An Electron-Cyclotron-Resonance Plasma as a Source of Multiply Charged Ions

The properties of an electron-cyclotron-resonance (ECR) plasma (3 cm microwaves up to 2.4 kW) have been investigated. A total of 80 μA noble gas ion current has been extracted from a 1 mm dia. hole so far. The charge state distributions show a maximum above the 1+ state, indicating that multiple impact ionization is a dominant process. X-ray spectra, sheath potential and microwave reflection were measured to gain some physical understanding of the discharge. The applicability of our device as an ion source is discussed.