H(-)-Conversion Aided Detection of Low-Energy H-0 Fluxes from the Tortur Tokamak in a Time-of-Flight Analyzer

A time-of-flight spectrometer has been developed to examine the velocity distribution of the hydrogen charge-exchange particles emitted from the TORTUR tokamak. To investigate the scrape-off layer, the spectrometer has been made sensitive to low-energy hydrogen atoms. This has been done by converting the hydrogen atoms into more easily detectable negative hydrogen ions on a cesiated monocrystalline tungsten surface. This detection technique enables examination of the neutral particle flux in a large energy range (5-2000 eV). Typical examples of time-of-flight spectra recorded during TORTUR discharges will be shown.