High voltage insulating structures for accelerators: simulation of transient electrical stresses

Calculations have been made to increase the HV performance of some components and to explain electrical failures of electrostatic accelerators. These involve simulations of static stresses and transient overvoltages, especially on insulating boards and electrodes occurring before or during breakdown. Changes made in the structure of the machines over the last years and new ideas to improve the static and dynamic behaviour are presented. The application of this study and HV tests recently led to a nominal potential near 20 MV without sparking.