EUV spectral shape variation of tungsten unresolved transition arrays in electron temperature range of 2–4 keV observed in the Large Helical Device

Abstract Spectroscopic studies of emissions released from tungsten ions combined with a pellet injection technique have been conducted in the Large Helical Device. The Unresolved Transition Array (UTA) spectrum was observed wavelength ranges extreme ultraviolet (EUV) 6–60 Å and 130–340 Å, electron temperature dependence UTA spectral shape investigated region < 4.3 keV. UTAs W 24+ –W 33+ at 20–33 37+ 42+ 45–47 27+ 29+ 48–55 7+ – 170–210 were observed. Unidentified also found 230–270 280–320 Å. As increased further above 4 keV, maintained, while other became less intense.