Neutral Density Measurements by Charge Exchange Analysis on the Heliotron E Plasma

Abstract

Measurements of neutral density in ECRH, Ohmically heated and neutral beam heated plasmas on the Heliotron E device are described. Profiles of neutral density determined by the vertically scanned charge exchange neutral flux are compared with the results of the Monte Carlo simulation. In Ohmic and ECRH plasmas, the obtained profiles agree well with the simulation results using Franck-Condon neutral (∼3 eV) as incident particles. In NBI case, the recycling particle with higher energy (typically ∼30 eV) dominates the particle source. The dependence of the neutral density on the average electron density is represented by the parameter I_p. Although the neutral density in Ohmic and ECRH plasmas decreases as \barN_e increases, NBI plasma does not have such dependence. The global particle confinement time is estimated, and τ_p decreases as I_p increases.