Direct Observation of the M1 Transition between the Ground Term Fine Structure Levels of W VIII
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292, Japan
Department of Fusion Science, SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292, Japan
Author to whom correspondence should be addressed.
Academic Editor: Elmar Träbert
Received: 1 November 2016 / Revised: 4 February 2017 / Accepted: 28 February 2017 / Published: 8 March 2017
We present a direct observation of the M1 transition between the fine structure splitting in the
ground term of W VIII. The spectroscopic data of few-times ionized tungsten ions are important for the future ITER diagnostics, but there is a serious lack of data. The present study is part of an ongoing effort to solve this problem. Emission from the tungsten ions produced and trapped in a compact electron beam ion trap is observed with a Czerny–Turner visible spectrometer. Spectra in the EUV range are also observed at the same time to help identify the previously-unreported visible lines. The observed wavelength
nm (air), which corresponds to the fine structure splitting of 17,402.5 ± 0.9 cm
, shows reasonable agreement with the previously reported value 17,410 ± 5 cm
obtained indirectly through the analysis of EUV spectra [Ryabtsev et al., Atoms 3
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Mita, M.; Sakaue, H.A.; Kato, D.; Murakami, I.; Nakamura, N. Direct Observation of the M1 Transition between the Ground Term Fine Structure Levels of W VIII. Atoms 2017, 5, 13.
Mita M, Sakaue HA, Kato D, Murakami I, Nakamura N. Direct Observation of the M1 Transition between the Ground Term Fine Structure Levels of W VIII. Atoms. 2017; 5(1):13.
Mita, Momoe; Sakaue, Hiroyuki A.; Kato, Daiji; Murakami, Izumi; Nakamura, Nobuyuki. 2017. "Direct Observation of the M1 Transition between the Ground Term Fine Structure Levels of W VIII." Atoms 5, no. 1: 13.
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