High electric field ceramic-vacuum interface for high-current electron beam diodes

For a high-current electron beam diode, in order to make reliable vacuum sealing, a ceramic vacuum interface was developed, following the compact and transportable demand: a novel radial insulation structure was designed and the hydrodynamic loading of the ceramic component was considered. For the insulation design, according to the theories of vacuum flashover and the rules for radial insulators, the electrostatic field along the ceramic surface was simulated by ANSYS package. By optimizing the outline of the anode and reshaping the shielding rings, the electric fields were well distributed and the field around the cathode triple junction was effectively controlled. Furthermore, the mechanic properties of the ceramic component were analyzed. Calculations show that the static and dynamic load for the ceramic interface is 4.8 MPa and 60 MPa, respectively. Finally, a vacuum diode with the ceramic interface was tested on a 200 ns high-voltage pulser, and the results show that the interface can work stably with the hold-off field of 44 kV/cm.