Compact Metal-Ion Beam Source Using Thermal Contact Ionizer

A small, compact ion beam source which can function in an external magnetic field has been developed for use with a heavy ion beam probe for plasma diagnostics. The source consists of a thermal contact ionizer with a beam material reservoir and an electrostatic lens system for beam acceleration and focusing. The beam can be modulated by means of a beam-extracting electrode. An alkali or an alkali earth metal ion beam was produced at energies up to 3 keV. The source functioned sufficiently well in a magnetic field up to 2 kG. The operating parameters for Cs+ and Ba+ ion beams were investigated in detail. A beam current up to 10 µA and a small diameter of 1 mm at the focusing point were obtained.