An electron beam emitter comprises a housing enclosing a cathode capable of emitting electrons within the housing and a window for allowing the emitted electrons to exit the housing, wherein the housing has an opening adapted to be at least partly engaged with a high voltage connector assembly, the assembly being adapted to connect the cathode to a power supply, the electron beam emitter further comprising a cooling flange surrounding the opening and having an interior channel extending between an inlet port and an outlet port for receiving cooling fluid for cooling the high voltage connector assembly. The invention further relates to a method of cooling an electron beam device.