24F07
Labolatory experiments of generation plasma jets in a magnetic
field by using high-power laser system
高出力レーザーを用いた磁場中でのプラズマジェット生成実験
K.nishio1 , Y. Sakawa2 , Y. Kuramitsu2 , T. Morita2 T. Ide3 , M. Kuwada1 , H. Ide1 , K.
Tsubouchi3 , H. Yoneda4 , A. Nishida3 , T. Namiki4 , H. Tanji2 , T. Norimatsu1 , K. Tomita5 , K.
Nakayama5 , K. Inoue5 , K. Uchino5 , C. Gregory6 , M. Nakatsutsumi6 , H. Nakatsutsumi6 , A.
Pelka6 , A. Diziere6 , M. Koenig6 , K. Schaar7 , G. Gregory7 , S. Wang8 , D. Yuan8 , Q. Dong8 , H.
Takabe1
122
西尾健斗 , 坂和洋一 , 蔵満康浩 , 森田太智 2 , 井出尭夫 3 , 桒田三沙 1 , 井手張良 1 , 坪内邦男 3 ,米田仁紀 4 , 西田明憲 3 , 並木智紀 4 , 丹治浩樹 3 , 乗松孝好 2 , 富田 健太郎 5 , 中山和貴 5 , 井上和哉
5, 内野喜一郎 5 , C. Gregory6 , 中堤基彰 6 , 中堤晴美 6 , A. Pelka6 , A. Diziere6 , M. Koenig6 , K.
Schaar7 , G. Gregory7 , S. Wang8 , D. Yuan8 , Q. Dong8 , 高部英明 21

Graduate School of Science, Osaka University 1-1, Machikaneyama, Toyonaka, Osaka 560-0043, Japan
大阪大学大学院理学研究科 大阪府豊中市待兼山 1-1
2
Institute of Laser Engineering, Osaka University2-6, Yamadaoka, Suita, Osaka 565-0871, Japan
大阪大学レーザーエネルギー学研究センター 565-0871 大阪府吹田市山田丘 2-6
3Graduate School of Engineering, Osaka University 2-6, Yamadaoka, Suita, Osaka 565-0871, Japan
大阪大学大学院工学研究科 大阪府吹田市山田丘 2-6
4
Institute for Laser Science, University of Electro-communications 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585,
Japan
電気通信大学レーザー新世代研究センター 182-8585 東京都調布市調布ケ丘 1-5-15Interdisciplinary Graduate School of Engineering Sciences Kyushu University 6-1, Kasugakoen, Kasuga,Fukuoka 816-8580, Japan
九州大学総合理工学府 816-8580 福岡県春日市春日公園 6-1
6LULI, École Polytechnique, CNRS, CEA, UPMC, Route de Saclay, 91128 Palaiseau, France
7
University of Oxford, Parks Road, Oxford OX1 3PU
8Institute of Physics, Chinese Academy of Sciences Beijing 100190, China
In recent years, the experiments simulated various astrophysical phenomena have been actively carriedout. We perform an experiment to simulate astrophysical plasma jets generation by using high-powerlasers.
The experiment was performd by using GekkoXII (GXII) HIPER laser system We shot CH plane(∼ 10 µm) and observed high-speed plasma flow, opposite from main laser. In the experiment wegenerated un-uniform plasma by moving each beam focal spots. And we observed the plasma flow
in external transverse magnetic field (0.2 ∼ 0.3 T) to main laser on the GXII experiment. We
used transverse diagnostics to observe the spatial and temporal evolution of plasma flows. For twodimensional transverse images, we used Normarski type interferometry and shadowgraphy with aprobe laser (wavelength: 532 nm, pulse length: ∼ 14ns). For the time evolution of plasma flow,
we used self-emission streaked optical pyrometry, and streaked interferometry. And we used X-ray
pinhole camera to confirm focal spot separations.
In the case we generated un-uniform plasma without magnetic field, the collimated plasma jets
formation was seen. On the other hand we generated un-uniform plasma in external magnetic field, themore collimated plasma jets formation was seen. Un-uniform plasma and the perpendicular magnetic
field are important to generate collimated plasma jets.

1Introduction

In recent years, the experiments simulated various astrophysical phenomena have been actively
carried out. These experiments are called laboratory astrophysics. We performed an experimentto simulate astrophysical plasma jets generationby using high-power lasers.
Labolatory experiments can help to study the observation and simulation astrophysics. Throughthe combined efforts of obseevation, simulation,and laboratory experiments, we can understandabout astrophysical objects more deeply.

2Experiment

The experiment was performed by GXII laser system at the Institute of Laser Engineering at theOsaka university. The laser conditions were; thewavelength was 351 nm, the pulse length was 500ps, the focal spot diameter was 300 µm, the pulseenergy was ∼ 100 J/beam × 12, the intensity was(0.2 ∼ 3.0) × 1015 W/cm2 .
To produce uniform and un-uniform plasmas, a(CH)n plane target (∼ 10 µm) was irradiatedwith the any laser beams moved focal spots. To
perform experiment in magnetic field, we usedneodymium permanent magnet (0.2 ∼ 0.3 T). We
set external magnetic field transverse to main laser
axis. Figure 1 shows schematic drawing of the configurations of the laser and the target. The plasmas were observed by the transverse diagnostics
with the probe laser and with the self-emission.
The optical probe conditions were; the wavelength
was 532 nm, and the pulse length was ∼ 14 ns.
With the probe laser we obtained the density information of the two-dimensional snapshot interferometry and shadowgraphy by ICCD cameras(1.6 ns gate width and 250 ps gate width). We
also measured the time evolution of the central
plasma by streaked interferometry. Using 450 nm
interference filters the self-emission was gated atthe wavelength. We obtained the two-dimensional
snapshot of the self-emission by ICCD (200 ps gatewidth) and of the time evolution by self-emission
streaked optical pyrometer (SOP). And we used
X-ray pinhole camera to confirm focal spot separations.
3Figure 1: Laser off set means making beam separation to produce un-uniform plasmas. Beam separation was 200 ∼ 300 µm. The CH plane thickwas ∼ 10 µm. The magnetic field was 0.2 ∼ 0.3T.

ResultFig.2 shows two-dimention interferogam. We cansee the collimated plasmas in this figure.
The electron density at colimated plasmas is ∼1018 /cm3 . The plasma flow speed is ∼ 250 km/s
and the electron temperature is 10 ∼ 20 eV from
SOP image. Ionic charge Z is 3.5. The plasmas
size is ∼ 15 mm. In ideal MHD the magnetic
reynolds number is  1. In the region of high Figure 2: Laser came from left side. Left figure
reynolds number a magnetic field is frozen, and shows collimated plasma in a condition fig.1, (4)considered to move with plasma flow.
after 25 ns from main laser. Right figure shows
un-uniform plasmas in a condition fig.1, (2) after
4 Conclusion
15 ns from main laser.
In the region of high reynolds number a magnetic
field is frozen, and considered to move with plasma
flow. The detail will be explained in my talk.