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クエスト装置（球状トカマク）においては、高周波発生装置などを用いた電流駆動実験をおこない、定常運転の研究を行っている。長時間運転においては水素リサイクリング制御、及びプラズマと壁の相互作用の研究をおこなうことを目的の一つとしている。このため壁との水素リサイクリングを減少させ壁への水素吸蔵を減らすためには、壁の温度を高温に維持することが必要になる。このためクエストでは、2012年度からクエスト真空容器内部に新たに高温第一壁を設置し、高温化（300～500℃）する改造が東芝により進められてきた。2014年末にはこのうちコニカル部の設置が終わり、高温第一壁を加熱制御する加熱制御システム（スカイブルー製）と高温第一壁のコニカル部ヒータ及び熱電対の接続も完了した。ただし、真空容器等の冷却機構が現在のところ未整備（今後整備の予定）なので高温壁の加熱温度は200℃程度までに抑える必要がある。2015年初めには、高温第一壁ほか各部位の温度を測定する熱電対の全信号が記録できるよう計測器の整備が完了したので、200℃までの加熱をおこなった。今回、この高温第一壁を制御する加熱制御システムが正常に動作することが確認できたのでここに報告する。

冬季に火山噴火が発生した場合, 火山噴出物が積雪上に堆積して, 急激に融雪が起こり, 噴出物や斜面土層を巻き込んで泥流化する危険性がある。実際, この融雪型火山泥流による甚大な被害が発生した事例が数件報告されている。しかし, 発生条件が特殊である事や, 複雑なプロセスのためか, 研究はあまり進んでおらず, 発生機構はほとんど不明のままである。本研究では, 積雪層に温泉水を噴射し, 積雪層表面からの融雪と融雪水の浸透を観察する基礎的な実験を行った。実験の結果, 限定的な条件の下ではあるが, 以下の事項が明らかとなった。1)積雪層の融解は, 層の表面から進行した。2)融雪水は積雪層を浸透し, 水路底面に水面を形成した。3)浸透においては, フィンガリングと呼ばれる選択流路を伴う不均一な浸透挙動を示した。4)融雪が進行する速度よりも, 融雪水の浸透速度の方が大きく, 積雪層上には表面流は発生しなかった。, On hillsides of a volcanic mountain, mud flows sometimes occur due to snow melting by volcanic eruption, and cause severe damage to the down stream areas. Triggering mechanism of this type of mud flow is not revealed yet. In the present study, a fundamental experiment is conducted to understand the processes of snow melting and water infiltration to the snow layer using experimental flume and hot water splaying equipment. As the result of the experiment, it is revealed that 1) the snow layer melts from the surface, 2) the water infiltrates to the bottom of snow layer, 3) fingering infiltration behavior is a dominant water infiltration in snow layer at an early stage, and 4) infiltration rata of water in snow layer is larger than snow melting rate, therefore saturate water table doesn't develop on the snow surface.

The supercooled water is interesting subject in material science, atmospheric science and life science. Thermo-physical properties of undercooled water show that the maximum undercooling temperature is about - 45 C. However, direct observation of supercooled water at - 45 C has not been succeeded still now. Thus the experimental apparatus for observation of large undercooling of water at near - 45 C has been developed. This apparatus consists of the Radio-Frequency (RF) trap and the cryogenic devices. Using this system, it is possible to levitate micro size water droplet under 0 C. In this experiment, maximum undercooling temperature of water droplet was - 20 C. This temperature was higher than expected value from the results of thermophysical properties measurements. On the basis of the experiment, a new experimental system has been developed to achieve larger undercooling of water droplets. Using this new system, undercooling temperature of about - 45 C will be possible., 資料番号: AA0048095007

資料番号: AA0048140004, レポート番号: JAXA-SP-04-011

The experimental study on thermocapillary convection of low Prandtl number fluid was carried out to understand transition behavior to oscillatory flow. The half-zone liquid bridge of molten tin was formed between hot and cold disks in high vacuum chamber (10(exp -5) Pa). The three radiation thermometers were used to measure the free surface temperature at a different azimuthal location at the same time. In addition, the temperature distribution at interface between liquid bridge and cold disk was measured by using very fine thermocouples to detect the transition point and to make clear the oscillation mode more precisely. It can be detected that the steady thermocapillary convection changes to oscillatory under certain condition. The observed phenomena of transition processes after the oscillatory onset were revealed by comparing to numerical result done by Imaishi et al. The effect of aspect ratio (L/r) on critical Marangoni number was investigated. The critical Marangoni number decreases with increasing aspect number. This behavior agrees with numerical simulation done by Imaishi et al. qualitatively except for region of smaller aspect ratio. The surface tension and its temperature coefficient were measured in the experimental chamber. A molten tin droplet was formed on an alpha-Al2O3 substrate in the evacuated experimental chamber. These analog photo images were transfer to digital images and the surface tension was calculated from the outlines of digital image, which was the sessile drop method. The value of surface tension and its temperature coefficient were 520 to 550 [mN/m] and 0.097 [mN/m/K]. The Fe-Ni/SB tracer particle has been developed for the visualization of the inner flow pattern of the Marangoni convection. Considering the traceability of the particle, high wettability and low reactivity with surrounding fluid, and high sphericity are required. Therefore, the multi-layer structure, which comprises Fe and Ni layers, was adopted. The plating techniques of both Fe and Ni layers were developed and the heat treatment technique to make the high sphericity particles was also developed. The test particle has already been manufactured and its reflectance of ultrasonic beam has been evaluated., 資料番号: AA0046980006, レポート番号: NASDA-TMR-030004E

資料番号: AA0045913038

Experiments on waste fuel combustion in environments of high temperature and low oxygen concentration have been carried out to examine the fundamental characteristics such as flame development and stabilization of solid waste fuels which are produced from domestic and industrial fields. The ambient temperature and oxygen concentration in electric furnace can be set up at the range of 400 to 800 C and 3 to 21 percent by volume, respectively. The acquisitions obtained in the study as follows: 1) The combustion behavior of solid waste fuels can be classified by three process of ignition luminous flame and surface combustion, 2) the variation of each combustion behavior on stable and surface combustion regions shows an inverse relationship between ambient temperature and oxygen concentration., 資料番号: AA0045438045

The velocity of sound in liquid Sn was measured by the transmission method in the temperature range from 523 K to 773 K. Obtained results are in good agreement with previous data of the velocity of sound in liquid Sn. The estimation was performed for the isothermal compressibility and the structure factor in the long wavelength limit of liquid Sn by using the obtained velocity of sound., 資料番号: AA0033133009, レポート番号: NASDA-TMR-010019E

航空宇宙技術研究所の大型極超音速風洞では、空力加熱測定を赤外線カメラを用いて行っている。この赤外線カメラによる空力加熱測定法は、従来の離散的なセンサによる測定法に比べ、機体全体にわたる空力加熱を2次元的な面情報として捉えられるため、局所的なピーク加熱も捕捉できる点で優れている。また、これまで定量測定精度の問題が指摘されていたが、誤差量の見積もり、補正方法の確立、3次元マッピングソフトウェアの開発、従来型のセンサとの比較試験などを行い、総合的な測定精度として10％以内の測定が可能であることを確認した。赤外線カメラによる空力加熱測定法は、極超音速風洞における空力加熱測定の実用的なシステムとしてほぼ確立した。ここでは、赤外線カメラによる空力加熱測定法の概要と定量測定精度を高めるために行った誤差の検討と補正法、センサとの比較試験などについて報告する。, 資料番号: AA0032235012, レポート番号: NAL SP-51

Marangoni convection experiments have been conducted with acetone (Pr = 4.3) and methanol (Pr = 6.8) liquid bridges to investigate the flow structures and temperature fields during transition from steady to oscillatory convection in a half floating zone. The disk diameters of 5.0 mm and 10.0 mm were used for both fluids and the liquid bridge height was changed from 1.5 mm to 4.5 mm, covering aspect ratios from 0.3 up to 1.6. Various advanced measurement techniques were employed to yield detailed experimental data useful for both understanding the mechanism responsible for transition as well as verifying linear stability analysis and three-dimensional numerical simulation predictions. In order to reduce the surface evaporation rate, a quartz tube was fitted around the liquid bridge for both fluids. The liquid bridge shape data were obtained for both fluids covering a wide range of volume ratios for each aspect ratio and disk diameter. For acetone, the transition from steady to oscillatory convection was found to occur at disk temperature differences of 1.3 to 2.3 K, and liquid temperature fluctuations with amplitudes of 0.02 to 0.1 K were detected. For methanol, oscillatory flow appeared at disk temperature differences ranging from 1.6 to 4.3 K. For acetone, the transition was also accompanied by the appearance of an azimuthal component of surface velocity. At the same time, the toroidal vortex started to expand and contract in size, and the radial flow field started to rotate. Although the surface displacement was measured, surface oscillations could not be detected probably because of an insufficient driving force arising from small temperature differences. The critical Marangoni numbers for acetone were found to be higher than the values extrapolated from existing data, due to the effects of evaporation and added heat loss from the liquid surface. On the other hand, the critical Marangoni numbers for methanol showed good agreement with the existing data for a similar Prandtl number., 資料番号: AA0010763003, レポート番号: NASDA-TMR-000006E

宇宙往還機などの耐熱材料評価試験において表面温度の評定や内部への入熱量の推定を精度よく行うためには、高温での放射率を正確に知ることが極めて重要である。この放射率を試料移動法により試験温度範囲1,073Kから2,773Kまで計測する高温放射率計測装置が1993年に導入された。本装置により求められた放射率の値は、供試体の材質によっては装置の特性により、必ずしも満足した結果が得られないため補正が必要となった。そこで計測結果の精度向上を図るため、供試体に熱電対を埋め込みその計測値から放射率を算出する補正方法を考案した。その結果、比較的放射率の高い材料においてはほぼ妥当な値が求められ、放射率計測試験結果の精度向上の見通しが得られた。本報告は、装置の計測原理、装置構造の詳細な説明、データ補正方法および解析結果などについて述べる。, Emissivity is one of the most important parameters for evaluation the high-temperature behavior of refractory materials used in aerospace applications. An emissivity measuring apparatus (emissiometer) has been introduced for the development and testing of Thermal Protection System (TPS) materials. It can determine the emissivity under very high-temperature conditions up to 2,773 K. Built-in data reduction procedures were examined and a correction method was developed in order to obtain valid results. Analysis based on this method showed reasonable results on a graphite specimen. This paper outlines the apparatus and measurement principle are given first and a series of verification tests., 資料番号: AA0001070000, レポート番号: NAL TM-715

集合胴における温度分布とスロット壁に沿った試験部分の静圧分布を測定した。集合胴における温度分布は手で互に交差した2つの熱電対で測定した。集合胴における温度の変化は集合胴の壁に沿った熱的な境界層を除いてプラスマイナス1K以内であった。熱的な境界層の厚さは50ミリ以下であったが、脚部のどの部分よりも厚かった。試験部分の静圧の測定結果は、浮力効果が7.5ミリのAGARD-Bモデルの6カウント分の抗力上昇を引き起こす圧力傾斜を明らかにした。, Temperature distributions at the settling chamber and test section static pressure distributions along the slotted wall are dealt with. Temperature distributions at the settling chamber were measured by two thermocouple probes which were traversed by hand alternately. The variation in temperature at the settling chamber was within +/- 1 K except for the thermal boundary layer along the settling chamber wall. The thermal boundary layer thickness was less than 50 mm, but was more than any other station near the leg. Test section static pressure measurements revealed a pressure gradient whose buoyancy effect causes six counts of drag rise of the 7.5 mm AGARD-B model., 資料番号: AA0004161000, レポート番号: NAL TM-677

The experimental study on thermocapillary convection in the Half-Zone Liquid Bridge of low Prandtl number fluid was carried out. The Half-Zone Liquid Bridge of molten tin was used as test configuration. In order to detect the minute temperature fluctuation at second critical point, the temperature measurement system was improved. The behavior just after the onset of oscillatory convection was clarified., 資料番号: AA0048095031

The experimental study on thermocapillary convection of low Prandtl number fluid was carried out to investigate the transition behavior to oscillatory flow. The half-zone liquid bridge of molten tin was used as a test fluid. It can be detected that the steady thermocapillary convection changes to oscillatory under certain condition. It could be experimentally detected that a slow oscillation (approximately 0.02 Hz) appeared after the onset of oscillatory flow, and then the oscillation became faster (approximately 0.3 Hz) when the temperature difference increased. As for the experimental result, it matched the circumstance of the temperature vibration in the transition process of the thermocapillary convection which is expected with numerical simulation well., 資料番号: AA0046917049

Surface-tension-driven flow of molten silicon was investigated under microgravity and on earth for liquid bridge configuration. In order to investigate instability structure in a molten silicon bridge, observed were temperature oscillation and its phase relationship using thermocouples, oscillation of a molten silicon bridge surface using phase shift interferometry, oscillation of melt/solid interface position oscillation and so on. Instability structure shows azimuthal wave number m, depending on an aspect ratio of a liquid bridge: Gamma = h(height)/r(radius). Surface-tension-driven-flow shows oxygen partial pressure dependence of an ambient atmosphere. This is due to oxygen partial pressure dependence of temperature coefficient of surface tension., 資料番号: AA0045947018, レポート番号: NAL SP-56

In turning steels at elevated temperatures, the specific cutting force becomes remarkably small as compared with that at the room temperature, but the tool life should be taken into account at the same time. Thus, in hot machining, suitable selection of carbide tool materials is necessary. Therefore, the Author carried out an investigation on the behaviour of carbide tool materials in hot machining: the carbide tools used were S1, S2 and S3, and the work piece was a carbon steel (0.26 %C). The results of the experiment may be summarised as follows;-- 1. In hot machining, the tool life depends mainly upon its Titanium and cobalt contents. 2. For long economical tool life, preferably fine feed should be adopted at high cutting speed, but low cutting speed should be adopted for coarse feed., 高温切削を行う場合切削力は或る温度と或る作業条件の下では室温切削の場合に比して著るしく低減されることは第1報に詳細発表した通りである。然れども切削カが如何に低減されても使用する刃物の経済的寿命が極端に短命化する様では真に作業能率の飛躍とは言えない。故に高温切削に於いては被削材の材質及び加熱温度に適応した刃物を選定することが高温切削に於ける不可欠の要件であってその真価を発揮することとなる訳である。此の点に鑑み筆者は被削材として炭素量0.26%の炭素鋼を叉刃物材質には超硬合金パイトS_1, S_2, S_3の三種を選び室温並びに500℃の高温に於ける種々の作業条件に対するパイ卜の摩耗状況を観察し更らに各刃物に対するV-L曲線を見出し，これより或る作業条件に対する刃物の適性を究明した。

In this research, dilatation of the hypereutectoid steel at Ar_1 point was measured.Increment of the specimen's length cooled from 750℃ is almost twice of it cooled from 900℃ at Ar_1 point. The reason is that the proeutectoid cementite precipitates at the same time with the Ar_1 transformation. Cooling speed and the dilatation of the various carbon steels were measured. And the author noticed that the cementite precipitaton of the abnormal steel was slow than that of the normal steel., 炭素鏑の変態膨脹収縮に関する研究は，鉄鋼の研究に於ては最も基礎になるものであるから，古来多くの研究が発表されて居る。1899年，G.Svedelius & H. Lechatelierの研究以来，G. Charpy & L. Grenet, Rosenhain & Humfrey, W. Broniewsky, Benedicks, 日本でも今野，本多，菊田，佐藤，佐藤，の研究があり，A_1, A_3, A_4変態点及び変態量について測られて居り，更に1943年には木戸の測定がある。これらの殆んど大部分は平衡状態の決定を目的としたものであるが，そうでなければAr" 変態の研究であって，Ar'の挙動については殆んど触れて居らない。1940年前後に於ける鋼の変態理論に関する華かな討議の際に，例えばH. LangeはそのAr'変態理論に関して変態膨縮曲線を求めて居るが，高炭素鋼については極めて簡単に過ぎている。筆者は高炭素鋼の研究中に認めた特異な現象について既にその要旨を日本金属学会誌に報告して置いたが，以下，その報告を行うと共にその現象について考察した結果について述べる。