Materials Science Experiments Research Articles

A review of the Stanford Mark III infrared FEL program

The performance of the Mark III infrared FEL with a new microwave gun will be reviewed. Operation of the accelerator is now close to design values. The Mark III has provided over 2000 hours of laser time to experiments in FEL physics, materials science and medical physics. Highlights of the experimental program will be presented and the new facility at Duke will be described.

News and Views

Carbolite Furnaces will play an important role in next year's Anglo‐Soviet Juno space mission. The company has been asked to supply a series of automated laboratory tube furnaces for the materials science experiments to be carried out on the Mir space station.

Future experiments and improved service system for automated MAUS payloads

The German MAUS project for autonomous material science experiments was initiated in 1980 for optimum utilization of NASA's Get-Away-Special (GAS) program. It is one of the flight opportunities which is offered by the F.R.G. to scientists for performing experiments under microgravity conditions. MAUS payloads are housed in GAS containers and consist of the experimental mounting structure, the batteries, the standard electronics for experiment control and data acquisition, the house-keeping systems and the individual experiment hardware. The standard service system was developed to offer a range of services within a framework of standardized interfaces to the experimenter and to meet NASA requirements. A payload can either be flown in the American GAS-program or with specific carrier structures, like SPAS, OSTA or USS, the latter being considered for the D-2 mission. Up to now, ten MAUS experiments were flown and currently seven payloads are in preparation for future Space Shuttle missions. The top four experiments are already equipped with the recently modified and modernized standard system which has been improved in experiment control, data management and semiconductor memory. The experiments to be performed deal with critical Marangoni convection, oscillatory Marangoni convection, gas bubbles in glass melts and pool boiling in liquids. A promising means of increasing resources in the field of MAUS-experiments is the interconnection of GAS containers. In the TWIN-MAUS configuration, electrical power and data will be transferred between two containers mounted adjacent to each other.

THERMODYNAMICALLY CONSISTENT SET OF EXPLICIT CONSTITUTIVE STATE EQUATIONS FOR INELASTIC SOLIDS

This study applies the theory of continuum thermodynamics with internal state variables to determine the nature of and the restrictions on the constitutive response functions of inelastic solids. An explicit expression for the Helmholtz free energy functional is then proposed leading to explicit expressions for stress and entropy functionals in terms of thermodynamic state variables. The temperature-dependent thermoinelastic material properties involved are determined by a novel application of the results of thermodynamics, materials science and mechanics experiments, and mathematical analysis. The state equations in conjunction with the heat conduction equation and the evolution laws for the internal state variables give a complete formulation of the constitutive relations. The nonlinear material model so developed is applicable over a wide range of temperatures and takes into consideration thermomechanical coupling in addition to the coupling of thermoelastic and thermoinelastic variables. It also expli...

The Trieste Synchrotron Radiation Project

We present the project for a superhigh brilliance soft X-ray source at Trieste. At present, the project is fully funded and the conceptual design is being developed. The facility, scheduled to become operational in 1992, will deliver unprecedented levels of brilliance, and will be used for a variety of experiments in physics, chemistry, materials science, engineering, biology, technology, and medical research, involving scientists from Italy, from a number of European countries, and from the USA.

Motions in fluids caused by microgravitational acceleration and their modification by relative rotation

The primary reason for conducting many materials science experiments in space is to minimize or eliminate undesirable effects that might result because of convective motions in fluids which are driven by buoyancy effects. Of particular interest are the low-frequency accelerations caused by the earth's gravity gradient field, spacecraft attitude motions, and atmospheric drag, since it is known that these can give rise to sustained fluid motion. In order to gain a limited understanding of the effects of these accelerations their magnitude and orientation have been examined, and the Stokes' motion of a spherical particle in a fluid has been calculated for various types of spacecraft attitude motions. In addition, the effect of slowly rotating the experimental system relative to the spacecraft (in order to increase the residence time of the particle in the neighborhood of its initial position) is assessed.

Measurement of surface temperature in microgravity experimentation - problems and solutions

Potential application of non invasive surface temperature measurements in Material Science and Fluid Science microgravity experiments is reviewed by analyzing the experiments that can benefit of thermographic techniques and by identifying the parameters that can be directly or indirectly measured. The hardware and software requirements of a thermographic equipment are indicated for a system of use in space.The capabilities and the relevant features are described of a computerized system, conceived and breadboarded in connection to ESA activities related to Fluid Science Facilities.

Development of the SCA/FEL for use in biomedical and materials science experiments

The Stanford SCA/FEL system is being modified to be used as a versatile source of photons for a wide range of biomedical and materials science experiments. Characteristics of the FEL beams to be provided are presented, as well as results of recent experiments on energy recovery. A new high brightness injector will be developed and tested, and the possibility of UV operation of an FEL has been assessed, assuming either fundamental or third harmonic output.

Development of an electrostatic positioner for space material processing

This paper describes an electrostatic positioning instrument which was developed at the Jet Propulsion Laboratory to enable experimenters to conduct containerless material science experiments in space. Samples that are to be studied are electrically charged and controlled by the electrostatic force produced by a set of properly arranged electrodes. Three different types of positioners are described, i.e., the dish type, the ring type, and the tetrahedral type. In all these systems, the positioning and the damping of the sample is accomplished by a feedback control system. The advantage of this electrostatic positioning method, in comparison to the other methods, such as acoustic and electromagnetic, lies in the fact that it can operate in a high vacuum and does not require the material to be electrically conductive as long as the material can carry a certain amount of charge.

Non-intrusive methods for temperature measurements in liquid zones in microgravity environments

Material Science and Life Science experiments in microgravity both have urgent needs of evaluating the temperature distribution within and on the surface of liquid zones. Non intrusive methods are available which measure the IR radiations emitted by the surface. The thermograph systems have a number of advantages since they supply a thermal picture of the surface with sufficient time, space and temperature accuracy. A computerized system has been designed for data acquisition and elaboration and used for ground experiments; the system can also be used for space experiments with some modifications. Non intrusive measurements of bulk temperature in two dimensional liquid flow fields can be made by means of optical methods which detect variations of the index of refraction. A method is proposed which is able to take with the same optical apparatus shadowgraph. Schlieren and differential interferometers pictures. A computerized system is proposed for data acquisition and elaboration.

Indian sounding rockets for material science experiments

The capabilities of Indian sounding rockets for conducting material science experiments are briefly described in this paper.

The magnitude of thermocapillary convection in larger melt volumes

Thermocapillary convection (TC) has been studied experimentally in a NaNO 3-melt of some cm 3 volume. TC has been identified, its streamlines and flow velocities have been visualized and measured. TC dominated over natural convection in this ground based experiment and will be a very significant flow phenomenon in the relevant μ-g materials science experiments with melts with free surfaces. The sensitivity of TC to surface perturbations is pointed out. TC is very difficult to control.

Technological research and development activities of ESA in the instrumentation for material science and fluid physics experiments in microgravity

Technological research and development activities of ESA in the instrumentation for material science and fluid physics experiments in microgravity

Electrostatic and acoustic instrumentation for material science processing in space

The use of electrostatic forces in the design of a positioning system and acoustic forces in the implementation of a mixing system for material science experiments on Spacelab are described. The electrostatic positioning of samples is described with special reference to its advantages and disadvantages with regard to other positioning methods. The design of such a positioner is described including the considerations relating to the processing of both high and low vapour pressure materials in a positioner compatible with both the isothermal heating facility (IHF) and the mirror heating facility (MHF) of Spacelab under microgravity (10 −4–10 −3 g) conditions. The application of acoustic and ultrasonic forces to the problem of sample mixing in material science experiments is explained. The design of a mixer compatible with existing furnace hardware for Spacelab and capable of effectively mixing samples at temperatures up to 1200°C is described. Tests of the mixer show that a 15 μm displacement adequate for good mixing can be achieved with a d.c. power input of 23 W and a conversion efficiency of 70%. Tests on alumina particles and carbon fibres in various alloy matrices show that complete wetting can be achieved.

Swedish Materials Science Experiment in the Texus 1 and 2 Rockets

Texus is a sounding rocket project for materials science experiments in low gravity. A 40-kg experiment module is included in the reusable payload. The experiments on the first and second Texus flights in 1977 and 1978 were 12 metal solidification experiments, two involving directional solidification in a gradient furnace and ten *'thermal analyses of small samples in so-called mirror furnaces. The gradient furnace is designed for studies of samples with melting points <1000°C. The furnace consists of a tubular resistive heating element inside which the sample is placed and a phase-change heat sink which extracts heat from one end of the sample to get a unidirectional solidification. The mirror furnace is designed for thermal analysis experiments below 1000° C. The radiation from two halogen lamps focused by ellipsoidal mirrors on the sample provides the heating.

Significance of fluid dynamics aspects for material science experiments

Fluid dynamics aspects for material science experiments may be treated with respect to purely space experiments and preparatory experiments on the ground. Preparatory experiments are necessary because little experience of material science experiments in space is available. Preparatory experiments on earth are needed in the field of surface tension and viscosity, surface layers, forming and positioning of liquids. Concerning space experiments the following subjects may be treated: convection phenomena, capillarity and kinetics of liquids. Convection phenomena (Marangoni convection) can be studied without disturbance by gravitation which has a considerable technological relevance. Under space conditions the kinetics of fluids may be studied in large model structures with changing capillarity and wetting properties.

I. Experiments in the Spacelab project - Spacelab and material processing facilities and experiments

The paper is introduced by a summary of the services available to the Spacelab user. Typical Shuttle- Spacelab flight profiles and Spacelab configurations are mentioned. The load carrying capacity and the capability and characteristics of the main subsystems, like electrical power and energy, environmental control as well as data management, are briefly described. The special constraints for the experiments to be flown on the first Spacelab payload will be discussed and the general purpose facilities (like furnaces and process chambers) to be used for carrying out the materials science experiments are described briefly. The cost aspects for performing experiments on Spacelab missions after the first mission are discussed.

Spar I Liquid Mixing Experiment

The Liquid Mixing Experiment had as its objective the observation of effects of residual acceleration on a confined fluid system. The fluid system was chosen to be similar geometrically and in fluid properties to a range of materials science experiments. Samples were constructed as cylinders 2.2 cm long by 0.6 cm diameter. Half of each cylinder was composed of pure indium, and the other half of each was an alloy of 80 wt% indium and 25 wt% lead. The samples were enclosed in aluminum cartridges and placed in heaters mounted in three mutually perpendicular directions. The experimental procedure consisted of melting the samples when the low-g phase of the payload trajectory was attained, holding the samples in a molten state for approximately 200 seconds, and then quenching to resolidification before leaving low-g. Two of the samples exhibited very little fluid motion. The third sample, which was oriented nearly parallel to a payload radius, showed a great deal of flow.