JAXA Repository / AIREX 未来へ続く、宙(そら)への英知

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Other TitleGround-based experiments of current collection to electrodynamic tether in a high-speed plasma generated by a Hall thruster
Author(jpn)田原 弘一; 内海 良介
Author(eng)Tahara, Hirokazu; Utsumi, Ryosuke
Author Affiliation(jpn)大阪工業大学 工学部 機械工学科; 大阪工業大学 工学部 機械工学科
Author Affiliation(eng)Osaka Institute of Technology Department of Mechanical Engineering, Faculty of Engineering; Osaka Institute of Technology Department of Mechanical Engineering, Faculty of Engineering
Issue Date2008-05
PublisherInstitute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA/ISAS)
Publication title第27回宇宙エネルギーシンポジウム 平成19年度
The Twenty-seventh Space Energy Symposium
Start page68
End page72
Publication date2008-05
AbstractElectroDynamic Tether (EDT) is a long, thin conductive string deployed from a spacecraft. Traveling across the geomagnetic field and driving a current inside itself, EDT may be used to reboost/deboost a spacecraft to which EDT is attached. This is made possible by the Lorentz force acting on EDT. It is considered to be an alternative propulsion system for station-keeping, orbit-raising or de-orbiting purpose. EDT needs plasma contactor to collect ionospheric electrons. Bare-tether is one of the most efficient electron collectors. It has an uninsulated portion of the metallic tether itself to collect ionospheric electrons. It is extremely economical propulsion system because it can be operated without propellant. In order to put into practice EDT technology, we still need to solve several problems. One of them is the current-voltage characteristic of an electron collector. There exist some theories. When the radius of the electron collector is smaller than the local Debye length, current collection is limited by Orbital Motion Limit (OML). OML is the upper limit of the current collection in the steady-state collisionless uniform plasma. However, current collection to the bare-tether in space does not always drive OML because it is not taken into account plasma velocity and magnetic field. So ground-based experiments of current collection to a bare-tether were carried out to investigate the influence of surrounding plasma parameters, configuration of bare-tether, magnetic field and plasma velocity on the current-voltage characteristic. An anode-layer-type Hall Thruster was used as a plasma source. We could produce plasma velocity of approximately over 8 km/sec which is orbital velocity in Low Earth Orbit (LEO) where bare-tether is used, varying discharge voltage of Hall thruster. Experimental results showed that plasma velocity and configuration of bare-tether sample affected the current collection. In addition, for all cases, current collection to bare-tether sample was less than that predicted by OML. Accordingly, we need to modify OML when we estimate current collection to bare-tether in space.
Keywordsaerospace environment; spacecraft power supply; tethered satellite; electrodynamic tether; electric conductor; Hall thruster; space plasma; plasma contactor; Earth ionosphere; low Earth orbit; magnetic field; 航空宇宙環境; 宇宙機給電; テザー衛星; 導電性テザー; 導電体; ホールスラスタ; スペースプラズマ; プラズマコンタクタ; 地球電離層; 低高度地球周回軌道; 磁場
Document TypeConference Paper
JAXA Categoryシンポジウム・研究会

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