Characteristics of electron cyclotron resonance plasmas for large area ion source application

Abstract

The characteristics of electron cyclotron resonance (ECR) plasmas at the plug chamber of the “Hanbit” plasma facility have been investigated. The chamber length and diameter are 2.25 m and 1.5 m, respectively, and three pairs of solenoids are used to produce a variety of magnetic field configurations. Two magnetrons of 5 kW maximum output power each are used to produce the ECR plasma, and the microwaves are launched in extraordinary mode (X-mode) and/or right-hand circular polarized mode (R-mode). The dependence of the radial plasma density profile and the energy distribution of end loss ions upon the magnetic field strength and geometry, gas pressure, microwave power, and the mode of microwave are investigated. The plasma parameters are measured by using a position-controllable electrostatic probe, an x-ray spectrometer, and a multigrid ion energy analyzer. Transitions, occurred by threshold magnetron powers between low and high density modes, are found on certain conditions of magnetic field geometry and gas pressure. The density profile and the ion energy distribution are strong functions of magnetic field geometry and gas pressure, respectively.