Use of the AURORA Flash X-Ray Machine as a Source-Region EMP Simulator and Antenna Coupling Analysis Facility

摘要

In the AURORA flash x-ray machine, a bremsstrahlung spectrum is produced in four thick tantalum targets by four synchronous 10-MeV electron beams. The bremsstrahlung then produces an electromagnetic pulse (EMP) signal through the same mechanism as does a nuclear bomb. It induces Compton electron currents in the AURORA test cell chamber (20 x 15 x 5 m). As the Compton electrons are slowed down, they ionize the air and also produce an electromagnetic field in the chamber. However, the Compton current is confined to a relatively small volume so that a relatively small electromagnetic field is produced, rendering the unmodified AURORA machine unsuitable as a source-region EMP (SREMP) simulator. A large parallel-plate transmission line has been designed to produce a (threat-like) EMP pulse. This transmission-line simulator can be placed in the AURORA test cell. When AURORA and the line are fired synchronously, an SREMP-like environment is produced, with AURORA providing the time-varying air conductivity. The configuration described above has been used to study the behavior of antennas in a time-varying conductive medium. Experimental data are presented. Also presented are equivalent circuit models used in the analysis of the data. Circuit models for antennas are obtained using the method of moments --a frequency-domain technique.