船木 一幸

平成25年度宇宙輸送シンポジウム（2014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: SA6000016076

平成25年度宇宙輸送シンポジウム（2014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: SA6000016077

The JIEDI (JAXA's Ion Engine Development Initiative) tool has been developed to assess the ion acceleration grid erosion of an ion thruster. The sensitivity analysis of the input parameters of the JIEDI tool is conducted in this paper. We compare the simulation results of the JIEDI tool and show that it successfully reproduces the full lifetime test of the μ10 prototype model. Through sensitivity analysis, we found that the sticking factor is the most sensitive input parameter when estimating the accelerator grid erosion and electron backstreaming time. For the worst case scenario of grid erosion (without re-deposition), the uncertainty in the neutral mass flow rate through grid holes is important when estimating the accelerator grid erosion. A 30% change in the neutral mass flow rate caused by a 6% change in the propellant utilization efficiency, corresponds to about a 20% change in the accelerator grid mass loss as well as the increasing rate of minimum potential on the axis of the ion optics. In contrast to the accelerator grid erosion, the uncertainties in the discharge voltage and grid gap (that affect the trajectory of the mainstream ions), are important when estimating decelerator grid erosion. A 40% change in the discharge voltage corresponds to about a 90% change in the decelerator grid mass loss. In addition, a 30% change in the grid gap between the screen grid and the accelerator grid corresponded to about a 40% change in the decelerator grid mass loss.

During rocket flights, ionized exhaust plumes from solid rocket motors may interfere with radio frequency (RF) transmission under certain conditions. To clarify the physical process involved and to establish the estimation methodology, a plume-RF interference experiment during a sea-level static firing test of a full-scale solid rocket motor was conducted. The result of the ground experiment was adequately matched by a computational fluid dynamics (CFD) model of the plume flow field coupled to a finite-difference time-domain (FDTD) model of RF transmission. The CFD/FDTD coupling method was then refined for predicting interference and RF attenuation levels during an actual rocket flight. The calculated far-field received levels were compared with the in-flight attenuation data at different look angles (angles between the vehicle axis and the line-of-sight of the antennas). The calculated results showed good agreement with the flight data over a wide range of look angles. An adaptation of the model, based on the diffraction theory, proved appropriate both for rough estimation of attenuation and for conducting a preliminary analysis of signal/rocket plume interactions.

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 Space Transportation FY2012 (January 17-18, 2013. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan Thrust-measurement experiment was carried out using a four-cylinder pulse detonation rocket engine (PDRE) with a rotary valve. This PDRE used three types of gases, oxidizer (N2O), fuel (C2H4), and purge gas (He) to generate detonation wave intermittently. We used a rotary valve attached coaxially to a motor for supplying these three gases. We achieved time-averaged thrust of 258.5 N and specific impulse of 138.7 sec in the operation for 1000 msec. 形態: カラー図版あり 形態: PDF Physical characteristics: Original contains color illustrations Physical characteristics: PDF 資料番号: AA0061856062 レポート番号: STCP-2012-062

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, 神奈川県自己誘起磁場型MPDスラスタの実機開発において最も重要な課題の１つとなる熱設計について、アルゴン推進剤を対象に推進剤流れの電磁流体解析とスラスタヘッドの熱解析を連携して行うことで数値的に検討を行った。推進剤流れの電磁流体解析とスラスタヘッドの熱解析を連携させる本研究の解析手法は、スラスタの形状パラメータ変化による電極への着弧様態の変化に追従した放電室の温度分布の詳細な解像を可能とする。スラスタヘッドでは特に陽極出口端および陰極先端で高温化がみられた。陰極半径を減少させると、推進性能は向上する一方で、Hall効果の顕著化に起因する陽極出口端の更なる高温化および熱通過率の低下に起因する陰極先端の更なる高温化に至り、陰極径の減少は熱的には厳しくなる状況を招くことがわかった。形態: カラー図版あり形態: PDF資料番号: AA0061856085レポート番号: STEP-2012-002

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: AA0061856133レポート番号: STEP-2012-050

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 Space Transportation FY2012 (January 17-18, 2013. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 形態: カラー図版あり 形態: PDF Physical characteristics: Original contains color illustrations Physical characteristics: PDF Translation title: Thrust measurement of magneto-plasma sail in laboratory experiment 資料番号: AA0061856097 レポート番号: STEP-2012-014

A magnetoplasma sail (MPS) spacecraft produces an artificial magnetosphere to reflect the solar wind particles approaching the coil, and the corresponding repulsive force exerts on the coil to accelerate the spacecraft in the solar wind direction. In this paper, numerical study of plasma equilibrium in an artificial magnetosphere in interplanetary space is updated to check if the idea of plasma equilibrium is applicable to for MPS or not. It is numerically shown that releasing a low-velocity plasma from an MPS spacecraft excites an equatorial ring-current, which makes a larger magnetosphere and correspondingly a larger thrust level becomes possible. Thrust gain, which is defined as a thrust ratio between MPS and pure magnetic sail without releasing plasma, was found to be as much as 40; this thrust gain is predicted from a limited model describing the interaction between a dipole magnetic field and ions. In addition to the limited simulation, some full numerical simulations of MPS, including a solar wind to magnetosphere interaction as well as plasma equilibrium in a magnetosphere, were conducted to indicate a thrust gain as much as 3.77 is possible in an MHD regime.