@article{oai:repo.qst.go.jp:00077627,
 author = {Ohashi, Hayato and Hara, Hiroyuki and Li, Bowen and Dunne, Padraig and Gerry, O'Sullivan and Sasaki, Akira and Suzuki, Chihiro and Tamura, Naoki and A. Sakaue, Hiroyuki and Kato, Daiji and Murakami, Izumi and Higashiguchi, Takeshi and Akira, Sasaki},
 issue = {12},
 journal = {Journal of Optical Society of America B},
 month = {Dec},
 note = {We determined the optimum electron temperature for water-window soft x-ray emission by observing the spectral behavior in the 2.3–4.4 nm region of highly charged zirconium (Zr) ions in hot hydrogen plasmas produced in a magnetically confined fusion device. In the water-window soft x-ray spectral region, the main emission involved resonant 3d-4f transitions. According to the collisional-radiative (CR) model verified by the experimental results, the ionic population for the charge states from Zr 14+ to Zr 20+ required to produce the emission was maximized in the electron temperature range of 80–180 eV. For laboratory-scale water-window soft x-ray source application, it is therefore important to produce an electron temperature significantly lower than 200 eV for the production of the suitable ionic charge states.},
 pages = {3555--3561},
 title = {Electron temperature optimization for efficient water-window soft x-ray emission from discharge-produced highly charged zirconium ions},
 volume = {36},
 year = {2019}
}