Measurement of the electric current profile of particle clusters in gases and in a vacuum

摘要

The invention relates to the measurement of current profiles of ion or electron clusters. The faraday detector electrode consists of a large number of structural elements 15, 16 in a bipolar arrangement, where neighboring structural elements have opposite polarities and structural elements with the same polarity are electrically connected. A voltage is applied between neighboring structural elements so that before ions or electrons impinge on the detection electrode, they are deflected onto the structural elements with one of the two polarities. The current profiles on the structural elements of the two polarities are measured separately and subtracted from each other providing a current profile which corresponds to the pure ion or electron current profile. This overcomes the issue of image/mirror current generated in the detector by the approaching charged particles.