EUV spectra from the NIST EBIT

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1 EUV spectra from the NIST EBIT D. Kilbane and G. O Sullivan Atomic and Molecular Plasma Physics group, UCD, Ireland J. D. Gillaspy, Yu. Ralchenko and J. Reader National Institute of Standards and Technology, Gaithersburg, MD 899, USA The 1 th ADAS WORKSHOP 3 5 September 1 Château de Cadarache

2 Outline Motivation EBIT Experimental set up Collisional-radiative modeling of plasma EUV Spectra Gadolinium Dysprosium Tungsten Potential lowering of f n ions Summary

3 Motivation Atomic and Plasma Theory Hf, Ta, W, Au ions advance atomic / plasma codes predict trends in atomic structure Next-Generation Lithography Modeling of sources at 6.x nm ITER Diagnostics of hot plasmas in fusion devices 3

NIST Electron Beam Ion Trap (EBIT) EBIT creates, traps and excites HCI Electron beam collides with, ionizes and excites atoms monoenergetic, width ~6 ev tuneable, 1-3 kev radius ~3 µm density ~1 11

4 NIST Electron Beam Ion Trap (EBIT) EBIT creates, traps and excites HCI Electron beam collides with, ionizes and excites atoms monoenergetic, width ~6 ev tuneable, 1-3 kev radius ~3 µm density ~1 11 cm -3 Ions are trapped radially by space charge axially by electrodes and magnetic field EUV radiation from the ions is observed with a flat field grazing incidence spectrometer Gillaspy Phys. Scr. T 1 99 (199) Blagojević et al. Rev. Sci. Instrum (5)

5 Collisional-Radiative Modeling All important physical processes in the EBIT plasma Atomic Data Flexible Atomic Code (FAC) Relativistic potential to solve the Dirac eqn (CI and QED): energy levels, radiative decay rates, radiative recombination cross sections e - ion collisions are treated with distorted wave/coulomb Bornexchange approx: electron impact excitation, de-excitation, ionization cross sections CR model NOMAD non-maxwellian timedependent CR plasma code ~1 3 levels/ion typically 6-8 ions several million transitions runs in minutes one free parameter charge exchange CX between ions and neutrals Gu Can. J. Phys (8) Ralchenko and Maron J. Quant. Spectrosc. Radiat. Transfer 1 69 (1) 5

6 EBIT Spectra of Gd Rb-like to Cu-like gadolinium ion spectra Counts (AD DU) Rb Rb Kr Br Br Kr Br Kr Br Counts (ADU U) Ge Ga Ge Ga Ga Zn Ga Ion IP (ev) Rb-like 936 Kr-like 11 Br-like 11 Se-like 1189 As-like 133 Ge-like 13 Ga-like 1369 Zn-like 181 Cu-like Se Se Se Cu Cu As As As Ga Cu Zn Wavelength (nm) Wavelength (nm) Kilbane et al. accepted Phys. Rev. A (1) Rodrigues et al. At. Data Nucl. Data Tables () 6

7 EBIT Spectra of Gd Ge-like Gd ion 8 EXP: 1.3 kev CR database of singly + doubly excited s p, p, s d, sp 3, s pd, s pf, sp d, sp f, s p5l, sp 5l, s p6l, sp 6l Energy levels of all singly, doubly, triply and quadruply excited n= complex sd 3, sf 3, d, f p d, p f and p.5 df CR database is updated with new energies of the lowest levels Excellent agreement between measured and simulated spectra e.g. Se, As, Ge-like Emissivity (arb.units) Counts (1 ADU) TH: 1.8 kev Ge As Se As As Ge Se second order Wavelength (nm) Kilbane et al. accepted Phys. Rev. A (1)

8 Gadolinium Data Tables 59 new lines: s-p, p-d and d-f transitions ranging from 6.63 nm to 1.9 nm (mostly E1) Forbidden lines Kr-like (9.6 nm) (M) p 6 (p +) p 5 d(p 3 +,d + ) Se-like (9.68 nm) (M) s p (p +) p 3 d(p +,d + ) Se-like (.86 nm) (M) s p (p +) p 3 d((p -,p +) 3/,d - ) Spectra were calibrated with known lines of Ba, Xe, C and O ions accuracy.3 nm Cu-like lines NIST EBIT NIFS 9.86 nm 9.91() nm.5 nm.5() nm Kilbane et al. accepted Phys. Rev. A (1) Suzuki et al. J. Phys. B (1) 8

9 Next-Generation EUV Lithography at 6.x nm Churilov identified Gd and Tb in LPPs and spark discharges d-f + p-d UTAs Intense emission due to overlap of many open d and f subshell ions La 15+ Ce 16+ Pr 1+ Nd 18+ Pm 19+ (a) Sm + 1 (b) Wavelength (nm) 1 Churilov et al. Phys. Scr (9) Kilbane and O Sullivan Phys. Rev. A 8 65 (1) ga (1 13 s 1 ) Eu 1+ Gd + Tb 3+ Dy + Ho 5+ Er 6+ Tm + Yb 8+ Lu 9+ E (ev) Z 9

10 Spectra of Gd and Dy at 6.x nm Gadolinium Dysprosium Ag-like d 1 f d 9 f 6.3, 6.65, 6.88 nm Pd-like d 1 d 9 f nm Gd Ion IP (ev) Ag-like 358 Pd-like 565 Rh-like 61 Cou unts (1 ADU) Wavelength (nm) Ag-like d 1 f d 9 f 6.63, 6.596, 6.58, nm Pd-like d 1 d 9 f 6.8 nm Dy Ion IP (ev) Ag-like 3 Pd-like 66 Rh-like Coun nts (1 ADU) Wavelength (nm) Note: Very low current ~5 ma at.69 kev Absence of strong resonant transitions Sugar et al. J. Opt. Soc. Am. B 1 99, 131, 19 (1993) Rodrigues et al. At. Data Nucl. Data Tables () 1

11 Spectra of W Ag-like d 1 f d 9 f 5.15, 5.895,.89,.93 nm Pd-like d 1 d 9 f.898, nm Rh-like d 9 d 8 f.9856,.985,.9938, 5.65 nm W Ion IP (ev) Ag-like 881. Pd-like 113. Rh-like Strong resonant transitions observed at lower beam energies in Pd-like ions Note: Feature observed at ~.5 nm at 1.3 and 1.15 kev at the Berlin EBIT is absent ts (1 3 ADU) Count Wavelength (nm) Sugar et al. J. Opt. Soc. Am. B 1 99, 131, 19 (1993) Kramida and Shirai At. Data Nucl. Data Tables (9) Biedermann et al. Phys. Scr. T 9 85 (1) 11

12 Potential Lowering of f n ions Metastable states Many low lying excited states of Ag-like ions are populated by collisions These metastable states remain well populated 1 Beam energy required to generate excited states of Pdlike 5 ions is reduced Energy (ev) IP=881. ev d 1 5s d 1 5p s p 6 d 1 nl d 1 d 1 6f d1 6gd 1 6h 6d d 1 6s d1 6p d 1 5g d 1 5f d 1 5d d 9 d 9 f5p f5s s p 6 d 9 fnl d 9 f5d d 9 f5f d 9 f d 9 f5g d 1 f Ag like W IP=358 ev s p 6 d 9 fnl d 9 f5f d 9 f5g Energy (ev) 3 1 d 1 5s d 1 5p s p 6 d 1 nl d 1 6f d1 6gd 1 6h d 1 6d d 1 5g d 1 6s d1 6p d 1 5f d 1 5d d 1 f d 9 f5d d 9 f5p d 9 f5s d 9 f Ag like Gd 1

13 Summary EUV spectra of Gd, Dy and W ions from the NIST EBIT 59 new lines identified in Rb-like to Cu-like gadolinium Potential lowering observed in f n ions Uses: validate atomic / plasma codes predict trends in atomic structure model EUV sources for next-generation lithography diagnostics of hot plasmas in fusion devices such as ITER 13

14 Thanks The Atomic Spectroscopy Group at NIST Acknowledgement: This work was supported by Science Foundation Ireland under grant number /IN.1/I11 and in part by the Office of Fusion Energy Sciences of the U.S. Department of Energy. The 1 th ADAS WORKSHOP 3 5 September 1 Château de Cadarache 1

NIST Research on Spectroscopy and Collisional-Radiative Modeling of Highly-Charged Ions of Tungsten

NIST Research on Spectroscopy and Collisional-Radiative Modeling of Highly-Charged Ions of Tungsten Yuri Ralchenko National Institute of Standards and Technology Gaithersburg, USA Vienna, Austria, Dec