  We found 12 unknown visible emission lines from the core plasma of large
helical device with highly charged tungsten ions accumulated. The observation
was made with our home-built echelle spectrometer, which covers the wavelength
range of 450-715 nm with a wavelength resolution of<0.05 nm for two lines of
sight; one line passes both the core and edge plasmas and the other passes only
the edge plasma. These emission lines are attributed to highly charged tungsten
ions because (1) they were observed only after a tungsten pellet was injected
into the plasma, (2) they were observed only from the core plasma where the
electron temperature is 1 keV, (3) they show line broadenings that are close to
the Doppler widths of tungsten ions with 1 keV temperature and (4) the
wavelengths of some of these emission lines are close to the calculation
results for tungsten ions in the charge state of 25-28.
