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1992-01-01 | Silicon diode cryogenic thermometry has been designed and tested for use on the Cryogenic Systems of the SSCL Magnet Test Facilities (MTL, ASST). This paper describes the test setup, results of testing, final design configuration, and performance specification. | Effects of Mounting Methods on Temperature Sensor Accuracy Below 10K | 10.1007/978-1-4615-3454-9_76 |
1992-01-01 | A new approach is suggested to the design of multi-channel systems for biomagnetic applications, based on a combination of several autonomous small-size measuring modules within one system. Small-diameter second- order gradiometers have been developed for practical realization of the new design; the gradiometers are based on integrated dc-SQUIDs and have an intrinsic noise level of $$5 \cdot {10^{ - 15{\kern 1pt} }}T/\sqrt {Hz} $$ . Small-size 1.3 liter fiberglass helium dewars have been designed; the operating period of such dewars is more than two days. Tests have been carried out on a 3-channel version of the modular system. Ways are suggested for future development of modular multi-channel measuring system. | Biomagnetic Multi-Channel System Consisting of Several Self-Contained Autonomous Small-Size Units | 10.1007/978-3-642-77457-7_87 |
1992-01-01 | Results of 77 Kelvin creep tests on OFHC copper specimens have been obtained and are shown to support previously published results presented by researchers at the National Institute of Standards and Technology (NIST). The reproduction of the copper results obtained by NIST using the Texas A&M system provides credibility to both systems. This is particularly important when the lack of commercial cryogenic creep systems results in individualized measurement techniques and the degree of measurement difficulty is high. A suggested standard for the simplified comparison of materials which exhibit “exhaustive” creep behavior is also given. | 1100 Hour Creep Test Results for OFHC Copper: Validation of Previously Published Results | 10.1007/978-1-4757-9050-4_16 |
1992-01-01 | A low noise 19-channel SQUID system was developed. It is part of a complete system for functional diagnosis of human brain or heart. The thin film DC-SQUIDs with integrated coupling coils are based on the refractive materials NbN-MgO-NbN. First order wire wound gradiometers with 20mm diameter are used. The cryogenic system is modular in a way that every channel can be optimized or replaced individually without warming up of the dewar. The electronics are based on the flux locked loop scheme with a new bias modulation technique. The system is installed inside a magnetically shielded chamber. The noise level of all 19 channels measured simultaneously is below 12fT/√Hz. | A Modular 19-Channel SQUID System for Biomagnetic Measurements | 10.1007/978-3-642-77457-7_88 |
1992-01-01 | Nitrogen-strengthened 32Mn-7Cr austenitic steel was cyclically deformed at various maximum stress amplitudes. The deformation structures induced by fatigue at cryogenic temperatures were examined by transmission electron microscopy. The dominant deformation mode was the {111}–<110> slip system, and dislocation motion was planar, especially at low stress levels. Cross slip of dislocations was strongly suppressed, and dislocation movements were restricted to their slip planes. At higher stress levels, mainly slip bands were observed. At lower stress levels, microslip or dislocation pile-ups were blocked or sharply localized at grain boundaries. Deformation twinning and E-martensite are not presumed to play a major role in the cyclic deformation. | Deformation Structures in High-Cycle Fatigue of 0.1N-32Mn-7Cr Steel at Cryogenic Temperatures | 10.1007/978-1-4757-9050-4_18 |
1992-01-01 | In order to find the most appropriate vacuum-pressure impregnating epoxy resin for superconducting coils, three types of epoxy resin were experimentally investigated from various points of view. Those epoxy resins were amine curing type A, anhydride curing type B with tertiary amine accelerator, and anhydride curing type C without accelerator. From the investigations, resin A was found to be superior in thermal shock resistance than resins B and C because of its large tensile fracture strain at cryogenic temperature and its small cure shrinkage. However, the test coil impregnated with resin A experienced more repeated premature quenches than the coil impregnated with resin C. This result might be related to the crackings which started from microscopic defects, and which occurred gradually in resin A compared with resins B and C. Moreover, the viscosity of resin A increased more rapidly during the impregnating process than that of resins B and C, so that resins B and C appear to be more appropriate for large superconducting coils than resin A. | Several Properties of Impregnating Epoxy Resins Used for Superconducting Coils | 10.1007/978-1-4757-9050-4_43 |
1992-01-01 | Uniaxially reinforced composites exhibit nonlinear load displacements when loaded in shear, even at very low temperatures. The nonlinearity can be attributed to both elastic and plastic deformation. Information on nonlinear and plastic strain can be obtained by closely analyzing data from low-temperature shear tests. This paper describes the nonlinear elastic and plastic deformation resulting from solid-rod torsion tests at low temperatures. Nonlinear elastic and plastic strain was measured as a function of shear stress to detect the onset of irreversible deformation. At both 77 and 4 K, nonlinear strain measurements also showed finite strain differences among various composite materials, including unique strain variations of different epoxy resin systems. A third-order stress-strain relationship for predicting yield strength was investigated. | Shear Behavior of Glass-Reinforced Systems at Low Temperatures | 10.1007/978-1-4757-9050-4_44 |
1992-01-01 | Fully densified ß-SIALON ceramics (Si_6Al_2O_2N_8), were prepared by a normal sintering and a post-sintering HIP (hot isostatic pressing) treatment. After exposure to corrosion by molten copper oxide (CuO) at 1200°C in air for 1 hour, both samples were evaluated by measuring their specific heat at cryogenic temperatures. Due to the fast cooling rate during sintering, the HIPed sample contained more grain boundary glassy phases than the normally sintered one. This was evaluated by a newly developed copper oxide etching method. Cryogenic specific heat is a powerful and a sensitive property for evaluating the grain boundary glassy phases of ß-SIALON ceramics. The copper oxide etching method used was found to be an effective method for observing ceramic structures with siliceous grain boundary glassy phases. | Evaluation of Grain Boundary Phases of ß-Sialon by Cryogenic Specific Heat Measurements | 10.1007/978-94-011-1878-1_9 |
1992-01-01 | The intent of this document is to provide a brief summary of the execution, by Process Systems International, Inc. (PSI), of the Design and Construction of the SSCL Magnet Test Laboratory Cryogenic Systems. This $30 million project requires the expenditure of over 200,000 manhours and the procurement of $17 million in materials within a two year period. | Design and Construction of the SSCL Magnet Test Laboratory Cryogenic Systems | 10.1007/978-1-4615-3454-9_23 |
1992-01-01 | The investigation of hydrogen effect on the mechanical properties of Incoloy 907, a Fe—Ni—Co superalloy, was made from ambient to cryogenic temperature (77 K) with and without hydrogen charging under different aging treatments. It was found that there exists an obvious IHE tendency in Inco 907 from ambient to cryogenic temperature, which is affected by the microstructure of the alloy. From ambient to LN temperature an obvious maximum of IHE susceptibility in the alloy was found at the temperature of —50^°C for all the aging treatments. The occurance of the hydrogen embrittlement in Inco 907 and its temperature dependence can be well explained by the interaction between the hydrogen and the dislocation in the alloy | Hydrogen Effect on the Mechanical Properties of Incoloy 907 from Ambient to Cryogenic Temperature | 10.1007/978-1-4757-9050-4_12 |
1992-01-01 | The subcooler assembly installed in the MAGCOOL test area at Brookhaven National Laboratory has been used for testing SSC magnets since 1989. As part of the test program, magnets are quenched routinely in the system. The system description and steady state capacity have been given previously^1. In this paper, the thermal behavior of the subcooler cryogenic system after quenches of the 50 mm SSC dipole magnet DCA207 are presented. Pressures, temperatures and flow rates in the magnet cooling loop are given as a function of time. The heating/cooling and venting mechanisms are illustrated. The cooling rates and the total energy removed by cooling during quench recovery have been calculated for quench currents of 6000, 6883 and 7406 ampere at 4.35 K, and for 8413 ampere at 3.5 K. Results show that the total energy removed by cooling during quench recovery is in good agreement with the stored energy released by the magnet during the quench. No operating difficulties were encountered during the magnet tests. System recovery time varies from 50 minutes for a 6000 ampere quench to 90 minutes for an 8413 ampere quench. | Performance of the Magcool-Subcooler Cryogenic System After 50 mm SSC Dipole Quenches | 10.1007/978-1-4615-3454-9_61 |
1992-01-01 | High-cycle fatigue properties were investigated for Ti-5A12.5Sn ELI and Ti-6A1-4V alloys (in the mill-annealed condition) at cryogenic temperatures. Subsurface crack initiation occurred in the long-life range for all alloys. The rolled materials of Ti-6A1-4V had much higher fatigue strength in the long-life range than the forged materials and the Ti-5A1-2.5Sn ELI alloy. The significant difference of fatigue strength in the long-life range for Ti-6A1-4V alloys was caused by morphological changes in their microstructure. | High-Cycle Fatigue Properties of Titanium Alloys at Cryogenic Temperatures | 10.1007/978-1-4757-9050-4_22 |
1992-01-01 | Herschel (1800) was the first to describe the infrared portion of the solar spectrum. The infrared wavelength region is a less well-defined part of the spectrum than is the visible. While the visible region covers all wavelengths to which our eyes are sensitive, the infrared deals with radiation beyond the red cut-off wavelength of the visible domain, say from about 800 nm up to about 1 mm. Beyond 800 nm the human sensory system switches from the eye to other receptors which are sensitive to heat radiated by warm and cool objects. In the 800 nm-1.1 μm wavelength region, red-sensitive photographic emulsions, silicon CCDs and also red-sensitive photocathodes can still be used. However, longward of 1.1 μm Si becomes completely transparent, and these detectors become ineffective and special detectors must be used instead (see Section 12.3). | Infrared photometry | 10.1007/978-94-011-2476-8_12 |
1992-01-01 | Previous studies indicate that the work hardening characteristics of a Vintage III 2090-T81 12.7-mm (0.5-in.) plate is highly dependent on the through-thickness position.^[1,2] This dependency has been linked to two distinctly different microstructures existing as laminates within the plate.^[3] An investigation of the two microstructures by both optical and transmission electron microscopy reveal a difference in the distribution of grains and subgrains. It is believed that these factors affect the work hardening characteristics by governing the manner in which slip is transmitted from grain to grain. The findings are positive as they suggest a practical means by which improvements in work hardening can be obtained through modifications of the microstructure at the polygranular level. | Microstructural Influence on the Work Hardening of Aluminum-Lithium Alloy 2090 at Cryogenic Temperatures | 10.1007/978-1-4757-9050-4_5 |
1992-01-01 | In this paper, we discuss the conceptual design of the superconducting magnets for a magnetohydrodynamic thruster for a “generic” full-size submarine. The advantages of this propulsion system are the elimination of the screw, and gears, and the acoustic signature they produce. The major magnet design issues are: low magnetic signature, robustness, and light weight. Low external magnetic signature was achieved by a unique toroidal magnet array that produces an azimuthal magnetic field around the hull, and still allows conducting sea water to enter the channel. This configuration also results in maximum use of the field to produce thrust. Detailed design of the coil ends, as well as the use of shielding materials may allow further reductions in the magnetic signature. Robustness of the coil is achieved by the use of a CICC 80 kA conductor, that uses NbTi at 4.2 K. Low magnet system weight is achieved by use of a filament wound structure for the coil, honeycomb steel for the vacuum vessel, and detachable leads. | Conceptual Design of a Superconducting Mhd Propulsion System | 10.1007/978-1-4615-3454-9_80 |
1992-01-01 | The dynamic interaction between the beam-gas scattering induced energy deposition and the SSC cryogenic system is studied by integrating a cryogenic system dynamic simulator with an adsorption model and a beam-gas scattering and energy deposition model. Simulation results are obtained for a 1 km long SSC arc section where the beam tube pressure in one of the dipoles is increased up to 150 times its nominal operating pressure. The beam-gas scattering induced heat loads arising from such high pressure perturbations can be very high locally but do not overload the cryogenic system. They are more likely to induce a magnet quench as they result in coil temperatures that largely exceed the desired operating limit. Simulations are also carried out for the case where a large external heat load of 1 W/m is imposed on the coldmass of a half-cell in the section. Results show that the coldmass temperatures rise significantly with the added heat load but the energy deposition in the coldmass due to beam-gas scattering remains low despite the increase in the beam tube temperature. | A Dynamic Model for Beam Tube Vacuum Effects on the SSC Cryogenic System | 10.1007/978-1-4615-3454-9_109 |
1992-01-01 | To evaluate filament-reinforced, vacuum-impregnated, epoxy-resin systems at cryogenic temperatures, new compression-shear tests have been developed for stainless-composite-stainless sandwiches. Results at 76 K are reported and analyzed for a series of weaves and surface finishes. | Compression and Shear Tests of Vacuum-Impregnated Composites at Cryogenic Temperatures | 10.1007/978-1-4757-9050-4_46 |
1992-01-01 | The microstructure and cryogenic tensile properties of an Al-Li-Zn-Zr alloy in different aging conditions have been studied. The temperature dependence of the tensile properties of the alloy were evaluated from ambient to liquid nitrogen temperature in the long transverse direction. The results show that the tensile strength and elongation of the alloy are much increased with the decrease of test temperature. The variation in tensile fracture mode and deformation behavior are proved to depend on the aging conditions and test temperature closely. The effect of microstructure on tensile deformation and fracture behavior of the alloy at room and cryogenic temperatures have been discussed. δ ′ particles are the major fractor to the improvement of ductility for the alloy at low temperatures. | Microstructure and Cryogenic Tensile Fracture Behavior of an Al-Li-Zn-Zr Alloy | 10.1007/978-1-4757-9050-4_4 |
1992-01-01 | In view of applications of fiber reinforced plastics at cryogenic temperatures, the mechanical properties of these materials have to be tested both at low temperatures and under various loading conditions (e.g. in tension, compression, shear and in particular in the crack opening mode). The main difficulty with a characterization of the crack growth (mode I) in glass-fiber reinforced materials lies in the fact that the crack length as well as the crack tip cannot be assessed with sufficient accuracy because of delamination and bridging of broken and unbroken fibers. Hence, linear elastic fracture-mechanics cannot be employed. In the present work, first attempts to characterize crack growth in mode I under quasi-static loading conditions in terms of fracture-mechanics have been made. Tests and evaluation procedures based on the fracture-energy-concept, which does not require the knowledge of the exact crack length, have been made at room temperature and at 77 K using a two dimensional glass-fiber reinforced epoxy (ISOVAL 10). Details of the technique as well as results of acoustic-emission investigations and of the influence of sample shape on the fracture-mechanical quantities will be presented. Advantages and disadvantages of the new technique will be discussed. | Fracture-Mechanical Characterization of Fiber Reinforced Plastics in the Crack-Opening-Mode (Mode I) | 10.1007/978-1-4757-9050-4_49 |
1992-01-01 | This paper briefly describes the cryogenic test capabilities of the Magnet Test Laboratory (MTL). The instrumentation for controlling the operating condition of the magnet cryogenic test and for verifying the requirements of the SSC magnet performance is introduced. The development of the thermometer system, particularly the He vapor pressure thermometers with differential pressure transducer, is presented in detail. The 10-kA vapor-cooled power leads were optimized thermally, with consideration for the different fin shapes, diameters, lengths, and RRRs of the power lead material. Two mechanical designs are introduced. The anti-cryostats, so-called warm bore and warm finger, that provide a warm environment to allow the magnetic field-measuring probe to run through the 4.2-K beam tube are described. The warm finger for SSC short-magnet cryogenic tests was manufactured and successfully used. Finally, the feed and end cans—used to provide cryogens to the magnet being tested as well as cryogenic vacuum—and the support of other instrumentation are described. | The Cryogenic System for the MTL Magnet Test Stands | 10.1007/978-1-4615-3454-9_134 |
1992-01-01 | The method of high-pressure hydrogen charging was used to charge hydrogen into smooth and notched tensile specimens of γ′ precipitate-strengthened austenitic steel JBK-75. The hydrogen content in the charged specimens was 25.2 ppm (by weight). In the test temperature range 293 to 77 K, hydrogen had no obvious effect on strength, but it caused some decrease in ductility at 223 to 295 K. The steel is not notch sensitive, and hydrogen charging had little effect on notch sensitivity at ambient and low temperatures. With decreasing temperature, both strength and ductility increased, and hydrogen damage greatly decreased. Increasing the aging temperature and time tends to increase the hydrogen damage of the steel, but hydrogen had less effect on aged strength. The steel that had been given an appropriate heat treatment had excellent cryogenic mechanical properties and resistance to hydrogen damage. The steel had very stable microstructure at low temperatures; no phase transition occurred as a result of strain and hydrogen at 293 to 77 K. Fine grain and fine γ′ precipitates decreased hydrogen damage; the presence of ŋ phase at grain boundaries increased hydrogen damage. | Effect of Hydrogen Charging on Ambient and Cryogenic Mechanical Properties of a Precipitate-Strengthened Austenitic Steel | 10.1007/978-1-4757-9050-4_10 |
1991-12-01 | Investigation of the capacity coefficient of a high-pressure reciprocating pump for cryogenic fluids | 10.1007/BF01155438 | |
1991-11-01 | Design development of a vacuum cryogenic pump with air delivery rates of 20,000 liters/sec | 10.1007/BF01221084 | |
1991-09-01 | Predesign analysis method for schematic variations in cryogenic units and plants | 10.1007/BF01151944 | |
1991-09-01 | The weldability of alloys of the system Al-Cu-Li is studied and promising alloyingranges are established for weldable alloys: 5.5-6.5% Cu, 0.8-1.4% LI and 2.5-3.5%Cu, 1.9-2.5% Li. The positive effect of adding small amounts of scandium on theweddability and mechanical properties of alloys of the system Al-Cu-Li is demonstrated.Properties at normal and cryogenic temperatures are given for a new weldablealloy 1460. | Possibility of creating weldable alloys on the basis of the system Al-Cu-Li | 10.1007/BF00811735 |
1991-09-01 | Single unit activity of 355 cells was recorded in the auditory thalamus of anesthetized cats before, during, and after the inactivation by cooling of the ipsilateral primary auditory cortex (AI). Most of the units (n = 288) showed similar functional characteristics of firing before and after the cryogenic blockade of AI. The spontaneous firing rate remained unchanged by cooling in 20% of the units and decreased in the majority of them (60%). In some regions, i.e. dorsal division of the medial geniculate body (MGB), lateral part of the posterior group of the thalamus, and auditory sector of the reticular nucleus of the thalamus, the maximum firing rate evoked by white noise bursts was generally affected by cooling in the same direction and to the same extent as the spontaneous activity. Units in the ventral division of MGB showed a characteristic increase of signal-to-noise ratio during cortical cooling. The corticofugal modulation led to the appearance or disappearance of the best frequency of tuning in 51 units and changed it by more than 0.5 octave in 34 units. The bandwidths of different response patterns to pure tones stimulation were used to define a set of functional properties. During cryogenic blockade of AI, two cortically modulated sub-populations of units were usually distinguished that exhibited changes for a given functional property. The complexity and diversity of the effects of cortical inactivation suggest that the corticothalamic projection may be the support for selective operations such as an adaptive filtering of the incoming acoustic signal at the thalamic level adjusted as a function of cortical activity. | Corticofugal modulation of the information processing in the auditory thalamus of the cat | 10.1007/BF00230524 |
1991-08-01 | FIFI is an imaging spectrometer with two or three Fabry-Perot interferometers (FPI) in series for airborne astronomical observations in the far-infrared range (λ=40...200μm). It employs 5×5 arrays of photoconducting detectors and offers spectral resolutions as small as 2km/s. Resolution and bandwidth can be set over a wide range to match a variety of astronomical sources. Cryogenic optics minimizes thermal background radiation and provides for in-flight step tunable spatial resolution. At 158 μm wavelength the background-limited NEP is 3 × 10^-15W/ℚHz at 40 km/s resolution and with two FPI's; with three FPI's the expected NEP is ≤10^-15W√Hz at 5 km/s resolution. The frequency-chopping mode of the high-resolution Fabry-Perot allows for line detection in extended objects. Absolute internal flux calibration ensures adequate “flat fielding” of the array elements. | The MPE/UCB far-infrared imaging Fabry-Perot interferometer (FIFI) | 10.1007/BF01009647 |
1991-07-01 | A cryogenic lesion was induced in the parietal cortex of neonatal rats at postnatal day 2, and the chronological sequence of cellular events during repair and reconstruction of the cortical plate examined. Serial sections of cerebra obtained at varying intervals ranging from 1 to 60 days postinjury were studied by light and electron microscopy and by immunocytochemistry for fibronectin, laminin, type IV collagen, vimentin and glial fibrillary acidic protein. In addition, localization of heavily labeled neurons (generated on embryonic day 20) in the cerebral cortical plate was examined by [^3H]thymidine radioautography. Repair of a welldefined coagulative lesion was accomplished with little or no mesenchymal cell proliferation in either the necrotic zone or the leptomeninges. Eventually, fusion of the adjacent cortical plates took place with the formation of a microsulcus. Migration of neurons continued to take place along the outer margins of the lesion, and postmigratory neurons accumulated within the upper cortical layers. Around the microsulcus, heavily labeled neurons aligned themselves with layers II–III of the adjacent normal cortical plate. Irregular clusters of neurons closely abutting the leptomeningeal surface were frequently noted when repair took place without an intervening molecular layer and/or a welldefined pial-glial barrier. Supplementing intrinsic information inherent in migrating neurons, local environmental signals provided by the radial glia, glia limitans, basal lamina and pial-glial barrier appear to influence the polarity and final positioning of postmigratory neurons within the cortical plate. The necrotic zone within the deeper layers of the cortex eventually healed with a cell-sparse gliotic layer. The end result was a histological pattern that, in many respects, resembled that of human micropolygyria. In contrast, identical cryogenic lesions induced in the brains of rats at postnatal day 10 healed with fibrous scar formation and/or caviation, and a micropolygyric pattern did not develop. | Repair and reconstruction of the cortical plate following closed cryogenic injury to the neonatal rat cerebrum | 10.1007/BF00293950 |
1991-06-01 | By making a combination of both point contact and barrier type tunnel junctions on a single sample of the high T _c superconductor BSCCO (2212) single crystal, we have shown that as the tunneling tip is slowly retracted from the surface a point contact junction gradually evolves from a N-S short to a high resistance tunnel junction. The scaled dynamic conductance (d I /d V ) of this point contact tunnel junction becomes almost identical to that of a conventional barrier type tunnel junction and both show a linear d I /d V — V curve. The observation implies that at high resistance a point contact junction behaves in the same way as a barrier type tunnel junction. We suggested that the almost linear tunneling conductance obtained in both the cases most likely arises due to an intrinsic characteristic of the surface of the crystal comprising of a mosaic of superconducting regions of the order of a few nanometers. We also conclude that the barrierless (N-S) point contact obtained by piercing the surface oxide layer of the crystal shows Andreev reflection which we suggest as the origin of the zero bias anomaly often observed in point contact junctions. | A comparison of barrier type tunnel junction and point contact tunnel junction formed on the same highT
_c material | 10.1007/BF02845800 |
1991-05-01 | Analysis of efficiency of cryogenic systems having a thermosorption compressor | 10.1007/BF01148545 | |
1991-05-01 | Alloy KhN35VTYu has high values of σ_u, σ_0.2, and a_0.25 at normal and cryogenic temperatures after hardening at 1050°C for 3 h in air and aging at 700°C for 3–8 h. The alloy is not sensitive to stress concentration. Increasing the hardening temperature to 1200°C leads to a significant decrease in the values of σ_0.2 and a_0.25. | Mechanical properties of alloy KhN35VTYu at low temperatures | 10.1007/BF00775591 |
1991-05-01 | Single-cylinder piston pump with large discharge for cryogenic liquids | 10.1007/BF01148546 | |
1991-04-01 | Possible specific fields of application of hollow microgranules in cryogenic technology are examined. It is pointed out how a high degree of monodispersity of granules helps to improve the performance of different cryogenic systems. | Applicability of monodispersed technology in cryogenic technology | 10.1007/BF00872138 |
1991-04-01 | This paper investigates the level of cytosolic and synaptosomal forms of calcium activated neutral protease activities in the normal brain and their changes following a freezing lesion in the rabbit. From 1 to 24 hours post lesion we observe a progressive disappearing of the enzyme activities from the cytosolic compartment and concurrently their increase in the membranal fraction. These changes are likely to be due to a rise in intracellular calcium concentration, a well documented consequence of many cellular insults. The specific role of the activation of calpain activities in the pathophysiology of trauma is discussed, an enhancement of excitotoxic mechanisms is proposed. | Calcium-activated neutral protease activities in brain trauma | 10.1007/BF00965570 |
1991-04-01 | ROSETTA — the Comet Nucleus Sample Return mission — is one of the four Cornerstone missions to which ESA has committed itself in its approved Long-Term Programme Horizon 2000 . The mission is currently being studied in collaboration with NASA. The comet-nucleus samples that ROSETTA is to provide will allow us to study some of the most primitive material in the solar system and the physical and chemical processes that marked the beginning of the system 4.6 billion years ago. For ESA, ROSETTA is a new type of mission: one which will return a sample at cryogenic temperature, and where as much effort has to be spent on preparing the laboratory analysis on-ground as has to be invested in preparing the space segment with the sample acquisition and in situ documentation. As part of the preparation for this mission, ESA is now starting to consider Planetary Protection issues. | Comet nucleus sample return: Plans and capabilities | 10.1007/BF00178398 |
1991-03-01 | Choice of design of cryogenic vessels with minimal weight | 10.1007/BF01150087 | |
1991-02-01 | Static balancing of high-speed drives of miniature gas cryogenic machines | 10.1007/BF01147665 | |
1991-01-01 | Cryogenic cooling improves sensor performance in any spectral band. The high cost of achieving improved performance has led to a ten-year lifetime requirement, along with already stringent requirements for vibration, size, weight, power and temperature. The development of cryogenic refrigerators capable of meeting these requirements is a challenge that has not yet been met. Sorption refrigeration has the potential to meet this challenge. Recent advances in sorption cooler technology have resulted in cryocooler designs that offer competitive performance and long life. Current hardware development efforts are expected to lead to a near-term flight experiment. This paper reviews the development status of sorption coolers, sorption materials and component technologies. Anticipated future developments, including potential commercial applications, are also discussed. | An Overview of the Development of Sorption Refrigeration | 10.1007/978-1-4615-3368-9_41 |
1991-01-01 | A numerical model has been developed for simulating the unsteady behavior of a dewar for helium storage. The model includes the dynamic behavior of the vapor cooled shields, MLI insulation, and the effect of parallel conduction and radiation paths. An implicit finite difference program was developed to take into account the time dependent variation of the gas flow through the heat exchanger of each shield, the heat capacity of the shield material, the conductive heat transfer and radiative heat transfer in the system. Initial conditions can be input to any of the shields, the outside temperature, or pumping pressure. The physical parameters representing a 250 L helium dewar are used to test the model. The dewar is one for which considerable data exists on the temperatures of the shields as a function of time. The data also includes flow rate and liquid level information. It was taken over a period of months on a continuous basis. During the tests the dewar was pumped down to superfluid temperatures and held in that state for long periods of time. One of those tests is used to compare with the model results. The dynamic behavior of the shield temperatures was observed to have time constants of the order days. | A Model of the Unsteady Behavior of Long Duration Helium Dewar | 10.1007/978-1-4615-3368-9_71 |
1991-01-01 | By thermally-coupling the pressure transducer to the cryogenic vessel or transfer line, the measurement uncertainty can be significantly reduced as well as the heat leak associated with sensing lines extending to ambient temperatures. Temperature compensation algorithms are presented along with experimental results using piezoresistive pressure transducers which are operated at the cryogen temperature. Pressure measurements with accuracies better than 0.5% of full scale can be obtained with piezoresistive transducers at any temperature from 70 K up to 300 K using appropriate algorithms. The resulting reduction in heat leak minimizes the effects of Thermo-Acoustic-Oscillations (TAO) and reduces measurement uncertainty. Data is presented from testing with liquid nitrogen and liquid hydrogen as well as implementation considerations. | Temperature Compensation for Piezoresistive Pressure Transducers at Cryogenic Temperatures | 10.1007/978-1-4615-3368-9_80 |
1991-01-01 | In an effort to operate Fermilab’s Tevatron synchrotron at higher beam energies, plans exist to reduce the working temperature of the superconducting components. A proposed upgrade will utilize cold compressors as an addition to each satellite refrigerator, lowering the pressure of the 2-phase helium returning to the refrigerator system from the magnets. Coil temperatures as low as 3.9K are anticipated. Since initial tests were performed with CCI reciprocating compressors and turbo compressors from Creare, Inc. and IHI Co., Ltd., the scope of the upgrade has broadened such that these machines no longer meet the pressure ratio, throughput, and efficiency requirements. Therefore new cold compressor development has been funded. In parallel with the purchase of a new centrifugal machine, Fermilab has developed a reciprocating unit capable of meeting the new performance criteria. The development history and operating characteristics of this machine are presented. | Design, Construction, and Operation of a Two Cylinder Reciprocating Cold Compressor | 10.1007/978-1-4615-3368-9_4 |
1991-01-01 | In types Kh7G28 and Kh7G32 steels the carbon content must be limited to ∼0.06% since an increase in it to 0.2% leads to a sharp drop in plasticity at cryogenic temperatures. | Mechanical properties of types Kh7G28 and Kh7G32 steels | 10.1007/BF00775033 |
1991-01-01 | Space cryostats require safety components to protect the cryogenic system against overpressure. The CRISTA cryostat (Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere), which contains 725 1 supercritical helium, will have a three stage safety system. A cryogenic rupture disc mounted directly on the helium tank will be the ultimate safety component. For qualifying cryogenic rupture discs a low temperature test facility was developed. The batch qualification of the cryogenic rupture disc, which is of the reserve buckling type, shows a standard deviation comparable with that at ambient temperature. The design of the rupture disc as well as test program and test results of the successfully performed qualification are described. Furthermore design and performance of the low temperature test facility are treated. | Development of Cryogenic Rupture Discs for the Space Borne Crista Project | 10.1007/978-1-4615-3368-9_76 |
1991-01-01 | Neodymium and Er_3Ni powders were produced and examined as possible candidates for use as regenerator matrices in the regenerative heat exchanger of the Gifford-McMahon cycle refrigerator. In the case of Er_3Ni, crushed powders were brittle and angular in shape, molten salt produced spheres were heavily oxidized, and gas atomized powder had a low yield (3%) and a large fraction of hollow particles. Neodymium powder, which was produced by the rotating electrode method, was smooth and spherical in shape and had a high yield (15%) of solid particles. | Development of Neodymium and Er_3Ni Regenerator Materials | 10.1007/978-1-4615-3368-9_30 |
1991-01-01 | A centrifugal compressor for a completely lubricant free helium refrigeration system is now being developed using magnetic bearings. The compressor has four compression stages and each stage is independently driven by a 25-kW built-in motor at the speed of 100, 000 rpm. The inlet of the compressor is maintained at a temperature of 80 K during operation by liquid nitrogen, and the motors are also maintained at the same temperature. Since the rotor of the motor has been fabricated from dissimilar materials to have a one piece construction using the hot isostatic press (HIP) technique, it is expected that it will deform when exposed to cryogenic temperature. The peripheral speed of the motor rotor will reach 340 m/s during operation. The peripheral speed of the impeller at the first stage will reach 568 m/s. This report summarizes the investigation results when the system was operated at 100, 000 rpm using dummy impellers. | 80 K Centrifugal Compressor for Helium Refrigeration System | 10.1007/978-1-4615-3368-9_3 |
1991-01-01 | The Magnet Test Laboratory (MTL) Cryogenic System will be used to support prototype and production testing of dipole and quadropole magnets for the SSC. The MTL Cryogenic Control System must be capable of providing remote and unattended operation of the cryogenic system. This paper discusses some of the design considerations involved in the selection and design of a control system that will have changing requirements over time; and must eventually interface with the overall MTL control system for which the requirements have yet to be determined. | Control System Design Considerations for the SSC Magnet Test Laboratory Cryogenic System | 10.1007/978-1-4615-3746-5_82 |
1991-01-01 | For redundant miniature Stirling-cycle cryocoolers in space applications, the off-state heat conduction down the coldfinger of one cooler is a parasitic heat load on the other coolers. At JPL, a heat flow transducer specifically designed to measure this load has been developed, and measurements have been performed on the coldfinger of a British Aerospace 80 K Stirling cooler with the tip temperature ranging between 40 and 170 K. Measurements have also been made using a transient warmup technique, where the warmup rates of the coldtip under various applied heat loads are used to determine the static conduction load. There is a difference between the results of these two methods, and these differences are discussed with regard to the applicability of the transient warmup method to a nonoperating coldfinger. | Cold-Tip Off-State Conduction Loss of Miniature Stirling Cycle Cryocoolers | 10.1007/978-1-4615-3368-9_34 |
1991-01-01 | Magnetic rare earth intermetallic compounds have properties of great utility in the construction of cryocooler regenerators. The magnetocaloric effect observed in these materials is the basis for regenerative magnetic refrigeration, and large magnetic heat capacities have been used to enhance low temperature performance of Gifford-McMahon cryocoolers. Development of reliable rare earth intermetallic regenerators has been limited in large part by poor mechanical properties of these materials and their consequent breakdown in service. We report on a new method for producing well formed spherical powders from the melt in the 0.3–0.75 mm size range via a low pressure, low velocity jet atomization technique. The method is adaptable to a wide range of materials and is limited chiefly by compatibility of the melt with the tungsten crucible assembly. Initial results of particulation experiments with GdNi_2 and Er_3Ni are reported. | Production of Spherical Powders of Rare Earth Intermetallic Compounds for Use in Cryocooler Regenerators | 10.1007/978-1-4615-3368-9_28 |
1991-01-01 | The British Aerospace (BAe) 80 K Stirling Cycle Cooler is unique in the world as the only cooler in production for long-life space applications. The performance of one of these coolers was recently characterized at TRW. This paper reports on the test results and the parametric sensitivities for the measured cooler. Measured data included cooldown rates, heat sink temperature sensitivity, load line parametrics and static conduction losses. In addition, the accrued running hours of flexure bearing coolers at Oxford and TRW are summarized. | Thermal Characterization of the BAe 80K Stirling Cycle Cooler | 10.1007/978-1-4615-3368-9_38 |
1991-01-01 | The scintillation and ionization properties of liquid argon, krypton and xenon have been investigated by means of a small laboratory apparatus. The setup consists of a cryogenic system which has the capability of cooling any liquid from ambient down to liquid nitrogen temperature and of a pulsed 10 to 100 kV electron gun used as excitation source of the liquids. By changing the electron beam intensity and the acceleration voltage, a total energy ranging from 1 MeV to 100 GeV per pulse can be deposited in the liquid (about a tenth of a liter). A forced circulation system allows continuous purification and recondensation of the evaporated gas. A description of the various purification methods, of the used materials and of the adopted cleaning procedure are given. The achieved degree of purity of liquid argon, krypton and xenon permitted an electron lifetime ≥ 200 μs corresponding to an oxygen equivalent contamination of less than 10 ppb. Measurements of the temperature uniformity of the liquid and its influence on the light scattering are presented. A scintillation yield in liquid xenon (at a wavelength of 175 nm) of 26×10^6 photons/GeV was measured. | A Cryogenic Apparatus with On-Line Purification System for Scintillation and Ionization Studies in Noble Liquids | 10.1007/978-1-4615-3368-9_46 |
1991-01-01 | The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquistion or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. In this study slosh wave excitation induced by the resettling flow field activated by 1.0 Hz medium frequency impulsive reverse gravity acceleration during the course of liquid fluid reorientation with the initiation of geyser for liquid filled levels of 30, 50, and 80% have been studied. Characteristics of slosh waves with various frequencies excited are discussed. | Slosh Wave Excitation Due to Cryogenic Liquid Reorientation in Space-Based Propulsion System | 10.1007/978-1-4615-3368-9_64 |
1991-01-01 | In reviewing the large variety of possibilities offered by superconductivity in the small scale applications, it is often neglected the important role which can be played by superconducting tunnel junctions as radiation detectors in physics and astrophysics. The growing interest of such devices in this context lies in the perspective of outstanding performances, partially already demonstrated, in the high energy spectrometry, in the fast discrimination, in the spatial resolution. In this article we shall confine our attention to the first topic. As far as the drawbacks of cryogenic requirements are concerned, it should be point out that conventional semiconductor junction detectors require liquid nitrogen not only during operation but also for storage since those devices are not thermally cyclable. In the other hand helium cryostat technology is dramatically improving and, if confined to a temperature of the order of a few degrees (1–4 K), cryocoolers extremely compact within today can provide the necessary cryogenic environment for space based equipment. | Superconducting Tunnel Junctions as Nuclear Particle Detectors | 10.1007/978-1-4615-3852-3_11 |
1991-01-01 | High-strength nonmagnetic stainless steel suitable for cryogenic services, mainly as material of collars and beam tubes of superconducting super collider (SSC) magnets, was developed using 10Mn-19Cr-6Ni steel as the base material. The carbon content should preferably be high for strength, but if it is too high, carbide precipitates and toughness is impaired. Permeability at a cryogenic temperature shows good correspondence with Néel temperature. Although Ni reduction and Mn addition are effective for nonmagnetization, excessive Mn decreases the coefficient of thermal expansion. The precipitation of δ -Fe in the spot welds should be prevented to nonmagnetize, and for this purpose, composition adjustment is necessary so that the value of δ -Fe calculated using Hull’s equation will be below zero. Based on the results in this study, 0.09C-10Mn-19Cr-6Ni-0.35N steel was selected as a steel of optimum composition, and was trial-produced by a commercial process. | Development of High-Strength Nonmagnetic Stainless Steel for the SSC | 10.1007/978-1-4615-3746-5_10 |
1991-01-01 | This proposal describes the research and development required, and the subsequent fabrication of, a system capable of making integrated magnetic multipole measurements of cryogenic 40-mm-bore SSC dipole magnets utilizing a cryogenic probe. Our experience and some preliminary studies indicate that it is highly unlikely that a 16-meter-long probe can be fabricated that will have a twist below several milliradians at cryogenic temperatures. We would anticipate a twist of several milliradians just as a result of cooldown stresses. Consequently, this proposal describes a segmented 16-meter-long probe, for which we intend to calibrate the phase of each segment to within 0.1 milliradians. The data for all segments will be acquired simultaneously, and integrated data will be generated from the vector sums of the individual segments. The calibration techniques and instrumentation required to implement this system will be described. The duration of an integral measurement at one current is expected to be under 10 seconds. The system is based on an extrapolation of the techniques used at LBL to measure cryogenic 1-meter models of SSC magnets with a cryogenic probe. It should be noted that the expansion of the dipole bore from 40 to 50 mm may make a warm-finger device practical at a cost of approximately one quarter of the cryogenic probe. A warm quadruple measurement system can be based upon the same principles. | Proposal for a Cryogenic Magnetic Field Measurement System for SSC Dipole Magnets | 10.1007/978-1-4615-3746-5_24 |
1991-01-01 | Insulation and structural supports made from organic-matrix composites for superconducting magnet applications must withstand high mechanical loads, cryogenic temperatures, and high levels of nuclear radiation for long periods of time. Review of the studies of radiation damage in organic materials over the past three decades shows that most tests used poorly defined radiation sources at room temperature. The literature also indicates that radiation damage in organic insulators depends on the type of radiation, the temperature of irradiation, and whether the material is under stress during irradiation. The implications of these results are discussed, and the importance of testing under simulated operating conditions is emphasized. Current research is summarized. | Superconducting Magnet Insulators: Radiation-Induced Damage and Effects | 10.1007/978-1-4615-3746-5_9 |
1991-01-01 | The focal plane of the AXAF X-Ray Spectrometer requires an operating temperature of 0.1 K with a mission lifetime of 5 years. This demanding task is accomplished with a hybrid cryogenic subsystem consisting of mechanical coolers, a superfluid helium dewar and an adiabatic demagnetization refrigerator. By using mechanical coolers to remove heat from the dewar outer vapor-cooled shield, a 5-year lifetime is achievable with only a 483-liter tank. This approach takes advantage of flight-proven, high-performance dewar technology and recent success in the development of split, Stirling-cycle mechanical coolers. Although the dewar design principles are similar to those used previously, parasitic heat flow is reduced to a new level by an optimized tension strap support system and careful attention to insulation system details. The benefit of the mechanical coolers is maximized by dewar interface design features that minimize parasitic heating and thermal impedance of the coupling. The dewar design and thermal performance analysis are discussed. Helium lifetime sensitivities and the effects of mechanical cooler failures are predicted. | 5-Year Lifetime Hybrid Superfluid Helium Dewar for the AXAF X-Ray Spectrometer (XRS) | 10.1007/978-1-4615-3368-9_68 |
1991-01-01 | Interlaminar shear strength is one of the most important properties of laminated composites, not only for fusion magnets, but for many other applications. Several processes that have been developed over the years to improve interlaminar shear strength include 3-D woven orthogonal fabrics, multiple warp weaving, stitch bonding of multi-layers of 2-D fabrics, and needle punching of non-woven and woven fabrics. | Development of 3-D Composites | 10.1007/978-1-4757-9232-4_16 |
1991-01-01 | We have designed and tested a compact heat switch that has a simple design and a very large ON/OFF ratio. The design uses concentric cylinders of copper that can be fabricated with higher precision and with thinner web thickness than other designs. It is assembled with a technique that carefully controls the narrow gap between adjacent segments. These features allow a very large surface area for conduction to be fitted into a small volume. The conduction medium is liquid or gaseous ^3He which is put into or taken out of the switch by a small nearby charcoal pump in order to avoid an external mechanical pump and a long pump line. Measurements of its performance down to 1 K show an ON/OFF conduction ratio of ~4000. | A ^3He-Gap Heat Switch for Use Below 2 K in Zero G | 10.1007/978-1-4615-3368-9_20 |
1991-01-01 | This study is concerned with the cryogenic preservation of intrafibrillar apatite distribution in type I collagen of turkey leg tendons. Cryogenic specimen preparations by the rapid freezing of nonfixed and noncryoprotected leg tendons were performed by two different protocols: (1) low temperature substitution, fixation and staining followed by low temperature embedment; (2) frozen hydrated and air-dried cryosections were examined with the electron microscope at −165°C and normal operating temperatures, respectively. These protocols revealed the axial periodicity for mineralized collagen to have a 65–69 nm range with a mean value of 67 nm as determined by point-to-point measurements. Mineral distributions and specific apatite visualization were examined by electron microscopic imaging in bright field and selected-area dark field, respectively. Fourier filtered images and image subtraction were used to separate the axial repeating and nonrepeating intrafibrillar mineral domains of collagen. The removal of these axial repeats revealed an underlying and integrated mineral distribution, demonstrating that apatite is not confined to axial periodicities such as those of the gap zone. | Image analysis of collagen-associated mineral distribution in cryogenically prepared turkey leg tendons | 10.1007/BF02555796 |
1991-01-01 | Cryogenic liquid transfer systems have proven to be the method of choice for most cooling applications for spectrophotometric studies. The application of such methods to biological systems requires a few modifications. The cryogenic systems can operate in any position but most liquid samples must be placed in cuvettes in the vertical position from the top. Temperature control from 77K to room temperature can be accomplished using a liquid nitrogen supply, a 20 ohm strip heater, a silicon diode transducer and an automatic temperature controller. Various designs are presented with limited test data, where standard cuvettes are mounted on OHFC copper in a vacuum shroud necessary for the low temperature studies. Some suggested approaches to expanding the versatility of the systems are given. A unique application is the use of a vacuum cooled sample plate and injecting the test sample into the chamber through a rubber septum giving instantaneous cooling of the sample. | Cryogenic Cooling of Biological Samples for Electron and Optical Microscopy | 10.1007/978-1-4757-9232-4_10 |
1991-01-01 | This paper opens with a brief review of cryogenic wind tunnels and their use for high Reynolds number testing. Emphasis is on operational and aerodynamic testing experience in the NASA Langley 0.3-m Transonic Cryogenic Tunnel (TCT). Since we built the 0.3-m TCT in 1973, it has logged over 8000 hours of running at cryogenic temperatures. We use the 0.3-m TCT for aerodynamic testing and to develop test techniques for cryogenic tunnels. Areas briefly covered in this paper include development of test techniques and aerodynamic testing in cryogenic tunnels. Based on our experience, we recommend using advanced testing techniques to increase the value of cryogenic tunnels to the research community. These include adaptive wall test sections , using solid but flexible top and bottom walls, magnetic suspension and balance systems and non-intrusive laser techniques. . | Cryogenic Wind Tunnels | 10.1007/978-1-4612-3108-0_2 |
1991-01-01 | The intended use of Stirling-cycle cryocoolers to cool infrared and submilli-meter imaging instruments on 5- to 10-year missions brings with it major challenges to cryocooler development. In particular, the voice-coil driven cryocoolers need to be electromagnetically compatible with the host instrument’s detectors as well as with neighboring instruments; specifically the cryocoolers must not generate levels of interference that degrade performance or cause malfunction of the cooled imaging detectors, payload instruments, or host spacecraft. To support the design and successful operation of NASA space instruments, the Jet Propulsion Laboratory (JPL) has an ongoing extensive cryocooler characterization, test and analysis program to identify cryocoolers capable of meeting the stringent requirements. The characterization activity focuses on sensitive performance measuring techniques for quantification of thermal performance, vibration, electromagnetic compatibility (EMC), and life-limiting reliability degradation mechanisms. This paper describes the EMC measurements of a British Aerospace (BAe) 80-K Stirling-cycle cooler. The measurements, performed in the JPL EMC test facility, include DC magnetic field characterization, radiated magnetic and electric field emissions, and conducted emissions on the internal lines between the cooler electronics and the cooler. The measurements conform to both the MIL-STD-461C specifications as well as to the specifications for the NASA Earth Observing System (Eos). | Electromagnetic Compatibility Characterization of a BAe Stirling-Cycle Cryocooler for Space Application | 10.1007/978-1-4615-3368-9_35 |
1991-01-01 | The cryogenic operation of NASA’s Cosmic Background Explorer (COBE) ended on September 21, 1990, with the depletion of the liquid helium cryogen. The COBE had successfully completed more than 10 months of dewar and instrument operation. We report on the cryogenic performance of the COBE dewar and of the two cryogenic instruments throughout the mission lifetime. We discuss the steady state dewar performance, and the dewar and instrument response to a variety of transient thermal phenomena, including external radiation (from the earth and the sun) and instrument power variation. We present the effectiveness of using approximate mass gauging techniques in determining the liquid helium content. Finally we discuss the dewar behavior during the depletion of the helium, and the expected thermal performance of the dewar cryogen tank and the cryogenic instruments as they approach final thermal equilibrium. | Final Cryogenic Performance Report for the NASA Cosmic Background Explorer (COBE) | 10.1007/978-1-4615-3368-9_51 |
1991-01-01 | The basic requirements and operating features of the collider cryogenic system have already been described in other publications.^1, 2, 3 The general arrangement of the refrigeration plant and its subsystems is presented, and the issue of how to provide redundancy in the cryogenic system is addressed, and some of the basic features of the refrigeration plants are described. The collider cryogenic system design is not final yet, and this report only reflects the direction and current status of the cryogenic system design. | Refrigeration Plants for the SSCL | 10.1007/978-1-4615-3746-5_76 |
1990-10-01 | Investigation of thermoelastic stresses in shells of cryogenic tanks by the finite difference method | 10.1007/BF01147994 | |
1990-09-01 | Degreasing cryogenic equipment with aqueous detergent solutions containing new constituents | 10.1007/BF01155771 | |
1990-06-01 | We report the optical absorption spectra of azurin ( Pseudomonas aeruginosa ) in the temperature range 290-20 K. The samples used are protein aqueous solutions containing 65% (by Vol.) glycerol as cryoprotectant. The measured spectra are deconvoluted in gaussian components and the temperature dependence of the zeroth, first and second moment of the observed bands is analyzed using the harmonic Franck-Condon approximation for the coupling between electronic transitions and nuclear vibrations. The analysis provides information on the stereodynamic properties of the active site of this protein. The possible functional relevance of these results is also suggested. | Dynamic properties of the active site of azurin studied by the temperature dependence of the optical spectrum | 10.1007/BF01179507 |
1990-05-01 | Hydrostatic pressing in making components for cryogenic pipelines | 10.1007/BF01149680 | |
1990-02-01 | Cooling by a cryogenic helium system | 10.1007/BF01155924 | |
1990-01-01 | The film-condensation heat transfer coefficient of normal hydrogen (25% para-hydrogen) was determined. In this investigation, hydrogen was condensed on the wall of a vertical copper tube (15 mm i.d., 70 mm long) under the steady-state condition. From the experimental results, the condensing heat transfer coefficient for saturated hydrogen vapors was shown to be in fairly good agreement with that predicted using Nusselt’s theory including the case in which the temperature difference across the condensate film was small, on the order of one Kelvin. | An Experimental Investigation of Film-Condensation Heat Transfer of Hydrogen in a Vertical Tube | 10.1007/978-1-4613-0639-9_50 |
1990-01-01 | LEP, the large electron-positron collider built at CERN, is now starting to operate. Its four experimental areas, installed in large caverns down to 150 m below ground, are equipped with two types of superconducting magnet, namely large detector solenoids and “low-beta” focusing quadrupoles, operated from common ancillary cryogenic systems. The large size, geographical dispersion, underground implantation and operating environment of LEP have set unusual constraints and dictated specific choices for the four helium cryogenic plants, distribution systems, magnet cryostats, and process operation, particularly as concerns operational flexibility, reliability, safety, remote control and automation. After describing the main design features of the cryogenic systems, we report on their installation, commissioning and first experience of operation. | Helium Cryogenics at the Lep Experimental Areas | 10.1007/978-1-4613-0639-9_108 |
1990-01-01 | The cryogenic system for the TRISTAN superconducting RF cavities (SCC) was constructed and commissioned successfully. Sixteen 5-cell SCC in 8 cryostats were installed in the TRISTAN electron-positron collider at KEK. The cryostats were connected to the helium refrigerator (4 kW at 4.4 K) through a helium transfer line (total length about 330 m) and cooled by pool boiling liquid helium. It took about 3 days to cool down the 16 SCC, a total cold mass of about 8000 kg, from room temperature to liquid helium temperature and 1 day to fill the liquid helium up to about 830 L in each SCC cryostat. The liquid helium level and the pressure fluctuation due to the RF losses in the cryostats were automatically controlled by liquid supply valves and the compensation heaters in the cryostats respectively. The performance test, the present equipment status of the cryogenic system and the six months of operational experience are described. | Cryogenic System for the Tristan Superconducting RF Cavities: Performance Test and Present Status | 10.1007/978-1-4613-0639-9_112 |
1990-01-01 | Estimating the cost of cryogenic equipment at the design stage | 10.1007/BF01148153 | |
1990-01-01 | Cold silicon piezoresistive strain gauge pressure sensors have several advantages over the conventional pressure measuring devices/systems used in cryogenics. A cryogenic pressure sensor calibration facility has been set up at Pressure Systems, Inc. for calibrating cryogenic pressure sensors in the temperature range 1.5 – 400 K. This paper presents a brief review of this calibration facility together with the low temperature characteristics of the cryogenic piezoresistive pressure sensors. The pressure sensors calibrated so far include 202 k Pa absolute (30 psia), 202 k Pa differential (30 psid) and 1013 k Pa absolute (150 psia) range devices. These calibrations are linear and are repeatable to within +/− 0.1% and +/− 0.5% full scale outputs for 202 k Pa and 1013 k Pa range pressure sensors respectively. | Cryogenic Pressure Sensor Calibration Facility | 10.1007/978-1-4613-0639-9_186 |
1990-01-01 | The reaction centre components of Photosystem 2 are bound to a complex consisting of the D1, D2 and Cytochrome b559 polypeptides. This was shown to be photochemically active by the photoaccumulation of reduced pheophytin (1). The characteristic spin polarised triplet esr signal has also been detected in this preparation (2). The complex, however, does not contain bound quinone (1). | ESR Characterisation of the Photosystem 2 Reaction Centre | 10.1007/978-94-009-0511-5_91 |
1990-01-01 | The performance of pulse tube coolers is being studied in order to determine their suitability for development into long life space coolers. Coolers based on the pulse tube phenomenon appear to be attractive for long life space application because of their inherent simplicity. Single-stage and two-stage pulse tube test coolers have been designed and tested. In these early tests a single stage cooler has achieved a low temperature of 53K while rejecting heat above 3O0K. An unoptimized two-stage cooler has reached 26K while rejecting heat above 30OK. Performance measurements for the coolers is presented. | Pulse Tube Refrigerator Performance | 10.1007/978-1-4613-0639-9_144 |
1990-01-01 | The development of superconducting (SC) dipole magnets for the UNK rests upon the cold-iron design. The support system of the helium vessel of a SC UNK dipole consists of four vertical suspensions and four horizontal extension rods placed in two cross sections across the magnet length and also of two anchor extension rods fixing the centre of the helium vessel in thermal cycles. To reduce the value of thermal radiation, use is made of the nitrogen shield fixed with vertical suspensions and of a multilayer insulation put onto the nitrogen shield and helium vessel. The heat load and the heat leak through the supports to the helium vessel of the SC UNK dipole have been studied. The techniques applied to study these heat loads are presented. The measured value of the heat load is 5–6 W, 1 W falls at the supports. The experimental results obtained are compared with the calculational estimates and feasibilities for a further reduction of a heat load to the helium vessel of the magnet are discussed. | Heat Load on a Superconducting UNK Dipole | 10.1007/978-94-009-0769-0_17 |
1990-01-01 | Gifford-McMahon (GM) cycle cryocooler operating at about 4 K has been developed. The most important component of this cryocooler is a regenerator. This paper describes effects which regenerator materials, porosity of regenerators, and configurations of regenerators have on no-load temperatures and net cooling capacities. It was found that no-load temperature of a regenerator used GdRh is only 1 K lower than that of a regenerator used Pb. | Effect of Regenerator on Gifford-Mcmahon Cycle Cryocooler Operating at About 4 K | 10.1007/978-1-4613-0639-9_151 |
1990-01-01 | Determination of the optimum refrigeration plant arrangement for the SSC will require consideration of many factors. Starting from the latest information on the SSC cooling requirements and the given number of cooling sectors, an arrangement is proposed which will provide an optimum combination of low investment cost, low power consumption and simplicity of operation, while providing an adequate degree of redundancy. | A Refrigeration Plant Concept for the SSC | 10.1007/978-1-4615-3728-1_17 |
1990-01-01 | Serrated deformation behavior at very low temperatures such as AK has been studied by many researchers. Details of this discontinuous unstable deformation, however, have remained unclarified, especially the deformation behavior under constant loading rate conditions which has been examined by only a few researchers. The objective of the present paper is to investigate the deformation under constant loading rate conditions, especially the effects of stiffness, that is, back-stress due to the constraint of surrounding structures on the rapid discontinuous deformation. The onset stress of the discontinuous deformation was lower under constant loading rate conditions than under constant cross-head velocity conditions. It was shown by computer simulation that the amount of rapid deformation under constant loading rate conditions could be effectively decreased and the onset of the first discontinuous deformation delayed by small back-stress. | Effect of Stiffness on Serrated Deformation at Very Low Temperatures Under Constant Loading Rate Conditions and its Computer Simulation | 10.1007/978-94-009-0769-0_127 |
1990-01-01 | Piston expansion engines for the final cooling stage of cryogenic helium installations | 10.1007/BF01148157 | |
1990-01-01 | The fabrication of a large series of magnet development models, 70 pre-production models (beginning in 1993), as well as many thousands of production magnets requires the early construction of a Magnet Test Laboratory (MTL) to provide the testing capability for design, quality control and acceptance testing. The exact testing protocol is still in planning, although outlines of the magnet test program are sufficiently well understood to permit development of the performance and fabrication specifications for the MTL. | The Cryogenic System for the SSC Magnet Test Laboratory | 10.1007/978-1-4615-3728-1_19 |
1990-01-01 | A cryogenic penetration has been developed to facilitate the use of cryogenic liquids within EMI / RFI shielded enclosures. The device enables the placement of a storage dewar outside the enclosure. The cryogen can then be transferred through the wall of the shielded enclosure and on to the use point. There are three distinct benefits of this device: 1. The pressure vessel is removed from an environment that is potentially very confined and has a difficult egress. 2. The difficult and potentially hazardous task of moving the dewar into and out of the enclosure is eliminated. 3. The device allows the cryogen to be “on tap” at the use point without the need for chilling siphons or venting gas within the enclosure. The penetration consists of a vacuum jacketed transfer line with an electrically non-conductive section. The transfer line is contained within a wave guide for flange mounting through the wall or ceiling of the enclosure. The device has been proven in use with both Liquid Helium and Liquid Nitrogen and is compatible with other cryogens as well. | A Cryogenic Penetration for Electromagnetic Interference Shielded Rooms | 10.1007/978-1-4613-0639-9_217 |
1990-01-01 | Investigation of the hydraulic characteristics of cryogenic heat exchanger coils | 10.1007/BF01148156 | |
1990-01-01 | The cryogenic system for two 508 MHz 5-cell superconducting RF cavities in two cryostats was designed and constructed in the TRISTAN accumulation ring at KEK for the reliability study of the SCC and the cryogenic system. Two superconducting cavities, mounted in parallel cryostats and having a total cold mass of about 2000 kg, were cooled down from room temperature and refigerated by pool boiling liquid helium. Various beam tests were performed. | Cryogenic System for the Tristan-Ar Superconducting RF Cavities | 10.1007/978-1-4613-0639-9_111 |
1990-01-01 | The major advantages of liquid nitrogen and neon cooled heat intercepts over those cooled with helium gas are that nitrogen and neon boiling at constant temperatures holds the shield temperatures constant and these cryogens can be stored for long time operation without refrigeration. The major problem with helium cooling is that the shield starts to warm up immediately whenever refrigeration is interrupted because there is no reserve. The purpose of this work is to develop a procedure to minimize the total refrigerator power input requirement by locating the liquid nitrogen and neon cooled heat intercepts both on supports and in multilayer insulation. The optimization method is based on the Lagrange multipliers method and obtained results are normalized. | Minimization of Total Refrigeration Power of Liquid Neon and Nitrogen Cooled Intercepts for SMES Magnets | 10.1007/978-1-4613-0639-9_100 |
1990-01-01 | The behavior of liquid helium in porous materials continues to be of interest for the purpose of helium fluid management in a weightless environment. The present paper reports on measurements of He II pressure drop across two porous SiO_2 ceramic filter materials. These materials vary only in porosity, having values of 0.94 and 0.96. The average fiber diameter in both cases is approximately 5 µ m. The experiment consists of a glass tube containing a piece of this sponge in one end. The tube is rapidly displaced downward in a bath of helium and the liquid levels allowed to equilibrate over time producing variable velocities up to 10 cm/s. The results are compared with those previously obtained using fine mesh screens. Good qualitative agreement is observed for turbulent flow; however, the behavior in the laminar flow regime is not fully understood. | Pressure Drop of He II Flow Through a Porous Media | 10.1007/978-1-4613-0639-9_23 |
1990-01-01 | Fracture toughness tests were made on 304 stainless steel at 4 K, varying the precracking temperature (300 K and 77 K) and magnetic field (0 T and 8 T). The obtained results are discussed, taking the TRIP* effect and the promotion of martensite formation in magnetic fields into consideration. Fracture toughness values (J_IC) of 43 — 62 kJ/m^2 and tearing modulus values (T_mat) of 11 — 20 were obtained under various test conditions. The highest values of J_IC and T_mat were obtained for cases in which a remarkable TRIP effect was expected. Low values of T_mat were obtained in cases of applying a magnetic field (8 T). The acceleration of martensite formation in the magnetic field might be considered to result in such low values of T_mat in these cases. | Fracture Toughness of 304 Stainless Steel in High Magnetic Fields at Cryogenic Temperature | 10.1007/978-94-009-0769-0_119 |
1990-01-01 | LMSC’s Super Fluid Helium Tanker Study, J. Wohl, T. Nast, LMSC, Sunnyvale, CA 94089 — A Conceptual Study for a Superfluid Helium Tanker (SFHT), to replenish AXAF, SIRTF, ASTROMAG, and other Superfluid Helium users on orbit was undertaken for NASA Johnson Space Center. | A Conceptual Study for a Superfluid Helium Tanker (SFHT) | 10.1007/978-1-4613-0639-9_41 |
1990-01-01 | We have designed a system for the COBE flight dewar to measure its liquid helium fill. We apply a small known amount of heat to the helium tank and monitor the temperature rise in the liquid and the tank. Working with a detailed thermal model of the tank and liquid we can determine the amount of liquid present. COBE uses a 117 mW, 7 mA heater to warm the helium. It is planned to use the mass gauging system only after the projected midpoint of the mission, after one full sky survey. The system is optimized for use with 50–75 liters of helium (≈8–12% of the cryogen tank volume). Ground testing of the system in a one gravity environment is difficult, but from tests conducted so far we estimate an on-orbit temperature rise of ≈2.5mK/min. A similar system is planned for the S uperfluid H elium O n- O rbit T ransfer (SHOOT), a Shuttle-based experiment. The SHOOT’s specific requirements call for a high power pulse heater, applying 40 W for approximately 20 seconds. | A Calorimetric Mass Gauge System for the Cosmic Background Explorer (Cobe) | 10.1007/978-1-4613-0639-9_201 |
1990-01-01 | The results of tests performed on a recently developed reusable cryogenic seal are reported. The seal is fabricated entirely from metal and uses an indium alloy as a sealant. The seal has been successfully tested at temperatures ranging from 1.6 K to 416 K, and at pressures in excess of 3 MPa. Leak-tight joints were achieved at all conditions tested, including those in super-fluid helium. Tests also demonstrated the seal’s ability to withstand thermal cycling, bending moments, and vibration. | An All-Metal, Reusable, Cryogenic Seal | 10.1007/978-1-4613-0639-9_98 |
1990-01-01 | Rare Gases: Krypton, Neon, Xenon | 10.1007/978-1-4613-0673-3_50 | |
1990-01-01 | The feasibility of a passive quench protection system for the Superconducting Supercollider (SSC) main ring magnets depends on the radiation resistance and reliability of the diodes used as current bypass elements. These diodes would be located inside the magnet cryostat, subjecting them to liquid helium temperature and a relatively high radiation flux. Experimental and theoretical efforts have identified a commercially available diode which appears to be capable of surviving the cryogenic temperature and radiation environment of the accelerator. High current IV measurements indicate that the usable lifetime of this diode, based on an estimate of the peak junction temperature during a quench pulse, is an order of magnitude greater then than the expected lifetime of the SSC itself. However, an unexpected relationship was discovered between the diode turn-on voltage at 5 K and the most recent reverse voltage or temperature excursion. This turn-on voltage as a function of radiation exposure appears to be erratic and indicates a need for further investigation. | Studies of Cold Protection Diodes | 10.1007/978-1-4615-3728-1_3 |
1990-01-01 | Reciprocating and centrifugal cold helium compressors have been incorporated into part of the Tevatron satellite refrigeration system on a test basis. Results to be presented include compressor performance and overall system behavior under steady state and upset conditions. The effects on quench current of reductions in magnet temperature are included for one sector (a sixth) of the Tevatron. The results of these tests will determine the effectiveness of adding cold compressors to all 24 satellite refrigerators, allowing for Tevatron beam energy increases up to perhaps 1 TeV. Also described are specific test results from individual machines from CCI, Inc., Creare, Inc., and IHI Co., Ltd. | Trial Operation of Cold Compressors in Fermilab Satellite Refrigerators | 10.1007/978-1-4613-0639-9_123 |
1990-01-01 | The multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film fabricated in the form of blankets and installed as blankets to the 4.5K cold mass and the 20K and 80K thermal radiation shields. Approximately 40,000 MLI blankets will be required in the 10,000 cryogenic devices comprising the SSC accelerator. Each blanket is nearly 17 meters long and 1.8 meters wide. This paper reports the blanket design, an apparatus, and the fabrication method used to mass produce pre-fabricated MLI blankets. Incorporated in the blanket design are techniques which automate quality control during installation of the MLI blankets in the SSC cryostat. The apparatus and blanket fabrication method insure consistency in the mass produced blankets by providing positive control of the dimensional parameters which contribute to the thermal performance of the MLI blanket. By virtue of the fabrication process, the MLI blankets have inherent features of dimensional stability, three-dimensional uniformity, controlled layer density, layer-to-layer registration, interlayer cleanliness, and inter layer material to accommodate thermal contraction differences. | A Blanket Design, Apparatus, and Fabrication Techniques for the Mass Production of Multilayer Insulation Blankets for the Superconducting Super Collider | 10.1007/978-1-4613-0639-9_60 |
1990-01-01 | We have developed a self-contained, recyclable ^3He refrigerator suitable for use in space. The refrigerator is compact, has no moving parts, and requires only electrical connections and thermal contact in order to operate from a 2 K cold stage. A charcoal adsorption pump is used to efficiently condense and cool the ^3He. Sintered copper confines the ^3He to the evaporator in zero-gravity and, in fact, allows the refrigerator to operate upside-down in the laboratory. Mounted on a 2 K cold stage, the refrigerator provides 100 microwatts of cooling power at 346 mK, with a 7 hour hold time. On a 1.5 K cold stage, the lowest temperature achieved is 277 mK. The refrigerator has been vibration tested at 7.5 G amplitude from 30 to 400 Hz and 15 G amplitude from 400 to 2000 Hz. It will be flown in August, 1989, as part of a sounding rocket payload designed to measure the spectrum of the cosmic submillimeter background. A similar refrigerator suitable for orbital applications, which is able to condense ^3He in zero-gravity and which has a 2 week hold time, is currently under development. | A Rocket-Borne ^3He Refrigerator | 10.1007/978-1-4613-0639-9_172 |
1990-01-01 | Accidents involving compressed gases can be spectacular. One classic case, which was reported in the May 1969 Chemical Section Newsletter of the National Safety Council involved a cylinder of carbon dioxide with a faulty valve. It illustrates the incredible power that is stored in a cylinder, and points out that compressed gas cylinders must be treated with respect. | Handling Compressed Gases | 10.1007/978-1-4612-3320-6_18 |
1990-01-01 | Tensile properties, Charpy absorbed energy, and fracture toughness at room temperature, 77 K, and 4 K were determined for unalloyed titanium and titanium alloys. The titanium alloys with reduced content of oxygen and iron showed an excellent combination of high yield strength and high toughness at 4 K. Fracture behavior at cryogenic temperatures is also discussed. Fracture mode transition at low temperature was observed for higher oxygen unalloyed titanium and b.c.c. type titanium alloys. High cycle fatigue data were also determined at 4 K for some titanium alloys. Sub-surface fatigue crack initiation prevailed at lower cyclic stress and influenced the longer life property. | Fatigue and Fracture of Ti Alloys at Cryogenic Temperatures | 10.1007/978-94-009-0769-0_130 |
1990-01-01 | This paper reports on an experimental study into gas spring heat transfer in reciprocating machinery and its effect on these machines at cryogenic temperatures. A closed volume piston-cylinder apparatus was used to measure gas spring heat transfer under a variety of conditions at room temperature and at cryogenic temperatures. Experimental results were expressed in terms of nondimensional parameters and reduced to Fourier series coefficients for compactness, ease of use and mathematical manipulation. The results showed that gas spring heat transfer was primarily affected by the piston cycle frequency and the thermal diffusivity of the working gas. This heat transfer is potentially detrimental for room temperature reciprocators and for reciprocators operating near 77 K. Higher cycle frequencies at these temperatures would help reduce the gas spring losses. For temperatures near 10 K, the effects of gas spring heat transfer were found to be small because of the large density and low thermal conductivity of the gas. | An Experimental Study of Gas Spring Heat Transfer in Reciprocating Cryogenic Machinery | 10.1007/978-1-4613-0639-9_55 |
1990-01-01 | Oxygen | 10.1007/978-1-4613-0673-3_47 |
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