Faculty Profiles - KITAGAWA Koki

Report on the 68th Space Science and Technology Conference

KITAGAWA Koki, MATSUI Kohei, ITO Takahiro

Aeronautical and Space Sciences Japan ( THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ) 73 ( 6 ) 207 - 210 2025.06

Development status of a laser-initiated ignition device Reviewed

MATSUURA Yoshiki, KITAGAWA Koki, MATSUI Kohei, TOKUDOME Shinichiro, MORISHITA Naoki

Journal of Evolving Space Activities ( International Symposium on Space Technology and Science ) 2 ( 0 ) n/a 2025.02

Language：English Publishing type：Research paper (scientific journal)

Laser-initiated ignition systems (LIISs) have been developed with the aim of providing essential immunity to electrical disturbances. In the basic configurations of such systems, the electric circuits for generating the laser and detonator signals are electrically separated by a non-conductive optical fiber, increasing the resistance to ignition stimuli other than laser light on the detonator side. In this study, the various environmental resistance tests required for the detonators currently used in rockets were conducted for a new laser-initiated detonator (LID). As all of the tests show results satisfying the requirements, it is considered that the LID has reached the stage of practical use.

DOI： 10.57350/jesa.175

High-speed imaging of the combustion surface with high-intensity ultraviolet light during laser ignition of B/KNO3-based ignition charge

MONDORI Sasuke, SAGAWA Shunichi, ITAKI Ryuga, MATSUI Kohei, IWASAKI Akihiro, KITAGAWA Koki, YAMAGUCHI Soichiro

Proceedings of Space Transportation Symposium FY2024 2025.01

Construction of the Calculation Model to Clarify the Energy Conversion Ratio in the Entire Area of an LSD Wave Reviewed

ARAI Ten, MATSUI Kohei, KITAGAWA Koki

Journal of Evolving Space Activities ( International Symposium on Space Technology and Science ) 2 ( 0 ) n/a 2024.12

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

In laser propulsion, there is a method that uses the atmosphere as a propellant and laser energy from the ground. This method utilizes Laser Supported Detonation (LSD) in which a laser is absorbed and thrust is generated by detonation. To estimate the thrust of laser propulsion with LSD, the energy conversion ratio is an important parameter. The energy conversion ratio is the ratio of energy conversion from laser to working fluid. In a previous study, the energy conversion ratio was obtained experimentally and analytically, but the results have a large discrepancy. To eliminate the discrepancy, it is necessary a new calculation method for the energy conversion ratio. The purpose of this study is to establish a new method for calculating the energy conversion ratio across the entire LSD wavefront using the specific heat ratio of LSD obtained theoretically under the assumption of the Chapman-Jouguet state, and to evaluate the calculation method. The results show that the energy conversion ratios are 0.25 and 0.38 at the termination time under the laser energy of 8 and 10 J, respectively, which are close to the experimental values. This agreement could indicate that the newly proposed method for calculating energy conversion ratios is useful in laser propulsion.

DOI： 10.57350/jesa.191

Laser Ignition System for a Solid Kick Stage for Deep Space Missions Reviewed International journal

Naoki MORISHITA, Yoshitaka MOCHIHARA, Satoshi ARAKAWA, Masashi MIURA, Yuki SAKAMOTO, Yoshiki MATSUURA, Masanori SAKAINO, Toshiaki TAKEMAE, Shinichi TAKEDA, Shinsaku HISADA, Hirotaka IGAWA, Shinichiro TOKUDOME, Takeshi TAKASHIMA

Journal of Evolving Space Activities 2 ( 199 ) 論文ID:199 2024.12

Evaluation of Measurement System for Heat Transfer Characteristics ofLiquid Oxygen Flow in a Thin Tube under High Heat Flux Conditions Reviewed International journal

KITAGAWA Koki, MATSUI Kohei

Journal of Evolving Space Activities ( International Symposium on Space Technology and Science ) 1 ( 0 ) n/a 2023.06

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Heat transfer characteristics of liquid oxygen under high pressure and high heat flux should be elucidated to design a regenerative cooling nozzle for a hybrid rocket. Previously, we developed an experimental system using Joule heating to a thin tube in which liquid oxygen flows. The objective of this study is the evaluation of the measurement system to obtain the heat transfer characteristic under high pressure and high heat flux. We conducted a cold flow experiment and an experiment of heat transfer characteristic measurement. The friction factor of the tube is estimated with the Colebrook-White equation. The heat transfer coefficient was calculated by solving the heat conduction equation in the tube and the conservation laws of the fluid. The calculated heat transfer coefficient is in the same order as the experimental value. Consequently, we confirmed that experimental and analytical methods are appropriate to obtain heat transfer characteristics.

DOI： 10.57350/jesa.45

Function Test of Experimental System to Obtain Laser Ignition Characteristics of Low-Temperature Boron/Potassium Nitrate Reviewed International journal

MATSUI Kohei, MATSUURA Yoshiki, TOKUDOME Shinichiro, KITAGAWA Koki

Journal of Evolving Space Activities ( International Symposium on Space Technology and Science ) 1 ( 0 ) n/a 2023.06

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

In order to use laser ignition systems for solid rocket motors operating in deep space environments, it is necessary to elucidate the laser ignition characteristics of the ignition charge in low-temperature environments. This study aims to design an experimental system that can confirm the ignition threshold, ignition delay, and ignition temperature by irradiating an ignition charge with a diode laser in a low-temperature environment. Ignition experiments at room temperature were conducted. The data were evaluated statistically to obtain an ignition threshold with the maximum likelihood method. The relationship between the laser irradiation duration and the laser power with respect to the ignition threshold was obtained. The target value of the low-temperature environment temperature was determined as -50 °C. We examined the requirements of the experimental system and conceptually designed the system to simulate the low-temperature environment. It was confirmed that the constructed experimental system cooled the ignition charge to -50 °C. In the ignition experiment, the ignition charge was successfully ignited at room temperature and at low temperature. The ignition delay, the ignition temperature, and the high-speed image were obtained. Eventually, the validity of the experimental system was confirmed through the function tests.

DOI： 10.57350/jesa.17

Evaluation of Radiative Heat-Transfer Effect on Paraffin-Wax Regression Rate in Hybrid Rocket Reviewed International journal

Naka G., Carmicino C., Messineo J., Kitagawa K., Shimada T.

Journal of Propulsion and Power 39 ( 2 ) 258 - 273 2023.03

Performance Evaluation of the Launch Vehicle Using WAX-Based Altering-Intensity Swirling-Oxidizer-Flow-Type Hybrid Rocket Engine by Means of Evolutionary Algorithms

KANAZAKI Masahiro, IMAMURA Taro

The Proceedings of OPTIS ( The Japan Society of Mechanical Engineers ) 2022.14 ( 0 ) U00073 2022.01

Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

To improve the thrust by the O/F shift, which is one of the weak points of the hybrid rocket, a method with a variable oxidizer strength has been proposed. In this study, the superiority of this type of hybrid rocket over the conventional hybrid rocket without variable oxidizer supply was compared through several launch vehicle designs, such as altitude maximization by vertical launch and downrange extension problems with an optimized launch angle. A multi-objective evolutionary algorithm and the multi-disciplinary evaluation method of the launch vehicle were applied.

DOI： 10.1299/jsmeoptis.2022.14.u00073

Other Link： https://www.jstage.jst.go.jp/article/jsmeoptis/2022.14/0/2022.14_U00073/_pdf

Development Results of Laser Ignition System for Solid Rocket Motor Reviewed International journal

MINAMI Keisuke, MATSUURA Yoshiki, KITAGAWA Koki, ARAKAWA Satoshi, MORISHITA Naoki, TAKEMAE Toshiaki, IWABUCHI Shota, WADA Asato, TOKUDOME Shinichiro

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ) 19 ( 5 ) 807 - 811 2021.01

Language：English Publishing type：Research paper (scientific journal)

This paper describes the development status of a laser ignition system for a solid rocket motor. This system is being developed as a simple, lightweight, and small design with a high resistance to electrical disturbances and a high level of safety. The most notable advantage of this system is that its high level of safety can decrease the cost of launching rockets into space. A laser initiator and a laser safe-and-arm device (laser S/A), which are essential components of the proposed system, were developed. In particular, prototypes of the laser initiator and laser S/A for the ignition of an upper stage rocket motor were manufactured, and some environmental tests, which are required for space rocket devices, were conducted. In addition, the lowest laser energy that is needed to ignite the laser initiator was determined by changing the laser power and operating time of the laser S/A. Furthermore, a small rocket motor vacuum fire test was successfully conducted.

DOI： 10.2322/tastj.19.807

Other Link： https://ci.nii.ac.jp/naid/130008084441

Flight Results of Solid Propulsion Systems for Epsilon-4 Reviewed International journal

KITAGAWA Koki, TOKUDOME Shinichiro, HORI Keiichi, UI Kyoichi, KINOSHITA Masahiro, HASHIMOTO Junichi, ICHIMURA Kotaro

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ) 19 ( 3 ) 400 - 406 2021.01

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Epsilon-4, which was the Enhanced Epsilon launch vehicle optional configuration with a multi-satellite mount structure, was successfully launched with seven satellites in January 2019. The seven satellites consist of 200 kg-class small-satellite, three micro-satellites and three CubeSats in the Innovative Satellite Technology Demonstration-1 program. The post flight analysis was conducted. The chamber pressure and thrust of three main motors and chamber pressure of SMSJ and SPM were analyzed to confirm the effectiveness of design and production methodologies. All solid propulsion systems for Epsilon-4 showed a very good behavior during the flight. As a result, the validity of the design and operation of the Enhanced Epsilon launch vehicle was confirmed.

DOI： 10.2322/tastj.19.400

Other Link： https://ci.nii.ac.jp/naid/130008034521

Reconstructed Ballistic Data Versus Wax Regression-Rate Intrusive Measurement in a Hybrid Rocket Reviewed International journal

Jerome Messineo, Koki Kitagawa, Carmine Carmicino, Toru Shimada, Christian Paravan

Journal of Spacecraft and Rockets ( American Institute of Aeronautics and Astronautics ) 57 ( 6 ) 1295 - 1308 2020.07

Prediction of space and time distribution of wax-based fuel regression rate in a hybrid rocket Reviewed

Naka G., Messineo J., Kitagawa K., Carmicino C., Shimada T.

AIAA Propulsion and Energy 2020 Forum 1 - 30 2020.01

Language：English Publishing type：Research paper (international conference proceedings)

A numerical set up has been developed to predict the axial distribution and time history of fuel regression rates with the aim of comparing numerical results with the experimental data. The numerical approach is based on a quasi-one-dimensional CFD strategy, which is coupled with chemical equilibrium combustion; the wax-fuel regression rate has been simulated with the liquefying fuel theory developed by Karabeyoglu. In this model, local radiation heat transfer from both the hot gas combustion molecules (CO, CO2, and H2O) and soot particles is considered. It is shown that, when radiation heating of the fuel is taken into account, the calculated fuel regression rates exhibit values and axial profiles close to the ones observed experimentally.

DOI： 10.2514/6.2020-3768

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85091289443&origin=inward

Evaluation of safety distance for blast of hybrid rocket propellants Reviewed

Takahashi A., Kitagawa K., Shimada T.

AIAA Propulsion and Energy Forum and Exposition 2019 2019.01

Development and Flight Results of Solid Propulsion System for Enhanced Epsilon Launch Vehicle Reviewed International journal

KITAGAWA Koki, TOKUDOME Shinichiro, HORI Keiichi, TANNO Haruhito, NAKANO Nobuyuki

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ) 17 ( 3 ) 289 - 294 2019.01

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The development of enhanced propulsion system for the next Epsilon rocket was progressed. The development of Enhanced Epsilon is mainly the renewal of the second stage, and also includes each subsystem's improvement. The second stage motor M-35 was newly designed and manufactured. In order to verify the design, the static firing test of the second motor M-35 under the condition of vacuum ambient was conducted in 2015. The JAXA successfully launched the first Enhanced Epsilon launch vehicle. All solid propulsion systems for the Enhanced Epsilon launch vehicle showed a very good behavior during the flight

DOI： 10.2322/tastj.17.289

Other Link： https://ci.nii.ac.jp/naid/130007642475

Hybrid rocket firing experiments at various axial–tangential oxidizer-flow-rate ratios Reviewed

Ozawa K., Kitagawa K., Aso S., Shimada T.

Journal of Propulsion and Power 35 ( 1 ) 1 - 15 2019.01

Language：English Publishing type：Research paper (scientific journal)

A breadboard model (BBM) of an altering-intensity swirling-flow-type (A-SOFT) hybrid rocket engine was recently developed, and static firing experiments of the BBM were performed under various axial and tangential oxidizer mass-flow rates. A-SOFTs are intended to control thrust at an optimal oxidizer-to-fuel-mass ratio and achieve a high baseline of regression rates with a fixed motor configuration. This is possible by controlling both the oxidizer mass-flow rate and the effective geometric swirl number. A simple model based on a continuous and monotonic function of oxidizer mass flux and effective geometric swirl number was able to accurately predict the performance of experiments conducted on the A-SOFT BBM. The local fuel regression behavior in the axial direction of the A-SOFT BBM was shown to be like that of a swirling-oxidizer-flow-type hybrid rocket engine. Combustion efficiency was evaluated indirectly using equations for the efficiencies of thrust and specific impulse to eliminate errors due to local pressure shifts and the centrifugal force in swirling flows. In most cases, this indirect method compensated for the overestimations of c efficiency that resulted by directly using chamber-pressure data.

DOI： 10.2514/1.B36889

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85076482957&origin=inward

Flight results of solid propulsion system for epsilon launch vehicle from the third flight Reviewed

Kitagawa K., Tokudome S., Hori K., Ui K., Kinoshita M., Hashimoto J., Ichimura K.

Proceedings of the International Astronautical Congress, IAC 2018-October 2018.01

Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)

The third Epsilon launch vehicle, which was the Enhanced Epsilon launch vehicle optional configuration, was successfully launched with the payload of ASNARO-2 in January 2018. The post flight analysis was conducted. The chamber pressure and thrust include residual thrust of three main motors and chamber pressure of SMSJ and SPM were analysed to confirm the effectiveness of design and production methodologies. All solid propulsion systems for the third Epsilon launch vehicle showed a very good behaviour during the flight.

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85065301986&origin=inward

Image analysis for velocity profile estimation in A-SOFT hybrid rocket combustor Reviewed International journal

Kimura N., Obata K., Kitagawa K., Shimada T.

Journal of Fluid Science and Technology ( The Japan Society of Mechanical Engineers ) 13 ( 4 ) JFST0029 - JFST0029 2018.01

Language：English Publishing type：Research paper (scientific journal)

Altering-intensity Swirling-Oxidizer-Flow-Type (A-SOFT) hybrid rocket engine (HRE) was proposed as a technique to solve problems of current hybrid rockets. It uses axial and tangential oxidizer injections and their mass flow rates are manipulated independently to control the thrust and O/F. The visualization experiment of combustion of gaseous oxygen (GOX) and polymethyl methacrylate (PMMA) of A-SOFT HRE is carried out under combustion pressure of 1 bar. Combustion gas flow in the combustor is captured by high speed cameras whose fps is 30000. In order to capture the nature of the flow field quantitatively, obtaining velocity profiles by image analysis applied to its visualization images is effective. Basic image analysis method is Direct Cross Correlation method and, for high precision and spatial resolution, Correlation Based Correction is applied recursively. Averaged velocity profiles are obtained by averaging the calculation results of 10000 images corresponding to the actual time duration of 0.3 s. Flames with strong white light emission are characteristic of hybrid rockets and regarded as traceable markers for the image analysis. These luminous flames are considered to flow in the boundary layer and velocity of flames in the boundary layer is important to capture the characteristics of combustion flow field. Axial velocity of the luminous flame is proportional to the total mixed mass flow rate for each location x. Tangential velocity is proportional to angular momentum given by tangential GOX injection and inversely proportional to the total mixed mass flow rate for each location x. And how much GOX injected in axial and tangential directions are mixed is speculated by velocity profiles. It is found that mixing of GOX injected in axial and tangential directions occurs at almost the same constant rate regardless of the ratio of GOX mass flow rate injected in axial and tangential directions.

DOI： 10.1299/jfst.2018jfst0029