“…Though the electron temperature is not necessarily kept constant during one exposure time of the detector, the representative central electron temperatures at the middle of the corresponding period are indicated in Figures 1 and 2. As reported in our previous papers [19][20][21][22], the spectral feature of highly charged lanthanide ions changes from a quasi-continuum to discrete as the electron temperature rises. As the spectra in Figures 1 and 2 were observed in relatively high temperature conditions, above 0.8 keV, the quasi-continuum spectra emitted from lower ion stages were very well suppressed, and the spectra are composed only of discrete features due to higher ion stages such as Cu-, Zn-, and Ga-like ions.…”