On the Temporal and Spatial Evolution of Energetic Ion Production in the Texas Turbulent Torus

Abstract

Ion heating by the strong current in the Texas Turbulent Torus has been investigated with the charge exchange fast neutral measurement with respect to correlation with a current penetration into the plasma column. At relatively low density (\(n{\cong}2\times 10^{12}\) cm -3 ), the number of heated ions increases as the current penetrates into the central region of plasma column until the current peak (\(t{\cong}1.5\) µsec). Ion energy distribution function is Bi-Maxwellian and bulk ions are heated up to temperature in excess of 300 eV at about 200 nsec from the start of heating current. Temperature of the high energy tail, of which population is several % of total ions, increases to a maximum temperature of 3.5 keV at 0.8 µsec. At high density (\(n{\cong}7\times 10^{12}\) cm -3 ), temporal evolution of radial distribution of heated ions shows that energetic ion production is restricted within the skin current region during 1.5 µsec.