26pB05
磁気スラストチャンバーにおけるプラズマの振る舞いに関する実験
Experiment of plasma behavior in a magnetic thrust chamber川島 諒祐1), 山本 直嗣2), 森田 太智2), 齋藤 直哉1), 中島 秀紀2), et al
Ryosuke Kawashima, Naoji Yamamoto, Taichi Morita, Naoya Saito, Hideki Nakashima, et al
九州大学大学院総合理工学府先端エネルギー理工学専攻
2)
九州大学大学院総合理工学府研究員

1)

1)

Department of Advanced Energy Engineering Science, Kyushu University
2)
Faculty of Engineering Sciences, Kyushu University

Laser Fusion Rocket (LFR) is a spaceship utilizing
an extravagant amount of nuclear fusion energy andcontrolling fusion plasma with an external magnetic field.
LFR has a potential to produce large thrust and highspecific impulse simultaneously, so that it is expected as arocket of interplanetary missions [1]. In interplanetary
missions, long duration of the exposure of cosmic ray andliving in an enclosed space deteriorate both physical andmental health of astronauts, and reducing mission period
is indispensable. LFR is expected to solve this issue
because of its potential to generate large thrust. In
addition, the thruster can control the exhaust mass andvelocity with wide range so that it enables an optimaldesign of the thruster depending on missions [2-3]. In thispaper, such a thruster is called “Magnetic ThrustChamber”.
In previous researches, some experiments in laser
facilities with the energy of 4 J to 1 kJ have been
performed. Maeno et al have directly measured thrustgenerated by a magnetic thrust chamber [4]. Yasunaga et
al have examined the interaction between magnetic field
and laser-produced plasma, and observed the diamagnetic
cavity [5]. We examined the plasma structure in amagnetic thrust chamber by observing the light emissionof a laser-produced plasma with several magnetic fieldstrength as shown in Fig. 1. We observed the plasma
deceleration.

Fig.2

Mach-Zehnder interferometerIn this paper, we examine plasma density by
Two-wavelength Mach-Zehnder interferometer to observe
the plasma behaviour in strong magnetic field.
The experiment was performed at the Extreme
Ultra-Violet (EUV) database facility of the Institute ofLaser Engineering (ILE) in Osaka University as shown inFig. 2. A plasma was created by focusing a 1064 nm
Neodymium: Yttrium Aluminum Garnet (Nd:YAG) laser
onto a polystyrene ([-CH2-CH(C6H6)-])n spherical target
with a diameter of 500 µm. The pulse width of laser is 9.0
 0.5 ns and the laser energy is 5.5 0.7 J. The target issuspended by a carbon fiber attached to a glass rod toreduce the plasma formation of glass rod. The distance
between the coil surface and the target is 13 mm.
Magnetic field was generated by flowing current
into a 96-turn electromagnetic coil with the inner radiusof 13 mm and outer radius of 25 mm. The magnetic fieldof 1.1 T was generated at the initial target position by
applying 500 V on the capacitor bank.
We measured plasma electron and neutral particle ofplasma and compare these results with the results ofplasma light emission.
References

Fig. 1 The light emission from the plasma (a)without and with the magnetic field of (b) 1.1 T, at 0.3
s after laser irradiation. In these figures, target was set
at the coordinate
and was irradiatedwith the laser from left side through the hole of thecoil. The magnetic field is in horizontal direction andthe center axis of the magnetic field corresponds to thex-axis at y = 0.

[1]
[2]
[3]
[4]
[5]

C.D. Orth et al., UCRL-TR-110500 (2003).
S. Uchida, J. Plasma Fusion Res 81, 186 (2005) (in Japanese)
S. Uchida, Plasma Fusion Res 83, 271 (2007) (in Japanese)
A. Maeno et al., Appl. Phys. Lett., 99, 071501 (2011).
M. Yasunaga et al., Trans. JSASS Aerospace Tech. Japan, 10,28, 109-114 (2012).