Emission of water-window soft x-rays under optically thin conditions using low-density foam targets

Hiroyuki Hara, Hiromu Kawasaki, Toshiki Tamura, Tadashi Hatano, Takeo Ejima, Weihua Jiang, Hayato Ohashi, Shinichi Namba, Atsushi Sunahara, Akira Sasaki, Masaharu Nishikino, Gerry O’Sullivan, Takeshi Higashiguchi

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3 Citations (Scopus)

Abstract

The effect of optical thickness in a bismuth water-window soft x-ray source is considered by comparing the emission from laser-produced plasmas of a 7.5% atomic density foam target and a solid-density target. The number of photons recorded in the 4 nm region was comparable for both targets at a plasma-initiating laser pulse duration of 6 ns. From experiments at different pulse durations of 150 ps and 6 ns, self-absorption (opacity) effects were found to be relatively small for bismuth plasmas as compared to those of tin, based on the same emission mechanism and which are used in 13.5 nm sources for extreme ultraviolet lithography.

Original languageEnglish
Pages (from-to)3750-3753
Number of pages4
JournalOptics Letters
Volume43
Issue number15
DOIs
Publication statusPublished - 2018 Aug 1

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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    Hara, H., Kawasaki, H., Tamura, T., Hatano, T., Ejima, T., Jiang, W., Ohashi, H., Namba, S., Sunahara, A., Sasaki, A., Nishikino, M., O’Sullivan, G., & Higashiguchi, T. (2018). Emission of water-window soft x-rays under optically thin conditions using low-density foam targets. Optics Letters, 43(15), 3750-3753. https://doi.org/10.1364/OL.43.003750