Anisotropic dielectronic resonances from magnetic-dipole lines
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Transcript of Anisotropic dielectronic resonances from magnetic-dipole lines
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Anisotropic dielectronic resonancesfrom magnetic-dipole lines
Yuri Ralchenko
National Institute ofStandards and TechnologyGaithersburg, MD, USA
ADAS Workshop, 2013Supported in part by the Office of Fusion Energy Sciences, U.S. DoE
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Analyzing 10,000-eV dielectronic resonanceswith 80-eV forbidden lines
Yuri Ralchenko
National Institute ofStandards and TechnologyGaithersburg, MD, USA
ADAS Workshop, 2013Supported in part by the Office of Fusion Energy Sciences, U.S. DoE
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Yu. Ralchenko & J.D. GillaspyPhysical Review A 88, 012506 (2013)
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Radiative recombination
Continuum
Bound states
𝐴( 𝑍+1 )+¿+𝑒→ 𝐴𝑍 +¿+h𝜈 ¿¿
Ion recombined
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DR step 1: dielectronic capture
Continuum
Bound states
Resonant process!
𝐴( 𝑍+1 )+¿+𝑒 → 𝐴𝑍 +∗∗¿
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Continuum
Bound states
Dielectronic capture + autoionization= no recombination
DC and AI aredirect and inverse
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DR step 2: radiative stabilization
Continuum
Bound states
𝐴( 𝑍+1 )+¿+𝑒 → 𝐴𝑍 +∗∗ → 𝐴𝑍 +∗+h𝜈¿
Stabilizing transition:Mostly x-rays
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Dielectronic recombination in plasmas
Z
Z+1…
Maxwellian
Electrons are presentat all energies
(Infinite) Series of transitions areto be accounted for
DR
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DR measurements on EBITsEBIT electron
beam
extractedions
Is ionization distribution the sameinside and outside the trap?..
NO!
1. Extract ions2. Measure ionization distribution
Beam energy
time
ER
ER
ER
Fast beam ramping
DR energy generally does not coincide with the energy of max abundance
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DR resonances with M-shell (n=3) ions
LMN resonances:L electron into M,free electron into N
1s22s22p63s23p63dn
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Calculation of LMn DR strength: Ca-like 3d2 W54+
2s1/2 3d2p1/2 3d2p3/2 3d
e 3de 4le 5l
1s2(2s2p)83s23p63d + e 1s2(2s2p)73s23p63d2nl
Relativistic model potential+ QED corrections(Flexible Atomic Code, Gu 2008)
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Strategy1. Scan electron beam
energy with a small step (a few eV)
2. When a beam hits a DR, ionization balance changes
3. Both the populations of all levels within an ion and the corresponding line intensities change as well
4. Measure line intensity ratios from neighbor ions and look for resonances
5. EUV lines: forbidden magnetic-dipole lines within the ground configuration
A(E1) ~ 1015 s-1
A(M1) ~ 105-106 s-1
I = NAE (intensity)
Ionization potential
Ca-like W54+
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Beam energy: 0.1 keV – 30 keVBeam resolution: ~50 eVBeam current: ≤ 150 mABeam radius: ~30 μmElectron density: ~1012 cm-3
Can produce > 60-timesionized atoms
Ar, Kr, Xe, Sn, Ti, Sm, Gd, Dy,Er, Hf, Ta, W, Pt, Au, Bi,…
NIST Electron Beam Ion Trap1.0
0.8
0.6
0.4
0.2
0.0
Nor
mal
ized
Cro
ss S
ectio
n
140120100806040200
Speed [106
m/s]
EBIT Electron Beam (width x10) Maxwell-Boltzmann distribution
8 keV
x10
Monoenergetic beam allows one to “touch” dielectronic resonances
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Yu. Ralchenko et al, Phys. Rev. A 83, 032517 (2011)
Almost all lines are M1Good statisticsIsolated lines
Pair of lines:(a) within 3d in K-like W55+ (b) within 3d2 in Ca-like W54+
EUV spectrum of W47+-W56+: M1 lines within 3dn ground configurations
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[Ca]/[K]𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
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[Ca]/[K]:𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
THEORY:no DR
Modeling: CR code NOMAD, atomic data from FAC
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[Ca]/[K]𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
THEORY:no DR
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[Ca]/[K]𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
THEORY:no DRisotropic DR
Non-Maxwellian (40-eV Gaussian) collisional-radiative model: ~10,500 levels
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[Ca]/[K]𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
THEORY:no DRisotropic DRanisotropic DR
atomic level degenerate
magneticsublevels
Jm=-J
m=+J
Impact beam electrons are monodirectional
Non-Maxwellian (40-eV Gaussian) collisional-radiative model: ~10,500 levels
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[Ca]/[K]𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
THEORY:no DRisotropic DRanisotropic DR
atomic level degenerate
magneticsublevels
Jm=-J
m=+J
Impact beam electrons are monodirectional
Non-Maxwellian (40-eV Gaussian) collisional-radiative model: ~18,500 levels
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[Ca]/[K]𝑊 54+¿3 𝑑2
𝐽 =2 −3𝑑 2𝐽=3
𝑊 5 5+¿3 𝑑3/ 2 −3𝑑5 /2 ¿¿
2p3/2 3de 4l
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One EBIT run, several ions…
Can=4 Sc Ti
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Where are the 10-keV photons?..
2p53s23p63dn+14l
2s1/22p1/2
2p3/2
3s 3p3d
4s 4p 4d 4f
~8keV~9keV
~11keV
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X-ray emission (Ge detector)
2p53/2-4l
2p53/2-3d
2p53/2-3s
B and C: horizontal
A: slant
n>0 transitions into the 2p3/2 hole
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Conclusions•A new in situ method to measure multi-
keV dielectronic resonances in 3dn ions using ratios of EUV magnetic-dipole lines
•First resolved measurements of LMN resonances in ~55-times ionized W
•CR modeling shows importance of anisotropic effects on ionization balance
•Isolated resonances allow determination of the beam width