報告題目：Basic knowledges for tungsten spectroscopy in next-generation fusion devices with DT burning plasmas

報告時間：2025年12月4日（星期四）14:00

報告地點：四號樓601會議室

主持人：張凌

報告人：Shigeru MORITA 教授

Emeritus Professor,National Institute for Fusion Science,Toki,509-5292,Gifu,Japan

Visiting Professor,Institute of Plasma Physics Chinese Academy of Sciences

報告簡介：In next-generation fusion devices with tungsten wall and divertor plates the tungsten atom is expected to undergo high-ionization stages,at least up to neon-like ionization species of W64+, because in the plasma core region the electron temperature is extremely high,e.g.10<T_e￡20keV, and the particle confinement time is very long,e.g.0.1<t_p￡1.0s. The wavelength range of spectral lines emitted from tungsten ions in such high-ionization stages is mainly shifted to soft-x-ray range of 3￡l￡8?, while the tungsten diagnostic in the core plasma of existing devices has been done in extreme ultraviolet (EUV) range of 10￡l￡400?. In high-Z ions like tungsten (Z=74), on the other hand, the selection rule for line transition is broken, and forbidden lines such as magnetic dipole (M1) transition appear with strong intensities in the spectra in addition to electric dipole (E1) transition as an allowed line because the intensities of E1 and M1 transitions are proportional to Z4and Z10, respectively. Therefore, the tungsten diagnostic becomes possible in visible/UV ranges when the M1 transition between the sublevels in the ground state is measured, e.g. titanium-like W52+M1 transition (3d45D2-5D3) at 3627.1?. In the D-T [2D+3T?4He(a:3.52MeV)+n(14.06MeV)] burning plasma experiment it is extremely important to study behaviors of the a?particle. The intensity of the visible M1 transition is sensitive to the a?particle collision in addition to the electron collision because of the small transition energy. The a?particle diagnostic might be possible by taking an intensity ratio of M1 to E1 transitions. In addition, radial intensity profile measurement of highly ionized tungsten ions may be possible using the M1 transition since the visible M1 emission can be transferred by reflection mirrors and optical fibers. In the lecture basic knowledges necessary for tungsten spectroscopy are presented on next-generation fusion devices with burning plasmas.