Effect of RPA transparency dependence on ion masses upon ion temperature and density determination with direct space measurements

Abstract

The impact on the total transparency of field inhomogeneity around the grid wires of a plane retarding potential analyser (RPA) is taken into consideration at normal incidence of the ion flux. The RPA transparency is determined mainly by the suppressor grid's geometry and attractive potential and not so much by the analysing grid's repulsive potential. Whereas in a floating potential regime the suppressor grid transparency differs for different ion species, in a retarding ion regime it is the same for all. However, at all swept voltage values of the analysing grid the total RPA transparency remains dependent on the ion masses and the grid potentials.