Experimental data for electron-impact ionization, electron-ion ......Photoionization of W3+ ions:...

Experimental data for

electron-impact ionization,

electron-ion recombination and

photoionization of tungsten ions

3rd Research Coordination Meeting on

Spectroscopic and Collisional Data for W from 1 eV to 20 keV

IAEA, Vienna, October 07 – 09, 2014

Alfred Müller

Institut für Atom- und Molekülphysik

JUSTUS-LIEBIG- UNIVERSITÄT GIESSEN

I M PA

Outline

I. Introduction

II. Electron-ion recombination of Wq+ ions

III. Photoionization of Wq+ ions

IV. Electron impact ionization of Wq+ ions

V. Summary

Outline

I. Introduction atomic data needs – atomic data situation




V. Summary

Evolution of tungsten ion charge states in a plasma

T Pütterich, R Neu, R Dux, A D Whiteford, M G O’Mullane and the ASDEX Upgrade Team Plasma Phys. Control. Fusion 50 (2008) 085016

rate coefficients for ionization and recombination required Ionization: CADW calculations of Loch et al. (2005) Recombination: Burgess – Bethe (1965 – 1976) with ad hoc modifications

Tungsten spectroscopy in ITER

spectrometers

plasma

N. J. Peacock et al., Can. J. Phys. 86, 277 (2008)

Spectroscopic data for tungsten are needed

Data situation

Theoretical predictions for

ionization and recombination

of complex many-electron ions

such as Wq+ ( with q << Z )

have been unreliable in the past.

Experiments were (and still are) needed to

test and to guide theoretical approaches

electron-impact ionization of Wq+

photoionization of Wq+

electron-ion recombination of Wq+

e + Wq+ ® W(q+1)+ + 2e : q = 1,…,10

hn + W ® W+ + e : q = 0

e + Wq+ ® W(q-1)+ + hn (time-reversed photoionization)

no absolute cross section measurements available

Before this CRP: experimental cross section data

available for

Example of existing experimental data:

electron-impact ionization of W1+

10 100 1000

0

5

10

15

20

25

30

s1,2

for W1+

Stenke et al. 1995 Montague & Harrison 1984

Cro

ss s

ect

ion

(

10

-17 c

m2 )

Electron-ion collision energy ( eV )

Both experiments used crossed-beams techniques

Ioniz

atio

n t

hre

shold

of

gro

und-s

tate

W+

the presence of long-lived metastable ions is a general issue

Example of existing theoretical data:

electron-impact ionization of W5+

Experiment: M. Stenke, K. Aichele, D. Hathiramani, G. Hofmann, M. Steidl, R. Völpel, and E. Salzborn, J. Phys. B 28, 2711 (1995) Theory: M. S. Pindzola, D. C. Griffin, Phys. Rev. A 56, 1654 (1997)

CADW theory looks quite good but did not account for the metastables

The only previously existing data for photoionization

of tungsten atoms or ions

30 35 40 45 50 55 60 650

10

20

30

40

50

60absorption data

of Costello et al. normalized to MBPT theory

MBPT calculation by Boyle et al. shifted by -3 eV

Cro

ss s

ect

ion (

Mb )

Photon energy ( eV )

Experiment: J.T. Costello, E.T. Kennedy, B.F. Sonntag, C.L. Cromer, J. Phys. B 24, 5063 (1991) Theory: J. Boyle, Z. Altun and H.P. Kelly, Phys. Rev. A 7, 4811 (1993)

Outline

I. Introduction




V. Summary

Principle of electron-ion merged beams experiments

independently absolute cross sections and rate coefficients obtained

electron

beam

Ion

beam

A(q-1)+

charge-state

analyzer

long interaction path

Recombination of Wq+ ions using the TSR ring

TSR ion storage ring in Heidelberg unique facility with optimal features for the purpose cooler plus target excellent energy resolution

The storage ring TSR

The TSR has been shut down but might be moved to CERN A cryogenic electrostatic ring (CSR) is being built in Heidelberg Even a storage ring cannot guarantee the absence of metastables

Excited-state population in a beam of W18+ ions

K. Spruck, N. R. Badnell, C. Krantz, O. Novotný, A. Becker, D. Bernhardt, M. Grieser, M. Hahn, R. Repnow, D. W. Savin, A. Wolf, A. Müller, and S. Schippers, Phys. Rev. A 90, 032715 (2014)

1671 levels in configurations 4f10, 4f9 5s, 4f9 5p

sum of 1652 short-lived levels

4d10 4f10

4d10 4f10 (t »12 years)

(DR of excited levels normally suppressed by strong autoionization)

17 long-lived levels from 4f10 and 4f9 5s configurations

Metastable ions can be present even in storage-ring experiments

Recombination of W20+ ions at the TSR storage ring

S. Schippers et al., Phys. Rev. A 83, 012711 (2011)

huge recombination at low energies

26.09.2014: 31 citations in google scholar

Plasma recombination rate coefficient of W20+ ions

S. Schippers et al., Phys. Rev. A 83, 012711 (2011)

Theory for W20+

N. R. Badnell, C. P. Ballance, D. C. Griffin, M. O’Mullane, PRA 2012

fine structure included (IC)

4d®4f contribution (IC)

no fine structure (LS-coupling)

TSR

TSR

statistical approach (full mixing) see also: V. A. Dzuba, V. V. Flambaum, G. F. Gribakin, C. Harabati, PRA 2012

Recombination of W18+ ions: Just published K. Spruck, N. R. Badnell, C. Krantz, O. Novotný, A. Becker,

D. Bernhardt, M. Grieser, M. Hahn, R. Repnow, D. W. Savin, A. Wolf, A. Müller, and S. Schippers, Phys. Rev. A 90, 032715 (2014)

PD: „partitioned and damped“ ST: statistical theory (Dzuba et al. 2012) IC: intermediate coupling RR: radiative recombination

Plasma recombination rate coefficient of W18+ ions: Just published

K. Spruck, N. R. Badnell, C. Krantz, O. Novotný, A. Becker, D. Bernhardt, M. Grieser, M. Hahn, R. Repnow, D. W. Savin, A. Wolf, A. Müller, and S. Schippers, Phys. Rev. A 90, 032715 (2014)

Further DR measurements for W19+ and W21+ ions are under analysis

Experimental Cooperation Working on

Wq+ Recombination

IAMP, Giessen

Stefan Schippers Kaija Spruck Dietrich Bernhardt Alfred Müller

MPI-K, Heidelberg

M. Grieser, C. Krantz, R. Repnow, A. Wolf Columbia University, Astronomy &

Astrophysics, New York

M. Hahn, O. Novotný, D. W. Savin GSI Helmholtz Center, Darmstadt

M. Lestinsky

Arno Becker

Outline

I. Introduction




V. Summary

ion source

Overview of the experimental setup at the ALS

IAMP in collaboration with

R. A. Phaneuf et al.,

University of Nevada, Reno

Photoionization of W+ and W2+ ions: absolute data

20 40 60 80 1000

10

20

30

40

PI

cro

ss s

ect

ion

(M

b)

Photon energy (eV)

hn + W+ ® W

2+ + e

100 meV resolution

40 50 60 70 800

1

2

3

4

5

6

7

hn + W+ ® W

3+ + e

100 meV resolution

PI cr

oss

se

ctio

n (

Mb

)

Photon energy (eV)

20 30 40 50 60 70 800

20

40

60 hn + W2+

® W3+

+ e-

100 meV resolution

PI cr

oss

se

ctio

n (

Mb

)

Photon energy (eV)

60 70 800

1

2

3

4

5

PI

cro

ss s

ect

ion

(M

b)

Photon energy (eV)

hn + W2+

® W4+

+ 2e-

100 meV resolution

Photoionization of W3+ ions: experiment and theory

30 40 50 60 70 800

20

40

60

80 normalized ALS absolute ALS DARC173cc:

stat. weighted 4F states

convoluted with 100 meV gaussian shifted by -2.0 eV

PI

cro

ss s

ect

ion (

Mb

)

Photon energy (eV)

W3+

(4f14

5s25p

65d

3 4F

3/2) is g.s.

Photoionization of W3+ ions: 379-level calculation

B. M. McLaughlin and C. P. Ballance

The higher-order calculation takes care of the energy shift and some of the remaining discrepancy.

40 45 50 55 60 65 70 75 80 85 900

50

100

150

200

J=3J=4

J=2

J=3

J=2

J=1

J=2

5p

6 5

d6s

1D

2

5p

6 5

d6s

3D

J

J=4

J=3

experiment theory

Cro

ss s

ect

ion

( M

b )


J=2

5p

6 5

d2 3

FJ

J=4

J=3

J=2

50 52 54 56 58 60 620

50

100

150

contributions of individual fine-structure states

W4+

500 meV resolution

Photoionization of W4+ ions:experiment and theory

Theory (52-levels close-coupling Dirac-Coulomb R-matrix calculations): C. P. Ballance and B. M. McLaughlin Calculations for Wq+ with q=0,1,2,3,4 and with up to 392 levels are underway

Experiment (200 meV and 500 meV resolution measurements available)

Photoionization of W5+: a nightmare for theory

20 30 40 50 60 70 80 90 100 1100

10

20

30

ion

iza

tion

th

resh

old

of th

e

4f1

45

d g

rou

nd

sta

te

hn + W 5+

® W 6+

+ eat 100 meV resolution

Cro

ss s

ect

ion (

Mb )


ionization thresholds of the

126 levels in the excited 4f13

5d2

and 5p54f

145d

2 configurations

The huge number of possible metastable levels calls for a new different theoretical approach

Photoionization of W5+: detail of measured spectrum

71 72 73 74 75 76 770

10

20

30

hn + W 5+

® W 6+

+ eat 100 meV resolution

Cro

ss s

ect

ion

(

Mb

)


It is all real resonances

Experimental Cooperation Working on

Wq+ Photoionization

IAMP, Giessen

Alfred Müller, Stefan Schippers Jonas Hellhund

Physics Department, UNR, Reno

R. A. Phaneuf Advanced Light Source, Berkeley

A. L. D. Kilcoyne

Outline

I. Introduction




V. Summary

Versatile apparatus

for studying atomic

collisions

Electron-ion crossed-

beams setup at IAMP

Electron-ion interaction region

cathode

ions

collector

energy-defining electrode

electron current: 450 mA at 1 keV

Electron-impact single ionization of W5+ ions

10 100 1000

0

1

2

3

4

5

6e + W

5+ ® W

6+ + 2e

Cro

ss s

ect

ion

(

10

-17cm

2 )

Electron-ion collision energy [eV]

Stenke et al., 1994

g.s

. th

resh

old


10 100 1000

0

1

2

3

4

5

6

g.s

. th

resh

old

e + W 5+

® W 6+

+ 2e

Cro

ss s

ect

ion

(

10

-17cm

2 )


Stenke et al., 1994

present absolute


10 100 1000

0

1

2

3

4

5

6

g.s

. th

resh

old

e + W 5+

® W 6+

+ 2e

Cro

ss s

ect

ion

(

10

-17cm

2 )


Stenke et al., 1994

present absolute

present scan


10 100 1000

0

1

2

3

4

5

6

g.s

. th

resh

old

e + W 5+

® W 6+

+ 2e

Cro

ss s

ect

ion

(

10

-17cm

2 )


Stenke et al., 1994

present absolute

present scan

theory V. Jonauskas

24% metastables

Electron-impact single ionization of W8+, W11+, and

W12+ ions

200 400 600 800 1000

0

5

10

W8+

W11+

W12+

Cro

ss s

ect

ion

(

Mb

)



The experimental absolute cross sections can be nicely reproduced by CADW calculations

400 500 600 700 800 900 1000

0.0

0.5

1.0

1.5

2.0

2.5

e + W19+

® W20+

+ 2e

4f8

5s

I.P

.

Direct ionization: 4f, 4d, 4p

Excitation autoionization: 4d, 4p, 4s

Direct Ionization: 5s, 4f, 4d, 4pCro

ss s

ect

ion (

10

-18 c

m2 )


Excitation-autoionization: 4f, 4d, 4p, 4sGround-state

Excited 4f85s

gro

und-s

tate

I.P

.

Plasma rate coefficients for electron-impact single

ionization of W19+ ions

4 5 6 7 8 91E-5

1E-4

1E-3

0.01

0.1

Ground configuration Mix of ground- and excited

Pla

sma r

ate

coeff

icie

nt

( 10

-10 c

m3s-1

)

Electron temperature ( 105 K )

40 50 60 70 80

Electron energy ( eV )

Electron-impact

ionization of low

to moderately

charged Wq+ ions:

q = 1,2,3,…,19

10 100 1000

1

2

3

4

W3+

W13+

W15+

W5+

x 55

x 55

x 50

x 45

x 40

x 20

x 13

x 6

x 3

x 2.2

x 2.2

W+

x 60

x 1.6

x 30

x 25

W8+

W11+

W17+

W19+


s (

10

-16 c

m2 )

all scan measurements are from the present tungsten ion project; the red curves cover „the new terrain“ we can provide reliable rate coefficients for ground-state ionization on the basis of CADW modeling of the data

Group involved in the measurements on electron-

impact ionization of Wq+ ions

IAMP Giessen

Alexander Borovik Kaija Spruck Arno Becker Daniel Schury Benjamin Ebinger Joachim Rausch Stefan Schippers Kurt Huber Alfred Müller

Outline

I. Introduction




V. Summary

Summary

Completed work on Wq+ ions (absolute experimental cross sections with accompanying theoretical work and plasma rate coefficients)

recombination: W18+, W19+, W20+, W21+ photoionization:

electron impact

ionization: verified and complemented work by Stenke et al. for single ionization of Wq+, q=1,2,…,10 added new theoretical background and

W1+ s1®2 , s1®3 , s1®4

W2+ s2®3 , s2®4

W3+ s3®4

W4+ s4®5

W5+ s5®6

Summary

electron impact ionization: (cross sections and rate

coefficients - new terrain)

W11+ s11®12

W12+ s12®13 W13+ s13®14 W14+ s14®15 W15+ s15®16 W16+ s16®17 W17+ s17®18 , s17®19 W18+ s18®19 W19+ s19®20

Thank you

for your

attention!

Experimental data for electron-impact ionization, electron-ion ......Photoionization of W3+ ions:...

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Transcript of Experimental data for electron-impact ionization, electron-ion ......Photoionization of W3+ ions:...