均質核形成によるダスト生成実験と古典的核形成論
Yuki Kimura Tohoku Univ.
Katsuo Tsukamoto Tohoku Univ.
Hitoshi Miura Tohoku Univ.
Takao Maki Olympus Corp.

(7７) GFWS/銀河のダスト研究会、神戸CPS、Sep. 2, 2010．

均質核形成によるダスト生成実
験と古典的核形成論
Why nucleation?
• Number• Morphology• Habit• Size• Size distribution

Evolved Star

Not only industrially,
Nucleation is also important to know
the formation process of Cosmic dust
particles.
We need understand Nucleation!

Planetary Nebula

99% gas, but 1% solid

nm sized particles

Building block of Planetarysystem & LifeStar Forming Region

Planetary Nebula
SN Remnant

AGB star
Molecular Cloud

Planetary System

Credit of all photos: NASA/JPL/Space Science Institute99% gas, but 1% solid

nm sized particles

Building block of Planetarysystem & Life
Molster et al.
2002
500 nm

惑星系

500 nm

500 nmNozawa, et al., 2009.

100 nm

200 nm

惑星状星雲
500 nm

500 nm惑星系

Condensation temperature of major
elements as a function of C/O ratio.

ガスの温度が下がるにつれて高融点物質から順に凝縮する。
Cor. Corundum, コランダム, Al2O3
Per. Periclase, ペリクレイス, MgO
Gehl. Gehlenite, ゲーレナイト, Ca2Al(AlSi)O7
Sp. Spinel, スピネル, MgAl2O4For. Forsterite, フォルステライト, (Fe,Mg)2SiO4Fe
Iron, 鉄, Fe

Lodders et al. Meteoritics 30 (1995) 661.

Constraints on the formation conditions
and environment have been calculated.

(Lodders & Fegley 1995; Sharp & Wasserburg 1995; Chigai et al.
1999, 2002)

Condensation sequence
Sizes of core-mantle
Croat et al., 2004 LPS, 1353.

C/O abundance ratio
Total gas pressure
Gas outflow velocity
Stellar mass loss rate

Smoke generator
Nickname is now wanted!

Smoke generator + InterferometerSmoke generator + Interferometer
100 nm50 nm100 nm

200 nmobjective lens, pinhole, collimate lens

632.8 nm

900 ｍｍHe/Ne laser
cameraND filter

cameramirror

600 ｍｍband-pass filter beam splitter
ND filter

pyrometerlenspolarizer

mirrormirrorIR filter
dichroic mirror

objective lens, pinhole, collimate lens

632.8 nm

900 ｍｍHe/Ne laser
cameraND filter

cameramirror

600 ｍｍband-pass filter beam splitter
ND filter

pyrometerlenspolarizer

mirrormirrorIR filter
dichroic mirror

objective lens, pinhole, collimate lens

632.8 nm

900 ｍｍHe/Ne laser
cameraND filter

cameramirror

600 ｍｍband-pass filter beam splitter
ND filter

pyrometerlenspolarizer
70.0 mm

W wire 0.3 mm

mirrorIR filter
dichroic mirror

mirrorInterferogram
Temperature: 298 K (25oC)
Gas: Ar 1×104 Pa
Heating
Refractive index: 1.00002714

Temperature: 323 K (50oC)
Gas: Ar 1×104 Pa
Refractive index: 1.00002503

Difference of refractive
index is only 2×10-6.

W wire 0.3 mm

3 mm

Interferogram
Temperature: 298 K (25oC)
Gas: Ar 1×104 Pa
Heating
Refractive index: 1.00002714

Temperature: 323 K (50oC)
Gas: Ar 1×104 Pa
Refractive index: 1.00002503

W wire 0.3 mm

3 mm

3 mm

We can detect only a difference of 10-6-10-7 orders!!
Thermo couple
0.1 mmΦpyrometer

thermocouple

Interferogram
Temperature: 298 K (25oC)
Gas: Ar 1×104 Pa
OxygenRefractive index: 1.00002714

3 mm

Temperature : 298 K (25oC)
Gas : Ar 9×103 Pa, O2 1×103 Pa
Refractive index: 1.00002703

3 mm
HeatingRT1570 K

Only Temperature

Temperature & concentration

Temperature information is subtracted by oxygen free experiment.

In-situ observation using interferometer

0-55 mmA tungsten wire (0.3 mm and 70 mm depth) is heated in a mixture gasof Ar (9×103 Pa) and O2 (1×103 Pa).
1st, 2nd and 3rd fringes correspond to 320, 500 and 1150 K, respectively.

In-situ observation using interferometer
1570 K  WO3 particles are1150 K condensed 700 K
870 K lower than equilibrium
T due to homogeneous
500 K nucleation!
Evaporation Source
Pe=1.3×103 Pa at 1570 K
Position of Smoke
Pe=~10-9 Pa at 870 K Degree of supersaturation is at least 1011!!

 Nucleation occurs below
the evaporation source.

Convection current and Smoke
104 PaWO3 vapor
Diffusion velocity: 95 cm s-1

1570 K

Flow velocity (cm s-1)

150~100 cm s-1

100500Convection current
He gasT= 1873 K

26
1.3 6.5 1339
3Gas pressure (10 Pa)

Yatsuya et al. J. Cry. Growth 70 (1984) 536.

 The heated source generated a hightemperature atmosphere and convection
currents (~100 cm s-1).
 Evaporated WO3 vapor diffuses in
uniformly with 9.79 cm2 s-1.

Convection current and Smoke
WO3 vapor
Diffusion velocity: 95 cm s-1

Convection current of
ambient gas: ~100 cm s-1

 Since there is a strong convection current, rising vapor is accelerated
and down flow is restrained.
 As the result, concentration of WO3 vapor is getting higher below theevaporation source.

Convection current and Smoke
WO3 vapor
Diffusion velocity: 95 cm s-1

Convection current of
ambient gas: ~100 cm s-1

 Finally, nucleation occurs at the highest supersaturation
environment between convection current of ambient gas andevaporated WO3 vapor.
 Nuclei follow the convection current and grow to makenanoparticles in smoke.

Convection current and Smoke
WO3 vapor
Diffusion velocity: 95 cm s-1

Convection current ofambient gas: ~100 cm s-1

 Finally, nucleation occurs at the highest supersaturation
environment between convection current of ambient gas andevaporated WO3 vapor.
 Nuclei follow the convection current and grow to makenanoparticles in smoke.
 We can derive a lot of information from Interferogram.

Condensation temperature of major
elements as a function of C/O ratio.

ガスの温度が下がるにつれて高融点物質から順に凝縮する。
Cor. Corundum, コランダム, Al2O3
Per. Periclase, ペリクレイス, MgO
Gehl. Gehlenite, ゲーレナイト, Ca2Al(AlSi)O7
Sp. Spinel, スピネル, MgAl2O4
For. Forsterite, フォルステライト, (Fe,Mg)2SiO4Fe
Iron, 鉄, Fe

Lodders et al. Meteoritics 30 (1995) 661.

Constraints on the formation conditions
and environment have been calculated.

(Lodders & Fegley 1995; Sharp & Wasserburg 1995; Chigai et al.
1999, 2002)

Condensation sequence
Sizes of core-mantle
Croat et al., 2004 LPS, 1353.

C/O abundance ratioTotal gas pressure
Gas outflow velocity
Stellar mass loss rate

Conclusion
 Temperature and concentration can bemeasured in-situ during smoke experiment.
 Condensation occurs under very highsupercooling (T=~400-700K).
 Nucleation takes place below evaporation
source in smoke experiment.
 Nucleation theory may be verified.