Experimental study of ion extraction from a 2.45 GHz electron cyclotron resonance multicharged ion source

Abstract

Extraction and transport of multicharged ions have been experimentally investigated on a 2.45 GHz electron cyclotron resonance (ECR) source. The extractor consists of an electrode facing the ECR plasma (plasma electrode) and three cylindrical electrodes (E1–E3). The extractor is moved at several positions on the geometrical axis. The gap length between the plasma and E1 electrodes can be moved in vacuum while keeping gaps of the other electrodes constant. Characteristics of the total extraction current are investigated by a Faraday cup set just downstream at the extractor while simultaneously monitoring the currents flowing to electrodes and the drain in various experimental conditions. Several kinds of potential forms of the electrodes are investigated and the gap lengths are surveyed and optimized experimentally. The mass/charge spectrum of the extracted multicharged ion current is investigated by the Faraday cup set downstream at the sector magnet. The features of the extraction condition for the charge states are also investigated. After optimization in these procedures, the multicharged ion currents have been enhanced by 1 order of magnitude more than those in the previous experiments.