Mass-resolved retarding field energy analyzer and its measurement of ion energy distribution in helicon plasma

A novel type of plasma analyzer, which combines five-grid ion energy analyzer and a quadrupole mass spectrometer (QMS), has been developed to simultaneously measure the energy distribution and the mass of ions in a helicon plasma. The ions of the plasma were collected and analyzed through an aperture at the center of the sample holder so as to minimize plasma disturbance. The mass/charge ratios (m/e) of the three types of distinguishable ions in an argon plasma, Ar2+, Ar+ and Ar2+, are 20, 40 and 80, respectively. Fixing the mass of Ar ions one at a time, their energy distributions (IED) are measured at rf power of 1000 W. The results show that the fairly broad energy distributions of different kinds of ions are rather different. Possible mechanisms are tentatively explained.