First results from the neutral particle analyzer on the COMPASS tokamak

Abstract

The Neutral Particle Analyzer (NPA) for the COMPASS tokamak was recently upgraded and ab-solutely calibrated in the Ioffe Institute, St. Petersburg. NPA allows simultaneous measurements of the energy spectra of fast hydrogen and deuterium atoms and determination of the ion temperature. Energy spectra of the neutral fluxes are measured by NPA in Ohmic as well as in the NBI heated plasmas. The measured ion temperature in L-mode plasmas varies in the range of 300-500 eV. After the L-H transition, the ion temperature increases by δTi ≈ 250 eV. A relatively high temporal resolution of the NPA data acquisition system allows study of fast transient phenomena, such as the Edge Localized Mode and saw-Tooth oscillation.