Measurement of 0-25 eV Ions With a Retarding Potential Analyzer on the Cluster Ion Spectroscopy Experiment

Abstract

We describe a retarding potential analyzer (RPA) which extends the energy range of the Cluster ion spectroscopy (CIS) experiment down to 0-25 eV [Rème et al., 1993]. The CIS experiment will make comprehensive measurements of 3D ion distribution functions from 0-40 keV over the broad range of plasma regions the Cluster orbit will traverse. Mass composition, obtained using a time-of-flight technique, yields distribution functions for the different ion species. The incorporation of the RPA into an electrostatic analyzer (ESA) makes efficient use of spacecraft resources. We will describe the RPA optics design and implementation, and compare simulation work with the performance realized in the laboratory.