Theoretical Simulation for Spectra Emitted from Sn and Xe ions as an EUV Light Source

T. Kagawa, K. Nishihara1), A.Sasaki2), F. Koike3)

Department of Physics, Nara Women’s University, Nara 630-8506, Japan
1)Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan
2)Advanced Photon Research Center, JAERI, Kyoto 619-0215 Japan
3)Phys. Lab. School of Medicine, Kitasato University, Sagamihara 228-8555 Japan

Using relativistic configuration-interaction (RCI) atomic structure code developed by Kagawa [1-4], we have carried out simulation for spectra emitted from Sn ions from 9+ to 14+ charge state and Xe ions from 8+ to 13+ in the extreme ultra-violet (EUV) wavelength range including 13.5nm. In the simulation it is assumed that each ion is imbedded in a LTE plasma, where population in an excited state of ions is obtained by assuming that the electron temperature is 30 eV for all plasmas under consideration. Relative intensity of each line in an ion was estimated as a product of a gA value for the electric dipole optical transition and a population in an upper state for the transition. When making simulated spectra for an ion, the wavelength range is divided into narrow intervals of 0.5 nm and total line intensity for each wavelength interval is obtained as a sum of the intensities for the E1 transitions whose transition wavelength is included in the interval.
In the present simulation, large intensity at 13.5 nm wavelength region in the spectra from Sn 11+ and 12+ ions is observed. In the experiment for a laser-irradiated Sn plasma [5], a large broad peak near 13 nm wavelength in the EUV spectra from Sn ions has been observed. Our simulation suggests that an efficient way of obtaining large intensity in the spectra near 13.5 nm wavelength region, which is required for an EUV light source, is to produce a plasma so as to contain a large fraction of 11+ and 12+ Sn ions in it. On the other hand simulated spectra from Xe ions do not necessarily give large intensity in the wavelength near 13.5 nm.


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[4] T. Kagawa, Comput. Phys. Commun. 72, 165 (1992).
[5].K. Nishihara et. al., Proc. 3rd IFSA (2003).

This work was performed under the auspices of the Leading Projects promoted by MEXT (Ministry of Education, Culture, Science and Technology).