ABSTRACT
The rapid development of high power microwaves (HPM) during the 1980s was due to the availability of a technology base that had been developed for other applications. Figure 5.1 shows the subsystems of an HPM device operating in an HPM facility. Pulsed electrical systems, referred to as
pulsed power
, were developed in the 1960s to enable nuclear weapons effects simulation. Later, inertial confinement fusion became a driver for pulsed power technology. HPM has largely made use of existing pulsed power equipment to perform initial experiments. The intense beams generated by pulsed power devices have been studied in some detail, including beam generation and beam propagation in various media such as vacuum, plasma, and gases. In diagnostics for HPM, the bulk of the devices used are conventional diagnostic techniques with additional attenuation to reduce power levels before the diagnostic data are taken. An exception to this is calorimetry, which must handle high electric fields but little total energy. Some microwave components, such as waveguides, have been borrowed from the conventional microwave technology base. For example, evacuated waveguides of conventional design can support electric fields of 100 kV/cm for short pulses. Similarly, antennas have used direct extrapolation of conventional antenna design with some care taken to avoid air breakdown, with the major exception of the Impulse Radiating Antenna (IRA; see Sections 5.5 and 6.3). With the emergence of facilities specifically designed to study HPM effects and develop HPM technologies, the primary issues are the operational and safety constraints for protection of personnel and ancillary electronic equipment from the effects of high power pulses.
