Plasma immersion ion charge state and mass spectrometer

Abstract

This work is devoted to the development and investigation of a new spectrometer for the measurement of ion charge state and mass composition of a plasma based on the combination of two methods—plasma immersion ion acceleration and time-of-flight ion separation. Ion acceleration in the spectrometer is carried out in the short-pulse mode by applying a negative bias potential to the plasma-immersed drift tube. The measurement of the ion current at the end of the tube using time-of-flight ion separation must be done after the bias potential pulse termination. The investigations of the ion charge state were carried out using a dc vacuum-arc Ti metal plasma. It is experimentally shown that the application of a negative bias potential with a pulse amplitude of more than 1.5 kV and duration in the range from 50 to 1000 ns allows measuring the spectra with good charge state and mass resolution for various plasma concentrations and drift tube lengths from 0.5 to 0.9 m. The spectrometer is noted for the design simplicity and compactness. It can be used for ion charge state and mass composition investigation in the wide range of concentration of most Periodic Table metal element plasmas.