Ion temperature measurements in the ATF torsatron using titanium forbidden lines (abstract)

Abstract

Several forbidden lines of titanium have recently become strong enough to be identified in ATF plasmas in the ultraviolet and in the visible. The increase in intensity has resulted from gettering of the vacuum vessel with titanium both to suppress light impurities and to control hydrogen recycling. Three orders of the forbidden Ti xiv line at 2117.1 Å have been observed in vacuum, and the second and third orders have been observed in air using two different Czerny–Turner spectrometers. Doppler broadening of this line has been used to infer ion temperatures in the interior of ATF plasmas. These data supplement ion temperature measurements employing lines from carbon, nitrogen, and oxygen reported earlier [R. C. Isler et al., Nucl. Fusion 29, 1391 (1989)]. Tentative identifications of other forbidden lines such as Ti vii at 1938.4 Å, Ti xv at 2544.8 Å, Ti xvii at 3370.8 Å and 3834.4 Å, and Ti xviii at 1778.1 Å have also been made. Research was sponsored by the Office of Fusion Energy, U.S. Department of Energy, under contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc.