24E12
Preliminary Thrust Measurement in Development of Long Lifetime Helicon
Plasma Rockets by Use of Lissajous Method
リサージュ方式によるヘリコンプラズマを用いた
長寿命ロケット開発における推力の予備計測
Takeshi Matsuoka,1 Syuhei Satoh,2 Ikkoh Funaki,1 Takahiro Nakamura,3 Shunjiro Shinohara,3Hiroyuki Nishida,3 Kenji Yokoi,3 Timofei S. Rudenko,4 Konstantin P. Shamrai,4 Tohru Hada,5Takao Tanikawa,6 and Takayasu Fujino2
松岡健之,1 佐藤周平,2 船木一幸,1 中村隆宏,3 篠原 俊二郎,3 西田 浩之,3 横井 賢治,3Timofei S. Rundenko,4 Konstantin P. Shamrai,4 羽田 亨,5 谷川 隆夫,6 藤野貴康2
1

Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, 252-5210, Japan
2
University of Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan
3
Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
4
Institute for Nuclear Research, Nauki, Kiev 03680, Ukraine
5
Kyushu University, Kasuga, Fukuoka 816-8580, Japan
6
Tokai University, Hiratsuka, Kanagawa, 259-1292, Japan1
宇宙航空研究開発機構 〒252-5210 相模原市
2
筑波大学 〒305-8573 つくば市3
東京農工大学 〒184-8588 小金井市4
Institute for Nuclear Research, Nauki, Kiev 03680, Ukraine
5
九州大学 〒816-8580 春日市
6東海大学 〒259-1292 平塚市A thrust model for a Lissajous method has shown that a potential of a longer lifetime with competitive
performance compared with the rockets using, e.g., ion engines or Hall thrusters. Previous experiments
showed a slight increase of plasma flow velocity by this method, however, experimental conditions werenot optimized and the thrust was not measured. In this study, in order to develop helicon plasma sources
and a thrust measurement method, thermal thrust is measured by using a 26 mm diameter helicon plasma
rocket without Lissajous acceleration. A future plan of experiments for verifying the thrust model is alsopresented.

1. Introduction
For deep space missions, high plasma exhaust
velocity (high specific impulse), and a long
lifetime are required. Electric propulsion [1] canmeet those requirements. Combination of ahelicon plasma production and magnetoplasma
dynamics acceleration which is powered by radio
frequency waves could be a solution because ofno physical contact between the plasma andelectrodes (electrodeless). Various schemes havebeen under development to realize electrodelesselectric propulsion: VASIMR [2], HDLT [3], andothers [4,5].
We have been studying one of the electrodelessthruster, which is called Lissasjous acceleration
method [6], whose concept is shown in Fig. 1.
This study becomes a part of the HEAT (HeliconElectrodeless Advanced Thrusters) project [7,8].
The thruster consists of two sections, a plasma
generation section by helicon plasma discharge
and a plasma acceleration section by theLissajous method. In the acceleration section,
rotating electric fields are applied to the plasma
in order to excite electron azimuthal currents. TheLorentz force, which is the product of the currents
and the static magnetic field produced by thesolenoid coil, accelerates plasma and produces
thrust.

Fig. 1 Concept of Lissajous Method

Plasma acceleration has been observed inexperiments. However the exhaust velocity is small
compared for practical applications [9]. This
indicates that there is a room for improvement byresearch. Thrust by this method was not measured,and therefore the thruster performance is unknown(exhaust velocity and power efficiency).
In this paper, we report a progress fordevelopments of helicon plasma sources and athrust stand. The measurements of thermal thrust(thrust due to electron thermal pressure) areconducted in order to clarify tasks for Lissajous
thrust measurements.
3. Experimental Results
Experiments are conducted by use of the “Large
Helicon Plasma Device” (LHPD) [10] in theInstitute of Space and Astronautical Science (ISAS).
A quartz tube was placed inside the LHPD. Two
inner diameters (I.D.) of 26 and 50 mm are used.
Thrust is measured by a pendulum type thrust standwhich is placed inside the LHPD. In thisexperiment, the static magnetic field is applied bythe solenoid coils outside of the thrust stand andtherefore the electromagnetic thrust is not measured.
Details of the experimental set up are reported inRef. 11.
The first plasma is successfully ignited for 26mm and 50 mm I.D. tubes. The thermal thrust is
shown in Fig. 2 as a function of mass flow rate. The
data points in the Fig. 2 are obtained with the I.D.
26 mm tube, the axial magnetic field of 0.008 T and
input RF power for plasma generation of 2.1±0.1
kW. The slope of the linear fit curve in the Fig. 2
corresponds to the exhaust velocity of 2.5 km/s.
The thrust power efficiency is estimated to be
0.13 %.

Fig. 2. Thrust as a function of the Ar gas mass flow rate.

4. Future Plan
A laboratory model is fabricated in order tomeasure Lissajous acceleration by use of permanent
magnets. Thrust by the Lissajous acceleration actson the magnet. Therefore the magnet should beplaced on the thrust stand. In order to reduce massof the thruster, we decided to use permanent
magnets instead of a solenoid coil for producing thestatic magnetic field. It was found that the totalmass of the thruster for the I.D. 26 mm tube would
be too heavy for the developed pendulum typethrust stand in order to detect thrust by theLissajous method [11]. Improvement for sensitivityof the thrust stand is under progress.
.

5. Summary
Preliminary experiments of thermal thrustmeasurements from an I.D. 26 mm plasma source
are reported. The first plasma is successfully ignited.
The developed pendulum type thrust stand is tested
by measuring thermal thrust from the plasma source.
The thrust is found to be proportional with the mass
flow rate. The thrust is 2 mN with 2.1 kW input RF
power with exhaust velocity of 2.5 km/s. It is foundthat the sensitivity of the thrust stand is not enoughfor detecting thrust by the Lissajous acceleration.
Those experimental findings will be used for future
experiments for the Lissajous acceleration.
Acknowledgments
This work is supported by the Grants-in-Aid for
Scientific Research under Contract No. (S)21226019 from the JSPS. Experiments wereconducted in and supported by the Space Plasma
Laboratory, ISAS, JAXA. We would like to thankstaffs of the ISAS machine shop for fabrication ofthe thrust stand and hardware supports. We would
like to thank Mr. Yamamoto for experimental
equipments support.
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