[PPT] - Experimental evaluation of W 45+ recombination and W 44+ Ionization PowerPoint Presentation

SLIDE 1

T. Nakano

Japan Atomic Energy Agency Acknowledgements

Dr. N. Nakamura (Univ. of Electro-Communications)
Dr. H. Ohashi (Toyama Univ.)

Experimental evaluation of W45+ recombination and W44+ Ionization cross-sections

14SEP2015 IAEA CM on W Deajeon, KAERI, Korea

SLIDE 2

Tungsten: a candidate for PFCs in reactors

W plasma-facing component ! Merit : high melting point : high heat conductivity : low sputtering yield : low hydrogen (T) retention ⇒ safety, economy ! Demerit : melting : cracking (Bulk W) : high Z (74) ⇒ accumulation in plasma core ⇒ highly radiative (nW/ne < 10-5) ⇒ W transport in plasmas For quantitative transport study, absolute W density is required.

http://www.iter.org/mach/vacuumvessel

SLIDE 3

Various W atomic data needed for W density measurement

I q+ W spatial / charge state distribution

<= Ioniz/recomb. rates Plasma

nW q+ Line identification

<= spectral data

Photon Emission Coefficient

<= excitation rate, A coef, Energy level

nW q+ nW nW (total W density)

(Fractional abundance of Wq+)

(Wq+ density) Ioniz.Eq / Transport model Collisional-radiatve model

SLIDE 4

Availability of W atomic data

1 W 20 40 60 80 1 20 40 60 80 Charge Atomic number Present tokamak

*) NIST ASD version5. http://physics.nist.gov/ASD

ITER Spectral data(wavelength, Acoef): NIST is Worlds’ standard database But still far from ‘a complete set’ ⇒ Evaluated Mo Collisional data(Ioniz./recomb. Rates): Derived data(Photon emission coef,

Cooling rates):

ADAS high availability ⇒ Not evaluated Spectral data holdings at NIST*

SLIDE 5

W fractional abundance under Ionization equilibrium still different amongst datasets

0.001 0.01 0.1 1 Fractional Abandance 0.001 0.01 0.1 1 Fractional Abandance 10

3

10

4

Te ( eV )

Te ( eV ) Te ( eV ) 103 104 103 104 FLYCHK code1) LANL code2)

1)http://nlte.nist.gov/FLY/ 2)http://aphysics2.lanl.gov/tempweb/lanl/

44+45+ 46+

ADAS4) ADPACK3) Uncertainty of collisional data ( Ioniz./Recomb. rates ) needed ⇒ Evaluation

3)K. Asmussen, et al., Nucl. Fusion 38 (1998) 967-986. 4)T. Puetterich et al PPCF 50 (2008) 085016.

W Fractional Abundance

SLIDE 6

Issue 1: W density measurement

I 54+ W spatial / charge state distribution

<= Ioniz/recomb. rates Plasma

nW 54+ Line identification

<= spectral data

Photon Emission Coefficient

<= excitation rate, A coef, Energy level

nW 54+ nW nW (total W density)

(Fractional abundance of W54+)

Ioniz.Eq / Transport model Collisional-radiatve model

*H.-K Chung et al., HEDP 9 (2013) 645.

7% 14% Factor of 2 deviation

SLIDE 7

10

26

10

25

10

24

Radative power rate ( W cm

3 )

10

2 2 4 6 8

10

3 2 4 6 8

10

4 2 4

Te ( eV ) Lw = !q LW

q+ Fa(q)

Lw*

**T Nakano et al J. Nucl. Mater 415 (2010) S327 *T Puetterich et al Nucl. Fusion 50 (2010) 025012

Issue 2: W cooling rate

Shift of the cooling rates originates from ioniz. Eq calculation ** shifted

SLIDE 8

*T. Nakano et al 41st EPS conference (2014), submitted to J. Phys. B

Uncertainty of collisional data ( Ioniz./Recomb. rates ) needed

3 2 1 x10

5

3 2 1 x10

5
50%

+50%

nW / ne from W45+ line nW / ne from W46+ line 20% lower

x10-5 x10-5

Issue 3: W density measurement

SLIDE 9

Outline

! Introduction ! Motivation ! Evaluation of W44+ ionization / W45+ recombination

Experiment in Tokyo EBIT device
Calculations for Excitation Auto-ionization

and Dielectronic Recombination by FAC

Comparison

! Conclusions

SLIDE 10

*) H. Ohashi et al, Rev. Sci. Instrum. 82 (2011) 083103

Experimental setup

W source: W(CO)6 Beam Energy : 2.5 – 3.3 keV Energy width : ~ 10 eV Beam Current: 20 – 50 mA Grating: 2400g/mm λ/Δλ = 1100 @ 5 nm (W) Format: 1340 x400 Pixel: 20µm

SLIDE 11

10

11

10

10

10

9

10

8

Excitation rate ( cm

3 / s )

10

1

10

2

10

3

10

4

Te ( eV ) 1.5 1.0 0.5 0.0 Ratio of Excitation rates W

44+

W

45+

W

45+ / W 44+ ~ 0.44

LANL FAC ORNL

Ce

45+(4s,4p)•nW45+(4s)•ne

I W45+(6.2 nm): 4s 2S1/2 - 4p 2P3/2 =

Excitation rate

Constant excitation rate ratio of W44+ and W45+ useful for direct comparison btw Exp and Theory

I W44+(6.1 nm): 4s4s 1S0 - 4s4p 1P1

Close excitation energy (199 ev and 204 eV) ⇒ Similar energy dependence of Ce

Ioniz. Equi.

S44+→45+ α 45+→44+

(Ioniz.rate) (Recomb.rate) 10

24

10

23

10

22

10

21

eXcitation cross-section ( m

2 )

10

2

10

3

10

4

10

5

Ee ( eV ) 1.5 1.0 0.5 0.0 W

45+ / W 44+ excitation X sec.

W

45+ / W 44+~ 0.43

W

45+

W

44+

Excitation Xsec

S44+→45+ α 45+→44+

(Ioniz.Xsec) (Recomb.Xsec)

~ 0.43 Calculation Measurement

SLIDE 12

6000 4000 2000 Term energy ( eV ) 3d

104s

3d

104s 2

3d

104snl

Cu-like (W

45+)

Zn-like (W

44+)

direct ionization: DI Ee e

3600

3200 2800 2400 Ee ( eV ) 10

28

10

27

10

26

10

25

10

24

10

23

Xsec ( m

2 )

DI

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

=

SLIDE 13

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Zn-like (W

44+)

5l

3p

54s 24l

3s4s

2 4l

3s4s

2nl

3d

94s 2nl

3p

54s 2nl

........ ........ 4s nl ........ auto-ionization: radiation: excitation: 3d excited 3p excited 3s excited e

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

= 3d10 4s2 = Excitation => 3d9 4s2 nl = Auto-ionization => 3d10 4s 3d10 4s2 = Excitation => 3d9 4s2 nl = Radiative decay => 3d10 4s2 Ionization Excitation & emission Need branching ratio!

SLIDE 14

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

= Electron energy (eV) Excitation Auto-ionisation Cross sections (10-24 m2) 3s excited(W44+) 3p excited(W44+) 3d excited(W44+) Total (W44+) Total (W45+)

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Zn-like (W

44+)

5l

3p

54s 24l

3s4s

2 4l

3s4s

2nl

3d

94s 2nl

3p

54s 2nl

........ ........ 4s nl ........ auto-ionization: radiation: excitation: 3d excited 3p excited 3s excited e

SLIDE 15

20 16 12 8 4 W

45+ / W 44+ density ratio

3600 3200 2800 2400 Ee ( eV ) 10

28

10

27

10

26

10

25

10

24

10

23

Xsec ( m

2 )

DI EA

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

=

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Cu-like (W

45+)

Zn-like (W

44+)

5l

3p

54s 24l

3s4s

2 4l

3s4s

2nl

3d

94s 2nl

3p

54s 2nl

........ ........ 4s nl ........ auto-ionization: radiation: excitation: 3d excited 3p excited 3s excited e

SLIDE 16

20 16 12 8 4 W

45+ / W 44+ density ratio

3600 3200 2800 2400 Ee ( eV ) 10

28

10

27

10

26

10

25

10

24

10

23

Xsec ( m

2 )

RR DI EA

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

=

6000 4000 2000 Term energy ( eV ) 3d

104s

3d

104s 2

3d

104snl

Cu-like (W

45+)

Zn-like (W

44+)

Radiative recombination: RR Ee e

SLIDE 17

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Cu-like (W

45+)

Zn-like (W

44+)

5l

3p

54s 24l

3s4s

2 4l

3s4s

2nl

3d

94s 2nl

3p

54s 2nl

........ ........ 4s nl ........ auto-ionization: radiation: excitation: 3d excited 3p excited 3s excited e

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Cu-like (W

45+)

Zn-like (W

44+)

5l

3p

54s 24l

3s4s

2 4l

3s4s

2nl

3d

94s 2nl

3p

54s 2nl

........ ........ 4s nl ........ 3d excited 3p excited 3s excited

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

=

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

4l 5l 6l 3d

10

3d

94s 2

3d

94s 5l

4s 6l

5l

4s 9l

3d

94s

3d

94s 2nl

........ ........ 4s nl Ar Aa e Ar Ee

Zn-like (W

44+)

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Cu-like (W

45+)

Zn-like (W

44+)

4l 5l 6l 3d

10

Ni-like (W

46+)

3d

94s 2

3d

94s 5l

4s 6l

5l

3p

54s 24l

3s4s

2 4l

3s4s

2

3s4s

2nl

3s4s5l 3s4s9l 4s 9l

3d

94s

3p

54s

3s4s

3p

54s 2

3p

54s 5l

4s 9l

3d

94s 2nl

3p

54s 2nl

........ ........ ........ ........ ........ ........ ........ ........ Ee e Aa Ar DC 3d10 4s = e capture => 3d9 4s2 nl = Auto-ionization => 3d10 4s 3d10 4s2 = Excitation => 3d9 4s2 nl = Radiative decay => 3d10 4s2 Nothing changes DR

SLIDE 18

E. Behar JQSRT 58 449 (1997)

Electron energy (eV) 2 4 DR Cross sections (10-24 m2) Present Comparison of W45+ DR via 3d9 4l 4l’

SLIDE 19

E. Behar JQSRT 58 449 (1997)

Present Comparison of W45+ DR via 3p5 4l 4l’ Electron energy (eV) DR Cross sections (10-23 m2) 2 3 1

SLIDE 20

Present Via 4f2 Present : Two peaks via 4f2 Ref : One peak via 4f2

SLIDE 21

3600 3200 2800 2400 Ee ( eV ) 10

28

10

27

10

26

10

25

10

24

10

23

Xsec ( m

2 )

RR DI DR EA 20 16 12 8 4 W

45+ / W 44+ density ratio

3600 3200 2800 2400 Ee ( eV ) 10

28

10

27

10

26

10

25

10

24

10

23

Xsec ( m

2 )

RR DI DR EA

nW

45+ S44+->45+ S = Sdirect (DI) + Sexcit.autoioniz. (EA)

nW

44+ α 45+->44+ α = αradiative (RR)+ αdie-electronic(DR)

=

6000 4000 2000 Term energy ( eV )

3d

104s

3d

104s 2

3d

94s 24l

Cu-like (W

45+)

Zn-like (W

44+)

4l 5l 6l 3d

10

Ni-like (W

46+)

3d

94s 2

3d

94s 5l

4s 6l

5l

3p

54s 24l

3s4s

2 4l

3s4s

2

3s4s

2nl

3s4s5l 3s4s9l 4s 9l

3d

94s

3p

54s

3s4s

3p

54s 2

3p

54s 5l

4s 9l

3d

94s 2nl

3p

54s 2nl

........ ........ ........ ........ ........ ........ ........ ........ Ee e Aa Ar DC

SLIDE 22

*) Y. Ralchenko, et al., J. Phys. B 40 (2007) 3861.

nW

45+ S44+->45+ 1

nW

44+ α 45+->44+ 0.43

= I W45+(6.2 nm): 4s 2S1/2 - 4p 2P3/2 I W44+(6.1 nm): 4s4s 1S0 - 4s4p 1P1 = Comparison of Experiment and Calculation shows:

Quantitatively ~ 2x difference

⇒ Need 2x higher EA, or 2x lower DR.

20 16 12 8 4 W

45+ / W 44+ density ratio

3600 3200 2800 2400 Ee ( eV ) 10

28

10

27

10

26

10

25

10

24

10

23

Xsec ( m

2 )

RR DI DR Tokyo EBIT exp. EA NIST EBIT exp.

SLIDE 23

Comparison of DR & EA rates

10

19

10

18

10

17

10

16

10

15

10

14

Rate coefficient (m

3/ s)

10

2

10

3

10

4