Radiation process of carbon ions in JT-60U detached divertor plasmas

- 1 -

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

• 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)

- 3 -

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+

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

Radiation zone moves towards the X-point

Viewing chordsVisible spectrometerBolometer

C2+ emission also peaks around the X-point

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

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

-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 )

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

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

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.

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)

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)

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

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

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

- 18 -

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

- 19 -

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

- 20 -

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 ）

- 21 -

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 ）