experimentally for temperature ranges between 20.4K (423 F) and 1186K (1675 F). The cryogenic data were obtained using a cryostat whereas the high temperature data were measured using a heat flow meter and a comparative thermal conductivity instrument respectively. Comparisons were made between analysis and experimental data. Analytical methods appear to provide reasonable definition of the honeycomb panel effective thermal conductivities.
Deriugin, V.↗
Superfluid Helium Experiment for Spacelab 2
The Superfluid Helium Experiment is designed to study the properties of superfluid helium in zero gravity and demonstrate the operation of a versatile reusable superfluid helium experiment facility. The superfluid experiment will consist of three subexperiments. The quantized surface wave experiment is intended to contribute to an understanding of the quantum nature of He-2 and the interactions between the normal and superfluid components. The bulk fluid dynamics experiment will determine the response of the bulk helium to known accelerations. The thermal dynamics experiment will attempt to obtain a detailed understanding of the spatial distribution of temperatures and the thermal frequency spectrum in the bulk liquid. In addition, the superfluid helium cryostat will be instrumented to measure its performance in several critical areas.
Mason, P.↗
Low thermal conductance rigidizer for reducing torsional oscillations in cryogenic Dewars
A rigidizer, which provides greater rigidity against torsional oscillations, is highly resistant to radial motions, and has low thermal conductivity, has been developed to decrease vibrational levels affecting infrared detectors operated in cryostats (e.g., HD-3L Dewar) in aircraft such as NASA's Kuiper Airborne Observatory. The rigidizer is composed of two triangular elements and an intermediate support structure which joins them at the centers of their sides. The reentrant design provides a long heat path, while the triangular truss structure provides high rigidity in the horizontal plane. The structure is relatively compliant in the vertical direction, a desirable feature since the internal structure of the Dewar contracts as it cools. Rigidity in the vertical direction is provided by the neck tube. The support structure is quite compact. Several variants of the rigidizer have been fabricated, using flat sheets of G-10 fiberglass epoxy in thicknesses between 0.75-1.5 mm for the upper and lower truss assemblies, and either G-10 or stainless steel for the intermediate structure.
Harper, D. A.↗