Optimization of accelerating structure in dielectric wall accelerator

In the dielectric wall accelerator (DWA), the intensity and the distribution of the axial and radial electric fields generated by the electrode structure are obviously different. In order to enhance the axial accelerating field, improve the accelerating gradient and suppress the beam profile expansion caused by the radial electric field, metal grids are embedded in between each accelerating unit. Electromagnetic simulation software based on particle-in-cell method is used to numerically simulate structures with and without metal grids, and to analyze the distribution of electric field as well as the change of the beam profile under different structures. The experimental results agree well with the simulation outcome, which demonstrate that the DWA with the metal grid structure has stronger and more uniform axial accelerating field than the DWA without metal grids. Furthermore, for the metal grid structure, the radial electric field is suppressed efficiently and the radial divergence of the accelerated particle beam in free drift space is improved.