Development and evaluation of ion energy analyzer for energetic ion measurement in a linear plasma device NUMBER

In order to directly measure high energy ions in a plasma and to establish a new energetic-ion-production method, we have developed an ion energy analyzer for measuring the ion energy distribution. The analyzer is a retarding potential analyzer consisting of three grids and a collector. By applying a voltage to each grid, the electrons are retarded and the ions are separated by energy. In the measurement of the plasma with the electron density of higher than 10¹⁷ m^-3, it was found that the collector current was smaller than that deduced from the geometrical transparency of the grids. Measurement of the current flowing into each grid and a particle-in-cell simulation revealed that collector current decreased due to space charge between the 2nd and 3rd grids. (author)