Atomic and Molecular Data provided by Multiply Charged Ion Beam - - PowerPoint PPT Presentation

Atomic and Molecular Data provided by Multiply Charged Ion Beam Collision Experiments at Low Energies

Hajime Tanuma

Department of Physics Tokyo Metropolitan University

Technical Meeting on Uncertainly Assessment and Benchmark Experiments for Atomic and Molecular Data for Fusion Applications Vienna, Austria, 19-21 December, 2016

Charge eXchange Spectroscopy (CXS) Pq+ + T → P(q-t)+* + Tt+ ↓ photon : energy, intensity P(q-t)+

Experimental method for measurements of

• 1. Charge transfer cross sections
• 2. Transition wavelengths

P : projectile, T : target

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Today’s three messages from CXS

• 1. CX spectra of lower charged W ions might be

not suitable for plasma diagnosis.

• 2. Meta-stable He-like ions are interesting, but

make cross section measurements complicated.

• 3. Triplet-Singlet ratios are very important in

collisions of H-like ions with neutrals.

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Multiply Charged Ion Beam Lines in TMU

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Switching Magnet 14.25 GHz ECR Ion Source Analyzing Magnet

Spectrometers

• Silicon Drift Detector for X-ray
• Grazing Incident Spectrometer

for Extreme Ultra-Violet

• Czerny-Turner Spectrometer

for Visible and UV Collision cell

Setup for X-ray measurements

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Magic Angle = 54.736°

Ion Beam Collision Cell target gas inlet to capacitance manometer

Ta instead of W

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Z = 73 Z = 74 Ta W A NA A NA A : mass number 180 0.012% 180 0.12% NA : natural abundance 181 99.988% 182 26.50% 183 14.31% 184 30.64% 186 28.43%

For ion beam experiments with charge state separation, Ta is much suitable.

Isotopes of Ta & W

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Mass Spectrum of Ta Ions

T ~ 1x106 K

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Intensity / arb. units Wavelength / nm

Ta

18+- O2

Ta

17+- O2

Ta

14+- O2

EUV Spectra in collisions with O2

Ta17+ Ta16+ Ta13+

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Charge dependence of UTA Peaks

8 10 12 14 16 18 20 22 8 10 12 14 16 18 20

Wavelength / nm Charge state of Ta ion

Two series of UTAs with wide spreads

Identification of transitions is now in progress. But, it seems to be difficult by the Cowan code.

Without charge separation, it might be difficult to distinguish charge states in EUV spectra of Ta.

The production mechanism of the excited states Plasmas (LPP, LHD, EBIT, etc.) : excitation from the ground state by electron impact → Almost Resonance Lines (RL) CXS : electron transfer to the excited orbital from the neutral targets → Transitions between excited states (TBES) Different mechanism = Complementary data → “Complementary Spectroscopy”

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5 10 15 20 25

Wavelength / nm Sn21+-He

5 10 15 20 25 07042105 Ee~693eV Ie= 6.4mA qmax=21+

Wavelength / nm

5 10 15 20 25 07042106 Ee~613eV Ie= 6.5mA qmax=19+

Wavelength / nm

Sn20+

20+ 20+ 20+

q ≤ 22 q ≤ 20

CXS@TMU EBIT@UEC

Ee = 693 eV Ee = 613 eV

q IP / eV +22 1127 +21 642 +20 608 +19 537 IP = Ionization Potential 3 RL of Sn20+ & many TBES

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Meta-stable He-like Ions

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Un-expected Soft X-ray emissions in collisions of He-like ions with He

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200 300 400 500 600 700 800

Intensity / arb. units Photon Energy / eV O6+ - He N5+ - He C4+ - He E = 15 keV/q

C3+ (1s2 nl) : < 64 eV N4+ (1s2 nl) : < 98 eV O5+ (1s2 nl) : < 138 eV

~ 560 eV ~ 620 eV Silicon Drift Detector : DE ~ 70 eV

Energy Level Data in NIST ASD

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O5+ 1s22s 2S1/2 : IP = 138.12 eV 1s2s(3S)2p 4PJ : 554.24 eV 1s2s(3S)2p 2PJ : 562.59 eV 1s2s3s 4S3/2 : 636.03 eV hn ~ 560 eV : O5+ 1s22s – 1s2s2p hn ~ 620 eV : O5+ 1s22s – 1s2s3s

Meta-stable states in a primary ion beam He-like ions : few % of 1s2s 3S1 from ECRIS O6+(1s2s 3S1) + He → O5+(1s2snl) + He+ → O6+(1s2) + e- : Auger O6+(1s2s 3S1) + He → O5+(1s2snl) + He+ → O5+(1s22s) + hn

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Influence of 1s2s states on cross section measurements are not clear.

Why 1s2snl states are produced?

Theoretical Auger and X-ray emission rates

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• M. H. Chen et al., Phys. Rev. A 27 (1993) 544.

C N O

Auger < (or <<) X-ray

Triplet-Singlet Ratios

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Triplet-Singlet ratios in CX

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σ Triplet σ Singlet = 3

Statistical weights

• J. L. Nolte et al., J. Phys. B 45 (2012) 245202.

Preliminary Cross Section Data

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SC (Single Capture) : H-like → He-like (1snl, Total) True SC + Transfer Ionization (TI) X-ray : Emission from He-like w (1s2 ←1s2p 1P1) + partially y (1s2 ← 1s2p 3P1)

σS + σT σS > σSC σXray > 4

Summary

• 1. CXS of Ta (instead of W) ions in the EUV region

Taq+ : q = 10 – 20

• 2. The first observation of UTAs in 8 - 20 nm
• 3. Complimentary data from EBITs are required.
• 4. We need theoretical calculation for identification
• f emission lines.
• 5. Meta-stable states in the primary He-like beams

might contribute to the uncertainty of cross section measurements using ECRIS.

• 6. Triplet-Singlet ratios might be far from the

statistical weights in charge exchange collisions of H-like ions with neutral targets.

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Collaborators Nobuyuki NAKUMURA, Univ. of Elecro-Communications Kunihiro OKADA, Sophia Univ., Tokyo Gerry O’SULLIVAN, Univ. College Dublin Ling LIU & Jianguo WANG, IAPCM, Beijing (Phillip Stancil, Univ. of Georgia) Present students Past students Naoki NUMADATE Hirofumi SHIMAYA Yoshiyuki UCHIKURA Takuya ISHIDA Kento SHIMADA Takuma KANDA Takuto AKUTSU Hayato OHASHI

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Thank you for your attention.

御静聴ありがとうございました。

謝 謝 감사합니다 Go raibh maith agat.