24D13
Measurements of Sound Velocity of Laser-Irradiated Single Crystal Diamond
Foils Around the Melting Temperature
高強度レーザー照射された融点付近の単結晶ダイヤモンドの音速計測
Keisuke Shigemori, Katsuya Shimizu, Yasuhiro Asakura, Yuki Nakamoto, Tomoko Kagayama,
Tatsuhiro Sakaiya, Tadashi Kondo, Hitoshi Sumiya, Tetsuo Irifune, Toshihiko Kadono, Yoichiro
Hironaka, and Hiroshi Azechi
1
2
重森啓介 ，清水克哉 ，浅倉康弘2，中本有紀2，加賀山朋子2，境家達弘3，近藤忠3，
角谷均4，入舩徹男5，門野敏彦1，弘中陽一郎1，疇地宏1
ILE, Osaka Univ.1, KYOKUGEN, Osaka Univ.2, Department of Earth and Space Science, Osaka Univ.3,Sumitomo Electoronic Industries Ltd4, GRC, Ehime Univ.5
2-6 Yamada-Oka, Suita, Osaka 565-0871, Japan1
1
阪大レーザー研 ，阪大極限センター2，阪大理3，住友電工4，愛媛大地球深部研5〒565-0871 大阪府吹田市山田丘2-61

1. Introduction
Diamond is of great interest for many filelds inindustries and sciences. High power laser can create
post-diamond phase of carbon at multi-TPa regime.
Recent experimental and theoretical studies suggestthat the diamond starts to melt at around 700 GPa
on the principal Hugoniot, then complete themelting at around 1 TPa [1-4]. There exists twocomplex phases in between, that is, “diamond andliquid carbon” and “BC8 carbon and liquid carbon”.
Since diamond has very large shear modulus, thesound velocity would significantly decrease due tomelting.
2. Experiment
We have measured the sound velocity of thediamond foils at around the melting pressures (500– 1500 GPa). Experiments were done on
GEKKO-XII glass laser system with HIPER
irradiation facility. Schematic view of theexperimental setup is shown in Fig. 1. Single
crystal diamond foils (Ia) of 20~30 mm thickness
were irradiated at intensities of 0.2 – 1.5 × 1014
W/cm2. We measured the sound velocity by side-on
x-ray backlighting technique [5]. Trajectories of foil
surfaces were observed by x-ray streak camera. We
also measured the shock velocity by two VISARs(velocity interferometer system for any reflector),and shocked temperature by an SSOP (streaked
spectral optical pyrometer) [6] in order to determine
the pressure and the temperature at around themelting.
Acknowledgments
This work was performed under the joint
research project of the Institute of Laser
Engineering, Osaka University. This work was
supported by
Grant-in-AidforScientificResearch.
Target (for sound velocity measurements)

Streaked optical pyrometer（SOP）

Backlight
Laser
2 mm

Diamond: 20~35 pmt
Cu coating: 5 pmt

Target: Diamond (Ib)Be

200 pm or 1 mm

DriveLaser

Pulse shape(by pulse stacking)Shock:Drive pulse:Backlight pulse60.).ua(yitsnet
In

Backlight target: Ti

Probe laser (p: 532 nm)

50

Imaging slit

40

Velocity interferometer system
for any reflector（VISAR）

Ti filter

30
20

X-ray streak camera1000246810Time (ns)Fig. 1 Schematic view of the experimental setup
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