Investigation of a photoconductive array for emp simulation

The sub-nanosecond jitter and closing speeds of photoconductive power switches (PCPS) has been proposed for construction of a phased array for free-space EMP simulation. Historically, EMP simulators capable of exciting nonlinear system responses have used single point switching because jitter made synchronization impractical. Some recent EMP simulation has used a synthesized excitations/responses method which assumes operation in a linear regime. The objective of this experiment is to demonstrate that the precise timing available with optically controlled switching will allow synchronization of a phased array for radiating an EMP-type waveform. This paper describes the initial results obtained for a single element of this array. The radiated waveform is a close fit to the EMP pulse for the time period to the first zero-crossing. The high frequency content of the radiated signal is also being investigated using a Blumlein pulser similar to the EMP pulser and the results of these experiments are also presented. Based on these signals the electric field intensity and power level at the aperture has been estimated at 36 kV/m and 135 kW, respectively.