Preliminary experiments on the ground for the growth of SiGe crystals using a ground model of gradient heating furnace (GHF) are reported. For successful space experiments growth conditions obtained using a laboratory furnace should be transferred to a flight model furnace. However, use of a flight model is limited and a ground model which has similar configuration to a flight model is used for establishing appropriate growth conditions. We noted that temperature profile control using a GHF is more complicated than that achieved in a laboratory furnace since heater length is shorter in the GHF. However by several trials we established appropriate growth conditions. Here we report how we tuned temperature profiles in the GHF and how we established appropriate growth conditions for space experiments.

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Interferometric observation was attempted to the gas evaporation method to investigate the homogeneous nucleation and growth process of nanoparticles in vapor phase. For the first step, temperature distribution around evaporation source was measured with respect to the source temperature in the gas evaporation method for the first time in a half century. We visualized a condensation of smoke particles in gas phase and temperature history including a cooling rate of produced particles after nucleation was recognized. Homogeneously condensed WO3 nuclei initially maintain their temperature for ~5 ms and then cool down with a rate of ~5×104 K/s. The degree of supersaturation during the nucleation was at least as high as 107 .

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Designing and developing a facility that can be used for pulverized coal combustion experiment in microgravity are presented. It is used to research pulverized coal combustion characteristics in microgravity. The structure, the working principle and the experimental results of this facility are introduced. Especially, the facility can record the image of the whole process of coal combustion clearly, and it can measure the ignition temperature of pulverized coal accurately. The Further improvements of the facility are presented.

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Polystyrene latex particles showed gas-liquid condensation under the conditions of large particle radius （a ≫κ -1 ）and intermediate κa, where κ is the Debye-Hückel parameter and a is the particle radius. The particles were dissolved in deionized water containing ethanol from 0 to 77 vol.% settled to the bottom of the glass plate within 1 hour and, then, laterally moved toward the center of a cell over a 20 hour period in reaching a state of equilibrium condensation. All the suspensions of 1 and 3 μm in diameter and of 0.01-0.20 vol.% in concentration realized similar gas-liquid condensation with clear gas-liquid boundaries. A phase diagram of the gas-liquid condensation was created as a function of KCl concentration at a particle diameter of 3 μm, 0.10 vol.% in concentration, and 50:50 water/ethanol solvent at room temperature. The miscibility gap was observed in the concentration range from 1 to 250 μM. There was an upper limit of salt concentration where the phase separation disappeared, showing near critical behavior of macroscopic density fluctuation from 250 μM to 1 mM. These results add new experimental evidence to the existence of colloidal gas-liquid condensation and specify conditions of like-charge attraction between particles.

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A planar magnetron plasma system was developed for the research of fine particle plasmas. Fine particles were successfully confined above the center of loop of magnetron plasma forming a three-dimensional structure against the gravity. Distribution of plasma density and potential measured by the method of Langmuir probe suggests that the horizontal confinement of fine particles is caused by electrostatic force, while the vertical lifting is not caused by the force but by another mechanism. A small cubic magnetron plasmas system, which has a potential to drive fine particles to the center of plasma, was developed for microgravity experiments.

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Fine particle (dusty) plasmas provide us with a unique system in the sense that constituent particles are strongly coupled enough to manifest collective properties and, at the same time, their orbits are separately observed. We are thus able to investigate long-ranged statistical phenomena at the kinetic level. The only difficulty is the large effect of the gravity acting on fine but still macroscopic particles. Therefore the microgravity is the ideal environment of experiments for these purposes. Among many interesting phenomena, we have been especially working to observe peculiar behavior of thermodynamic quantities of strongly coupled plasmas as modeled by one-component plasma (OCP). This has been long known to be common in many systems including the Yukwa system but the possibility to observe in fine particle plasmas has been pointed out only recently by one of the authors (H. T.). After brief general introduction of fine particle plasmas, the critical point and related phenomena are described in relation to experiments under microgravity.

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The aim of this study is to investigate the effects of 2D clinostat-simulated weightlessness on biological characteristics of MLO-Y4 osteocyte-like cells. MLO-Y4 cells were incubated for 24 h and rotated using a 2D clinostat for 2 h. The bioeffects of clinostat culture on cellular morphology, cytoskeleton, and gene expression were investigated. The results show that 2D clinostat-simulated weightlessness induce actin cytoskeleton rearrangement, but unaffected the cellular morphology and number of processes/cell. Also, after 2 h of clinostat culture, expression of RANKL and IL-6 decreased by 19%±5% and 20%±4%, respectively, while cox-2 level increased by 65%±8%. These results provide some clue to explore the cellular mechanism of bone loss caused by weightlessness

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ECM-integrin-CSK system is normally considered as gravity-sensor of cell and most researches focus on the cytoskeleton (CSK). How about the extracellular matrix (ECM) protein? In previous work, we found that fibronectin (FN) gene expression in MG-63 cells under simulated weightlessness condition was increased significantly compared to other conditions and this result was verified by microarray test. Here the FN’s alterations of another human osteoblast like cell hFOB1.19 on the protein level under diverse gravitational condition were investigated. Both cellular FN and soluble FN were detected. More FN was expressed in hFOB1.19 cells medium after co-cultured with RGD-peptide and integrin antibody. These results hint that FN changes in altered gravity maybe involved with the interference of the interaction between FN and integrin.

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Weightlessness conditions result in bone loss, which may be partly attributed to the dysfunction of osteoblast. Random positioning machine (RPM) was often used to simulate the weightlessness effects on animal cells. The aim of this study was to explore the response of MC3T3-E1 osteoblast-like cells to the specific mechanical environment in RPM. The results showed that RPM exposure for 12 and 24 h inhibited the cell proliferation, and changed the cell shape for 12h, but had no effect for 48 h. The stress fibers of MC3T3-E1 cells cultured in RPM for 12 and 24 h disrupted detected by rhodamine-labeled phalloidin, but partially recovered for 36 and 48h. The cytosolic free calcium concentration ([Ca2+]i) of MC3T3-E1 cells cultured in RPM for 12 and 24h increased. The cell migration of MC3T3-E1 cells cultured in RPM inhibited for 12, 24, 36 and 48 h. Based on these findings, it appears reasonable to suggest that RPM affects the osteoblastlike cell shape, F-actin distribution, proliferation for 12 and 24 h, but the cells recovered for 36 and 48 h except cell migration. From these results, we conclude that MC3T3-E1 cells cultured in RPM at early stage could response to the new mechanical stress and display the weightlessness effects.

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As a preliminary experiment for the near future microgravity experiment, InxGa1-xSb bulk crystal was grown under 1G condition using GaSb(seed)/InSb/GaSb(feed) sandwich sample. In order to prepare the seed and feed crystals for GaSb(seed)/InSb/GaSb(feed) sandwich sample, GaSb single crystals with different orientations viz., , , were grown by CZ method. Moreover, heavily (1×1020 cm-3 in solution) tellurium (Te)-doped poly crystalline InSb sample was synthesized to prepare the sandwich sample. The effect of various heat pulses on the Te-impurity induced growth striations was investigated by introducing various kinds of heat pulses during the growth experiment. An appropriate heat pulse which is capable to produce a clear and thin striation was identified. Based on the observed growth striations, the growth rate of the crystal was roughly estimated.

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The low oxygen partial pressure Po2 of an ambient atmosphere is considerably effective for phase selection in the RMnO3 system, since the Mn ion changes its valence states depending on Po2. Containerless solidification of the undercooled RMnO3 melt was carried out to study phase formation behavior under precisely controlled Po2. The orthorhombic and hexagonal RMnO3 phases were solidified from an undercooled melt at Po2=105 Pa. X-ray diffraction patterns and cross-sectioned microstructure revealed the existence of orthorhombic and hexagonal RMnO3. Thermodynamic stabilities were studied at various temperatures. The oxygen deficiencies in the as-solidified samples were calculated through annealing at 105 Pa using TG-DTA. These results suggest that the containerless solidification is one of the most suitable methods for phase equilibrium study under controlled Po2.

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Sm-Fe magnetostrictive material was produced by unidirectional solidification of Sm-Fe alloy with atomic ratio from 1/2 to 2/17 in microgravity within ±4x10-3g for 1.43s obtained using 10-m drop tower and with fluctuating gravity between 0.1 and 0.02g obtained by parabolic flight. SmFe2 and a small amount of Sm2Fe17 as well as Fe were formed from unidirectional solidification in microgravity of Sm-7Fe alloy, obtained using the drop tower and parabolic flight. The structure consisted of sheet dendrites of SmFe2 and Fe-rich Sm-Fe layers between the sheet dendrites having no gaps with an orientation along the solidification direction. A crystalline orientation of of SmFe2 along the solidification direction was found in the products formed in microgravity using the drop tower, but not in those using parabolic flight. The formation mechanisms of SmFe2 sheet dendrites can be explained by microsegregation caused by the lack of convection in melt in microgravity. In contrast, Sm2Fe17 and a small amount of Fe were formed in normal-gravity, and the resulting structure consisted of sheet dendrites without orientation. Magnetostriction of -3328ppm at the outer magnetic fields of 0.12T was achieved on a sample synthesized by unidirectional solidification of Sm-7Fe in microgravity obtained using the drop tower.

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Using CO2 laser equipped electro-magnetic levitator, we carried out the crystallization of Si at undercoolings from 0 K to 200 K. From the point of the interface morphologies, the relationship between growth velocities and undercoolings was classified into two regions, I and II, respectively. In region I where the undercooling is approximately less than 100 K, thin plate crystals whose interface consists of faceted plane were observed. In region II, the morphology of growing crystals changed to massive dendrites. Although the interface morphologies look quite different between region I and II, the growth velocities are expressed by two dimensional (2D) nucleation-controlled growth model, and at undercoolings larger than 150 K, the growth velocities asymptotically close to the analysis of the mono-parametric linear kinetics growth model. In this stage, the kinetic coefficient of 0.1 m/sK is equivalent with that derived by the diffusion-controlled growth model. This result means that with increase of undercooling, the rate-determining factor changes from 2D nucleation on the faceted interface to random incorporation of atoms on the rough interface.

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Undercooling a melt often facilitates a metestable phase to preferentially nucleate. In the present study, the formation of a metastable phase from undercooled melts was investigated from the point of the competitive nucleation criterion. The classical nucleation theory shows that the most critical factor for forming a critical nucleus is the interface free energy γ. In fact, on the simple liquid such as the melt of a mono-atomic metal, Spaepen’s negentropic model regarding γ suggested the scaling factor α between γ and the entropy of fusion to be the decisive factor for forming the critical nucleus. However, recent numerical simulations such as the molecular dynamics or density functional theory show ambiguous relations between α and the crystal structures. Furthermore, in compound materials such as oxides, in which polyhedrons of oxygen are the structural units both in the solid and liquid phases, it is suggested that the decisive factor for forming the critical nucleus isn’t α but the entropy of fusion. According to this idea, we proposed the entropy-undercooling regime criterion for metastable phase formation and, using REFeO3 (RE: Rare-earth element) as the model material, experimentally verified the validity of the criterion.

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Cu2ZnSnS4 is used for chalcopyrite thin film solar cells with a high absorption coefficient and 1.5eV band-gap energy because elements of Cu2ZnSnS4 are non-toxic and abundant in the Earth’s crust. High performance chalcopyrite thin film solar cells with homogeneous composition and structure are expected to be produced by laser ablation of Cu2ZnSnS4 bulk. In order to synthesize the homogeneous Cu2ZnSnS4 bulk, the Cu2ZnSnS4 melt was solidified by splat solidification using braking of a drop tower. For the ground-based experiments, the melt sample was pushed by pressurized Ar gas that had a force equal to that of deceleration force of the drop tower, and was blown against Cu chill block to solidify. The solidified sample had homogeneous composition and no grain boundary; in contrast, the samples that were solidified by pressurized Ar gas and air-cooled in normal gravity had heterogeneous composition and grain boundaries.

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The authors already conducted a series of diamond thin film synthesis under high gravity with a centrifugal facility with DC-plasma CVD method. In present paper, the results of high gravity experiments with graphite rod heating will be reported. The effect of high gravity was confirmed by 1 G ~ 50 G experiments. On the bases of the experimental results of 1 G ~ 50 G experiments, 70 G experiments were performed. With 70 G experiments, diamond particles with (100) and (111) surfaces were observed. And the maximum particle size was 5 microns in diameter. In present study, high gravity effects for diamond synthesis were confirmed and reported.

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Powder-using processing such as ceramic processing and powder metallurgy is one of the powerful tools to provide advanced materials or parts difficult to fabricate by other processing routes. One of key technologies for powder-using process lies on compacting method, since packing microstructure determines performance and reliability of finished products. Settling powders under high centrifugal force can provide dense, homogeneous and defect-free powder compacts. In the present paper, we observe settling behavior of particles in slurry under centrifugal force, varying initial condition of slurries. The settling phenomenon is basically depicted by Kynch plot, showing that the compacting speed under centrifugal force is basically insensitive not only to initial concentration but also to viscosity of the slurries. This is great advantage for practical application of the HCP to powder-using processing.

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An ultracentrifuge experiment was performed on a pure liquid-indium at centrifugal acceleration field of 8.2x105 g at 300℃ for 100 hours. The isotope ratio measurements were performed on the centrifuged specimen, which was cooled and solidified before release the acceleration, with Secondary Ion Mass Spectrometer (CAMECA IMS-6f). 113In/115In isotope ratio on the specimen changed with negative gradient in the direction of centrifugal acceleration approximately 1.4%. The measurement result indicated that the heavy 115In isotopes moved in the direction of the centrifugal acceleration and the light 113In isotopes moved in the counter direction in the specimen.

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In order to perform microgravity experiments successfully, analysis of the experiments is strongly recommended by a primary investigator from the viewpoint of system engineering. Thermophysical property measurement using the PFLEX (Parabolic Flight Levitation Experiment facility) under the microgravity condition was analyzed. The experiment system was decomposed into subsystem and component levels, and a bottle neck for the experimental system was extracted, i.e. gravitational change as high as 1.5G during the climb-up phase. The numerical simulation of temperature and velocity fields of gas flow around the high temperature sample indicates that the conventional method for oxygen partial pressure control, i.e. a gas flow method in open space, can not control oxygen partial pressure under the 1.5G condition. Instead, we propose a new control model, i.e. gas flow at a velocity over 0.5 m/s using a glass tube, and CFD (computational fluid dynamics) verified that this model shows a good controllability of oxygen partial pressure even under the 1.5 G condition. The CFD program is more effective than empirical methods on board the aircraft, so as to optimize a gas flow condition.

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An inter-diffusion experiment between a ternary alloy of SnBiIn and pure Sn was performed using the shear cell technique on the ground. The capillary was set vertically and the SnBiIn sample was set in the lower side of the capillary. The obtained concentration profiles were smooth and were able to be fitted by theoretical functions. The diffusion coefficients of In and Bi obtained by fitting and corrections for the shear convection and the averaging effect agreed well with those obtained in a microgravity experiment performed in Foton-M2. Under assumption of the power law, the obtained data were lying on the same curves of temperature dependence as other available reference data of inter-diffusion of SnIn-Sn and SnBi-Sn. It was found that the addition of Bi to SnIn does not bother the diffusion of In and stabilizes the density layering to suppress convection in an experiment on the ground.

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An optical grid line method with image correlation analysis processor has been developed for study of the kinetics of buoyantthermocapillary convection，it gives out the information of liquid free surface of buoyant-thermocapillary convection in a rectangular cavity. In the present paper, the free surface deformations of the thin liquid layer and the thick liquid layer have been discussed and compared. The present experiment results prove that surface deformation is related with temperature gradient and the thickness of liquid layer. In other words that surface deformation depends on capillary convection and buoyancy convection.

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Design of condenser planned to be installed on boiling flow experiment on ISS was conducted. In this condenser, rectangular vapor tube was installed on flat type cold plate which had experienced on-orbit experiments. Arithmetic thermal model was constructed, which considered tube wall conductivity, heat transfer coefficient on condensation and cooling water flow. Specification of condenser which can condensate vapor of 400W was determined through analysis by this arithmetic model.

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A condenser system is manufactured and tested for ISS program on two-phase boiling flow experiments promoted by JAXA according to the analysis of thermal management in the experimental system. Eight rectangular copper tubes of which circular channel of 6mm in diameter are connected directly by U tubes and arranged in parallel on the given ISS cold plate. The maximum pressure loss of the tube is 7kPa in the experimental condition. FC72 and water of 23ºC are used as working fluid for boiling experiment and cold plate, respectively. Heat of 400W is able to transport to cold plate from FC72 steam at 45kg/h of water flow and higher liquid subcooling than 10K at the exit of condenser tube. Those test results have satisfied the requirements for condenser system in the ISS microgravity experiments on two-phase boiling flow.

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Bubble behaviors, particularly the number density, size and velocity of bubbles and other relevant factors, in quasi-steady pool boiling on a plain plate in microgravity aboard the Chinese recoverable satellite SJ-8 were reported and analyzed in the present paper. Degassed FC-72 was used as the working liquid in the space experiments. The heating voltage was controlled to increase exponentially with time to achieve quasisteady state of pool boiling process. It’s found that primary bubbles generated continually, slid on the surface, and coalesced with each other to form a larger coalesced bubble. The coalesced bubble engulfed small bubbles around it, and oscillated on the heating surface throughout the boiling process in microgravity. Generation of primary bubbles was also observed underneath the coalesced bubble. The growth rate of bubbles decreased with the increase of subcooling, which is caused by the strong condensation near the top of the coalesced bubble.

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The computational and experimental studies have been performed to investigate the process of liquid propellant reorientation flow dynamics for the tank of CZ-3A launch vehicle series fuel tanks in microgravity environment. The volume-of-fluid (VOF) method was used to simulate the free surface flow of gas-liquid. The process of the liquid propellant reorientation started from initially curved interfaces. The characteristic time of propellant reorientation flow was obtained from numerical simulation. The results agree well with the experiments. It’s found that the method of small thrust for liquid reorientation is effective and thrust impulse consumption for reorientation could be saved by using a small thrust Bond number. In addition, a series experimental investigation was conducted in the Drop Tower Facility of National Microgravity Laboratory of China. Preliminary drop tower experimental results shows that the sponge PMD is effective in holding the liquid in microgravity environment..

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Marangoni Experiment in Space (MEIS) has been conducted in the International Space Station (ISS) in order to clarify the transition processes of thermocapillary convection in liquid bridges. The use of microgravity allows us to generate long liquid bridges, 30mm in diameter and up to 60mm in length. Several flow visualization techniques have been applied to those large liquid bridges. 3-D PTV is used to reveal highly three-dimensional flow patterns that appear after the transition. Three CCD cameras are used to observe the motions of the tracer particles from different view angles through the transparent heated disk made of sapphire. Particle images are recorded in the HDD recording system in ISS and they are downloaded to the ground for data analysis. A conventional 3-D PTV technique and a newly-developed multiframe particle tracking method are combined to obtain the results that can help better understanding of oscillatory 3-D flow fields in the liquid bridges. It is shown that the flow pattern changes from a 2-D axisymmetric steady flow to an oscillatory 3-D non-axisymmetric flow under the supercritical conditions.

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