X-ray Spectral Analysis on Electron Interaction with Highly-Charged Ions in Tokyo-EBIT

D. Kato, N. Nakamura1), and S. Ohtani1)

National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
1)Institute of Laser Science, Univ. of Electro-Communications, Tokyo 182-8585, Japan

Electron collision with highly charged ions (HCIs) is an important process to be studied for diagnostics of extreme plasma conditions at nuclear fusion devises and astronomical objects (e.g. super nova remnant). Electron-Beam-Ion-Trap (EBIT) [1] is a unique device which enables us the precise study of the high energy electron interaction with cold trapped HCIs. In the EBIT, the HCIs are excited by impact of high energy electron, and subsequently decay radiating photons. The photon emission spectra manifest relativistic atomic structures and radiative properties of the HCIs, as well as dynamical behavior in the interaction with electrons.
X-ray spectra of highly charged Sn(Z=50), Sb(51), Te(52), I(53), Xe(54), Cs(55), and Ba(56) ions in the Tokyo-EBIT [2] were measured using a flat crystal spectrometer [3]. The electron energy dependence of line intensities for 3l-2p transitions of Xe XLV (Ne-like) indicated clearly indirect excitation through higher excited levels of n>3. Charge-state distribution was predicted using an energy and particle transport model [4] for the EBIT with atomic data obtained from HULLAC code [5]. Using a given synthetic spectra with the predicted charge-state distribution, we identified unknown satellite lines of Na-like through Si-like HCIs observed at the experiment.

References

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[2]N. Nakamura et al., Rev. Sci. Instrum. 69 (1998) 694
[3]N. Nakamura, Rev. Sci. Instrum. 71 (2000) 4065
[4]B. M. Penetrante et al., Phys. Rev. A 43 (1991) 4861
[5]A. Bar-Shalom et al., “The HULLAC Package Computer Set of Codes for Atomic Structure and Processes in Plasmas” (unpublished)