The insertion of a small Mevva source inside an electron cyclotron resonance: Status report

A miniaturized Mevva source, designed to be inserted in an electron cyclotron resonance (ECR) source in order to sputter metals, was proposed to supplement our ECR source Alice. The major problem was to control the Mevva arc at the low level of current (20–30 A for Al, Cu), which are required to limit metal consumption. Installation of our Mevva in a separate test stand was completed. Extensive electrical tests are here reported, discussing components that were rebuilt and optimized during experiments. The improvement in trigger voltage (10 kV) and rise time (3 μs) obtained by an air transformer, with little help from a ferrite core, allowed a reliable arc start-up. Increasing the main voltage was also important, as was evident from the new ferrite transformer (giving 3.5 kV instead of 2 kV) and from the detailed shape of arc voltage in some shots, where wide fluctuation appeared. A neutral beam spectrometer for the MetAlice experiment is being developed. Perspective of schematic improvement and of installation in Alice are discussed.