Improvement study on the influence of plasma electrode edge on the emittance of ECR ion source

In the design of extraction systems for intense ion sources, particularly Electron Cyclotron Resonance ion sources, the overall configuration of electrodes is the main consideration. However, a detailed aspect has not received sufficient attention, that is, the influence of the front edge of the plasma electrode. Near this edge, the direction of the electric field changes abruptly, causing ions subjected to these electric field forces to move aberrantly, which subsequently increases the emittance of the ion beam. The extent of this phenomenon may be underestimated. By chamfering the front edge, emittance is significantly improved. Two types of chamfering have been investigated, and both perform well. It is suggested that chamfering be a practical way to design plasma electrodes and improving emittance.