S2-4
ヘリコン静電加速スラスター
Helicon Electrostatic Thruster
市原大輔，内賀嶋瞭，岩川輝，佐宗章弘(名大)山崎拓也，原田翔太，笹原松隆，岩崎知仁(三菱重工業株式会社) 和文
Daisuke Ichihara, Akira Uchigashima, Akira Iwakawa and Akihiro Sasoh(Nagoya University)
Takuya Yamazaki, Shota Harada, Matsutaka Sasahara and Tomoji Iwasaki(Mitsubishi Heavy Industries)
Electric propulsion has higher exhaust velocity
capability than chemical propulsion, which leads to anincrease in the payload ratio. From this advantage,
many satellites use electric propulsion for station
keeping or even orbit transfer1). However, due to its
low thrust density, the orbit transfer period becomes atleast a hundred times longer than with chemical
propulsion. A promising method to increase thrust
density is utilizing helicon plasma source, which has
capable of making high density plasma on the order of1019 m-3.Charles and Boswell et al demonstrated that
helicon plasma can be accelerated up to 100eV
through the double layer2). But, this ion energy is still
lower than accelerated ion thrusters in ion engine orHall thrusters with about 800-1000V. In order toincrease the ion beam energy, radiofrequencyheating3), steady4) and quasi-steady5) electromagnetic
acceleration were examined.
Harada et al developed the Helicon electrostatic
thruster (HEST) and electrostatically accelerated
helicon plasma. Fig. 1 shows the schematic image of
HEST in side view. HEST had helicon plasma source
in upstream (left side in Fig. 1) and acceleration
section in downstream (right side). Helicon plasma
source was consists of 27mm inner diameter ceramic
tube and 170mm length helical antenna whichconnected to 13.56MHz radio-frequency power
supply through an auto matcher. Solenoidal coilapplied diverging magnetic field up to 100mT atantenna exit. NdFe magnets and pure iron yokes makefield free region in downstream. Anode was set at25mm downstream from antenna exit and hollow
cathode (DLHC1000, Kaufman & Robinson Inc.) was
set inside the field free region. The result of ion beamenergy using Retarding Potential Analyzer (RPA),
electrostatically accelerated ion energy is almost equal
to supplied discharge voltage6). However, how affectthe each operation conditions to ion beamcharacteristics have not been much investigated. Toclear this influence, both ion beam energy
measurement varying anode geometry and ion beam
current and its distribution were measured using
circumference direction sweeping Faraday cup (Fig.
2). In this presentation, the effect of anode geometry
to ion beam characteristics was especially focused on

to understand of ion acceleration mechanisms andthruster performances.

Fig. 1 Schematic illustration of HEST, side viewFig. 2 Beam survey path, top vie

1)

2)

3)

References
D. Y. Oh et al ,”Solar electric propulsion for
discovery-class missions,” J. Spacecraft Rockets,vol.51, pp. 1822-1835, Nov. 2014.
C. Charles et al, “Anexperimental investigationof alternative propellants for the helicon double
layer thruster,”Art.ID. 175213.
B. W. Longmuir et al., “Ambipolar ion
acceleration in an expanding magnetic nozzle,”
Plasma Sources Sci. Technol., vol. 20, Jan. 2011,
Art.ID. 015007.

4)

5)

6)

S. Shinohara et al., “Development ofelectrodeless plasma thrusters with high-density
helicon plasma sources,”pp. 1245-1254, May
2014.
K. Takahashi et al, “Low pressure, high-density,and supersonic plasma flow generated by ahelicon magnetplasmadynamic thruster,” Appl.
Phys. Lett., vol. 105, Nov. 2014, Art.ID. 193503.
S. Harada et al, “Electrostatic acceleration ofhelicon plasma using a cusped magnetic field,”
Appl. hys. Lett., vol. 105, Nov. 2014, Art.ID.
194101.