Upgrade of a vacuum arc ion source using a strong pulsed magnetic field

摘要

A pulsed magnetic field of up to 10 kG was incorporated into a vacuum arc ion source. The field was established by a small coil surrounding the arc discharge region, powered by either an additional power supply (capacitor bank) or by the arc power supply (arc current and coil current in series). This addition has led so a number of improvements in source performance: the mean charge state of the metal ions produced was enhanced by a factor of up to two, for 30 different cathode materials from carbon to bismuth; hybrid metal/gaseous ion beams could be generated when an additional gas (nitrogen, oxygen or argon) was admitted into the source, with gaseous ion fraction as high as 50%; triggering of the source could be done by a very long lifetime gaseous pre-discharge technique. We also report on the use of a wire mesh to stabilize the plasma emission surface at the extractor as a means for achieving a flat beam current characteristic as a function of extraction voltage.