羽生 宏人

Ammonium dinitramide (ADN)-based energetic ionic liquid propellants (ADN-EILPs) present considerable potential as monopropellants due to high energy density, high thermal/chemical stability, and low toxicity. Consequently, a chemical thruster system based on ADN-EILPs can be employed in the development of high-performance ultrasmall/small satellites. However, the characteristics of the ADN-EILPs present various problems in their ignition during the thruster development. To solve this problem, the authors have previously achieved the continuous-wave (CW) laser ignition of ADN-EILPs using laser absorbers composed of carbon wools. However, the conventional propellant injection of ADN-EILPs with carbon wool using high-pressure gas faces several limitations. Therefore, a propellant feed system suited for the ignition method is proposed here, as well as a conceptual model of a 0.5 U/0.5 N-class thruster operated by the CW laser ignition of ADN-EILPs (1U=100 x 100 x 100 mm). Additionally, an attempt is made to manufacture a laboratory model (LM) thruster, and its fundamental operation properties are determined. The future research implications of this study include the further observation of the combustion of the decomposed gas before its emission from the throat of the LM thruster, along with the further development of the propellant feeding system proposed in this study and the hot-fire tests performed for the feeding systems.

A detonation engine system is successfully demonstrated for the first time in space using sounding rocket S-520-31 of the Japan Aerospace Exploration Agency/Institute of Space Astronautical Science. Detailed flight results of an S-shaped pulse detonation engine (PDE) installed in the rocket are presented herein. The flight is conducted to confirm that the PDE and its system operate at scheduled sequences in space, confirm the reproducibility of the PDE cycle, and despin the rocket around its axis. It is confirmed that the PDE operated successfully for 14 cycles in space. The experimental plateau pressure of 2.0 0.1 MPais 80 3% of the calculated plateau pressure, which suggests that detonation occurred in 14 cycles. The pressure profiles of the cycles are similar, and the pressure integrals are 2.0 0.1 kN⋅ s∕m2, confirming the excellent reproducibility of the PDE cycle. A probability statistical approach assuming a Gaussian distribution is applied to determine the average angular acceleration difference between processes of the PDE operation, mixture supply, and oxygen supply. The results suggested that the PDE despun the rocket via the thrust produced via detonation combustion, which is consistent with a quasi-steady-state model with an accuracy of 101 15%.

To create a new flyable detonation propulsion system, a detonation engine system (DES) that can be stowed in sounding rocket S-520-31 has been developed. This paper focused on the first flight demonstration in the space environment of a DES-integrated rotating detonation engine (RDE) using S-520-31. The flight result was compared with ground-test data to validate its performance. In the flight experiment, the stable combustion of the annulus RDE with a plug-shaped inner nozzle was observed by onboard digital and analog cameras. With a time-averaged mass flow of [Formula: see text] and an equivalence ratio of [Formula: see text], the RDE generated a time-averaged thrust of 518 N and a specific impulse of [Formula: see text], which is almost identical to the ideal value of constant pressure combustion. Due to the RDE combustion, the angular velocity increased by [Formula: see text] in total, and the time-averaged torque from the rotational component of the exhaust during 6 s of operation was [Formula: see text]. The high-frequency sampling data identified the detonation frequency during the recorded time as 20 kHz in the flight, which was confirmed by the DES ground test through high-frequency sampling data analysis and high-speed video imaging.

2021年7月27日早朝5：30，JAXA内之浦宇宙空間観測所からデトネーションエンジンシステムを搭載した観測ロケットS-520-31号機が打ち上げられた．高度約200kmにてメタン–酸素推進剤による回転デトネーションエンジン（RDE）の6秒間作動およびパルスデトネーションエンジン（PDE）の2Hz作動を実施した．取得されたフライトデータから，RDE作動で時間平均推力518N，比推力290±18sおよび速度増速量8.0m/sを達成した．PDE作動では1サイクル当たりの圧力時間積分値が5％以内の高精度での繰り返しインパルス生成およびロケット機軸周りのスピンレート減少が確認された．本結果は，地上燃焼試験データとよく一致し，宇宙空間でのデトネーションエンジン作動が実証された．デトネーション波の判定に用いた圧力・加速度センサの高速サンプリングデータおよびRDEプルーム撮影用のデジタルカメラ画像は，JAXA/ISASで開発された再突入データ回収システムRATSにて回収することに成功した．

In this study, the viscosity characteristics of bimodal Al/hydroxyl-terminated polybutadiene (Al/HTPB) suspensions were experimentally investigated to improve the propulsion performance and manufacturability of low-cost solid propellants with ease of application. Several Al particles with different mean volume diameters were used to prepare the bimodal Al. The Al/HTPB suspensions behaved like a continuum in solid propellant slurries. The reason is that Al particles were sufficiently small for ammonium perchlorate particles. The suspension viscosities were measured using a rotational viscometer at 1.92 s ^-1. The optimum coarse fraction of Al particles in the bimodal Al/HTPB suspensions was 0.75. The viscosity of bimodal Al/HTPB suspensions was suppressed with an increase in the diameter ratio. These results were attributed to the improvement of Al packing in the suspensions. The experimental results show that the viscosity reduction by applying bimodal Al particles was more effective when the minimum void fraction was reduced. Furthermore, the performance enhancement of solid propellants was confirmed by adding the bimodal Al/HTPB. The calculation results showed that the bimodal Al/HTPB enhanced the propulsion performance of the propellant without the viscosity variation to a higher side. Moreover, the suppression of viscosity of up to 23 % could be achieved using the bimodal Al/HTPB similar to the conventional composition of solid propellants. Therefore, replacing monomodal Al particles with bimodal ones in solid propellants effectively improved the performance of the propellants.

Ammonium dinitramide-based ionic liquids (ADN-EILPs) are a promising alternative to hydrazine monopropellants. Continuous wave (CW) laser heating using carbon wools is an effective approach to attain the rapid ignition of ADN-EILPs. This study aims to verify the influence of the dispersibility of carbon additives in ADN-EILPs on their ignition. The investigation was performed by performing fluorescence microscopy of samples imitating the mixture of ADN-EILPs with carbon additives and CW laser ignition tests of ADN-EILPs with several yarn-lengths of carbon wools. Based on these results, the dispersity mechanism of carbon additives in ADN-EILPs is proposed, which indicates that the use of high-power laser is not an effective approach to ignite ADN-EILPs consisting of carbon additives with high dispersibility. During sample preparation for the ignition tests, it was verified that the difference in the length of carbon yarns affects the bulk density and morphology of the prepared samples, and dispersibility of carbons. The results of the ignition tests indicate that samples whose morphology altered into a liquid-like morphology cannot be ignited and the ones who retained their original one can be ignited. The physical distribution of the residue of samples with a liquid-like morphology, observed after the ignition tests, agrees with the discussion regarding the dispersibility mechanism of carbon additives, obtained through fluorescence microscopy. Moreover, for the samples exhibiting an ignition capacity, the bulk density of additives would be crucial to be considered to achieve the effective ignition.

This paper presents the results of an S-shaped pulse detonation engine (PDE) ground firing test in the form of a detonation engine system. The world's first technology demonstration of PDE in space using a sounding rocket is planned, and the aim is to control the rocket spin rate in the axial direction using pulsed detonation. The PDE operation at full sequence was successful. The despin rate change of the rocket between continuous oxygen supply and successful PDE operation is expected to be 0.95 deg/s per run. This change in despin rate can be measured by an onboard gyro sensor, making the system flyable. The test results were compared with data from thrust measurement tests conducted in a laboratory, the results of which confirmed the thrust generation under an ambient pressure of 0.5 & PLUSMN;0.1 kPa. The average thrust values in the thrust measurement experiments showed good agreement of 101 & PLUSMN;3% with a quasi-steady-state model introduced to predict the PDE thrust. These results demonstrate the feasibility of the newly developed PDE and its system as the world's first technology demonstration of detonation propulsion in space.

We have been developing an ignition system for small satellites that uses energetic ionic liquid propellant (AMU) containing ammonium dinitramide (ADN), monomethylamine nitrate (MMAN), and urea. In this study, we investigated the effect of adding copper compounds to AMU in promoting the exothermic reaction of AMU in the condensed phase and increasing its ignitability by heating. We found that 2 wt% of basic copper nitrate (BCN) can dissolve in AMU. We used differential scanning calorimetry, thermogravimetry-differential thermal analysis, and a digital microscope to observe the condensed-phase reactions of ADN/BCN, MMAN/BCN, urea/BCN, and AMU/BCN mixtures, and we analyzed the thermal behavior to investigate the influence of BCN on their exothermic reactions. Although BCN dissolved by forming a complex with MMAN, it did not affect the initial exothermic reaction of AMU. BCN promoted the exothermic reaction at high temperatures, and the gross calorific value of the condensed-phase reaction was increased. Hence, adding BCN can potentially improve the ignitability of AMU. The promotion of exothermic reactions was attributed to the decomposition of the copper complex to copper oxide, which promotes the exothermic reaction of MMAN and ammonium nitrate, resulting from the decomposition of ADN.

© 2020. The Authors. We investigate the forces and atmosphere-ionosphere coupling that create atmospheric dynamo currents using two rockets launched nearly simultaneously on 4 July 2013 from Wallops Island (USA), during daytime Sq conditions with ΔH of −30 nT. One rocket released a vapor trail observed from an airplane which showed peak velocities of >160 m/s near 108 km and turbulence coincident with strong unstable shear. Electric and magnetic fields and plasma density were measured on a second rocket. The current density peaked near 110 km exhibiting a spiral pattern with altitude that mirrored that of the winds, suggesting the dynamo is driven by tidal forcing. Such stratified currents are obscured in integrated ground measurements. Large electric fields produced a current opposite to that driven by the wind, believed created to minimize the current divergence. Using the observations, we solve the dynamo equation versus altitude, providing a new perspective on the complex nature of the atmospheric dynamo.

© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Ammonium dinitramide–based energetic ionic liquid propellants (ADN-EILPs) exhibit the advantages of high energy density, low toxicity, and handling safety, and are therefore promising monopropellants. Herein, we characterized the ignition of ADN-EILPs induced by CW laser heating in the presence of carbon fibers, clarifying the effect of laser power and suggesting that ignition reproducibility is influenced by the difference of ADN-EILP osmotic state in carbon fibers or carbon fiber configuration. The observed ignition behavior allowed one to conclude that (i) high-power CW laser heating causes the formation of bubbles on the surface, which disturbs further heating; and (ii) an Arrhenius-type relationship exists between ignition delay and heating rate, suggesting that the strategy of foreshortening ADN-EILP ignition delay by increasing CW laser power has certain limits.

© 2019 IAA This paper investigates the launch capability of the SS-520 as a CubeSat launch vehicle. The SS-520 was developed by JAXA originally as a two-stage, spin-stabilized, solid-propellant sounding rocket. With less than 2.6 tons in total mass and 10 m in length, the SS-520-5 successfully launched a single 3U-sized CubeSat into orbit on February 3, 2018. The SS-520-5 obtained its capability as a CubeSat launch vehicle by installing a 3rd stage solid motor in addition to the RCS between the 1st and 2nd stages. However, its launch capability was limited due to its rocket system configuration. In order to pursue the SS-520's launch capability, two effective modifications from the SS-520-5 are proposed: thrust enhancement of the 1st stage motor and installation of an additional RCS between the 2nd and 3rd stages. The framework of launch capability analysis is established by a multi-objective genetic algorithm (MOGA), where its two objectives are selected as the altitudes of perigee and apogee. The analysis reveals that the two proposed modifications to the SS-520-5 work effectively but differently. The 10% increase of the 1st stage enhancement is particularly effective when the target altitude of perigee is low (e.g., 200 km), whereas the installment of the additional RCS with 30 kg increases accessibility to a much higher altitude of perigee, even to circular orbit reaching altitudes of 550 km for a 1U-sized CubeSat and 280 km for a 6U-sized CubeSat. The simultaneous application of both modifications would result in launch capability able to deliver a 10-kg payload. From a more general perspective, the results in this paper suggest that it is possible for a very small launch vehicle (VSLV) of the 3-ton class and 10 m in length to deliver a 10-kg-class payload into low Earth orbit.

Ammonium dinitramide (ADN)-based energetic ionic liquid propellants (ADN-EILPs) are promising monopropellants with high energy density, high thermal/chemical stability, and low toxicity. To predict the ignition and combustion characteristics of ADN-EILPs, this study aimed to construct a detailed reaction model of ADN-EILPs in the gas phase by combining conventional thermal decomposition models of the components in ADN-EILPs, the NO2 chain-growth reaction cycle, and additional reactions based on hydrogen abstraction between component species of ADN-EILPs and two radicals, NO2 and OH. The additional reactions were computed using quantum chemistry calculations. The structures of the reactants, products, and transition states were optimized at the omega B97XD/6-311G++(d,p) level of theory, and the total electron energies of these optimized structures were determined at the CBS-QB3 level. The simulated results with the constructed detailed chemical reaction model (EILPs-G-01 model) agreed with the experimental results at approximately 1.2 MPa. The EILPs-G-01 model revealed that the gas-phase combustion of ADN-EILPs has three reaction cycles depending on the radical-related reactions. Moreover, the EILPs-G-01 model clarifies the relationships between the pressure deflagration limit of ADN-EILPs and the weight ratio of methylamine nitrate in the ADN-EILPs.

© 2020, Univelt Inc. All rights reserved. ISAS/JAXA has successfully launched the micro-satellite “TRICOM-1R” by the world’s smallest orbit rocket “SS-520 No.5” from Uchinoura Space Center on February 3rd in 2018. ISAS modified the existing sounding rocket SS-520 adding a small 3rd-stage solid-motor and the attitude control system. It flies spinning for the attitude stabilization in the flight. Therefore, we devised the rhumb-line control system with a new scheme. This rhumb-line system has the high-performance functions; the high-preciseness, the high-maneuver rate and the suppression of the unnecessary nutation angle generated at the RCS injection. This paper reports the development of the G&C system and the flight results.

© 2019, Akadémiai Kiadó, Budapest, Hungary. Thermal and evolved gas analyses were carried out to assess the decomposition of an ionic liquid propellant consisting of ammonium dinitramide (ADN), methylammonium nitrate (MMAN) and urea, using thermogravimetry–differential scanning calorimetry–high-resolution time-of-flight mass spectrometry (TG–DSC–HRTOFMS). This technique simultaneously assesses the thermal and evolved gas behavior and is able to distinguish between products having similar mass-to-charge ratios, based on accurate mass determinations. ADN/MMAN and ADN/MMAN/urea mixtures were found to decompose to form NH3, H2O, HCN, CO, N2, CH2O, CH3NH2, HNCO, CO2, N2O and HNO3, and possible reaction schemes for the decomposition processes were developed. Interactions between ADN and MMAN appear to enhance the generation of N2, while the presence of urea reduces the net exothermic heat of reaction due to the endothermic pyrolysis reaction of urea to NH3 and HNCO, followed by the reaction HNCO + H2O → NH3 + CO2.

© 2019, Akadémiai Kiadó, Budapest, Hungary. Ammonium dinitramide (ADN) is a promising high energy oxidizer for rocket propellants because it offers a good oxygen balance and has a significant energy content. As a result, ADN-based energetic ionic liquid propellants (EILPs) have been studied, based on ADN combined with urea and monomethyl ammonium nitrate (MMAN). The thermal decomposition of ADN in the condensed phase affects the combustion of both pure ADN and ADN-based EILPs; thus, it is important to understand the reactions of EILPs in the condensed phase. The present study assessed the reactivity of ADN mixtures in the condensed phase, focussing on hydrogen abstraction reactions with NO2· formed from the thermal decomposition of ADN. The potential energy surfaces of these reactions were obtained using ab initio calculations. The effects of functional groups and of carbon chain length on hydrogen abstraction by NO2· were examined. Mixtures of ADN with urea and acetamide (AA) as amide compounds, and with MMAN and monoethanol amine nitrate (MEAN) as nitrate salts, were examined. Thermal analysis was conducted to investigate the properties of these mixtures, using differential scanning calorimetry (DSC). The calculation results shows that AA and MEAN are more reactive with ADN than urea and MMAN, which is supported by the DSC data. Hydrogen abstraction by NO2· is evidently an important condensed phase reaction in ADN mixtures, and substances having alkyl groups and longer carbon chains are more highly reactive.

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The ignition system for ammonium dinitramide-based non-solvent ionic liquids (ADN-EILPs) with a continuous-wave (CW) laser was investigated. The efficiency of conversion from CW laser power to ignition energy for ADN-EILPs is important, and carbon additives are expected to enhance the efficiency of conversion. The impact of additive shapes on ADN-EILP ignition by CW lasers is discussed herein by comparing the results of the ignition behavior observation using a high-speed infrared camera. The shapes of the carbon additives are of two different types: fine fiber mass, called carbon wool, and powder of graphite. The ignition delay of carbon wool mixed ADN-EILPs is shorter than that of the sample with graphite powder. The difference in these results might depend on the low dispersibility in ADN-EILPs of carbon wools and the presence of local heat spots owing to the CW laser. The addition of carbon wools in ADN-EILPs is expected to facilitate their ignition by CW laser heating.

© 2018, Akadémiai Kiadó, Budapest, Hungary. This paper focuses on the thermal behavior of mixtures of ammonium dinitramide (ADN) and amine nitrates. Because some mixtures of ADN and amine nitrate exhibit low melting points and high-energy content, they represent potential liquid propellants for spacecraft. This study focused on the melting behavior and thermal-decomposition mechanisms in the condensed phase of ADN/amine nitrate mixtures during heating. We measured the melting point and exothermal behavior during constant-rate heating using differential scanning calorimetry and performed thermogravimetry–differential thermal analysis–mass spectrometry (TG–DTA–MS) to analyze the thermal behavior and evolved gases of ADN/amine nitrate mixtures during simultaneous heating to investigate their reaction mechanisms. Results showed that the melting point of ADN was significantly lowered upon the addition of amine nitrate with relatively low molecular volume and low melting point. TG–DTA–MS results showed that the onset temperature of the thermal decomposition of ADN/amine nitrates was similar to that of pure ADN. Furthermore, during thermal decomposition in the condensed phase, ADN produced highly acidic products that promoted exothermic reactions, and we observed the nitration and nitrosation of amines from the dissociation of amine nitrates.

<p>本解説では，超小型衛星打上げ機（SS-520 4号機および5号機）の計画立案から打上げ実験について総括した．本ロケット実験は，先進的な民生技術を実装した宇宙機器の宇宙実証実験として計画立案され，宇宙科学研究所の観測ロケットを実行基盤として活用，準備からロケット打上げまで比較的短期間で実行した．2017年1月に打上げられたSS-520 4号機は，発射後約20秒で通信系の不具合が発生したため軌道投入実験を中断した．本報では推定原因究明の経緯を中心に述べた．2018年2月に打上げたSS-520 5号機により，超小型衛星TRICOM-1R（愛称たすき）の軌道投入に成功した．5号機実験を通じて4号機の不具合原因の推定および技術対策の妥当性や超小型衛星打上げロケットとしての成立性を実証することができた．そして，計画の主たる狙いであった宇宙機器に実装した民生品が宇宙機に適用可能であることを実証した．</p>

<p>In recent years, because development of space technology has been increasing for the purpose of improving social infrastructure, the expansion of space transportation system based on low-cost and high-frequency rockets is important. Due to the compactness, inexpensiveness, and easy-handling properties of solid propellants used in solid-fuel rockets, numerous studies on solid propellants have been conducted. However, solid propellants are highly viscous slurries and highly explosive. As there is no device capable of continuously and safely transporting the solid propellant, the process of manufacturing the solid propellant is a batch process. We focused on the movement of human intestines that knead and transport with a small force, as part of the development process. In this paper, we developed a peristaltic pump, Mk. III, for kneading a solid propellant. The pump was comprised of a heating system, an input device for the powder and fluid, and a rapid exhaust valve. An investigation into the amount of input of the raw materials was undertaken, and the tendency of kneading at the point of introduction of the powder and highly viscous fluid was determined.</p>

&lt;p&gt;Gel propellants have been recognized as future propulsion systems. Gel propellants are liquid fuels such as hydrazine, of which the rheological properties have been altered by the addition of gelation agents. Ammonium dinitramide (ADN) based energetic ionic-liquid propellants (EILPs) are expected to be used as replacements for hydrazine, which has high toxicity, and also for ionic liquid gel propellants (ILGPs). However, there have been few studies conducted on ADN based ILGPs. Here, ADN based ILGPs were prepared to obtain a better understanding of their thermal properties. The thermal behavior of the ADN based ILGP samples were measured using differential scanning calorimetry and the evolved gases were analyzed using thermogravimetry–differential thermal analysis with mass spectrometry. An ADN based ionic liquids (ILs) formed a gel using gelation agents of agarose and hydroxypropyl cellulose. The gas evolved from ADN based ILGPs was determined to be different from that from ADN based ILs due to reaction between the IL and the gelation agents.&lt;/p&gt;

Energetic ionic liquid propellants (EILPs) are expected to have applications in next-generation spacecraft propulsion, and ammonium dinitramide (ADN) is one of the most promising energetic materials for use in these propellants. The development of deep eutectic solvent systems, consisting of mixtures of two or more components, would allow the formulation of ADN-based EILPs that do not require traditional solvents. However, little is known regarding the effects of various additives on the melting point depression of ADN. In this study, the eutectic behaviors and melting points of small scale ADN mixtures with amide compounds or nitrate salts were investigated, using both visual inspection and differential scanning calorimetry (DSC). ADN/acetamide (AA) and ADN/monomethyl amine nitrate (MMAN) mixtures were found to be liquids at 60 degrees C, with the formation of a solid state at approximately 15 degrees C. Equimolar mixtures of ADN with AA, propionamide (PrA), MMAN and dimethyl amine nitrate (DMAN) each exhibited a eutectic point below 15 degrees C. The data show that equimolar mixing ratios are not ideal when formulating eutectic ADN compositions and that ADN-based EILPs have a tendency to supercool.

© 2016, Akadémiai Kiadó, Budapest, Hungary. Kinetics analyses were performed on the thermal decomposition of ammonium dinitramide (ADN) using thermogravimetry-differential thermal analysis–mass spectrometry–infrared spectroscopy (TG-DTA–MS–IR). The main evolved gases were determined to be NH3, H2O, N2, NO, N2O, and NO2. The apparent activation energies of the exothermic, mass-change and gas-evolving reactions were analyzed on the basis of Friedman methods. The apparent activation energy of evolving N2 has the same value as that of evolving H2O since they occur by the same mechanism. A Friedman plot obtained from the DTA data has a curve similar to those obtained from N2 and H2O. The reaction that generated N2 and H2O plays an important role in the exothermic reaction in the decomposition of ADN. The activation energy for the N2O evolution reaction has a range of approximately 120–152 kJ mol−1 with reaction progress values between 0.1 and 0.9. Quantum chemistry calculations revealed that the total energy barrier of dinitramic acid unimolecular decomposition and ammonium-dinitramic ions collision-induced decomposition is 149.9–156.0 and 160.6 kJ mol−1, respectively. These values are reasonable compared with the experimental value of 152 kJ mol−1.

Ammonium dinitramide (ADN) is one of the most promising new solid oxidizers for rocket propellants, sinceits oxygen balance and energy content are relatively high, and it does not contain halogens. To gain a betterunderstanding of the thermal decomposition mechanism of ADN, the thermal behavior and gaseous products fromdecomposition of ADN under pressurized condition (0.1-2.1 MPa) were investigated. The main reaction under allpressures was the decomposition of ADN to ammonium nitrate and nitrous oxide, although a new significantexothermic reaction was observed to occur beforehand. The relative amount of nitrogen dioxide decreased withincreasing pressure. These results of this work indicate that condensed phase reactions involving nitrogendioxide take place during the initial stage of the thermal decomposition of ADN. It was thought that thegeneration and decomposition of highly reactive materials to ammonium nitrate (AN) were promoted by nitrogendioxide, and the reaction mechanism changed when the amount of AN in condensed phase increases.

The liquefaction of highly energetic materials without the use of solvents is one means of increasing the performance of liquid propellants. In the present study, energetic ionic liquid propellants (EILPs) were prepared by forming eutectic mixtures of the oxidizer ammonium dinitramide (ADN) with monomethylamine nitrate (MMAN) and urea The physical properties, decomposition mechanism and combustion mechanism of these mixtures were assessed with the aim of eventually determining ignition methods and optimizing performance. Chemical equilibrium computations predict that the performance of ADN-based EILPs will be superior to that of hydrazine monopropellants. Thermal analysis of these EILPs during constant rate heating demonstrates that the majority decompose to generate various gases, including nitrous oxide, nitrogen dioxide, isocyanic acid, ammonia, carbon dioxide and water. Kinetics analysis also indicates that these EILPs can be safely stored for prolonged time periods at room temperature.

<p>In recent years, the demand for rocket launching has increased due to the development of space technology. However, using inexpensive rockets is not always possible. Although the cost of solid-propellant rockets is relatively reasonable, safely manufacturing a large amount of solid propellant is difficult, and the manufacturing process is disjointed. Therefore, safe and continues manufacturing of solid propellant is necessary. On the basis of the movements of the intestinal tract, we proposed that the movements required for transport and mixing of solid propellants are possible to achieve without the application of a large shear force. The peristaltic motion enables not only the mixing but also conveying even high viscosity slurry. By mimicking these intestinal movements, we have considered and developed the peristaltic pumping by driven artificial muscle as one of the candidates for the continuous and safety mixer. In this research, the mixing completeness of the composite solid propellant slurry by the peristaltic pumping mixer was estimated. The result showed that the mixer we proposed could mix the propellant slurry. In the propellant samples, these variances were sufficiently small. An appropriate combustion state as a solid propellant was confirmed.</p>

<p>As a replacement for hydrazine, ammonium-dinitramide-based ionic liquid propellant (ADN-based ILP) has been developed by JAXA and Carlit Holdings Co., Ltd. This propellant is made by mixing three solid powers: ADN, monomethylamine nitrate, and urea. The propellant's theoretical specific impulse is 1.2 times higher than that of hydrazine, and its density is 1.5 times higher at a certain composition. Although ionic liquids were believed to be non-flammable for a long time owing to their low-volatility, recently combustible ILs have been reported. The combustion mechanism of ILs is not yet understood. The objective of this paper is to understand the combustion wave structure of ADN-based ILP. The temperature distribution of the combustion wave in a strand burner test shows a region of constant temperature. This region would indicate boiling in a gas-liquid phase. Thus, the combustion wave structure consists of liquid, gas-liquid, and gas phases. The dependence of boiling point on pressure would identify chemical substances in the gas-liquid phase. The dependence of combustion and ignition characteristics on ADN content is also discussed. </p>

&lt;p&gt;The condensed phase decomposition reactions of ADN were investigated both experimentally and theoretically. Thermogravimetric-differential thermal analysis coupled with mass spectrometry (TG-DTA-MS) was employed to generate Friedman plots for the thermal decomposition of ADN with the evolution of N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt;. The activation energy associated with the evolution of N&lt;sub&gt;2&lt;/sub&gt;O during initial decomposition was found to be 150 kJ/mol. Chemical equilibrium calculations based on the reaction N(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; + NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; &lt;tt&gt;&amp;#8652&lt;/tt&gt; HN(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; + NH&lt;sub&gt;3&lt;/sub&gt; demonstrated that the concentration of HN(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; gradually increased with temperature, although the HN(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; to N(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; ratio was still only approximately 3.1 &amp;times; 10&lt;sup&gt;-6&lt;/sup&gt;, even at the decomposition temperature of 130&amp;deg;C. Thus, molten ADN was found to contain primarily N(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; and NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; with only minor amounts of liquid HN(NO&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; and NH&lt;sub&gt;3&lt;/sub&gt;. The reaction ADN &amp;rarr; N&lt;sub&gt;2&lt;/sub&gt;O + NH&lt;sub&gt;4&lt;/sub&gt;NO&lt;sub&gt;3&lt;/sub&gt; was also investigated using &lt;i&gt;ab-initio&lt;/i&gt; calculations at the CBS-QB3//&amp;omega;B97XD/6-311++G(d,p) level. It was determined that four reaction pathways are possible via different transition states. The energy barrier of 161 kJ/mol obtained from these calculations agreed with the experimental value.&lt;/p&gt;

The aim of this study was to fabricate moisture-proof, phase-stabilized, ammonium nitrate/potassium nitrate (AN/PN) particles, with a polymer used as the moisture-proofing agent. The particles were prepared with a spray drying technique. Water solutions (or water dispersions) containing AN/PN and one of five different types of polymer were spray-dried, which produced white powders with particle diameters of approximately 20-40m. Scanning electron microscopy and energy-dispersive X-ray spectroscopy indicated that each component was homogeneously distributed throughout the particles. The particles exhibited little aggregation compared to the reagent AN, even when left for 7d or more. In addition, the moisture absorption of the particles at less than 40% relative humidity (RH) was lower than that of the polymer-free particles. Even under high-moisture conditions (83% RH), the particles did not deliquesce immediately, and they retained their original shape for 30-60min, whereas the polymer-free particles were transformed into droplets within 5min.

Ammonium dinitramide (ADN) is one of the most promising new solid oxidizers for rocket propellants, since its oxygen balance and energy content are relatively high, and it does not contain halogens. To gain a better understanding of the thermal decomposition mechanism of ADN, the thermal decomposition of ADN and copper(II) oxide (CuO) mixtures was investigated. The thermal behavior and activation energy associated with the decomposition of ADN/CuO mixtures were analyzed using sealed cell differential scanning calorimetry (SC-DSC). SC-DSC results showed that CuO affects the thermal characteristics of ADN and promotes its decomposition. Thermogravimetry-differential thermal analysis-evolved gas analysis was also performed, and in addition, the decomposition behavior was observed using hot stage microscopy. From the results, a thermal decomposition mechanism was proposed for ADN/CuO. In this mechanism, copper dinitramide Cu[N(NO2)(2)](2) is generated at the surface of the CuO almost simultaneously with the melting of the ADN. Next, a significant exothermic reaction occurs, associated with the decomposition of Cu[N(NO2)(2)](2), followed by decomposition of CuO via [Cu(NH3)(2)](NO3)(2) and Cu(NO3)(2).

Ammonium nitrate (AN) is an affordable oxidant; however, it undergoes crystal structure transformations accompanied by a change in volume at comparatively low temperatures (approx. 30, 80, and 125 A degrees C) and exhibits high hygroscopicity. Both these properties are particularly problematic for the industrial application of AN. In a previous study, we prepared spray-dried particles comprising three components: AN, potassium nitrate (PN) as a phase stabilizer, and a polymer (e.g., polyvinyl alcohol, carboxymethylcellulose salt, and styrene-butadiene latex), which was confirmed to provide effective moisture proofing. In the present study, the crystal transformation behavior of AN/PN/Polymer particles is investigated by observing their thermal behavior by differential scanning calorimetry. The results reveal that phase-stabilized AN can be successfully prepared by the addition of PN. In addition, an intriguing possibility was identified in that carboxymethylcellulose ammonium salt and polyvinyl alcohol, which were both added as polymer components for moisture proofing, also acted as phase stabilizers for AN crystal transformation.

Certain properties of ammonium nitrate (AN), such as high hygroscopicity and the thermal transformation of the crystal structure accompanied by volume changes, pose problems for industrial applications of AN. To solve these problems, we previously prepared AN-based particles by spray-drying. The particles contained potassium nitrate (PN) as a phase stabilizer and a polymer (e.g., PVA, CMCs, and Latex) to produce a moisture-resistant material. Herein, we investigate the thermal decomposition of spray-dried AN/PN/polymer particles by differential scanning calorimetry and Thermogravimetry-Differential thermal analysis. Comparison of the thermal decomposition of AN/PN/polymer materials with different amounts and types of polymers suggested that thermal decomposition at lower temperatures resulted from the reaction of AN with the molten polymer or decomposition products derived from the polymer. Therefore, it can be concluded that the thermal stability of the AN/PN/polymer was exclusively determined by the thermal properties of the polymer components.

This paper reports on the thermal and combustion behaviors of ammonium dinitramide (ADN). The thermal behavior is measured by a pressure thermogravimetric analysis (TGA) at pressures below 8MPa. The burning rates of pure ADN and ADN/ammonium nitrate (AN) mixtures are measured in the range 0.2-12MPa, and the burning temperature profiles are obtained using thermocouples with diameters of 5 and 25m. This report mainly focuses on the condensed-phase behavior in the vicinity of a burning surface. The temperature profiles are complicated because the ADN decomposition and AN dissociation compete during the condensed phase, and the bubbles of the decomposition gas and gas-phase flame also affect the surface temperature. AN addition helps to understand the effects of AN during the condensed phase, and it was shown that the burning temperature rises to the critical temperature of AN. Based on these experimental results, the pressure dependency of the burning rates is also discussed.

The thermal decomposition behavior and combustion characteristics of mixtures of ammonium dinitramide (ADN) with additives were studied. Micrometer-sized particles of Al, Fe2O3, TiO2, NiO, Cu(OH)NO3, copper, CuO, and nanometer-sized particles of aluminum (Alex) and CuO (nano-CuO) were employed. The thermal decomposition was measured by TG-DTA and DSC. The copper compounds and NiO lowered the onset temperature of ADN decomposition. The heat value of ADN with Alex was larger than that of pure ADN in closed conditions. The burning rates and temperature of the pure ADN and ADN/additives mixtures were measured. CuO and NiO enhance the burning rate, particularly at pressures lower than 1 MPa, because of the catalyzed decomposition in the condensed phase; the other additives lower the burning rate. This negative effect on the burning rate is explained based on the surface temperature measurements by a physicochemical mechanism, which involves a chemical reaction, a phase change of the ammonium nitrate, and the blown-off droplets of the condensed phase.

Ammonium dinitramide (ADN) is a promising new oxidizer for solid propellants because it possesses both high oxygen balance and high energy content, and does not contain halogen atoms. A necessary characteristic of solid propellants is chemical stability under various conditions. This study focused on the thermal decomposition mechanism of ADN under pressurized conditions. The pressure was adjusted from 0.1 to 6 MPa, while ADN was heated at a constant rate. The exothermal behavior and the decomposition products in the condensed phase during heating were measured simultaneously using pressure differential scanning calorimetry (PDSC) and Raman spectrometry. PDSC analyses showed the multiple stages of exotherms after melting. The exothermal behavior at low temperatures varied with pressure. Analysis of the decomposition products indicated that ammonium nitrate (AN) was generated during decomposition of ADN at all pressures. At normal pressure, AN was produced at the same time as start of exotherm. However, the temperature at which the ratio of ADN in chemical species in the condensed phase began to decrease under high pressure was higher than that at atmospheric pressure despite the existence of significant exotherm. At initial stage, thermal decomposition of ADN that does not generate AN was thought to be promoted by increased pressure.

Pressure thermogravimetric-differential thermal analysis is used to study the thermal decomposition of ammonium nitrate (AN) in open and nonisothermal conditions as functions of the sample amount, heating rate, flow rate of purge gas, shape of sample pans, and pressure. The thermal decompositions are simulated using a physicochemical model. The thermal decomposition of AN consists of a chemical reaction and a thermal dissociation process-a physical process. The model considers thermal dissociation as a first-order diffusion model and succeeds in reproducing the experimental results. This method can be widely used for the thermal analysis of energetic materials.