High voltage, high current, long pulse electron beam injector for DARHT

An injector design for the long pulse option for the second axis of the Dual-Axis Radiographic Hydrotest Facility (DARHT) has been studied. This design is based on the LBNL Heavy Ion Fusion Injector technology. The proposed injector consists of a single gap diode extracting electrons from a thermionic source and powered through a high voltage ceramic insulator column by a Marx generator. The key issues in the design are the control of beam quality to meet the DARHT 2nd axis final focus requirements, to minimize high-voltage breakdown risks, and to fit the injector structure within the available space. We will present the injector conceptual design as well as beam dynamics simulations in the diode and in the injector-main-accelerator interface.