H−‐conversion aided detection of low‐energy H0 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.