Microwave to plasma coupling in electron cyclotron resonance and microwave ion sources (invited)

Coupling improvements between microwaves and plasmas are a key factor to design more powerful electron cyclotron resonance and microwave ion sources. On this purpose different activities have been undertaken by the INFN-LNS ion source team and a new approach was developed. Recent experiments confirmed the simulations, demonstrating that even in presence of a dense plasma, resonant modes are excited inside the cavity and the plasma dynamics depends on their structure. An overview of the coupling issues on microwave ion sources is also given along with a discussion on alternative coupling techniques.