Mass filter characteristic and design role of quadrupole mass spectrometer for radical measurement in low-pressure plasmas

Abstract

In this study, we confirmed through experiments that a noise signal appears in the low-mass region when measuring plasma using a quadrupole mass spectrometer. We conducted a numerical analysis to identify the cause of this occurrence. It was determined that high-energy ions generated in plasma are not filtered in the low quadrupole filter voltage region owing to the high velocity of the ions. We thus detected the signal in the low-mass region based on the stability area. In this paper, we identify through numerical analysis the quadrupole filter length and the radius of the incident ion beam that effectively reduce low-mass noise.