| 1. |
山本 直嗣, 小紫 公也, 荒川 義博, ホール型推進機の放電振動, プラズマ応用科学, Vol.8, pp.29-36, 2000.12. |
| 2. |
山本 直嗣, 中川 貴史, 小紫 公也, ホール加速器における放電振動と推進性能の関係, プラズマ応用科学, Vol.9, pp.31-36, 2001.12. |
| 3. |
山本 直嗣, 中川 貴史, 小紫 公也, 作動ガスに酸素を用いたホール加速器のイオンビーム特性, プラズマ応用科学, Vol.10, pp.30-35, 2002.12. |
| 4. |
N Yamamoto, T Nakagawa, K Komurasaki, Y Arakawa, Discharge plasma fluctuations in hall thrusters, VACUUM, 10.1016/S0042-207X(01)00445-6, Vol.65, No.3-4, pp.375-381, 2002.05, Characteristics of plasma fluctuations at the frequencies 10-100 kHz in Hall thrusters were investigated since the fluctuations might affect not only its performance but also its lifetime. Measured fluctuation characteristics varied with magnetic flux density of the applied field and they were categorized into the four regimes. Since the electron mobility strongly depends on applied field strength, it was thought that electrons would play an important role on this oscillation. Therefore, the oscillation model derived from ionization instability considering electron mobility was proposed. The predicted stable/unstable operating condition map agreed well with the measured one. (C) 2002 Elsevier Science Ltd. All rights reserved.. |
| 5. |
中川 貴史, 山本 直嗣, 小紫 公也, 荒川 義博, 酸素を推進剤に用いたホールスラスタの研究, 日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences, 10.2322/jjsass.51.606, Vol.51, No.598, pp.606-612, 2003.11, Thrust performance and internal efficiencies of a Hall thruster using oxygen as the propellant were investigated experimentally. The thrust efficiency reached at 9% with the specific impulse of 1,000s. The relatively poor performance is due to low propellant utilization, which is 45%, in comparison with that in the case of xenon propellant. The propellant utilization increased with mass flow rate and discharge voltage. The optimum channel length for oxygen was found longer than that for xenon, which was 12mm. The use of BN・AlN for the channel wall results in higher propellant utilization th.... |
| 6. |
山本 直嗣, 中川 貴史, 松井 信, ホール型イオン源プルーム中の酸素原子密度計測, プラズマ応用科学, Vol.11, pp.29-34, 2003.12. |
| 7. |
山本 直嗣, 中川 貴史, 小紫 公也, 荒川 義博, アノードレイヤ型ホールスラスタの作動特性, 日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences, 10.2322/jjsass.51.492, Vol.51, No.596, pp.492-497, 2003.09, Thrust performance and stable operation conditions of an anode layer type Hall thruster was investigated using a 1.5kW class anode layer type Hall thruster. The thrust efficiency reached at 53% with the specific impulse of 2,000s, which are competitive with these of SPT-100 thrusters. Anode shape and axial position of the anode were changed. Stability of the discharge was found sensitive to the anode configuration and applied magnetic flux density.. |
| 8. |
上田 善太郎, 荒川 義博, 山本 直嗣, ホールスラスタにおける放電振動の一次元数値解析, プラズマ応用科学, Vol.13, pp.69-74, 2005.12. |
| 9. |
N Yamamoto, S Yokota, K Watanabe, A Sasoh, K Komurasaki, Y Arakawa, Suppression of discharge current oscillations in a Hall thruster, TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 10.2322/tjsass.48.169, Vol.48, No.161, pp.169-174, 2005.11, Results of controlling a discharge current oscillation in Hall thrusters at a frequency range of 10-100 kHz are presented. To understand the discharge current oscillation mechanism, the plasma behavior in the acceleration channel was observed with a high-speed camera using a 1-kW class, anode layer type Hall thruster. The emission intensity oscillates equably in the acceleration channel at the same period of the discharge current oscillation; the number density of excited xenon ions oscillates at the same oscillation period and is proportional to the discharge current. These results indicate that the discharge current oscillation is caused by the ionization instability and the number density of plasma oscillates equably in the acceleration channel. Furthermore, the oscillation amplitude was sensitive to the applied magnetic flux density, indicating that this oscillation is affected by electron mobility. The proposed oscillation model based on the experimental results demonstrated that the momentum transfer corresponding to a plasma fluctuation is crucial to achieving stability. Thus, the oscillation amplitude for various acceleration channel configurations-parallel and convergent-was measured, because channel configuration could affect the momentum transfer. The oscillation was successfully suppressed by adopting the convergent configuration, as shown by this model.. |
| 10. |
N Yamamoto, S Yokota, M Matsui, K Komurasaki, Y Arakawa, Measurement of erosion rate by absorption spectroscopy in a Hall thruster, REVIEW OF SCIENTIFIC INSTRUMENTS, 10.1063/1.2001630, Vol.76, No.8, 2005.08, The erosion rate of a Hall thruster was estimated with the objective of building a real-time erosion rate monitoring system using a 1 kW class anode layer type Hall thruster. This system aids the understanding of the tradeoff between lifetime and performance. To estimate the flux of the sputtered wall material, the number density of the sputtered iron was measured by laser absorption spectroscopy using an absorption line from ground atomic iron at 371.9935 nm. An ultravioletAl(x)In(y)Ga((1-x-y))N diode laser was used as the probe. The estimated number density of iron was 1.1x10(16) m(-3), which is reasonable when compared with that measured by duration erosion tests. The relation between estimated erosion rate and magnetic flux density also agreed with that measured by duration erosion tests. (c) 2005 American Institute of Physics.. |
| 11. |
N Yamamoto, K Komurasaki, Y Arakawa, Discharge current oscillation in Hall thrusters, JOURNAL OF PROPULSION AND POWER, 10.2514/1.12759, Vol.21, No.5, pp.870-876, 2005.09, The discharge current oscillation at a frequency range of 10-100 kHz in Hall thrusters was investigated with the objective of extending their stable operational range. The amplitude of oscillation was measured using two types of Hall thrusters-the anode layer type and the magnetic layer type. The oscillation amplitude was found to be sensitive to the applied magnetic flux density, and this result indicated that the oscillation was affected by electron mobility. An oscillation model was proposed based on the experimental results, and the predicted frequency and stable operational range were found to agree qualitatively agreed with the experimental results. This model shows that the momentum transfer corresponding to plasma fluctuation, that is, the viscosity effect, is crucial to achieving stability. Thus, the oscillation amplitude for various acceleration channel configurations-divergent, parallel, and convergent-was measured because the momentum transfer could be affected by the channel configuration. The stable operational range was successfully extended by the adoption of the convergent configuration in each type of Hall thruster, as shown by this model.. |
| 12. |
鷹尾 良行, 片原田 弘, 山本 直嗣, 中島 秀紀, 30W級小型マイクロ波放電型イオンエンジンの性能評価, 電気学会研究会資料. PST, プラズマ研究会, Vol.2005, No.92, pp.19-22, 2005.10. |
| 13. |
Yoshiyuki Takao, Hiroshi Kataharada, Takashi Miyamoto, Hirokazu Masui, Naoji Yamamoto, Hideki Nakashima, Performance test of micro ion thruster using microwave discharge, VACUUM, 10.1016/j.vacuum.2006.01.071, Vol.80, No.11-12, pp.1239-1243, 2006.09, Several types of electric propulsions have been developed and used for artificial satellites on geostationary orbit keeping or planetary exploration. A series of small-scale satellites is recently expected to be used instead of traditional large-scale satellites for reducing launch cost and risk. The trend towards needs of small spacecraft requires micro thrusters with high specific impulse. In this study, a micro ion engine utilizing a microwave discharge plasma was fabricated and was tested. This ion engine comprises some components, such as electrostatic grids, antenna, and microwave power supply, which decide its performance. The performance dependence on the components was examined under several experimental conditions. The typical performance parameters of the engine were ion production cost of 770 V, propellant utilization efficiency of 72%, and thrust of 0.66 mN in conditions of input 2.45 GHz microwave power of 8 W and propellant (xenon gas) flow rate of 0.2 sccm with a star type antenna. (c) 2006 Elsevier Ltd. All rights reserved.. |
| 14. |
N Yamamoto, K Komurasaki, Y Arakawa, Discharge current oscillation in Hall thrusters (vol 21, pg 870, 2005), JOURNAL OF PROPULSION AND POWER, Vol.22, No.2, p.478, 2006.03. |
| 15. |
H Kataharada, Y Takao, N Yamamoto, H Ijiri, H Nakashima, Development of small microwave discharge ion thruster, THIN SOLID FILMS, 10.1016/j.tsf.2005.08.045, Vol.506, pp.605-608, 2006.05, A small-scale ion thruster of 18 mm in diameter for space propulsion has been developed and tested. Microwave discharge plasma is produced by a star-type antenna. Two tests were carried out. First, in order to optimize the ion source configuration, we measured the ion saturation current on various conditions measured for the indicator of the performance of an ion source. Next, to estimate the thrust, the ion beam was extracted and extracted ion beam current was measured with obtained optimization configuration. The maximum ion saturation current of 45 mA was obtained at At gas flow rate of 1.4 seem and input microwave power of 28 W. The maximum extracted ion current of 22 mA was obtained at Xe gas flow rate of 0.6 seem and input power of 18 W. (c) 2006 Published by Elsevier B.V.. |
| 16. |
Naoji Yamamoto, Hirokazu Masui, Hiroshi Kataharada, Hideki Nakashima, Yoshiyuki Takao, Antenna configuration effects on thrust performance of miniature microwave discharge ion engine, JOURNAL OF PROPULSION AND POWER, 10.2514/1.18833, Vol.22, No.4, pp.925-928, 2006.07. |
| 17. |
Hirokazu Masui, Yousuke Tashiro, Naoji Yamamoto, Hideki Nakashima, Ikkoh Funaki, Analysis of electron and microwave behavior in microwave discharge neutralizer, TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 10.2322/tjsass.49.87, Vol.49, No.164, pp.87-93, 2006.08, In the MUCES-C mission conducted by JAXA (Japan Acro Exploration Agency), a microwave neutralizer is mounted with a microwave ion engine on the HAYABUSA space probe. The neutralizer consists of an L-shaped antenna to inject microwaves and samarium cobalt magnets to provide ECR (electron cyclotron resonance). Plasma production of a higher density than the cutoff density is expected in the discharge chamber, but the neutralizer is so small that high-precision measurements using a probe are difficult. To clarify the plasma production mechanism in the microwave neutralizer, numerical analysis was conducted using a code coupling PIC (particle-in-cell) method, and a FDTD (finite-difference-time-domain) method. This paper describes effects caused by varying magnetic field configuration and antenna position in the neutralizer. The calculation results show that bringing the antenna closer to the ECR region is effective for plasma production.. |
| 18. |
大宅 将史, 小川 真司, 山本 直嗣, 高周波放電スラスタのエネルギーバランスに関する研究, プラズマ応用科学, Vol.15, No.1, pp.3-8, 2007.06. |
| 19. |
大宅 将史, 小川 真司, 山本 直嗣, 高周波放電スラスタのエネルギー収支に関する研究, 九州大学大学院総合理工学報告, 10.15017/14573, Vol.29, No.1, pp.1-6, 2007.11, An energy balance in inductively coupled radio frequency electrothermal thruster using water as a propellant was investigated with the objective of improving the thrust performance. Absorption efficiency was estimated by means of an I-V sensor, enthalpy transfer efficiency was estimated by means of a spectrometer and thrust efficiency was estimated by means of a thrust stand. The absorption efficiency using water is 0.75, which is worse than that using argon. This is because the number density using water is less than that of argon due to the low ionization coefficient. The enthalpy transfe.... |
| 20. |
山本 直嗣, 三好 誠, 増井 博一, 宮本 尚使, 宗貞 伸孝, 中島 秀紀, 均一・高密度プラズマ生成アンテナを用いたマイクロ波放電型イオンスラスタの高性能化, 日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences, 10.2322/jjsass.55.546, Vol.55, No.646, pp.546-553, 2007.11, The dependency of thrust performance on thruster configurations such as antenna length, antenna height, number of antenna, magnetic field configuration, and microwave frequency, was investigated with the objective of improving the thrust performance of microwave discharge ion thruster using antennas for uniform and dense plasma production. The experimental results showed that there was an optimum length of the antennas, and it was 3/4 times the wave length of incident microwaves. The ion beam current reaches its maximum value when the antenna was set at 2mm downstream of an electron cyclotron resonance layer. There was an optimum number of the antennas. This is due to the tradeoff between the coupling of plasma with microwave and the surface recombination on the antenna. The expansion of ionization zone was made successfully by changing magnetic field configuration. In addition, the thrust performance was slightly improved with increase in incident microwave frequency from 2.45GHz to 4.2GHz. A value for the ion beam current with 2.45GHz is compensated by high electron number density and less magnetized ions for the disadvantage of small plasma number density. Overall, the propellant utilization efficiency, ion production cost, and estimated thrust were found to be 0.62, 300W/A and 6.2mN, respectively at mass flow rate of 0.22mg/s for xenon, ion beam voltage of 1,500V and 2.45GHz microwave incident power at 32W.. |
| 21. |
山本 直嗣, 三好 誠, 増井 博一, 宮本 尚使, 宗貞 伸孝, 中島 秀紀, 均一・高密度プラズマ生成アンテナを用いたマイクロ波放電型イオンスラスタの高性能化, 日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences, 10.2322/jjsass.55.546, Vol.55, No.646, pp.546-553, 2007.11, The dependency of thrust performance on thruster configurations such as antenna length, antenna height, number of antenna, magnetic field configuration, and microwave frequency, was investigated with the objective of improving the thrust performance of microwave discharge ion thruster using antennas for uniform and dense plasma production. The experimental results showed that there was an optimum length of the antennas, and it was 3/4 times the wave length of incident microwaves. The ion beam current reaches its maximum value when the antenna was set at 2mm downstream of an electron cyclotron resonance layer. There was an optimum number of the antennas. This is due to the tradeoff between the coupling of plasma with microwave and the surface recombination on the antenna. The expansion of ionization zone was made successfully by changing magnetic field configuration. In addition, the thrust performance was slightly improved with increase in incident microwave frequency from 2.45GHz to 4.2GHz. A value for the ion beam current with 2.45GHz is compensated by high electron number density and less magnetized ions for the disadvantage of small plasma number density. Overall, the propellant utilization efficiency, ion production cost, and estimated thrust were found to be 0.62, 300W/A and 6.2mN, respectively at mass flow rate of 0.22mg/s for xenon, ion beam voltage of 1,500V and 2.45GHz microwave incident power at 32W.. |
| 22. |
Naoji Yamamoto, Shinya Kondo, Takayuki Chikaoka, Hideki Nakashima, Hirokazu Masui, Effects of magnetic field configuration on thrust performance in a miniature microwave discharge ion thruster, JOURNAL OF APPLIED PHYSICS, 10.1063/1.2822456, Vol.102, No.12, p.123304, 2007.12, The effects of magnetic field configuration on thrust performance in a miniature microwave discharge ion thruster were investigated in order to improve thrust performance. First, the extracted ion beam current was measured for various levels of strength of the magnetic field. It was found that there is an optimum magnitude of the magnetic field. That this is due to the tradeoff between magnetic mirror confinement and microwave-plasma coupling was confirmed by measurement of the ion saturation current into the antenna of the ion thruster. The ion saturation current was found to decrease with an increase in magnetic field strength, due to the improvement in magnetic mirror confinement. The estimated electron temperature also decreases with an increase in magnetic field strength. This result shows that the increase in magnetic field strength leads to a decrease in microwave-plasma coupling. Next, the ion beam current for three magnetic field shapes was measured by changing the length of the central yoke. The results show that the optimum magnetic field shape depends on the mass flow rate because of the tradeoff between magnetic confinement and ionization probability. For the configurations tested, the 3 mm length central yoke is optimal for low mass flow, whereas 7 mm is the best for high mass flow. Overall, the extracted ion beam current is 21.4 mA, at a xenon mass flow rate of 0.036 mg/s, beam voltage of 1500 V, and incident microwave power of 16 W. (c) 2007 American Institute of Physics.. |
| 23. |
山本 直嗣, 近藤 慎哉, 近岡 貴行, 金川 隆保, 中島 秀紀, 小型イオンスラスタの推進性能における形状依存性, 日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences, 10.2322/jjsass.56.383, Vol.56, No.655, pp.383-390, 2008.08, The effects of antenna shape and magnetic field configuration on thrust performance in a 30W class miniature microwave discharge ion thruster were investigated with the objective of improving its thrust performance. The ion beam currents were measured for three different antenna configurations: disc, star, and cross. The results showed that the optimum antenna shape depends on the desired mass flow level because of the tradeoff between microwave-plasma coupling efficiency and surface area recombination. The ion beam current with various magnitude of magnetic field was measured, since magnet.... |
| 24. |
L. Tao, A. P. Yalin, N. Yamamoto, Cavity ring-down spectroscopy sensor for ion beam etch monitoring and end-point detection of multilayer structures, REVIEW OF SCIENTIFIC INSTRUMENTS, 10.1063/1.2995765, Vol.79, No.11, p.115107, 2008.11, This contribution reports on the development of in situ sputter monitoring and end-point detection for ion beam etch systems using continuous-wave cavity ring-down spectroscopy (cw-CRDS). The demonstrated system is based on the detection of sputtered manganese atoms using a tunable external cavity diode laser in the vicinity of 403.07 nm. The cw-CRDS system is described and measurements from a manganese-iron target are presented. End-point detection is demonstrated by monitoring the time dependence of manganese concentration for a multilayer target comprised of alternating layers of manganese/iron and titanium. Detection limits are shown to be adequate for today's commercial ion beam sputter systems.. |
| 25. |
新谷 將, 金川 隆保, 山本 直嗣, 小型マイクロ波放電型イオンスラスタにおける磁場強度が電子の平均エネルギーへ及ぼす影響, プラズマ応用科学, Vol.17, No.2, pp.163-166, 2009.12. |
| 26. |
N. Yamamoto, L. Tao, A. P. Yalin, Single-mode delivery of 250 nm light using a large mode area photonic crystal fiber, OPTICS EXPRESS, 10.1364/OE.17.016933, Vol.17, No.19, pp.16933-16940, 2009.09, We demonstrate that large mode area (LMA) photonic crystal fibers (PCFs) can be used as single-mode patch-cords for 250 nm laser light. We have studied the transmission of the 250 nm output beam of a frequency-quadrupled diode laser through a triangular structure LMA PCF with 10 mu m core. We have achieved single-mode output with coupling loss of 1.8 +/- 0.6 dB and transmission loss of 1.5 +/- 0.2 dB/m. The critical bend loss radius is approximately 6 cm. The transmission loss is compared with published bulk silica measurements. Effects of optically induced damage were observed after prolonged operation and have been studied as function of laser power and time. The optical damage occurs primarily at the fiber input and can be partly ameliorated by cleaving the fiber input. For input power levels of <similar to 0.3 mW stable operation can be achieved for periods of >40 hours which is sufficient for many laboratory based applications. The results show the utility of these fibers for single-mode beam delivery in a spectral region where step-index single-mode fibers are not readily available. (C) 2009 Optical Society of America. |
| 27. |
N. Yamamoto, L. Tao, A. P. Yalin, Single-mode delivery of 250 nm light using a large mode area photonic crystal fiber, OPTICS EXPRESS, 10.1364/OE.17.016933, Vol.17, No.19, pp.16933-16940, 2009.09, We demonstrate that large mode area (LMA) photonic crystal fibers (PCFs) can be used as single-mode patch-cords for 250 nm laser light. We have studied the transmission of the 250 nm output beam of a frequency-quadrupled diode laser through a triangular structure LMA PCF with 10 mu m core. We have achieved single-mode output with coupling loss of 1.8 +/- 0.6 dB and transmission loss of 1.5 +/- 0.2 dB/m. The critical bend loss radius is approximately 6 cm. The transmission loss is compared with published bulk silica measurements. Effects of optically induced damage were observed after prolonged operation and have been studied as function of laser power and time. The optical damage occurs primarily at the fiber input and can be partly ameliorated by cleaving the fiber input. For input power levels of <similar to 0.3 mW stable operation can be achieved for periods of >40 hours which is sufficient for many laboratory based applications. The results show the utility of these fibers for single-mode beam delivery in a spectral region where step-index single-mode fibers are not readily available. (C) 2009 Optical Society of America. |
| 28. |
鷹尾 良行, 中島 秀紀, 山本 直嗣, 口径3cmおよび5cm級マイクロ波放電型イオンエンジンの開発, プラズマ応用科学, Vol.18, No.2, pp.182-185, 2010.12. |
| 29. |
山本 直嗣, 富田 健太郎, 真島 周, 山崎 尚人, 近藤 慎也, 鶴 哲平, 中島 秀紀, 内野 喜一郎, レーザートムソン散乱法による小型マイクロ波放電型イオンエンジンにおけるプラズマ状態の測定 (イオン加速グリッド耐久認定用数値解析 JIEDI(JAXA Ion Engine Development Initiatives) ツールの研究開発ワークショップ論文集), 宇宙航空研究開発機構研究開発報告, Vol.9, pp.39-46, 2010.02, The plasma parameters, electron number density and electron energy distribution function, in a miniature microwave discharge ion thruster were successfully measured by means of laser Thomson scattering without perturbations. A photon counting method and a double monochromator were used against small Thomson scattering signal and strong stray laser light. The result shows an electron energy distribution function is Maxwellian, since the scattered spectrum can be fitted by Gaussian at the temperature of 1.5 eV. An electron density is 2.3×10^<18> m^<-3>. The measured electron number density an.... |
| 30. |
Tomita Kentaro, Yamamoto Naoji, Yamasaki Naoto, Tsuru Teppei, Uchino Kiichiro, Nakashima Hideki, Thomson-Scattering Diagnostics of Plasmas Produced in a Miniature Microwave Discharge Ion Engine, JOURNAL OF PROPULSION AND POWER, 10.2514/1.39145, Vol.26, No.2, pp.381-384, 2010.03. |
| 31. |
Naoji Yamamoto, Lei Tao, Binyamin Rubin, John D. Williams, Azer P. Yalin, Sputter Erosion Sensor for Anode Layer-Type Hall Thrusters Using Cavity Ring-Down Spectroscopy, JOURNAL OF PROPULSION AND POWER, 10.2514/1.44784, Vol.26, No.1, pp.142-148, 2010.01, We report the development of a sputter erosion monitoring system to study Hall thruster lifetime and contamination. The laser-based sensor uses the continuous-wave cavity ring-down spectroscopy technique and allows for in situ measurements in near-real time. The continuous-wave cavity ring-down spectroscopy technique diagnostic allows direct probing of sputter products in their ground state, thereby providing a reliable quantitative measure of their overall number density. Combining the number density of sputtered particles with their velocity allows determination of the flux of sputtered particles and erosion rate. We perform proof of principle experiments, in which sputtered manganese atoms from the acceleration channel of an anode layer-type Hall thruster are measured. The measurement strategy is to detect the manganese atoms via an absorption line from the ground state at a wavelength of 403.076 nm (air). The measured path-integrated number density of sputtered manganese atoms is 1.7 +/- 0.3 x 10(13) m(-2) for an argon anode mass flow rate of 2.08 mg/s and a discharge voltage of 250 V. A finite element sputter model is used to compare the cavity ring-down spectroscopy results against validating mass loss measurements and shows good agreement.. |
| 32. |
Naoji Yamamoto, Lei Tao, Binyamin Rubin, John D. Williams, Azer P. Yalin, Sputter Erosion Sensor for Anode Layer-Type Hall Thrusters Using Cavity Ring-Down Spectroscopy, JOURNAL OF PROPULSION AND POWER, 10.2514/1.44784, Vol.26, No.1, pp.142-148, 2010.01, We report the development of a sputter erosion monitoring system to study Hall thruster lifetime and contamination. The laser-based sensor uses the continuous-wave cavity ring-down spectroscopy technique and allows for in situ measurements in near-real time. The continuous-wave cavity ring-down spectroscopy technique diagnostic allows direct probing of sputter products in their ground state, thereby providing a reliable quantitative measure of their overall number density. Combining the number density of sputtered particles with their velocity allows determination of the flux of sputtered particles and erosion rate. We perform proof of principle experiments, in which sputtered manganese atoms from the acceleration channel of an anode layer-type Hall thruster are measured. The measurement strategy is to detect the manganese atoms via an absorption line from the ground state at a wavelength of 403.076 nm (air). The measured path-integrated number density of sputtered manganese atoms is 1.7 +/- 0.3 x 10(13) m(-2) for an argon anode mass flow rate of 2.08 mg/s and a discharge voltage of 250 V. A finite element sputter model is used to compare the cavity ring-down spectroscopy results against validating mass loss measurements and shows good agreement.. |
| 33. |
N. Yamamoto, K. Tomita, N. Yamasaki, T. Tsuru, T. Ezaki, Y. Kotani, K. Uchino, H. Nakashima, Measurements of electron density and temperature in a miniature microwave discharge ion thruster using laser Thomson scattering technique, PLASMA SOURCES SCIENCE & TECHNOLOGY, 10.1088/0963-0252/19/4/045009, Vol.19, No.4, 2010.08, In order to improve the thrust performance of a miniature microwave discharge ion thruster, the relationship between electron number density/temperature and operational conditions, mass flow rate, incident microwave power and magnetic field strength were measured by means of laser Thomson scattering. A photon counting method and a triple grating spectrometer were used against a small Thomson scattering signal and a strong stray laser light. Electron number density increased with incident microwave power and was saturated at critical incident microwave power; it was about 1.2 x 10(18) m(-3) at incident microwave power > 8 W. In addition, electron number density increased with mass flow rate and became saturated; it was about 1.7 x 10(18) m(-3) at mass flow rate > 0.04 mg s(-1). The electron number density gradually increased with an increase in the number of magnets, i.e. magnetic field strength. There was a sudden jump at thirteen magnets, although the thruster failed to ignite at fourteen magnets. This is because there is an optimum distance between the antenna and the electron cyclotron resonance layer. These results suggest that future improvement in thrust efficiency in miniature microwave discharge ion thrusters may come from the fine adjustment of the magnetic field configuration inside the discharge chamber.. |
| 34. |
Lei Tao, Naoji Yamamoto, Alec D Gallimore, Azer P Yalin, Development of a cavity ring-down spectroscopy sensor for boron nitride sputter erosion in Hall thrusters, 2010.05, Sputter erosion of boron nitride (BN) is a critically important process in
Hall thrusters from the point of view of both lifetime assessment and
contamination effects. This contribution describes the development of a laser
based sensor for in situ monitoring of sputtered BN from Hall thrusters. We
present a continuous-wave cavity ring-down spectroscopy (cw-CRDS) system and
its demonstrative measurement results from BN sputtering experiments.. |
| 35. |
鷹尾 良行, 山本 直嗣, 中島 秀紀, 2-5cm級マイクロ波放電型イオンエンジンの開発, 電気学会研究会資料. PST, プラズマ研究会, Vol.2010, No.41, pp.7-10, 2010.08. |
| 36. |
石原 和大, 藤岡 慎介, ZHE Zhang, 重森 啓介, 弘中 陽一郎, 城崎 知至, 砂原 淳, 白神 宏之, 山本 直嗣, 中島 秀紀, 西村 博明, 疇地 宏, 高強度レーザーを用いた強磁場発生とその応用, レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, Vol.429, pp.17-21, 2012.08. |
| 37. |
N. Yamamoto, K. Tomita, K. Sugita, T. Kurita, H. Nakashima, K. Uchino, Measurement of xenon plasma properties in an ion thruster using laser Thomson scattering technique, Review of Scientific Instruments, 10.1063/1.4737144, Vol.83, 2012.07, This paper reports on the development of a method for measuring xenon plasma properties using the laser Thomson scattering technique, for application to ion engine system design. The thresholds of photo-ionization of xenon plasma were investigated and the number density of metastable atoms, which are photo-ionized by a probe laser, was measured using laser absorption spectroscopy, for several conditions. The measured threshold energy of the probe laser using a plano-convex lens with a focal length of 200 mm was 150 mJ for a xenon mass flow rate of 20 μgs and incident microwave power of 6 W; the probe laser energy was therefore set as 80 mJ. Electron number density was found to be (6.2 ± 0.4) × 10 17 m -3 and electron temperature was found to be 2.2 ± 0.4 eV at a xenon mass flow rate of 20 μgs and incident microwave power of 6 W. The threshold of the probe laser intensity against photo-ionization in a miniature xenon ion thruster is almost constant for various mass flow rates, since the ratio of population of the metastable atoms to the electron number density is little changed. © 2012 American Institute of Physics.. |
| 38. |
中村 祐輔, 中野 正勝, 山本 直嗣, 中島 秀紀, Nakamura Yusuke, Nakano Masakatsu, Yamamoto Naoji, Nakashima Hideki, JIEDIコードの高速化と遺伝アルゴリズムの適用, 平成24年度宇宙輸送シンポジウム: 講演集録 = Proceedings of Space Transportation Symposium: FY2012, 2013.01, 平成24年度宇宙輸送シンポジウム (2013年1月17日-1月18日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県形態: カラー図版あり形態: PDF資料番号: AA0061856134レポート番号: STEP-2012-051. |
| 39. |
石原 和大, 藤岡 慎介, Zhang Zhe, 西村 博明, 城崎 知至, 砂原 淳, 重森 啓介, 山本 直嗣, 白神 宏之, 近藤 康太郎, 疇地 宏, 26pKB-5 レーザー駆動強磁場発生時における溶融石英の不透明化(核融合プラズマ(慣性核融合,高速点火),領域2(プラズマ基礎・プラズマ科学・核融合プラズマ・プラズマ宇宙物理)), 日本物理学会講演概要集, Vol.68, No.2, p.187, 2013.08. |
| 40. |
楠田 将士, 中島 秀紀, 山本 直嗣, 弱連成を用いたマイクロ波放電式中和器の内部プラズマ電位についての数値解析, 宇宙科学技術連合講演会講演集, Vol.58, p.6p, 2014.11. |
| 41. |
伊藤 匠, 山本 直嗣, 中島 秀紀, パルス重畳電源を用いたホールスラスタの性能調査及び回路モデルの構築, 宇宙科学技術連合講演会講演集, Vol.58, p.4p, 2014.11. |
| 42. |
森田太智, 山本直嗣, 齋藤直哉, 藤岡慎介, 城崎知至, 川島諒祐, 森芳孝, 西村博明, 砂原淳, 余語覚文, 中島秀紀, 大型レーザー生成プラズマを用いた磁気ノズルによる推進システムの模擬実験, 日本物理学会講演概要集(CD-ROM), Vol.70, No.2, p.ROMBUNNO.18PCP-4, 2015.09. |
| 43. |
森田太智, 山本直嗣, 齋藤直哉, 川島諒祐, 枝本雅史, 三浦智之, 板谷佑太朗, 砂原淳, 藤岡慎介, 城崎知至, 森芳孝, 余語覚文, 西村博明, 中島秀紀, 磁気ノズルにおける推力発生の原理実証実験, 日本物理学会講演概要集(CD-ROM), Vol.71, No.1, p.ROMBUNNO.22ACB‐13, 2016.03. |
| 44. |
森田太智, 山本直嗣, 齋藤直哉, 枝本雅史, 三浦智之, 板谷佑太朗, 児島富彦, 砂原淳, 藤岡慎介, 長友英夫, 城崎知至, 森芳孝, 余語覚文, 西村博明, 中島秀紀, 磁気スラストチャンバーによるプラズマ排出制御の実験的検証, 日本物理学会講演概要集(CD-ROM), Vol.71, No.2, p.ROMBUNNO.14aKH‐5, 2016.09. |
| 45. |
齋藤直哉, 枝本雅史, 三浦智之, 板谷佑太郎, 児島富彦, 森田太智, 山本直嗣, 藤岡慎介, 余語覚史, 西村博明, 砂原敦, 森芳孝, 城崎知至, 中島秀紀, 小型イオンエンジンを用いた新しい磁場計測の構築, 日本物理学会講演概要集(CD-ROM), Vol.71, No.2, p.ROMBUNNO.14aKC‐1, 2016.09. |
| 46. |
淵上太貴, 森田太智, 山本直嗣, ホールスラスタにおけるニューラルネットワークを用いた推力の再構成, プラズマ応用科学, Vol.24, No.2, p.84‐88, 2016.12. |
| 47. |
中野 正勝, 山本 直嗣, Nakano Masakatsu, Yamamoto Naoji, CRDS 法を用いたグリッド損耗強度分布取得のための数値解析ツールの開発, 平成27年度宇宙輸送シンポジウム: 講演集録 = Proceedings of Space Transportation Symposium FY2015, 2016.01, 平成27年度宇宙輸送シンポジウム（2016年1月14日-15日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県資料番号: SA6000050115レポート番号: STEP-2015-051. |
| 48. |
小紫 公也, 山本 直嗣, 田原 弘一, 5kW級ホールスラスタRAIJINの共同開発, 宇宙科学技術連合講演会講演集, Vol.60, p.5p, 2016.09. |
| 49. |
川原 友太郎, 飯島 健介, 竹末 一平, 山本 直嗣, 森田 大智, 大川 恭志, 船木 一幸, 中野 正勝, Kawahara Yutaro, Iijima Kensuke, Takesue Ippei, Yamamoto Naoji, Morita Taichi, Ohkawa Yasushi, Funaki Ikkoh, Nakano Masakatsu, イオンエンジンにおけるOn/Off制御の可能性検討, 平成28年度宇宙輸送シンポジウム: 講演集録 = Proceedings of Space Transportation Symposium FY2016, 2017.01, 平成28年度宇宙輸送シンポジウム（2017年1月19日-20日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県資料番号: SA6000086073レポート番号: STEP-2016-035. |
| 50. |
中野 正勝, 山本 直嗣, 船木 一幸, 大川 恭志, Nakano Masakatsu, Yamamoto Naoji, Funaki Ikkoh, Ohkawa Yasushi, On-Off制御時のイオンビームの過渡シミュレーション, 平成28年度宇宙輸送シンポジウム: 講演集録 = Proceedings of Space Transportation Symposium FY2016, 2017.01, 平成28年度宇宙輸送シンポジウム（2017年1月19日-20日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県資料番号: SA6000086072レポート番号: STEP-2016-034. |
| 51. |
長野公勇, 森田太智, 山本直嗣, 窪田健一, 藤井剛, 杵淵紀世志, 200W級ホールスラスタの開発, プラズマ応用科学, 10.34377/aps.25.2_85, Vol.25, No.2, pp.85‐88-88, 2017.12. |
| 52. |
森田太智, 長友英夫, 児島富彦, 山本直嗣, 枝本雅史, 砂原淳, 森芳孝, 城崎知至, 齋藤直哉, 板谷佑太朗, 梶村好宏, 藤岡慎介, 中島秀紀, レーザー核融合推進にむけた磁気ノズルによるプラズマ制御の数値解析(2017B2‐MORITA), 大阪大学レーザー科学研究所共同利用・共同研究成果報告書(CD-ROM), Vol.2017, p.ROMBUNNO.7‐7, 2018.03. |
| 53. |
山本 直嗣, 池田 凌, 竹末 一平, 森田 太智, 中野 正勝, 大川 恭志, 船木 一幸, Yamamoto Naoji, Ikeda Ryo, Takesue Ippei, Morita Taichi, Nakano Masakatsu, Ohkawa Yasushi, Funaki Ikkoh, 電界放出型カソードを用いたイオンエンジンの中和特性, 平成30年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2019 Symposium on Laboratory Experiment for Space Science, 2019.02, 平成30年度宇宙科学に関する室内実験シンポジウム (2019年2月28日-3月1日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県資料番号: SA6000139038. |
| 54. |
木下 順平, 江川 裕貴, 山本 直嗣, 中野 正勝, 大川 恭志, 船木 一幸, KINOSHITA Junpei, EGAWA Yuki, YAMAMOTO Naoji, NAKANO Masakatsu, OHKAWA Yasushi, FUNAKI Ikkoh, イオンエンジンにおける FEC を用いた中和システムの検討, 令和元年度宇宙輸送シンポジウム: 講演集録 = Proceedings of Space Transportation Symposium FY2019, 2020.01, 令和元年度宇宙輸送シンポジウム（2020年1月16日-17日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県資料番号: SA6000147066レポート番号: STEP-2019-017. |
| 55. |
木下 順平, 白木 僚, 山本 直嗣, 大川 恭志, 船木 一幸, 中野 正勝, イオンエンジンのPWM制御時におけるOFF時のリーク電流低減に関する研究, プラズマ応用科学 = Applied plasma science : journal of IAPS, Vol.29, No.1, pp.29-34, 2021.06. |
| 56. |
山本直嗣, 渡邊裕樹, 将来ミッションに向けた電気推進ロケットエンジンの現状と課題, 2018.02. |
| 57. |
山本 直嗣, 田原 弘一, 小紫 公也, 船木 一幸, 大電力電気推進が拓くオール電化衛星, 10.14822/kjsass.65.8_236, 2017.08. |
| 58. |
山本 直嗣, 増井 博一, 金川 隆保, 新谷 將, 中島 秀紀, マイクロ波放電型イオンスラスタのシミュレーションコードの開発(電気推進・先端推進の数値シミュレーション), 日本航空宇宙学会誌, 10.14822/kjsass.59.691_238, Vol.59, No.691, pp.238-243, 2011.08. |
| 59. |
前野 旭弘, 山本 直嗣, 中島 秀紀, 5.レーザー核融合プラズマ推進の研究(大型レーザー装置を用いた科学研究の新展開), プラズマ・核融合学会誌, Vol.86, No.10, pp.594-597, 2010.10, 将来の火星などの太陽系惑星の有人宇宙探査のためには,従来にない高い比推力と大きな推力を併せ持つ宇宙推進システム(ロケット)を開発する必要がある.その候補の一つとして,莫大なエネルギーを生成するレーザー核融合と磁気スラストチャンバーを組み合わせたレーザー核融合ロケットが挙げられる.本章では,大阪大学レーザーエネルギー学研究センターの共同利用研究施設にて実施した磁気スラストチャンバーの原理実証実験について解説する.. |
