- 1 - radiation process of carbon ions in jt-60u detached divertor plasmas o-26(15+3min.) 29may2008...
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Radiation process of carbon ions in JT-60U detached divertor plasmas
O-26(15+3min.)29May2008
PSI-18@Toledo Spain
Japan Atomic Energy AgencyT. Nakano, H. Kubo, N. Asakura, K. Shimizu, H. Kawashima, S. Higashijima
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• Heat & particle control is essential in future fusion devices Remote radiative cooling by impurities ( 85% in Demo SS) Changes of plasma parameters and spatial distribution Radiation is not proportional to an impurity flux necessarily Radiation control requires understanding of physics
• Physics to be understood: elementary processes and transportRadiator ( C3+, C2+,,,,(Carbon devices))Recombination/IonizationSource (from divertor plates,
& main plasma)
Introduction
C3+ emissivityCq+
C
C
(q>3) Cq+
Cp+ Cp+
(p<3)
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What is known & new
C3+
C 2+
C 2+
C 2+
Kubo H. et al 1995 PPCF 37 1133Fenstermacher M.E. et al 1997 PoP 4 1761
Ioniz. flux (1018 /m2s)
Recomb. flux (1018 /m2s)
C 3+
C3+
Nakano T. et al 2007 NF 47 1458
C4+
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Outline
• ExperimentWaveforms of density-scan dischargeC2+ intensity distribution
• Analysis modelCollisional-radiative model for C2+
• ResultsDetermination of Te and ne
Flux balance ( Recombination vs. Ionization )Radiation power of C2+
• DiscussionTransport of C3+
• Summary
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Radiation zone moves towards the X-point
Viewing chordsVisible spectrometerBolometer
C2+ emission also peaks around the X-point
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1014
1015
1016
1017
1018
1019
1020
Intensity C
2+
(ph sr
-1m
2s-1 )
80604020Viewing chord
3s3S-3p
3P
3d1D
4f3F-5g
3G
5d3D-6f
3F
Vertical array
3p1P-
E045211
Horizontal arrayVUVSp
inSp
outSp
inSp
out
Xp
106
107
108
109
1010
1011
1012
nC
2+(p) L
/ w
g (p
) ( m-2 )
80604020Viewing chord
5g3G
3d1D
3p3P
6f3F
E045221
VUVVertical array Horizontal arraySp
inSp
inSp
outSp
out
Xp
Population
C2+ intensity peaks around the X-point 1 60
61
92
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C2+: population decreases rapidly
108
109
1010
1011
1012
1013
nC
2+(p)
L /
wg (
p) ( m-2 )
5040302010
2p1P 3p
3P
3s3S
3d3D
3d1D
5g3G
6f3F
Excitation Energy from the ground state C2+
( 2s2 ) ( eV )
Ionization potential (47.9 eV )
C2+ C
3+
From visibleFrom VUV
Population
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-49.7eV2s
n=4
n=7
n=3
n=6n=5
(De)
Exc
itatio
n
C2
+
(B
e-li
ke)
C 3
+
n=1
-13.6eVC
ha
rge
eX
chan
ge
re
com
b.
Spo
ntan
eous
tra
nsiti
on
Rec
ombi
natio
n
Collisional-Radiative model
Ioni
zatio
n
C2+ energy level
D+
D0 energy levell-,
Sin
g- &
trip
let
reso
lved
n=…
H-li
ke
D0
Solution of Rate Equation under Steady-State (~ 10-8s ) nC2+(p) = R0nenCV (Recombining )
+ R0'nDnCV (CX-Recomb. )
+ R1nenCIV (Ionizing )
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108
109
1010
1011
1012
1013
5040302010
2p1P 3p
3P
3s3S
3d3D
3d1D
5g3G
6f3F
nC
2+(p)
L / w
g
(p) ( m
-2 )
Excitation Energy from the ground state ( 2s2 )( eV )
Ionization potential (47.9 eV )
C2+ C
3+
measured Cal ( Ioniz. )
Te = 7.8 eVne = 1 x 10
20 m
-3
C2+: Ionization components dominates
No recombining component.
Pop
ulat
ion
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108
109
1010
1011
1012
nC
3+(p)
L / wg
(p) ( m
-2 )
65605550454035
Term Energy ( eV )
3s
3p
3d
4d6 7 9
Recomb.
ne = 7.8 x1020
m-3
Te = 6.3 eV
Ioniz.
nC4+ / nC
3+= 4.0
Ionization potential ( 64.5 eV )
C3+ :n < 4 : Ionizing component (Term Energy < ~50eV) n > 5 : Recombining component
Pop
ulat
ion
Nakano T. et al 2007 NF 47 1458Nakano T. et al 2007 NF 47 1458
TotalTotal
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108
109
1010
1011
1012
1013
5040302010
2p1P 3p
3P
3s3S
3d3D
3d1D
5g3G
6f3F
nC
2+(p)
L / w
g
(p) ( m
-2 )
Excitation Energy from the ground state ( 2s2 )( eV )
Ionization potential (47.9 eV )
C2+ C
3+
measured Cal ( Ioniz. )
Te = 7.8 eVne = 1 x 10
20 m
-3
C2+: Ionizing components dominatesP
opul
atio
n
No recombining component.
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0.1
1
10
100
Events / photon
0.1 1 10 100Te ( eV )
21
20
19
Flux balance : C2+ ioniz. >> C3+ recomb.
C4+
C2+
C3+
Transport loss of C3+ is suggested
Flux (1018 /m2s)Flux (1018 /m2s)
Ioni
zatio
n C
2+ (
3s3S
-3p3
P)
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10-17
10-16
10-15
10-14
1 10 100
Te ( eV )
19
21
20
C4+
C2+
C3+
Radiation power : C2+ contributes 30%
C4+
C2+
C3+
160
C3+ & C2+ contribute 90% of total radiation
Rad
iatio
n C
2+ (
3s3S
-3p3
P)
(J/p
h)(J
/ph)
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Source of C3+:main plasma and divertor comparable
Cq+
C
C
(q>3) Cq+
Cp+ Cp+
(p<3)
Suggesting C4+ source from
main plasma.
Suggesting C4+ source from
main plasma.
Suggesting C2+ source
from divertor
Suggesting C2+ source
from divertor
C4+
C2+
C3+
Recomb. flux (1018 /m2s)C4+
C2+
C3+
Ioniz. flux (1018 /m2s)
from divertorfrom divertor
from main plasmafrom main plasma
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Summary
In a detached plasma with an X-point MARFE of JT-60U, • Absolute C2+ line intensity was measured with a VUV and
a visible spectrometer.• The C2+ line intensity ratios ( population ratios ) were
analyzed with a collisional-radiative model.• C2+ population was dominated by an ionizing plasma component ( excitation from the ground state ).
No recombination of C3+ was observed.With the results of C3+ ,
• C3+ & C2+ radiate 60% and 30%, respectively, of total radiation power
• C3+ is produced by C2+ ionization and C4+ recombination• C3+ is NOT lost by C3+ ionization and C3+ recombination Significant transport loss of C3+ from the X-point • C3+ originates the main plasma and the divertor, comparably
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Thank your for your attention.
This work was partly supported by Grant-in-Aid for Scientific Research for Priority Area #19055005
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Specifications• Instrumental width (FWHM):
~ 0.74 nm (2.3 pixels)• Spectral band: ~ 430 nm ( 350 - 780 nm)• Spatial resolution (92ch): ~ 1 cm
Spectrometer• Grating : 300 g/mm• F : 2• f : 0.2 m
CCD• Back-illuminated• Pixel size : 20 x 20 m• Format : 1340 x1300
32ch
60ch
2D wide-spectral-band spectrometer
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Grating:Holographic ( 300g / mm )Incident angle : 85o
Dispersion : 2 nm / mmResolution:
Slit: 10m x 5mm
Detector : MCP 50 m x 1024ch
Vacuum Ultra Violet spectrometer
• Similar viewing chord to the visible spectrometer• Absolute calibration of sensitivity by a branching ratio method Comparison of visible and VUV spectrum
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555045403530Wavelength ( nm )
10090
4
2
0
x1020
4
2
0
x1021
Intensity ( 10
21
ph / sr m
2
nm s )
C III 2p
3P0,1,2
-3d3D1,2,3
E045211
C III 2p
3P0,1,2
-4d3D1,2,3
C III 2p
3P0,1,2
-5d3D1,2,3
C III 2p
3P0,1,2
-3s3S1
C III 2p
1P1
-3d1D2
Intensity ( 10
22
ph / sr m
2
nm s )
C III 2s
1S0
- 2p1P1
VUV スペクトル
可視 スペクトル1.0
0.5
0.0
x1018
750700650600550500450400Wavelength ( nm )
Intensity ( 10
18
ph / sr m
2
nm s )
C III 4f
3
F -5g3G
C III 3p
3
S -3p
3P
C III 3p
1P1
-3d1D2
C III 5d
3
D -6f3F
8 本の C III スペクトル線を同時解析
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1.0
0.8
0.6
0.4
0.2
0.0
x1021
50454035302520Wavelength ( nm )
Intensity ( 10
21
ph / sr m
2
nm s )
C IV 2s
2S1/2
- 3p2P
3/2,1/2
C IV 2p
2P
3/2,1/2
- 3d2D
5/2,3/2
C IV 2p
2P
1/2,3/2
- 3s2S1/2
C III 2p
3P0,1,2
-3d3D1,2,3
C IV 2s
2S1/2
- 4p2P
3/2,1/2
C IV 2p
2P
3/2,1/2
- 4d2D
5/2,3/2
C IV 2p
2P
1/2,3/2
-4s2S1/2
C IV ( 2 - 3, 4 ) が観測された
C IV スペクトル( VUV )
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1.5
1.0
0.5
0.0
x1020
3432302826242220Wavelength ( nm )
Intensity ( 10
20
ph / sr m
2
nm s )
C IV 2s
2S1/2
- 3p2P
3/2,1/2
C IV 2s
2S1/2
- 4p2P
3/2,1/2
C IV 2p
2P
3/2,1/2
- 4d2D
5/2,3/2
C IV 2p
2P
1/2,3/2
-4s2S1/2
C IV 2p
2P
3/2,1/2
- 5d2D
5/2,3/2
C IV ( 2 - 5 ) は弱く、解析は困難
C IV スペクトル( VUV )