Dual Laser Plasma Photoabsorption Studies Of Gadolinium In The Extreme Ultraviolet Region

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Arnold Gilmore
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1 Dual Laser Plasma Photoabsorption Studies Of Gadolinium In The Extreme Ultraviolet Region Paddy Hayden National Centre for Plasma Science & Technology (NCPST) / School of Physical Sciences, Dublin City University

2 Talk outline Introduction/motivation Dual Laser Plasma (DLP) Photoabsorption Previous Results for Sn Gd I absorption spectrum Summary

3 Talk outline Introduction/motivation Dual Laser Plasma (DLP) Photoabsorption Previous Results for Sn Gd I absorption spectrum Summary

4 Sn UTA (Unresolved Transition Array) R. Cowan, The Theory of Atomic Structure and Spectra, University of California Press (1981) 5 Sn VII 5 Sn XI Sn VIII 5 Sn XII Sn IX 5 Sn XIII Sn X 5 Sn XIV blue 4d-4f, red 4d-4p, green 4d-5p sum of all three is the black dashed

5 Sn Inband 1 Sn VII 4 2 Sn XI Sn IX Sn X Sn XII Sn XIII Sn XIV Assume we can not discriminated amongst the UTA, so Intrinsic Conversion Efficiency is the ratio of inband to out-of-band

6 Ratio of inband to broadband Sn Inband Efficiency 35 3 Broadband Inband 25 Sn XII is the brightest inband (2% nm) Ion stage.7.6 Sn XIV is the most efficient (6 %) Sn XII 42% efficiency Ion stage

7 Gd UTA Gd XXI 5 Gd XXV Gd XXII 5 Gd XXVI Gd XXIII 5 Gd XXVII Gd XXIV 5 Gd XXVIII blue 4d-4f, red 4d-4p sum of all is the black dashed

8 Ratio of inband to broadband Gd Inband Efficiency 25 2 Broadband Inband Gd XXIV is the brightest inband (.6% 6.78 nm) Ion stage Gd XXII is the most efficient (5%) Gd XXIV 3% efficiency Ion stage

9 Ratio of inband to broadband Gd Inband Efficiency Only 4 upper configurations included and only two inband Scaling factors fixed Broadband Inband To give a better idea: Shift mirror to peak of UTA, (7.6 nm) keeping a.6 % bandwidth Gd XXIII is the brightest inband Ion stage.2 Gd XXIII is the most efficient (16 %) Gd XXII (46%) if a 2% bandwidth is used Ion stage

10 Power Densities Required Sn Gd ~1.2 x 1 11 Wcm -2 for Nd:YAG [P. Hayden et al., J. Appl. Phys. 99, 9332 (26)] ~1 x 1 1 Wcm -2 for CO 2 [S. Fujioka, et al., Appl. Phys. Lett. 92, (28)] ~4 x 1 12 Wcm -2 for Nd:YAG [T. Cummins, et al., Appl. Phys. Lett. 1, (212)] This corresponds to ~ 4x 1 11 Wcm -2 for CO 2 To get this: x3.8 laser energy x.52 spotsize x.27 pulse width For the case where the laser energy is increased: 3.8 x 16%(max. Gd efficiency)=6.8%, similar to the Sn case, but half the number of photons

11 Talk outline Introduction/motivation Dual Laser Plasma (DLP) Photoabsorption Previous Results for Sn Gd I absorption spectrum Summary

12 L. Gaynor, PhD Thesis, UCD (27) DLP Photoabsorption J. T. Costello, et al, Phys. Scr. T34, (1991)

13 DLP Photoabsorption Record I 1 Relative absorption give by ln(i /I 1 ) Gd target Cylindrical Lens W target Optical axis Dt, from ns to ms Plano-convex Lens

14 Talk outline Introduction/motivation Dual Laser Plasma (DLP) Photoabsorption Previous Results for Sn Gd I absorption spectrum Summary

15 Previous Results for Sn M. Lysaght, et al., Phys. Rev. A 72, 1452 (25) Absolute 4d εf shape resonance cross sections (9 12 Mb) determined by comparison to relativistic time dependent local density approximation (RTDLDA) calculations [D. A. Liberman, A. Zangwill, Comp. Phys. Comm. 32, 75 (1984)], for Sn and a range of similar elements. the measured cross sections appear to be smaller than predicted especially at the peak cross section reproduced the cross section profile extremely well once the energies were shifted by a constant amount 1 1 ev

16 Talk outline Introduction/motivation Dual Laser Plasma (DLP) Photoabsorption Previous Results for Sn Gd I absorption spectrum Summary

17 Relative Absorption DLP Photoabsorption for Gd I J. P. Connerade and M. Pantelouris, J. Phys. B: At. Mol. Phys. 17, L173 (1984) Connerade Connerade DLP DLP Gd I Gd I Gd II Gd III Wavelength (Å) Mainly 4f εg shape resonance, along with 4d εf and 5p εd

18 (Mb) DLP Photoabsorption for Gd I Connerade DLP Gd I Gd II Gd III Wavelength (Å) Mainly 4f εg shape resonance, along with 4d εf and 5p εd

19 Talk outline Introduction/motivation Dual Laser Plasma (DLP) Photoabsorption Previous Results for Sn Gd I absorption spectrum Summary

20 Summary Similar emission f values for Sn and Gd Ratio of inband /out-of-band higher for Sn (42% vs 3%) 6.x nm, define x (ratio up to 16%) Maximum bandwidth (up to 46% if 2% bandwidth) Only f values, actual emission will depend on ionisation balance, level populations, radiation transport, etc. High power densities needed for Gd One way, by using x3.8 laser energy, should give similar intensities as achieved by Sn today, half the number of photons though. Cross sections due to shape resonance in lower ion stages similar for Sn and Gd ~7 12 Mb. Improved experimental and calculated data to be published soon

21 Acknowledgements DCU: J. Costello, T. Kelly, and C. Fallon UCD: G. O Sullivan, P. Dunne, E. Sokell, F. O Reilly, C. O Gorman, T. Cummins, Bowen Li... TCD: J. Lunney, I. Tobin Funding: Science Foundation Ireland 7/IN.1/I1771, ERASMUS MUNDUS - EMJD -EXTATIC - FPA EACEA programme

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