Design of a Vacuum Coaxial Line for Astérix to Study the Behavior of a MITL at High Voltage

AT PEM (Polygone d'Experimentation de Moronvilliers), the CEA will build a flash x-ray generator based on LTD technology. In this machine, the electrical energy is transmitted to the X-ray diode by a MITL (magnetically insulated transmission line). To study the behavior of this kind of high voltage line and the energy fed to the diode, the CEA has undertaken to install a new coaxial line on the Marx generator ASTERIX, located at the CEG (Centre d'Etudes de Gramat). This modification will associate to the present vacuum line, a new element that will increase the radius of the internal conductor and decrease the radius of the external conductor to the dimensions of the future LTD generator line. Also it will increase the length of the line to study with more details the MITL behavior. To design this new element and optimize the different dimensions, PIC simulations with the LSP code were used. They permit to control magnetic insulation by taking into account the electronic current flow along the internal conductor and to show the effects of this addition on the Marx bank. In this paper, the design of this additional element and the different simulation results are presented. Also, the different diagnostics needed to characterize the power transmission and the magnetically insulation are specified.