Yuko Inatomi

The Twenty-seventh Space Utilization Symposium (January 24-25, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa JapanTo know the formation process of cosmic dust particles, we attempted for the first time interferometric observation to a condensation experiment in vapor phase, the gas evaporation method. Homogeneous nucleation is a fundamental process of dust formation in universe. 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 quarter 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 ca.5 ms and then cool down with a rate of ca.5×10(exp 4) K/s. The degree of supersaturation during the nucleation was at least as high as 10(exp 7).Physical characteristics: Original contains color illustrations

Microgravity studies on the dissolution and crystallization of In_xGa_<i_x>Sb have been done using a sandwich combination of InSb and GaSb as the starting material using the Chinese recoverable satellite. The same type of experiment was performed under 1G gravity condition for comparison. From these experiments and the numerical simulation, it is found that the shape of the solid/liquid interface and composition profile in the solution was found to be significantly affected by gravity. The dissolution process of GaSb into InSb melt was observed by X-ray penetration method. GaSb seed was dissolved faster than GaSb feed even though the GaSb feed temperature was higher than that of GaSb seed temperature. These results clearly indicate that solute transport due to gravity affects dissolution and growth processes of alloy semiconductor bulk crystals.

The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan)This working group was started for joint research for thin films and fine powders of carbon and related materials, specially aimed for the future microgravity environmental experiment for diamond or fullerene synthesis. For this year, we tried synthesize diamond particles under pseudo-microgravity and high-gravity environment with closed reaction chamber.Physical characteristics: Original contains color illustrationsjoint hosting: The Science Council of Japan

The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan)FACET, which has been conducted onboard "Kibo" since April 9, 2009, was completed on June 12, 2009. FACET aimed to clarify the mechanism of a faceted cellular array growth by precisely observing the phenomena at the solid/liquid interface. Phenyl salicylate / t-butanol alloy was used as a sample material instead of semiconductors or oxides. The crystal growth processes were visualized in situ using a microscope and an interferometer, especially focusing on changes in temperature and concentration in the sample.Physical characteristics: Original contains color illustrationsjoint hosting: The Science Council of Japan

The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan)We are preparing for SiGe crystal growth experiments on board the ISS "Kibo". The two-dimensional model of the TLZ (traveling liquidus-zone) method will be studied by microgravity experiments because disturbance in constituent element by convection upon freezing is avoided in microgravity because convection in a melt is suppressed. For successful space experiments, growth conditions using a bread board model of a gradient heating furnace (GHF) for space experiments are examined. Design and fabrication of a FM cartridge are developed. Here, achievements in the present preparatory stage are reported.Physical characteristics: Original contains color illustrationsjoint hosting: The Science Council of Japan

FACET, which has been conducted onboard ``Kibo'' since April 9, 2009, was completed on June 12, 2009. FACET aimed to clarify the mechanism of a faceted cellular array growth by precisely observing the phenomena at the solid / liquid interface. Phenyl salicylate / t-butanol alloy was used as a sample material instead of semiconductors or oxides. The crystal growth processes were visualized in situ using a microscope and an interferometer, especially focusing on changes in temperature and concentration in the sample. Some experimental results were briefly reported in the present paper.

We introduce a growth technique to grow homogeneous In_xGa_<1-x>Sb ternary bulk crystal and a method to measure the composition profiles in the InGaSb solution. In_xGa_<1-x>Sb bulk crystal was grown on a GaSb seed under a constant temperature gradient using a GaSb (seed)/InSb/GaSb (feed) sandwich sample. During growth, heat pulse technique was applied to estimate the growth rate. Homogeneous In_<0,03>Ga_<0.47>Sb crystal was grown by cooling the sample at an optimized value estimated by the temperature gradient and the growth rate. It was also demonstrated that the X-ray penetration method was a good method to measure the composition profiles in the solution.

Diamond synthesis under microgravity environment with parabolic flights by DAS and rocket by JAXA was reported. Gaseous species on the reaction chamber were detected and analyzed with OES (optical emission spectroscopy), under terrestrial gravity environment and microgravity environment, and we expected that synthesized diamond particles might have some deferent morphology compare with terrestrial conditions. Unfortunately, this particular launch was not retrieved, so we don't have our diamond samples for confirm SEM and Raman spectra.Key wards: Diamond, Space Utilization, OES(optical emission spectroscopy)

The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan)Achievement of an extremely weak state of natural convection by utilization of microgravity environment is regarded as a promising method which leads us to investigate the influence of convection on growth process from liquid phase on the terrestrial condition. A main subject of this working group is to make proposals for microgravity experiments concerning to a bulk crystal growth from solution or from melt. In this fiscal year the working group performed the following subjects: (1) in situ observation experiment under a short-duration micro G using the S-520-24 sounding rocket, (2) preparation for crystal growth experiment of InGaSb on ISS, and (3) some exploratory experiments related to the above subjects.

The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan)We are preparing for crystal growth experiments in microgravity using a gradient heating furnace (GHF) on board the ISS "Kibo". The two-dimensionality in the traveling liquidus-zone (TLZ) growth should be avoided for obtaining large scale compositionally uniform alloy crystals. Factors affecting one-dimensionality are further studied theoretically and verification items are extracted. Cartridge design and fabrication of an engineering model are progressed. Here, achievements in the present preparatory stage are reported.

The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan)We have reported containerless diffusion experiments of Si-Ge and Al-Ag at the last symposium. Here the 3-dimensional concentration distributions after processing were investigated by X-ray CT using synchrotron radiation at SPring8. In this result, history of convection was observed, mainly because the densities of diffusion couple were too different. Therefore we additionally developed an electromagnetic-aerodynamic levitation equipment in a static magnetic field for improving temperature profile and using In-Sn as a diffusion couple.

The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan)This working group was started for joint research for thin films and fine powders of carbon and related materials, specially aimed for the future microgravity environmental experiment for diamond or fullerene synthesis. For this year, we tried synthesize diamond particles under microgravity environment with parabolic flights by DAS and rocket by JAXA.

A novel method for micro-gravity experiments using high altitude balloon is now under development in JAXA. The notable feature of this system is its double-shell structure. Dropped from the high altitude balloon, the inner shell falls freely for 30 to 60 seconds because the outer shell is controlled not to collide with the inner shell. Sixteen number of cold gas thrusters are installed on the vehicle to control not only its falling attitude but also spacing between the inner shell and the outer shell. This paper presents design strategy and verifi cation test results of the 50 N cold gas thrusters developed for this micro gravity experimental system. The preliminary results of the fl ight test are also presented to show its feasibility.

This paper proposes control system for a new micro gravity experimental system called BOV (Balloon-based Operation Vehicle). BOV uses a free-fall capsule with double-shell structure to prevent influence of aerodynamic disturbance. Additionally, BOV is raised to 40km by a high altitude balloon to extend micro gravity duration to 30 (or possibly 60) seconds. Thus we realize a medium duration micro gravity experimental system with good micro gravity environment. In this system, the most characteristic point is double-shell structure to realize drag-free system. The inner shell can fall freely since the outer shell is controlled not to collide with the inner shell. In the experiments, we realize good-quality micro gravity and realize to continue moderate micro gravity duration. This system is now improving and near future we can practically utilize BOV's system for moderate micro gravity duration with low-cost easily.

To realize micro-gravity environment of long duration and good quality with moderate cost, an experimental system which is released from a high altitude balloon has developed. The system has a double-shell drag-free structure and the outer shell, namely flight capsule, is controlled not to collide with the inner shell to realize micro-gravity environment of good quality. This paper shows the design philosophy and the configuration of the system. The system was successfully tested twice, in May, 2006 and in May, 2007. Outline of the test results and future development plan are also described. Key Words: High-altitude balloon, Micro gravity, Drag-free, Supersonic.

The scientific balloons have been used for varios space missions including the micro gravity experiments. To ensure the long experiment time, we developed the high altitude balloon using thin main shell covered by additional caps.This technique is to evaluate the possible maximum strain on the balloon film at various flight altitude assuming the axis symmetrical shape conserving the surface density and support the weak points by adding more films as caps. In this paper,after reviewing the balloon experiment and basic equations to determine the balloon shape,the capping technique will be introduced and its applications to the micro gravity experiment will be described.

A novel way to conduct microgravity experiments using high altitude balloon is now under development at ISAS/JAXA. By dropping the rocket shaped vehicle from the high altitude balloon, high quality microgravity environment can be served during its free fall of 30 to 60 sec. This paper summarizes the outline of free fall vehicle, which is called as BOV (Balloon based Operation Vehicle). The preliminary results of its second flight test are also presented to show its feasibility.

In situ observation experiments of faceted cellular array growth are carried out in transparent organic alloy, salol - t-butyl alcohol in a microgravity condition on the Japanese Experiment Module “KIBO” of International Space Station. Growth rate of the crystal, and temperature and solute concentration fields in the melt are simultaneously measured by an amplitude modulation microscope and by a Mach-Zehnder interference microscope in order to evaluate the morphological instability of the solid/liquid interface taking account of released latent heat in faceting material.

Our purpose is the diffusion coefficient measurement using containerless processing to clarify the mass transfer mechanism in high temperature melts. Therefore, diffusion experiments as couples of molten Si-Ge and Al-Ag alloys have been performed using electromagnetic levitator combined with superconducting magnet. In this result, possibility of diffusion coefficient measurement in levitated melts applied static magnet field can be suggested, because the convection becomes efficiently slow.