The mechanisms of atomic diffusion in metallic melts are elucidated by various experimental techniques and molecular dynamics (MD) computer simulation, as well as by the mode coupling theory (MCT) of the glass transition. Self-diffusion experiments in the bulk metallic glass former Pd40Ni10Cu30P20 performed under microgravity conditions on FOTON M2 and in the lab show that self-diffusion is controlled by the effective packing of the atoms. The temperature dependence of Ni-self diffusion as measured by quasielastic neutron scattering (QNS) can be described by a power law, as predicted by MCT. The relation between self- and interdiffusion is studied for an Al80Ni20 melt. Results from MD simulations are in good agreement with the Ni-self- and interdiffusion coefficients obtained from QNS and the long-capillary (LC) technique. The detailed information provided by the MD simulation reveals why the interdiffusion coefficient is up to a factor 5 larger than the self-diffusion coefficient. The relation between self-diffusion and interdiffusion is further studied for Zr2Ni by a combination of neutron diffraction and calculations in the framework of MCT. Comparisons to MCT calculations for hard spheres shed light onto the relation between chemical short-range order and diffusive mass transport.

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Space agencies of countries such as Canada experience particular challenges with respect to the establishment and maintenance of a flourishing space physical sciences community. The Canadian Space Agency has developed a longterm plan that will allow a relatively large number of Canadian scientists and industry partners to contribute to space physical science, and that will also provide a continual flow of flight experiments. This plan has inherent flexibility, allowing it to be adapted and used by space agencies of countries with a similar population base and resource capability as Canada. The plan can be visualized as a pyramid, with conceptual studies forming the base, and flight experiments the peak. Conceptual studies are solicited through a yearly Announcement of Opportunity (AO) that supplies grants to top-ranked proposals. Feasibility studies, which follow naturally from successfully completed conceptual studies, are solicited in the same AO. Depending on the maturity and complexity of the scientific and technical requirements for a flight experiment, a research team can submit proposals for flight experiment AOs de novo (i.e. without previous CSA funding) or after a successful feasibility study. Announcements of Opportunity for flight experiment will be offeredb every two years, depending on the number of successful proposals undergoing implementation. Applicants to these AOs will be able to tailor proposals to appropriate categories; i.e. proposals that have low resource (e.g. upmass, crewtime) requirements will be assessed separately from proposals that have significant resource requirements. It is expected that this AO scheme, combined with strategic support of workshops and a strong network of collaboration among international partner agencies, will allow CSA to develop and sustain a vigorous space physical science community.

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The German Microgravity Programme covers research in physical as well as life sciences. This paper deals with esearch on physical and chemical processes exposed to microgravity conditions. The Physical Sciences Programme goal, structure, priorities, research disciplines, scientific topics, hardware developments, and flight pportunities are outlined. All German microgravity activities are performed within the corresponding ESA Programmes, the National Space Programme, and the DLR R&D Programme in an integrated manner. The aim is o maximize the gained scientific knowledge for developing new materials, advanced technologies and to reveal some mysteries of the physical world.

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Applying the numerical program for the bubble migration in space, we performed a numerical simulation of the bubble behavior with the thermocapillary flow in an open cylindrical container under microgravity conditions. In the present study, 45° sector of the container were modeled. We assumed Marangoni forces on the bubble surfaces were negligible small and calculated a single bubble behavior in 3 dimensional thermocapillary flow in order to make clear the interaction between the thermocapillary flow and the bubble behavior. The following results were obtained by these results; (1) steady state results calculated by the present program agreed well with the results by the previous investigations, (2) the single bubble flowed largely along the streamline of the thermocapillary flow and the moving bubble did not largely change the temperature field, and (3) the repulsive forces were produced by the bubble motion and the magnitudes became larger as the bubble approached to the hot region.

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The effect of free surface heat transfer on the onset of oscillatory thermocapillary flow of high Prandtl number fluid is investigated in open cylindrical containers. The critical conditions are determined experimentally. The air flow above the container is simulated numerically for the experimental conditions and the free surface heat transfer rate is computed. The experiment covers both heat loss and gain conditions. It is shown that the free surface heat transfer does not affect the critical conditions within the parametric ranges of the present experiment. This is quite a contrast from the situation for the liquid bridge configuration where the critical condition is known to be very sensitive to the free surface heat transfer.

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The paper reports on the preparations for a SOUnding Rocket Compere Experiment (SOURCE) on MASER 11with (Convective boiling and condensation). One of the tasks of this experiment is the investigation of capillary dominated flow along a heated wall. The SOURCE experiment will also serve the needs of the COMPERE research group whose mandate is to investigate the behavior of propellant in spacecraft tanks. SOURCE is a benchmark type of experiment on fluid behavior in tanks to test hypotheses and numerical predictions (quantitative results on a tank scale). Several work packages have been distributed to the Center of Applied Space Technology and Microgravity (ZARM) to manage a part of the preparation of this experiment. Since ZARM acts also as a principal investigator, the subject of surface tension driven flows is one of the main topics. It includes the design of the experimental setup to study the free surface behavior as well as the numerical predictions to quantify the heat transfer at a non-isothermal boundary condition in the absence of gravity.

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A cylindrical liquid bridge supported between two circular-shaped disks in isorotation is considered. The effect of a lateral gravitational field on the stability of the liquid bridge is investigated. A numerical method is used to find stable and unstable shapes and to determine the stability limit for different values of lateral gravity.

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The effects of small vibrations on the surface oscillation of liquid bridges, especially the resonance behavior, were investigated numerically. The three-dimensional direct numerical simulation was based on the level set method to predict the surface oscillation of isothermal liquid bridges held vertically between solid disks. By subjecting the liquid bridges to various horizontal vibrations, the surface resonance frequencies were clearly determined numerically. The numerical resonance frequencies compared well with the analytical model predictions in another work. The effect of small vibrations on the induced flow structure inside the liquid bridge is also discussed.

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The present study is focused on the dynamics of a liquid film produced by spray impact. It is aimed at better understanding of the hydrodynamics and heat transfer associated with spray impact onto a heated target and at providing a basis for the reliable modeling of spray cooling. In this paper the phenomena associated with spray impact, observed under terrestrial and microgravity conditions, are compared. A robust method of film characterization is proposed. We show that a thin liquid film is created by spray impact even under microgravity conditions. However the film thickness increases as the gravity force reduces.

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Galvanostatic water electrolysis was conducted in 2 wt. % KOH solution for 5 s under terrestrial and quasi-μ-G condition. These conditions were realized by using two types of cell arrangement: (1) the vertical arrangement and (2) the downward facing horizontal electrode arrangement over the counter electrode, respectively. The latter arrangement can be regarded as a quasi-μ-G condition because the natural convection induced by generating gas bubbles is macroscopically excluded. The gas bubble formation of O2 or H2 was in-situ observed by using high speed camera. Sputter-deposited Pt film on transparent FTO glass was used as the working electrode to record backside images of evolving bubbles. O2 gas bubbles were less hydrophilic than H2 and tended to coalesce with each other to grow in larger size. They stayed much longer on electrode surface than H2. The attachment of bubbles decreased the effective reaction area to result in energy loss for O2 gas evolution. Quasi-μ-G experiment made it possible to measure the larger contact angle of O2 than H2, but difficult to realize H2 froth layer formation. Thus, the measured results in the downward facing electrode arrangement were partially coincident with those in microgravity experiment conducted in a drop tower. It suggests that careful and appropriate experimental design with downward facing electrode may sometimes reduce the expenses and time necessary for the scientific research in the international space station.

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Closely associated European teams are engaged in microgravity research on aqueous and metal foams in the framework of two MAP projects from ESA. They deploy a wide range of techniques in terrestrial experiments and are experienced in the design and execution of microgravity experiments. We outline their recent achievements and present plans

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Pool boiling experiments in microgravity performed during the past 3 decades demonstrate unanimously that up to a medium heat flux the overall heat transfer is nearly independent from gravity. So far it was assumed that buoyancy plays the essential roll for heat and mass transport expressed in the empirical correlations for technical applications. We refer in this paper on results of experiments performed with various liquids and heaters, using different carriers which provide low gravity like TEXUS rockets, aircraft KC135, and drops in the tower of ZARM and shaft of JAMIC, and as highlights, experiments during space lab missions. Beside the measurements of the experimental parameters like the liquid state, temperature and pressure, heat fluxes, and heater temperature, we observed the boiling process itself with movie films and videos. From these records we learned about the bubble dynamics, the mechanisms of heat and mass transport without gravity only generated by the bubbles themselves, and details about the boiling process itself not recognized up to this day. These findings are essential for a better understanding of the complex physical process, and are important for the formulation of empirical equations, and in future for numerical solutions to predict the heat transfer for technical applications.

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This paper addresses the experimental results of quenching in tubes at microgravity conditions with the objective to gather quantitative data and observations of the rewetting of hot surfaces at microgravity conditions. Test tubes are made of Pyrex with different inner diameters, 2.0, 4.0 and 6.0 mm. Tests are performed with vertical test section and upward fluid flow. The test fluid is FC-72, a fluorinert liquid. Measurements included wall temperatures along the flow channel, inlet and outlet temperatures, pressures and mass flow-rate. The 6.0 mm tube shows a significant decrease in the quenching velocity at reduced gravity, while the rewetting temperature is not affected by gravity level. For the smaller pipe diameters the effect is still present, though less evident. The observed flow patterns are: inverted annular flow and bubbly flow. These tests reveal the influence of mass flow-rate on the structure of vapour-liquid configuration during the inverted annular flow.

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The pool boiling heat transfer of FC-72 on a plain plate with a heating area of 15*15 mm2 in different pressure and subcooling has been studied experimentally both in normal gravity on the ground and in microgravity aboard the Chinese recoverable satellite SJ-8. A quasi-steady heating method is adopted, in which the heating voltage is controlled as an exponential function with time. Three modes of heat transfer, namely single-phase natural convection, nucleate boiling, and transition boiling, are observed, while the nucleate pool boiling are the major subject for discussion in the present paper. In normal gravity, the present data is compared with those obtained by other researchers, and a satisfactory agreement is evident and warrants reasonable confidence in the data. Compared with terrestrial experiments, the boiling curves in microgravity are considerably gentle, and CHF is no more than 40% of that in terrestrial condition. In microgravity, influences on boiling curves of the pressure and subcooling are similar with those in normal gravity, namely that the heat transfer coefficient and CHF will increase with subcooling for the same pressure, and that they will also increase with pressure for the same subcooling. Keywords: microgravity, pool boiling, subcooling, plate heater

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The ARIEL experiment was flown on May 2005 aboard of Foton-M2 satellite and was dedicated to the study of nucleate boiling of dielectric fluids on a flat plate, in the presence of an external electric field or less. The experiment was run for four days, however the unexpected high vapor production caused the early exhaustion of the nitrogen of the pressure compensation system. The experiment runs were continued in off-nominal conditions, at subatmospheric pressure, allowing for testing saturated pool boiling in microgravity. The results reported herein show that saturated pool boiling in microgravity can occur without originating immediately surface dryout. The application of a moderate electric field increases the surface wetting and decrease the size of departing bubbles. For the highest applied electric field, nucleation is suppressed and only single phase heat transfer takes place, at least in the power range investigated here, with degradation of the performance. Keywords. Microgravity, Boiling Heat Transfer, Electric Field

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Motion of metal spheres in gas with imposed temperature gradient was analyzed both theoretically and experimentally in the range of parameters favorable for the existence of negative thermophoresis. Polydisperse copper spherical particles with mean diameter of 74 μm were injected into nitrogen at normal pressure and particle-to-gas heat conductivity ratio (Λ being around 2.0・ 104) were the most extreme values reported until now. Particle sedimentation and gravity-induced convection were suppressed in microgravity conditions during free fall in the Bremen drop tower. Observed particle velocities have rather high spread, which we attribute to the presence of non-gravitational convection driven by thermal creep on the non-uniformly heated wire and its holders. Experimental estimates of the thermophoretic velocity normalized on the temperature gradient are positive, however, being far below the values reported in literature. Estimates taking into account perturbations from non-gravitational convection meet better predictions of gas-kinetic theories, which include thermal stress slip flow. Ways to improve experimental procedure and accuracy are identified, so that they will make it feasible to get crucial answer on the question of existence of negative thermophoresis in gases - a new physical phenomenon predicted theoretically and yet not observed experimentally.

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The spatiotemporal density and temperature variations induced by heating the walls of a closed domain filled with supercritical fluid are studied experimentally and numerically. The experimental results were obtained from the specially designed laboratory experiment carried out with the use of the Alice-1 instrument. The numerical results were obtained by the direct solving of the complete Navier-Stokes equations supplemented by the van der Waals or perfect gas equations of state. The numerical instrument proposed is shown to be capable to adequately describe the time dependences of density and temperature fields on short-term (

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We present a design of an optical cell dedicated to study the water properties near the liquid-gas critical point using the DECLIC-CNES instrument on board the International Space Station. This designed cell satisfies safety requirements for high pressure and high temperature operating conditions of the high temperature insert (HTI). This design is optimized for using high-resolution and high-speed optical diagnostics, local temperature controls and measurements of the DECLIC instrument, in particular to observe and to analyze the thermal and density response of critical water after a transient heating produced by one heat pulse actuator. Illustrations of the high-level performances are provided by the preliminary results obtained during the Earth's tests of the flight model of the HTI insert.

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We present a review of recent activity of the VIP-CRIT team in analyzing the previous space experiments, developing analytical methods, and carrying out the laboratory and numerical simulations devoted to the study of the effects of microgravity environment on the heat transfer and phase separation in the supercritical and near-critical fluids. The studies complement one another, and the results show that such kind of collective activity is extremely important for both obtaining new basic knowledge and optimizing the future space experiment onboard the ISS.

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Current experiments aboard the International Space Station (ISS) illustrate an extent to which liquid behavior aboard spacecraft can be controlled by wetting and container geometry. The experiments are referred to as the 'Vane-Gap' experiments and are part of a more general set of simple handheld Capillary Flow Experiments1) (CFE) designed and developed at NASA's Glenn Research Center for conduct on ISS. The CFE-Vane Gap experiments highlight the sensitivity of a capillary fluid surface to container shape and how small changes to said shape may result in dramatic global shifts of the liquid within the container. Understanding such behaviors is central to the passive management of liquids aboard spacecraft and in certain cases permits us the ability to move (pump) large quantities (potentially tons) of liquid by a simple choice of container shape. In particular, the Vane-Gap experiments identify the critical geometric wetting conditions of a vane structure that does not quite meet the container wall-a construct arising in various fluid systems aboard spacecraft such as liquid fuel and cryogen storage tanks, thermal fluids management, and water processing equipment. In this paper experimental results are compared with preliminary theoretical and numerical analyses.

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We report on the status of preparatory work in the GeoFlow Experiment which will take place on board Columbus Orbital Facility (COF) at the International Space Station (ISS). GeoFlow focus on investigations of the stability and dynamics of convective spherical gap flows under influence of a central force field. To exclude the unidirectional gravitational force which acts on earth’s surface the planed long-time measurements have to take place in microgravity environment. After a introduction and an overview of experiment hardware preparation status which includes application of measurement techniques, preparatory 3D numerical flow simulations as well as experimental work and the way of experiment data analysis are presented. Also some aspects of the experiment operation phase will be given. The paper is then closed with concluding remarks and an outlook on possible future GeoFlow reflight campaigns.

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The Fluid Science Laboratory (FSL) is an element of the ESA Microgravity Facilities for Columbus program, designed to operate on-orbit within the Columbus module of the International Space Station (ISS).The FSL supports scientific microgravity experiments in th0e field of fluid physics; it distributes standard utilities and specific services and retransmits images, science and housekeeping data. Each experiment is hosted into an Experiment Container, designed under the Science Coordinator direction.The FSL is one of the most complex microgravity laboratory never built. Based on multi-user capabilities, integrating very sensitive optical diagnostics, hosting the exchangeable largest experiment containers ever designed, the FSL represents the leading edge of the European technology. The possibility to ground control it totally ensures the independence of the experiment conduction from the on-board crew.In the last years, the FSL Operations Team, composed by Payload Developers and User Support & Operation Centers experts, worked jointly to prepare the flight operations and the related products to operate the facility.This paper intends to illustrate the peculiarity of the FSL, aimed at the exploitation of its scientific performances for future generations of experiments, and the operations activities that are making the laboratory ready to work.

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A cylindrical liquid bridge supported between two circular-shaped disks in isorotation is considered, with　attention paid to the combined effect of an axial gravitational field and an offset between the rotation axis and the axis of the supporting disks (eccentricity) on the stability of the liquid bridge. In previous work a numerical method used to determine the stability limit for different values of eccentricity was validated by comparing with analytical and experimental results at small eccentricity, which gave the same behavior. In this work we use an extension of that algorithm applied to liquid bridges in an axial gravitational field rotating around an eccentric axis to study the combined effect of rotation, eccentricity and gravity.

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A mathematical model of convective heat-mass transfer during crystal growth process is proposed. This model is based on the cluster approach of simulation of transient area in the melt near the front of crystallization. The melt structural model near the crystallization front considers the availability of clusters formation that cause resistance to the melt flow. This resistance of medium is described by means of specific double-phase coefficient introduction depending on the enthalpy value in each assigned mesh micro-volume under calculation. Basing onto space growth experiments aboard the Photon series satellites, the necessary empirical model parameters are evaluated. The results of the model testing are demonstrated, including the description of real orbital and groundbased GaSb :In crystallization experiments.

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Heat generation density from semiconductor devices increases with the rapid development of electronic technology. The cooling system using boiling two-phase phenomena attracts much attention because of its high heat removal potential. Most of heat transfer researches concerning the development of electronic devices are conducted for the cooling of small semiconductor chips, while there are limited numbers of innovative investigations for the cooling of a large area at extremely high heat flux larger than 2x 106W/m2. The technology can be applied to the cooling systems in space, e.g., cooling of laser medium in solar power satellites when solar energy is converted to laser power. To develop compact and high-performance cooling systems, a structure of narrow heated channel between parallel plates with auxiliary unheated channel was devised and tested by using water in three different kinds of experimental conditions. One of liquid supply method, where liquid is supplied to both of the main heated and the auxiliary unheated channel keeping the exit of the auxiliary channel closed, gives the highest CHF value at total volumetric flow rates more than 3.0x10-5 m3/s and 2mm gap size of main heated channel.

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A transparent heating surface with multiple arrays of 88 thin film temperature sensors and mini-heaters was developed for the clarification of boiling heat transfer mechanisms in microgravity through the investigation of the relation between local heat transfer coefficients and behaviors of liquid microlayer underneath vapor bubbles. Local surface temperatures were controlled to keep a constant on the entire heat transfer surface by feedback circuits. To examine the validity in the operation of the developed heating surface, preliminary pool boiling experiments from a downward-facing surface were conducted on ground by using FC72. The local heat flux change characterized by the heat transfer enhancement due to the microlayer evaporation and the heat transfer deterioration by the extending dry patch were detected corresponding to the liquid-vapor behaviors underneath a coalesced bubble observed directly through the glass substrate. Microgravity boiling experiments by parabolic flights campaign are planned using the heating surface developed.

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A numerical simulation study was carried out to investigate the effect of thermo-solutal Marangoni　convection occurring in the floating-zone (FZ) growth of an alloy of Silicon and Germanium under　microgravity. The simulation results show that the flow structures in the molten zone become three-dimensional when the thermal Marangoni number is larger than the critical Marangoni number even though the applied temperature profile is axisymmetric. It was also found that the three-dimensionality of the solutal Marangoni convection may be responsible for the unstable growth observed in the experiment of Ref [10].

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The occurrence of liquid-vapor phase transition and possible existence of a critical point in complex plasmas ‐‐systems that consist of charged micrograins in a neutralizing plasma background - is investigated theoretically.　An analysis based on the consideration of the intergrain interaction potential suggests that under certain conditions systems near and at the critical point should be observable. Measurements under microgravity conditions would appear to be required. The analysis aims at determining plasma parameter regime most suitable for experimental investigations.

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Thermodynamics of fine particle plasmas, systems composed of micron-sized fine particles, ions, and electrons, has been analyzed in the domain where fine particles are strongly interacting with eachn other. It is shown that we may possibly observe a divergence in the isothermal compressibility of the system when the coupling becomes sufficiently strong in the microgravity environment. This is regarded as a manifestation of the tendency of the one-component plasma (OCP) that it becomes thermodynamically unstable with the increase of coupling. This property is closely related to the definition of the OCP where the neutralizing background has no contribution to the pressure and is usually difficult to observe being suppressed by the rigidity of the background of real materials. In the case of fine particle plasmas, however, the background composed of ions and electrons is not completely rigid and extremely strong coupling between fine particles leads to a diverging isothermal compressibility of the whole system. In order to have a bulk three-dimensional system including fine particles with macroscopic masses, we have to perform experiments under the condition of microgravity. The phase diagrams including related phase separation and the critical point are shown and pointed out is a possibility to have a critical point in the solid phase.

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The particle-motion temperature in a two-dimensional structure was estimated from the time evolution of the speed of a fine particle to be around 0.1 eV with an accuracy of less than 0.1 eV. It was observed that fine particles were isotropically arranged in a planar magnetron plasma, which diffused upward, in three dimensions, without the formation of a void.

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Dynamics of dust particles in an rf discharge plasma is studied. The plasma is produced in a glass tube of 16 mm in diameter and 680 mm in length. Dust particles are introduced into the plasma from the top of the glass tube. A sheath is formed near the bottom of the glass tube. A dust particle charged negatively in the plasma moves downward into the sheath and is observed to move upward against gravity, while two dust particles injected into the sheath interact each other and are observed to form a vertical pair along the ion stream. The lower dust particle is trapped in the wake potential formed by the upper dust particle in the ion flow. A pair of dust particles is observed to move upward together against gravity in the wake channel.

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Tunable diode laser absorption spectroscopy (TDLAS) and more specifically, wavelength modulation spectroscopy is used in the course of this work as a non-intrusive in-situ diagnostic method for determination of oxygen concentration and local temperatures of a laminar diffusion flame over a solid fuel (PMMA) under microgravity. With the information gathered regarding the species' concentration at a given time step and location, the burning rate of the flame can be characterized.

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It is recognized that the burning of droplet arrays represents an idealized condition to study the complex, interacting phenomena of multi-phase flow, thermodynamics, and chemical kinetics. Droplet arrays provide a fundamental foundation upon which descriptions and models of the complex spray combustion can be developed. The major objective of the present study on droplet combustion is to investigate the burning characteristics and exhaust formation mechanisms. This paper presents the preparations for the exhaust sampling and analysis by burning an array of five n-decane droplets on a sounding rocket platform. The primary problem, which has to be solved, is to obtain a representative gas sample from every, specific combustion run. The pursued concept is intrusive as it is necessary to immerse four probes into the combustion chamber. After flame extinction the samples are withdrawn and stored in sampling cylinders for the succeeding analysis. High efforts are put into a reliable and ideal sampling system as well as the preparation of the experiment procedures to ensure high-quality results. This includes experimental testing and numerical studies. The analysis process itself is ground-based and carried out by FT-IR (Fourier Transform Infrared) spectroscopy after the payload retrieval.

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Modern aircraft turbines, which inject liquid hydrocarbon fuels into compressed air at high temperatures, aim for a limited residence time of the fuel in the combustion chamber before autoignition. The residence time however is important in terms of vaporizing and turbulent mixing of the fuel with air. A well stirred mixture with a lean overall equivalence ratio (near the adiabatic flammability limit) will reduce the combustion temperature and in turn reduce the production of nitric oxides (NO, N2O and NO2) through the Zel'dovich mechanism. This report details some of the results obtained under the ESA MAP project CPS (Combustion Properties of Partially Premixed Spray Systems), where (amongst other topics) n-heptane sprays are observed under machine conditions and these experimental results are compared to numerical results obtained with the ZARM closed vessel code for single droplet ignition.

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The influence of Acoustic field on the flame propagation is examined from FDTD (Finite Difference Time Domain) simulation. The influence is evaluated from the two points of view that are the enhanced transfers due to diffusion promotion and that due to convection in acoustic field. The particle velocity of sound is expected to enhance diffusive transport as is often explained through the similarity to turbulent diffusion, both having velocity fluctuations about the mean flows. A thermal convection that occurs when density difference exists in standing acoustic field had been previously found and it enhances convective transfer. To analyze the diffusive and convective influence of acoustic field, flame propagation experiments using a closed chamber, in which strong standing wave is made, is planned. To evaluate the influence of thermal convection, buoyancy convection should be suppressed. Microgravity experiments are expected and a preliminary examination is made using the FDTD simulation. As a result, negligible difference is found in the burning velocity with and without acoustic field in the case a flame started at the middle of velocity node and anti-node. Difference is found when the flame started at the anti-node, which is thought to be caused by the thermal convection.

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In this paper we like to compare the flame structure under micro (parabolic flight) and normal gravity environment. In primary we will underline the role of buoyancy forces on the structure of the reaction zone and consequently on the soot chemical path. Using CH* and OH* radicals spontaneous emission, PAH laser fluorescence and soot laser incandescence signals we attempt to get the geometric characteristics of the reaction zone (stand-off distance, flame thickness and length) and to provide a qualitative description of the soot formation/oxidation path.

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Normal-octane droplet fuel combustion under uniform electrical field is investigated by using experimental and numerical method. The flame properties including the deformation of flame shape and burning velocity is measured from captured flame pictures. In order to reveal the mechanism of deformation and combustion enhancement under electrical field the numerical prediction which includes the soot particle effect is implemented. The changes of deformation ratio and increasing of burning rate constant are obtained comparing the droplet flame with no applied voltage and 4kV case. Although the numerical results are underestimated than experimental results because of no consideration of soot formation, enhancement of vaporizing is shown in numerical predictions. The profiles of Coulomb force, charge density, electrical field and ion species are also simulated. Local increasing of momentum with electrical field changing is shown from results. The profile of charge density which is depending on ion species is considered and deformation mechanism is revealed. It is seen that the movement of flame under uniform electrical field caused the increasing of inlet heat into the surface of droplet, so then vaporizing of droplet is enhanced.

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The EML/TEMPUS facility is an electromagnetic levitation facility for the containerless processing of liquid metals under microgravity. For the scientific evaluation of the microgravity experiments with the EML/TEMPUS facility an application software was developed by the DLR-MUSC. The software enables the experimenter to analyze the experiment performance by the visualization of synchronized facility and video streams of the microgravity experiments. The speed of the display of the data and video streams can be defined and ranges from realtime to a display in slow motion. For the scientific evaluation of surface tension and viscosities edge defection algorithms have been implemented. With the measured sample edge the diameter, area or ellipse parameters of the sample are calculated. A Fast Fourier Transformation is performed on the data and sample surface oscillation frequencies can be measured. Another implemented tool enables the experimenter to calculate the surface tension of the sample. For earthbound measurements correction terms can be applied. The evaluation algorithms are tested and improved with simulated sample oscillations with known oscillation modes and frequencies and specified rotation of the sample. With this method the effect of the angle of view and rotation on the spectra is investigated. Some evaluations and spectra from parabolic flight measurements are shown as example for the utilization of the software for the evaluation of data of TEMPUS / EML video data under microgravity conditions.

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When a homogeneous liquid is cooled into its miscibility gap, phase separation sets in. In the early stages, liquid drops of the minority phase appear in the liquid matrix of the second phase. Due to supersaturation, even smaller drops of the majority phase form in these liquid drops, and so on, each drop encapsulating another drop. In the absence of gravity, the equilibrium configuration of a drop of two immiscible liquids consists of a liquid core, encapsulated by the second liquid phase. The oscillation spectrum of such a compound drop corresponds to that of two coupled oscillators, one being driven by the surface tension, while the other is due to the interfacial tension between the two immiscible liquids. Therefore the values of both, the surface and the interfacial tension, can be derived from the frequencies of the coupled oscillations. Such a configuration can be approximately realized by electromagnetic levitation, preferably under microgravity conditions. In this paper, the theory relating the frequency spectrum to the surface and interfacial tensions is presented, and a report on performed and planned microgravity experiments is given.

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A non-contact technique to measure the electrical resistivity of levitated samples is reported. The technique utilizes　the principle of the asynchronous induction motor, measuring the induced torque by applying a rotating magnetic field　to the sample. Relation between sample size and induced torque was experimentally checked with aluminum samples　and proved that induced torque is proportional to the fifth power of the sample radius. Based on this result, the electrical resistivity of solid zirconium at high temperatures was measured and showed a good agreement with literature data.

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To follow, in microgravity conditions, the evolution of opaque emulsions stabilized either by surfactants or particles, differential scanning calorimetry (DSC), performed at different time intervals on emulsion samples, has been proposed. The principle of the technique is based on the correlation between the freezing temperature of water and its volume. From nucleation theory, it is shown that the smaller the volume, the lower the freezing temperature. Due to a lack of data, the correlation is determined from experimental studies. For microsized droplets, the freezing temperature is found to be around - 40℃ whereas the value is around -15℃ for bulk water. DSC allows the detection of the water freezing temperature and energy, from which we can deduce how water is dispersed in the emulsion. Therefore intermediate temperatures show an evolution of the emulsion between a rather stable emulsion and a completely destabilized emulsion. Should a solute be present in water, the freezing temperatures are found to decrease as the concentration of solute increases. Therefore water transfer between pure water droplets and water + solute has been evidenced by using DSC. For water in crude oil emulsion containing NaCl, the DSC test permits to determine the amount of dispersed aqueous solution.

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The understanding of the nature and behavior of rare earth metals in their liquid phases requires accurate values of their physical properties. However, keeping samples in their liquid phases free from contamination for time scales long enough to carry out measurements represents a formidable challenge. This is due to high reactivity and melt contamination of lanthanum, praseodymium, and neodymium with a crucible or gaseous environment. The use of a vacuum electrostatic levitator and laser heating circumvented these difficulties and permitted the determination of the density, the surface tension, and the viscosity of several rare earth metals above and below their melting temperature. In this paper, the levitator and the non-contact measurement methods are introduced and preliminary experimental data of several thermophysical properties of La, Pr, and Nd are reported over large temperature ranges.

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Atomic Clock Ensemble in Space (ACES) is a mission in fundamental physics which will operate a new generation of atomic clocks in the microgravity environment of the International Space Station. Designed to be installed at the external payload facility of the Columbus module, ACES will accommodate the cold-atom clock PHARAO and the active hydrogen maser SHM. The on-board time scale will reach fractional frequency instability and inaccuracy of few parts in 1016. The ACES clock signal will be distributed on Earth by a link in the microwave domain and used for the comparison of atomic frequency standards, both space-to-ground and ground-to-ground. Based on these comparisons, ACES will perform accurate tests of Einstein's theory of general relativity and develop applications in time and frequency metrology, global positioning and navigation, geodesy, and gravimetry. After a general overview of the mission concept and its scientific objectives, the present status of the ACES mission is discussed.

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The dark matter hypothesis has been put forward to account for a discrepancy between the Newtonian dynamical mass and the observable mass in large astronomical systems. Dark matter is believed to dominate the universe and it should be in range of 90 to 99 % of its total mass. Modified Newtonian Dynamics (MOND) is an empirically motivated alternative to cosmic dark matter which satisfies an impressive proportion of observational tests. An experimental test of MOND is described, based on the mutual interaction of two bodies in an environment of very low residual gravity, such that an observable parameter of the motion, a frequency of oscillation, shall determine the possible validity of MOND.

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The Test of the Equivalence Principle with Optical readout in space (TEPO) project is proposed based on optical readout and space inertial sensor techniques. The main objectives are to test the weak equivalence principle at the level of 10-16 and the equivalence principle for the rotating extended macroscopic bodies at level of 10-14. The feasibility of the TEPO project is briefly described, and the requirements of key techniques are discussed.

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The principle and development of inertial sensors are simply introduced, and their applications to space fundamental physics are reviewed. The electrostatic suspension inertial sensor development in our laboratory is reported.

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A fast heat transport phenomenon occurring in supercritical fluids, known as the piston effect, has been studied in relation to the density wave generation and propagation. We carried out in situ observation of the density variation with a time resolution of 1 microsecond in supercritical CO2. The density-pulse generated by the piston effect has been observed, further an unexpected ‘vibrating tail’ of the density pulse has been generated. Keywords: Super-critical fluid, heart transfer, piston effect.

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Solidification is initiated by nucleation and completed by subsequent growth. In particular the growth conditions control the microstructure evolution. If the melt is undercooled prior to solidification a system of enhanced free energy is created that enables various solidification pathways into different metastable solids. Containerless processing is one of the most efficient methods to undercool metallic melts. In the present project electromagnetic levitation is applied both under terrestrial conditions and in reduced gravity. The non-equilibrium solidification during recalescence and segregation during post-recalescence phase is investigated and modelled. To solidify a spray of droplets a drop tube of 8m is used. A dedicated impulse Atomization facility and a closed coupled gas atomizer are employed to produce powders, which are solidifying in containerless state during free fall. Levitation experiments enable the measurement of undercooling and the corresponding dendrite growth velocity as a function of undercooling. Non-equilibrium effects during rapid solidification as solute trapping in alloys are investigated and analysed within current theories of dendrite growth. The comparison of experimental investigations on Earth and in reduced gravity allows for the determination of the effect of forced convection to the growth dynamics. Also, the evolution of grain refined microstructures upon undercooling is demonstrated and the influence of convection on the critical undercooling for the microstructural transitions from dendritic coarse grained to equiaxed grain refined microstructures is assessed within a model of dendrite break up.

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As part of the MONOPHAS (Advanced bearing alloys from immiscibles with aluminium) program of the European Space Agency, in-situ investigations of hypermonotectic Al-Bi(-Zn) alloys were undertaken to investigate liquid-liquid phase separation under terrestrial conditions. Hypermonotectic alloys are distinguished by a temperature region for which the homogeneous melt decomposes into two liquid phases. In Al-based hypermonotectics the minority phase is much higher in density than the matrix melt phase, and consequentially macro-segregation due to sedimentation is an inherent problem when casting these alloys1). Under the correct solidification conditions, however, it may be feasible to counteract sedimentation by thermocapillary forces arising due to the thermosolutal dependence of the surface tension between the two liquid phases. The current investigation involved in-situ X-ray video microscopy studies during directional solidification of Al-Bi samples of various compositions employing a Bridgman furnace. It was found that during liquid-liquid decomposition, the hydrodynamic forces coupled to external fields (i.e. temperature gradient and gravity) dominate L2 droplet motion and interaction. As a consequence these flow fields are superimposed on the short range coagulation mechanisms making quantitative data difficult to obtain. In-situ investigations in micro-gravity would eliminate the effect of gravitational field allowing short range coagulation mechanisms to be investigated providing important data for modelling of hypermonotectic systems. Keywords. MONOPHAS, hyper-monotectic alloys, directional solidification, X-Radiography.

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