A high-density RF ion source is an essential part of a neutral beam injector.In this study,the authors attempt to retrofit an original regular RF ion source reactor by inserting a thin dielectric tube through the symmetric axis of the discharge chamber.With the aid of this inner tube,the reactor is capable of generating a radial magnetic field instead of the original transverse magnetic field,which solves the E × B drift problem in the current RF ion source structure.To study the disturbance of the dielectric tube,a fluid model is introduced to study the plasma parameters with or without the inteal dielectric tube,based on the inductively coupled plasma (ICP) reactor.The simulation results show that while introducing the inteal dielectric tube into the ICP reactor,both the plasma density and plasma potential have minor influence during the discharge process,and there is good uniformity at the extraction region.The influence of the control parameters reveals that the plasma densities at the extraction region decrease first and subsequently slow down while enhancing the diffusion region.