Technical issues related to the design of third generation ECR ion sources

The design of third generation electron cyclotron resonance ion sources (ECRIS) had to take into account some technical issues that are usually not relevant for conventional ECRIS, either in terms of microwave power management or in terms of stray magnetic field. In fact, strong magnets originate high stray fields that are detrimental for beam optics, for the pumping system lifetime and mainly for the gyrotron normally used for power generation. Additionally, the presence of intense X-ray fluxes generated by the ECRIS plasma, observed in many experiments, can generate an unexpected heat load upon the thermal balance of the superconducting ECRIS cryostat, which can trigger a warm-up in the case of closed-loop cryostat connected to a cryocooler setup. These and other issues are presented by the authors along with a study of possible solutions.