High stability microwave discharge ion sources.

A new plasma heating mechanism for Microwave Discharge Ion Sources (MDIS) was discovered. Unprecedented beam stability was observed during the commissioning of the Proton Source for the European Spallation Source (PS-ESS) where several thousand source configurations were tested using a custom software tool. Data analysis and plasma simulation revealed that the new behaviour is generated by a completely new plasma heating schema activated by a precise magnetic configuration peculiarity. The stability showed in this configuration, denominated High Stability Microwave Discharge Ion Source (HSMDIS), is excellent and the emittance of the produced beam is lower than produced by standard MDIS configuration. High linearity between power and beam current was observed making easier the use of the source. This new mode of operation can be easily implemented in all existing sources.