An apparatus and a method of focusing a high-current-density electron beam emitted from a cold cathode electron emitter. The return duct includes a loop seal equipped with a heat exchanger and a supply of fluidizing medium and having an inlet and an outlet, which open into a chamber including the heat exchanger, i. Further, preliminary fire-suppression supply source means is coupled to the vehicle ducting means and is operable to provide a high volume flow of a preliminary fire-suppression agent. Additionally, a multitude of conduit sockets may be attached to the junction box, and mutually lock to the walls of the junction box by use of a specialized multiple-engagement nut member. An incident wavefront of electromagnetic radiation interacts with the instant element and is reradiated with controlled propagation characteristics imposed by the stored phase taper.