Mass-Sensitive Ion Probe for Plasma Boundary Characterization on the Tokamak ISTTOK

The principle of the mass-sensitive ion probe (MSIP) operation consists in a time-of-flight (TOF) analysis of the ions in the burst excited by a short (µ s-range) voltage pulse applied to a small grid immersed into the plasma. The ions in the burst propagate along the magnetic field lines of the tokamak with velocities determined by the value of the applied voltage and by the ions mass/charge (mi /Zi) ratio. The ions of different species and charges separated along some distance (TOF path) from the grid are detected by a retarding field energy analyzer (RFEA). This paper presents description of the MSIP design and first operation on the tokamak ISTTOK. The preliminary results of the obtained mass-spectra are presented and discussed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)