Electron cyclotron resonance negative ion source

Abstract

Production and control of electron cyclotron resonance (ECR) plasmas for negative ion sources have been studied. A new production method using permanent magnets is proposed as one possibility for a large diameter high density uniform microwave plasma. The microwave power is launched by an annular slot antenna into the circumference of a chamber with a line-cusp or a ring-cusp type permanent magnets, where magnetic field can be applied in a local region and plasmas can be efficiently produced if the ECR condition is satisfied. In this article, we report the structure of the ECR negative ion source, the characteristics of the ECR plasmas, and comparison of the ECR plasmas with dc discharge plasmas from the viewpoint of a negative ion source for neutral beam injector. H− volume production is confirmed in ECR plasmas although the effect of the magnetic filter for controlling plasma parameters is different from that in dc discharge plasmas.