Design, construction, and characterization of a flexible permanent magnet structure for a compact 2.45 GHz ECR proton source

This study presents the design, construction, and experimental characterization of a versatile permanent magnet structure developed for a 2.45 GHz electron cyclotron resonance ion source (ECRIS) dedicated to proton production. Three-dimensional finite-element simulations in COMSOL Multiphysics were employed to model the magnetic flux density. These simulations provided predictions of the magnetic flux density and the spatial location of the resonance surface. The modular design of the magnet assembly allows the generation of various magnetic field configurations, thereby enabling a systematic investigation of different operating conditions of the ECRIS. A dedicated supporting frame was designed and fabricated to ensure mechanical stability and precise positioning. Detailed analysis of the magnetic field distribution and resonance layer position was conducted for each configuration. Experimental validation was performed using a custom-built magnetic field mapping system, incorporating a high-precision Hall probe mounted on a motorized measurement stage. The measured field profiles exhibited excellent agreement with numerical simulations. By replacing power-consuming electromagnets, the permanent magnet structure eliminates the need for active cooling, significantly reducing the power consumption while enabling a more compact and cost-effective ion source design. Moreover, this energy-efficient solution is well-suited for laboratory-scale proton beam applications, including materials processing, ion implantation, and medical research.