Line Spectrum of Tungsten Ions at Low Ionization Stages in Large Helical Device in Wavelength Range of 300 - 2400 Å Measured Using 20 cm Normal Incidence VUV Spectrometers

Abstract

Vacuum ultraviolet (VUV) spectra of emissions released from tungsten ions at lower ionization stages were measured in the Large Helical Device (LHD) using three 20 cm normal incidence spectrometers in the wavelength range of 300 to 2400 Å. Tungsten ions were introduced in the LHD plasma by injecting a pellet consisting of a small piece of tungsten metal and polyethylene tube. The VUV spectroscopy revealed that WVI 639.683 Å, 677.722 Å, and 639.683 × 2 Å lines were useful lines for monitoring tungsten ion behaviors because they had large intensities and were isolated from other intrinsic impurity lines.