查看文章

Next generation fusion device will produce further heat load onto the first wall and divertor plates, and it may give rise to a serious damage to such plasma facing components. It is widely known that the high-Z materials instead of carbon become favorable to the plasma facing material, because such materials have less sputtering yield in addition to their high melting point [1]. At present, the use of tungsten [2] and molybdenum [3] is planned in ITER as a candidate for the divertor material. Then, the spectroscopic study on the high-Z impurities becomes important in the next generation fusion device. The spectral lines of the high-Z elements, however, have not been well investigated until now, eg, even their wavelengths. Most of the spectral lines from the high-Z elements are at least emitted in extreme ultraviolet (EUV) and soft X-ray ranges when the electron temperature is greater than 1-2 keV. An extensive study is necessary on the line analysis of the high-Z elements in addition to a theoretical work on atomic physics. For this purpose molybdenum and tungsten have been injected in large helical device (LHD) plasmas using an impurity pellet injector [4]. The emission spectra have been monitored with a flat-field EUV spectrometer [5] to iden-author’s e-mail: chowdhuri. malay@ nifs. ac. jp tify their wavelengths and to analyze their time behaviors as a function of electron temperature. In this paper results on possible identification of the spectral lines emitted from highly ionized tungsten and molybdenum are presented with EUV spectra in wavelength range of 20-500Å. The wavelengths of spectral lines identified here are also compared with previous …