Polarization separated Zeeman spectra from magnetic dipole transitions in highly charged argon in the large helical device

Abstract

Visible spectral emission lines from magnetic dipole transitions in ArX, ArXI, ArXIV, and ArXV are observed from plasmas heated with neutral-beam injection (NBI) in the Large Helical Device [O. Motojima et al., Phys. Plasmas6, 1843 (1999)]. Orthogonal linearly polarized components of the emission line profiles are observed with a polarization separation optical system and high-resolution spectrometer. Zeeman split profiles reveal polarization characteristics of magnetic dipole transitions. Ion temperatures and emission locations are estimated from the profiles with the magnetic field information on the lines of sight (LOS). The spatially resolved emissions are observed by the array of absolutely calibrated views. The time histories of line profiles and emission intensities at the poloidal view are presented. The observed line profiles and the intensity distribution at the poloidal view indicate the localization of these charge states in the edge region just inside the last closed flux surface. The emission line of ArX in the tangential observation indicates Doppler shifts of the Zeeman split profiles. The velocity components of ArX ion flow along the LOS at the tangential view are 7.7 and 2.0km/s at the outer and inner edge plasmas, respectively, in the opposite direction to the NBI.