Multiply-excited states and their contribution to opacity in CO2 laser-driven tin-plasma conditions

J. Sheil; O. O. Versolato; A. J. Neukirch; J. Colgan

doi:10.1088/1361-6455/abcedf

Multiply-excited states and their contribution to opacity in CO₂ laser-driven tin-plasma conditions

J. Sheil^*
, O. O. Versolato
, A. J. Neukirch
, J. Colgan

^*Corresponding author for this work

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

A recent study (2020 Nat. Commun. 11 2334) has found that transitions between multiply-excited configurations in open 4d-subshell tin ions are the dominant contributors to intense EUV emission from dense, Nd:YAG-driven (laser wavelength λ = 1.064 μm) tin plasmas. In the present study, we employ the Los Alamos Atomic code to investigate the spectral contribution from these transitions under industrially-relevant, CO₂ laser-driven (λ = 10.6 μm) tin plasma conditions. First, we employ Busquet’s ionisation temperature method to match the average charge state (Z) of a non-local-thermodynamic equilibrium (non-LTE) plasma with an LTE one. This is done by varying the temperature of the LTE calculations until a so-called ionisation temperature T_Z is established. Importantly, this approach generates LTE-computed configuration populations in excellent agreement with the non-LTE populations. A corollary of this observation is that the non-LTE populations are well-described by Boltzmann-type exponential distributions having effective temperatures T_eff ≈ T_Z. In the second part of this work, we perform extensive level-resolved LTE opacity calculations at T_Z. It is found that 66% of the opacity in the industrially-relevant 2% bandwidth centred at 13.5 nm arises from transitions between multiply-excited states. These results reinforce the need for the consideration of complex, multiply-excited states in modelling the radiative properties of laser-driven plasma sources of EUV light.

Original language	English
Article number	035002
Pages (from-to)	1-11
Number of pages	11
Journal	Journal of Physics B: Atomic, Molecular and Optical Physics
Volume	54
Issue number	3
DOIs	https://doi.org/10.1088/1361-6455/abcedf
Publication status	Published - 22 Jan 2021

Bibliographical note

Funding Information:
We would like to thank W van der Zande, W Ubachs and R Hoekstra for their useful comments on the paper. This project has received funding from European Research Council (ERC) Starting Grant No. 802648 and is part of the VIDI research programme with Project No. 15697, which is financed by the Netherlands Organization for Scientific Research (NWO). Part of this work has been carried out at the Advanced Research Center for Nanolithography (ARCNL), a public-private partnership of the University of Amsterdam (UvA), the Vrije Universiteit Amsterdam (VU), NWO and the semiconductor equipment manufacturer ASML. Part of this work was supported by the ASC PEM programme of the US Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of US Department of Energy (Contract No. 89233218NCA000001).

Publisher Copyright:
© 2021 IOP Publishing Ltd Printed in the UK

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Funding

We would like to thank W van der Zande, W Ubachs and R Hoekstra for their useful comments on the paper. This project has received funding from European Research Council (ERC) Starting Grant No. 802648 and is part of the VIDI research programme with Project No. 15697, which is financed by the Netherlands Organization for Scientific Research (NWO). Part of this work has been carried out at the Advanced Research Center for Nanolithography (ARCNL), a public-private partnership of the University of Amsterdam (UvA), the Vrije Universiteit Amsterdam (VU), NWO and the semiconductor equipment manufacturer ASML. Part of this work was supported by the ASC PEM programme of the US Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of US Department of Energy (Contract No. 89233218NCA000001).

Funders	Funder number
U.S. Department of Energy
Los Alamos National Laboratory
Adhesives and Sealant Council
European Research Council	15697, 802648
European Research Council
Nederlandse Organisatie voor Wetenschappelijk Onderzoek

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 13 Climate Action

Keywords

Effective temperature
Multiply-excited states
Non-LTE
Opacity

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10.1088/1361-6455/abcedf

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Cite this

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title = "Multiply-excited states and their contribution to opacity in CO2 laser-driven tin-plasma conditions",

abstract = "A recent study (2020 Nat. Commun. 11 2334) has found that transitions between multiply-excited configurations in open 4d-subshell tin ions are the dominant contributors to intense EUV emission from dense, Nd:YAG-driven (laser wavelength λ = 1.064 μm) tin plasmas. In the present study, we employ the Los Alamos Atomic code to investigate the spectral contribution from these transitions under industrially-relevant, CO2 laser-driven (λ = 10.6 μm) tin plasma conditions. First, we employ Busquet{\textquoteright}s ionisation temperature method to match the average charge state (Z) of a non-local-thermodynamic equilibrium (non-LTE) plasma with an LTE one. This is done by varying the temperature of the LTE calculations until a so-called ionisation temperature TZ is established. Importantly, this approach generates LTE-computed configuration populations in excellent agreement with the non-LTE populations. A corollary of this observation is that the non-LTE populations are well-described by Boltzmann-type exponential distributions having effective temperatures Teff ≈ TZ. In the second part of this work, we perform extensive level-resolved LTE opacity calculations at TZ. It is found that 66\% of the opacity in the industrially-relevant 2\% bandwidth centred at 13.5 nm arises from transitions between multiply-excited states. These results reinforce the need for the consideration of complex, multiply-excited states in modelling the radiative properties of laser-driven plasma sources of EUV light.",

keywords = "Effective temperature, Multiply-excited states, Non-LTE, Opacity",

author = "J. Sheil and Versolato, \{O. O.\} and Neukirch, \{A. J.\} and J. Colgan",

note = "Funding Information: We would like to thank W van der Zande, W Ubachs and R Hoekstra for their useful comments on the paper. This project has received funding from European Research Council (ERC) Starting Grant No. 802648 and is part of the VIDI research programme with Project No. 15697, which is financed by the Netherlands Organization for Scientific Research (NWO). Part of this work has been carried out at the Advanced Research Center for Nanolithography (ARCNL), a public-private partnership of the University of Amsterdam (UvA), the Vrije Universiteit Amsterdam (VU), NWO and the semiconductor equipment manufacturer ASML. Part of this work was supported by the ASC PEM programme of the US Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of US Department of Energy (Contract No. 89233218NCA000001). Publisher Copyright: {\textcopyright} 2021 IOP Publishing Ltd Printed in the UK Copyright: Copyright 2021 Elsevier B.V., All rights reserved.",

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AU - Colgan, J.

N1 - Funding Information: We would like to thank W van der Zande, W Ubachs and R Hoekstra for their useful comments on the paper. This project has received funding from European Research Council (ERC) Starting Grant No. 802648 and is part of the VIDI research programme with Project No. 15697, which is financed by the Netherlands Organization for Scientific Research (NWO). Part of this work has been carried out at the Advanced Research Center for Nanolithography (ARCNL), a public-private partnership of the University of Amsterdam (UvA), the Vrije Universiteit Amsterdam (VU), NWO and the semiconductor equipment manufacturer ASML. Part of this work was supported by the ASC PEM programme of the US Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of US Department of Energy (Contract No. 89233218NCA000001). Publisher Copyright: © 2021 IOP Publishing Ltd Printed in the UK Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

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N2 - A recent study (2020 Nat. Commun. 11 2334) has found that transitions between multiply-excited configurations in open 4d-subshell tin ions are the dominant contributors to intense EUV emission from dense, Nd:YAG-driven (laser wavelength λ = 1.064 μm) tin plasmas. In the present study, we employ the Los Alamos Atomic code to investigate the spectral contribution from these transitions under industrially-relevant, CO2 laser-driven (λ = 10.6 μm) tin plasma conditions. First, we employ Busquet’s ionisation temperature method to match the average charge state (Z) of a non-local-thermodynamic equilibrium (non-LTE) plasma with an LTE one. This is done by varying the temperature of the LTE calculations until a so-called ionisation temperature TZ is established. Importantly, this approach generates LTE-computed configuration populations in excellent agreement with the non-LTE populations. A corollary of this observation is that the non-LTE populations are well-described by Boltzmann-type exponential distributions having effective temperatures Teff ≈ TZ. In the second part of this work, we perform extensive level-resolved LTE opacity calculations at TZ. It is found that 66% of the opacity in the industrially-relevant 2% bandwidth centred at 13.5 nm arises from transitions between multiply-excited states. These results reinforce the need for the consideration of complex, multiply-excited states in modelling the radiative properties of laser-driven plasma sources of EUV light.

AB - A recent study (2020 Nat. Commun. 11 2334) has found that transitions between multiply-excited configurations in open 4d-subshell tin ions are the dominant contributors to intense EUV emission from dense, Nd:YAG-driven (laser wavelength λ = 1.064 μm) tin plasmas. In the present study, we employ the Los Alamos Atomic code to investigate the spectral contribution from these transitions under industrially-relevant, CO2 laser-driven (λ = 10.6 μm) tin plasma conditions. First, we employ Busquet’s ionisation temperature method to match the average charge state (Z) of a non-local-thermodynamic equilibrium (non-LTE) plasma with an LTE one. This is done by varying the temperature of the LTE calculations until a so-called ionisation temperature TZ is established. Importantly, this approach generates LTE-computed configuration populations in excellent agreement with the non-LTE populations. A corollary of this observation is that the non-LTE populations are well-described by Boltzmann-type exponential distributions having effective temperatures Teff ≈ TZ. In the second part of this work, we perform extensive level-resolved LTE opacity calculations at TZ. It is found that 66% of the opacity in the industrially-relevant 2% bandwidth centred at 13.5 nm arises from transitions between multiply-excited states. These results reinforce the need for the consideration of complex, multiply-excited states in modelling the radiative properties of laser-driven plasma sources of EUV light.

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