Optimized highly charged ion production for strong soft x-ray sources obeying a quasi-Moseley’s law
Yuta Shimada,
Hiromu Kawasaki,
Kanon Watanabe,
Hiroyuki Hara,
Kyoya Anraku,
Misaki Shoji,
Toru Oba,
Masaru Matsuda,
Weihua Jiang,
Atsushi Sunahara,
Masaharu Nishikino,
Shinichi Namba,
Gerry O’Sullivan,
Takeshi Higashiguchi
Affiliations
Yuta Shimada
Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
Hiromu Kawasaki
Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
Kanon Watanabe
Utsunomiya Junior Collage Attached High School, 1-35 Mutsumi, Utsunomiya, Tochigi 320-8585 Japan
Hiroyuki Hara
Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
Kyoya Anraku
Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
Misaki Shoji
Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
Toru Oba
Department of Material and Environmental Chemistry, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
Masaru Matsuda
Center for Bioscience Research and Education, Utsunomiya University, 350 Mine-machi, Utsunomiya, Tochigi 321-8505, Japan
Weihua Jiang
Department of Electrical Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
Atsushi Sunahara
Center for Material Under Extreme Environment, Purdue University, West Lafayette, Indiana 478907, USA
Masaharu Nishikino
Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Kizugawa, Kyoto 619-0215, Japan
Shinichi Namba
Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8527, Japan
Gerry O’Sullivan
School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
Takeshi Higashiguchi
Department of Electrical and Electronic Engineering, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
The extension of the roadmap of shorter wavelength extreme ultraviolet and soft x-ray sources is a topic of considerable interest. We have studied the optimized emission from high power and/or high brightness sources based on unresolved transition array (UTA) emission. The peak UTA wavelengths follow a quasi-Moseley’s law as λ=33.82×R∞−1(Z−20.86)−1.61 nm for the laser wavelength of 1064 nm (the critical density of 1 × 1021 cm−3) and λ=165.8×R∞−1(Z−12.44)−1.94 nm for the laser wavelength of 532 nm (the critical density of 4 × 1021 cm−3), respectively. The photon flux decreased with increasing atomic number. We also mapped the optimum electron temperatures and corresponding charge states required to produce strong soft x-ray UTA emission with a photon flux of the order of 1014 photons nm−1 sr−1. The present quasi-Moseley’s law is sufficient for identifying the optimum element for numerous applications, such as material ablation and ionization, nanolithography, and in vivo biological imaging.
