Cryogenic Facility Research Articles

Monochromator-based cryogenic radiometry at the NRC

A facility is being set up at the National Research Council of Canada for the monochromator-based spectral calibration of transfer standard radiometers using a cryogenic absolute radiometer. General design features and target performance of the new apparatus are discussed. The sources of error inherent to detector calibrations performed using monochromator-based sources are analysed in some detail, with special attention devoted to bandwidth errors, polarization effects and the effect of the angular subtense of the beam. Some detector effects, such as spatial uniformity and temperature dependence, are also discussed. A status report is given on the development of the new cryogenic radiometer facility.

Buffeting tests in a cryogenic windtunnel

SummaryMeasurements of wing buffeting, using root strain gauges, were made in the Nasa Langley 0-3 m cryogenic windtunnel to refine techniques which will be used in larger cryogenic facilities such as the United States National Transonic Facility (NTF) and the European Transonic Windtunnel (ETW). The questions addressed included the relative importance variations in frequency parameter and Reynolds number, the choice of model material (considering both stiffness and damping) and the effects of static aeroelastic distortion.The main series of tests was made on three half models of slender 65° delta wings with a sharp leading edge. The three delta wings had the same planform but widely differing bending stiffnesses and frequencies (obtained by varying both the material and the thickness of the wings). It was known that the steady flow on this configuration would be insensitive to variations in Reynolds number. On this wing at vortex breakdown the spectrum of the unsteady excitation is unusual, having a sharp peak at particular frequency parameter.Additional tests were made on one unswept half-wing of aspect ratio 1·5 with an NPL 9510 aerofoil section, known to be sensitive to variations in Reynolds number at transonic speeds. The test Mach numbers were M = 0·21 and 0·35 for the delta wings and to M = 0·30 for the unswept wing. On this wing the unsteady excitation spectrum is fairly flat (as on most wings). Hence correct representation of the frequency parameter is not particularly important.

Computer-aided system for cryogenic research facilities

A computer-aided system is developed for the more effective choice and optimization of the design and manufacturing technologies of the superconductor for the magnet system of the International Thermonuclear Experimental Reactor (ITER) with the aim to ensure the superconductor certification. The computer-aided system provides acquisition, processing, storage and display of data describing the proceeding tests, the detection of any parameter deviations and their analysis. Besides, it generates commands for the equipment switch off in emergency situations.

Superconducting super collider (SSC) collider dipole magnet (CDM) cold test stand integration and performance

Integration of the General Dynamics specified CDM cold test stand, including 10k ampere DC power supplies, high and low speed data acquisition systems, cryogenic facility, cryogenic distribution and end cans, coil protection system, vacuum leak test equipment and test stand controller is discussed. This paper addresses the lessons learned from the integration of these various equipment items. A description of systems is presented. Definition of the hardware and software systems and the interface to the CDM is included. >

Cryogenic benches for superfluid helium testing of full-scale prototype superconducting magnetsfor the CERN LHC project

The Large Hadron Collider (LHC) project at CERN will make massive use ofhigh-field superconducting magnets, operating below 1.9 K in pressurized superfluid helium. Reception testing of these magnets requires dedicated cryogenic facilities, consisting of an array of single-magnet test benches fed from a common large-capacity refrigeration system. Following installation and commissioning of general. cryogenic infrastructure, we have designed and constructed two such cryogenic benches, and are operating the first one for tests of 10-m long LHC prototype dipole cryomagnets supplied by European industry. We describe system architecture, cryogenic process and constructional features of these benches in the following, and report on test results in a companion paper.

Dealing with risk of fixed installations in The Netherlands

In a densely populated and highly industrialized country such as The Netherlands, the competent authorities face the problem of making sure that, on the one hand, the chemical industry can develop and, on the other, the population is not subjected to undue risk or nuisance. Cryogenic storage facilities are treated just as other industrial facilities would be in this respect. While up to the early 1970s such planning was done on the basis of qualitative insight into the hazards of chemical plants, since then it has been recognized that global insight and engineering judgement alone no longer form a solid enough basis on which to rest safety decisions, such as changes to an installation, siting and zoning. From the mid-1970s the Directorate General for the Environment in The Netherlands has been developing tools to support decision makers with quantified information about risks. The development of these techniques has been a complicated task in which the Directorate worked together with engineering companies and the research institutions of the EEC. The development of more accurate tools is a continuing process. The application of decision support techniques to areas other than the immediate risks to life, such as carcinogenic effects and ecological damage, may need even more work to develop suitable techniques. The Directorate General for the Environment has also developed preliminary guidelines for the acceptability of risk. The application of quantitative techniques to support decisions with respect to potentially hazardous chemical installations has been accepted by Parliament. Since the introduction of the Major Hazards Regulation more than 50 external safety reports, describing the risks of major chemical complexes, have been produced. These reports give an interesting insight into the risks of these types of installations and the necessary safety zones around them. They also give an indication to what sort of information can be used successfully by the authorities in licensing and zoning decisions.

Space-based LH 2 propellant storage system: subscale ground testing results

An orbital cryogenic liquid storage facility will be one of the essential elements of the US Space Program to realize the benefits of space-based cryogenic propulsion vehicles such as NASA's space transfer vehicle (STV) for transporting personnel and scientific packages from a space station in low earth orbit (LEO) to geosynchronous orbit (GEO), the moon and beyond. Long-term thermal control of LH 2 and LO 2 storage cryotanks is a key technical objective for many NASA and SDI programmes. Improved retention using refrigeration, boil-off vapour-cooled shields (VCSs), multilayer superinsulation (MLI) and para-ortho (P-O) hydrogen conversion are the required state-of-the-art techniques. The cryotank system level development testing (CSLDT) programme has supported the development of these technologies. Under the programme, trade studies and analyses were followed by the design and construction of a subscale LH 2 storage facility test article for steady-state and transient thermal tests. A two-stage gaseous helium (GHe) refrigerator was integrated with the test article and used to reduce boil-off and/or decrease the time required between passive test configuration steady-state conditions. The LH 2 tank, mounted in a vacuum chamber, was thermally shielded from the chamber wall by MLI blankets and two VCSs. The VCSs were cooled with either LH 2 boil-off gas (through an optional P-O converter) or refrigerated GHe. The CSLDT test article design, assembly and results from 400 hours of thermal tests are presented along with important conclusions. A comparison of predicted and measured steady-state boil-off rates is provided for 10 test configurations, and the system time constant is addressed. Also presented are some of the unique issues and challenges encountered during these tests that are related to instrumentation and control.

Long-term operational experience and upgrade of the cryogenic system for the superconducting cavities in the CERN SPS accelerator

Cryogenics at liquid helium temperature has been requested in the SPS for testing and operating superconducting accelerating RF cavities: in 1988 and 1989 a single LEP prototype cavity made of bulk niobium, in 1990 two cavities made of niobium sputtered copper and finally, in 1991, a single niobium sputtered cavity. To cope with the various cooling needs, we used the same refrigerator (120 watt at 4.5 K) and the associated cryosystem has been optimized to reduce the thermal load. The original transfer line has been replaced by a flexible and thermally shielded one made of six coaxial bellows. The achieved thermal performance for the various combination of superconducting cavities, the long-term behaviour and operational experience of the cryosystem are given. While the first cryosystem is maintained in operation, a new one (using a refrigerator of 400 watt at 4.5 K) is now being tested to increase, in 1992, the SPS accelerating field by means of two additional superconducting cavities. A description and the preliminary results of the new cryogenic facility are presented.

ISOCAM experiment cryogenic test results

ISOCAM is an infrared camera to be mounted aboard the Infrared Space Observatory (ISO) satellite. The 18-month mission of the satellite, scheduled for launch in 1993, is to collect data on near-infrared wavelength astronomy (2–200 μm) during its lifetime. ISOCAM will operate at temperatures from 2.4 to 3.4 K. A previous paper 1 described the general thermal analysis performed on ISOCAM, as well as the cryogenic test facilities to be used for analysis verification. This paper is an overview of the results of the main cryogenic system tests and a report on the associated fundamental measurements taken during testing. The paper also describes the degree of model validation suggested by analytical prediction versus test results. Predictions of thermal conduction through mounting screws, from ball bearings and of the heat distribution in the rotor and stator of a cryogenic stepper motor correlate well with actual test results. This correlation of test data with model predictions has led to a high degree of confidence in the ESATAN software used as the thermal modelling tool. The model predicated such phenomena as ‘chopped’ motor function and the twofold increase in temperature resulting from continuous motor operation.

International manned missions to Mars and the resources of Phobos and Deimos

I propose that an international manned mission to the moons of Mars be caried out with a sortie option to the Martian surface during the 1998–1999 opportunity. Such a mission is technically feasible. A number of reasons favor the 1999 opportunity, including small delta- V values, low probability of planet-obscuring dust storms, near-zero solar flare activity, and a potential world-wide celebration of unity at the turn of the millennium. As a low cost option, the U.S. space shuttle external tank can be adapted as a cryogenic propellant and cargo launcher to low Earth orbit (LEO), as a Mars mission module transfer vehicle, and as a cryogenic storage facility on-orbit and at Phobos/Deimos (PhD). This paper describes a synergistic four mission program in which approximately 10,000 metric tons of water extracted from PhD could be delivered to LEO and the surfaces of Mars and the Moon by 2005. As a result, Mars and lunar bases could be established, and a space industrial infrastructure could grow rapidly for other space development scenarios. The scientific, political and economic incentives for this mission warrant increased attention in manned Mars mission, program, and system studies. In a time of easing East-West relations and political change, the Mars 1999 mission could become a centerpiece for international cooperation and peace. The heavily vested aerospace weapons infrastructure could be rapidly converted to peaceful, cooperative efforts in space exploration and development.

Integrated Air Separation Facilities For Hydrocarbon And Sulphur Recovery

Abstract The concept of using an air separation plant to generate nitrogen jar enhanced hydrocarbon recovery and oxygen for sulphur production is reviewed. Nitrogen generation (for injection) and nitrogen rejection processes are discussed and cost curves are presented. Conventional oxygen enrichment and the COPE ™ (Claus Oxygen-based Process Expansion) sulphur recovery processes are compared. Locations where an air separation facility can be designed to produce both nitrogen jar injection and oxygen jar sulphur recovery are identified. Having identified potential sites for integration, oxygen and nitrogen economics are presented. Introduction North America contains vast reserves of conventional crude oil, heavy oil, oil sands, and natural gas containing sulphur (as hydrogen sulphide). In order to produce these reserves economically, industry is constantly investigating the application of new methods to enhance production. Some of these methods use industrial gases such as nitrogen (in secondary and tertiary hydrocarbon recovery projects) and oxygen (in situ combustion for heavy oil recovery and to displace air in sulphur recovery units). These gases are co-produced in cryogenic air separation facilities. However, to date, the application of air separation technology has been very site/project specific and designed to recover only one industrial gas. Many air separation facilities have been installed to deliver nitrogen for enhanced hydrocarbon recovery (EHR). At these locations the low-purity oxygen by-product is vented to the atmosphere even though it could be used as an efficient source of oxygen for combustion processes, such as sulphur recovery from a Claus unit. Hydrocarbon Recovery- Nitrogen Injection/Rejection The use of cryogenically produced nitrogen from an air separation unit (ASU) was initiated in the late seventies as a cost-effective alternative to natural gas injection(I.2). Its use for EHR has grown dramatically and has been applied primarily in the "lower 48" United States. In their June 1985 paper, Clancy et al.(2) provide a list of 33 reservoirs which have used nitrogen injection technology. Figure 1 locates the sites (illustrated by triangles) from this list which have used cryogenic air separation facilities to produce nitrogen. Sites where a nitrogen rejection unit (NRU) is installed as well are located by a darkened triangle in Figure 1. One of the eight sites where both nitrogen injection and rejection and are practiced is Dome's Willesden Green Field in Alberta(4). Exxon operates an integrated injection/ rejection project at Jay-Little Escambia Creek Field near the Florida/Alabama border(5). The remaining six sites are located at University Block 31 (Texas), Anschutz Ranch East Field (Wyoming), Andector-Ellenberger Field (Oklahoma), Fordoche Field (Louisiana), and two at the Painter Field (one triangle shown in Wyoming). Sulphur Recovery The primary method of producing elemental sulphur from natural gas is with the use of the Claus process. A typical modified Claus sulphur recovery unit (SRU) with two catalytic conversion stages and a modem reheat scheme uses air as the course of oxygen to recover 93% to 96% of the sulphur from a relativelyrich acid gas feed.

Cryogenic microstrain measurement using laser light interference

A new system which makes it possible to measure an absolute value of cryogenic microstrain and cryogenic creep has been developed. The system adopts a method of counting He-Ne laser light interference pulses to detect the microstrain in a sample specimen at cryogenic temperature. This laser method is superior to the conventional strain gauge method in three main respects (1) it is calibration free: (2) it does not need temperature compensation; and (3) there is no limitation on the maximum measurable value of a strain. The cryogenic creep test facility developed is presented in detail. Preliminary test results and typical cryogenic creep testing results on polytetrafluoroethylene (Teflon) are also presented.

Use of the TACL system at CEBAF for control of the cryogenic test facility

A description is given of a logic-based control software system called Thaumaturgic Automated Control Logic (TACL), which is under development at the Continuous Electron Beam Accelerator Facility. The first version of the software was placed in service in November 1987 for control of cryogenics during the first superconducting RF cavity tests at CEBAF. In August 1988 the control system was installed at the cryogenic test facility (CTF) at CEBAF. CTF generated liquid helium in September 1988 and is now in full operation for the current round of cavity tests. TACL is providing a powerful and flexible control environment for the operation of CTF. A description of the TACL control system covers the logic editor, the display editor, run-time processes, the graph-plotting program, the PID (proportional-integral-deviation) control algorithm, and fault protection. >

Dynamics of vibrationally excited ozone formed by three-body recombination. I. Spectroscopy

Spectrally resolved infrared fluorescence near 10 μm from vibrationally excited O3(ν3) has been observed in a cryogenic reactor facility at low pressure. The excited O3(v) is formed principally by three-body recombination of O and O2 in flowing, microwave-discharged O2/Ar mixtures at 1 Torr and 80 K. The spectral resolution is sufficient to permit identification and assignment of band centers for up to five quanta of stretching excitation. The observed transition frequencies are consistent with those predicted from a Darling–Dennison perturbation treatment. The spectra, which sample the recombination/deactivation sequence in its early to middle stages, indicate surprisingly little intermode coupling, being predominantly ν3 in character. There is also evidence of O3(v) excitation by near-resonant V–V coupling between O3 and O2(v=2). The spectroscopic analysis of the data is described, and considerations for scaling the spontaneous transition probabilities with vibrational level are discussed.

A CAMAC-Based Intelligent Subsystem for Atlas Example Application: Cryogenic Monitoring and Control

A subunit of the CAMAC accelerator control system of ATLAS for monitoring and, eventually, controlling the cryogenic refrigeration and distribution facility is under development. This development is the first application of a philosophy of distributed intelligence which will be applied throughout the ATLAS control system. The control concept is that of an intelligent subunit of the existing ATLAS CAMAC control highway. A single board computer resides in an auxiliary crate controller which allows access to all devices within the crate. The local SBC can communicate to the host over the CAMAC highway via a protocol involving the use of memory in the SBC which can be accessed from the host in a DMA mode. This provides a mechanism for global communications, such as for alarm conditions, as well as allowing the cryogenic system to respond to the demands of the accelerator system.

An Experimental Investigation of Combined Convection From a Short Vertical Cylinder in a Crossflow

An experimental investigation of combined convective heat transfer from a smooth, isothermal vertical cylinder to a surrounding gas medium is described. The study was motivated by the desire to predict the convective heat loss from the 10-MWe pilot plant solar receiver in Barstow, California. Hence emphasis is placed on the supercritical (Reynolds number Re greater than 105, turbulent (Rayleigh number RaL greater than 109) regime. The influences of the Reynolds number, the Rayleigh number, the Richardson number, and Tw/T∞—the ratio of the surface temperature, Tw to the ambient air temperature T∞—are deduced. Large ranges of these dimensionless parameters are covered with a single model by using a variable ambient temperature, cryogenic wind tunnel over the temperature range 80 K ≤ T∞ ≤ 300 K. The cryogenic facility also enables the simultaneous generation of large Rayleigh numbers and large Reynolds numbers.

Cryogenic System for a Superconducting Spectrometer

The Heavy Ion Spectrometer System (HISS) relies upon superconducting coils of cryostable, pool boiling design to provide a maximum particle bending field of 3 tesla. This paper describes the cryogenic facility including helium refrigeration, gas management, liquid nitrogen system, and the overall control strategy. The system normally operates with a 4K heat load of 150 watts; the LN2 circuits absorb an additional 4000 watts. 80K intercept control is by an LSI 11 computer. Total available refrigeration at 4K is 400 watts using reciprocating expanders at the 20K and 4K level. The minicomputer has the capability of optimizing overall utility input cost by varying operating points. A hybrid of pneumatic, analog, and digital control is successful in providing full time unattended operation. The 7m diameter magnet/cryostat assembly is rotatable through 180 degrees to provide a variety of spectrometer orientations.

Worldwide cryogenics-USA The Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology: Cryogenic research facilities

Activities in cryogenics research and development at the Francis Bitter National Magnet laboratory are described. The water cooled resistive magnets, NMR, low and high field facilities are detailed.

Development of a Pulsed Cable Test Facility for superconducting ohmic heating coils

This paper describes a Pulsed Cable Test Facility (PCTF) under development at Argonne National Laboratory (ANL). Its essential part is a pulsed superconducting split coil. The inner and outer diameters of the coil will be 45.1 cm and 88.3 cm, respectively, with an adjustable gap between the two halves of the coil. At a peak current of 11 kA, the coil will store an energy of 3.5 MJ and produce a magnetic field of 6.4 T. Using a 7MW pulsed (2.9 MW rms) power supply, the PCTF coil will produce field change of 6 T/s. With the addition of a solid state switch to the system, dB/dt values of up to 24 T/s can be obtained. Pancake coils, wound with developmental cables, will be placed in the adjustable gap of the PCTF coil and be tested at up to 50 kA furnished by a separate power supply. The PCTF cryogenic facilities include a non-metallic cryostat and a helium liquefier.

Construction program for a large superconducting MHD magnet system at the coal-fired flow facility

The Argonne National Laboratory has designed and is constructing a 6 T large aperture superconducting MHD magnet for use in the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute (UTSI) at Tullahoma, Tennessee. The magnet system consists of the superconducting magnet, a magnet power supply, an integrated instrumentation for operation, control and protection, and a complete cryogenic facility including a CTI Model 2800 helium refrigerator/ liquefier with two compressors, helium gas handling system and a 7500 liter liquid helium dewar. The complete system will be tested at Argonne, IL in 1981. This paper first briefly reviews the magnet design. Second, the coil fabrication programs are described in detail.