ECR Ion Sources Developments at INFN-LNS for the Production of High Brightness Highly Charged Ion Beams

The design of future high-performing ECRIS will require alternative approaches in microwave-to-plasma coupling, in order to maximize the electron density at relatively low frequency and to reduce the hot electrons formation and their consequences on beam stability and on source reliability. On these purposes, different activities have been carried out at INFN-LNS in the recent past, including advanced modelling, diagnostics, and studies about alternative methods of plasma heating based on electrostatic-waves generation. A description of these activities will be presented, with special emphasis to the microwave to plasma coupling and to the plasma diagnostics. Some of the already collected results have been a basis for the design of the new AISHa source (for hadrontherapy purposes) and for the construction of an innovative prototype named Flexible Plasma Trap: on this machine we will search for newschemes of microwave launching, in synergy with thefull-wave plus kinetic calculations of the wave-to-plasmainteraction mechanism.