An active plasma chamber design for ECR Ion Sources.

An innovative plasma chamber for Electron Cyclotron Resonance Ion Sources has been developed at INFN and will be tested inside the AISHa (Advanced Ion Source for Hadrontherapy) ion source. Its design allows reducing the ion losses induced by the anisotropic diffusion mechanism to improve plasma confinement and increase ion source performances. Indeed, in ECRIS plasmas, electrons diffuse mainly along the magnetic field lines while ions are mainly lost across the magnetic field lines. The inner walls of the plasma chamber are covered by 30 tiles each one polarized with a given positive voltage. The tiles are made of Al-6082 and anodized except for the surface directly facing the plasma. The anodization process makes each tile electrically insulated from the others and from the plasma chamber while preserving the correct operation of the cooling system. The tiles are wrapped by 2 half-cylinders made of Al-6082 acting as shells. Some tiles are equipped with a temperature sensor and machined to allow the wiring of the entire system. In this communication preliminary tests and future perspectives will be discussed.