Ion-burst method for positive and negative ion species measurements

Abstract

A simple method for positive and negative ion species measurements utilizing ion bursts is presented. In this ion-burst method, the ion bursts are excited by a potential applied to a mesh grid immersed in the plasma. Since the velocity of the ion burst is dependent on the excitation voltage and the ion mass, the ion species can be determined from measurement of the ion-burst velocity. In the DC discharge of an Ar/SF 6 gas mixture, the positive ion species are found to be Ar +, SF 3 + and SF 5 +, and the negative ion species are found to be F − and SF 6 −. These results are compared with the spectrum analysis using a quadrupole mass spectrometry system and show qualitative agreement with them.