A compact and portable EMP generator based on Tesla transformer technology
thesisposted on 12.11.2012, 14:18 authored by Partha Sarkar
High power electromagnetic pulses are of great importance in a variety of applications such as transient radar, investigations of the effect of strong radio-frequency impulses on electronic systems and modem bio-medical technology. In response to the current trend, a simple, compact, and portable electromagnetic pulse (EMP) radiating source has been developed, based on pulsed transformer technology and capable of producing nanosecond rise-time pulses at voltages exceeding 0.5 MY. For this type of application pulsed transformer technology offers a number of significant advantages over the use of a Marx generator, e.g. design simplicity, compactness and cost effectiveness. The transformer is operated in a dual resonance mode to achieve a high energy transfer efficiency, and although the output voltage inevitably has a slower rise-time than that of a Marx generator, this can be improved by the use of a pulse forming line in conjunction with a fast spark-gap switch. The transformer design is best achieved using a filamentary modeling technique, that takes full account of bulk skin and proximity effects and accurately predicts the self and mutual inductances and winding resistances of the transformer. One main objective of the present research was to achieve a high-average radiated power, for which the radiator has to be operated at a high pulse repetition frequency (pRF), with the key component for achieving this being the spark-gap switch in the primary circuit of the pulsed transformer. Normally a spark-gap switch has a recovery time of about ten milliseconds, and a PRF above 100 Hz is difficult to achieve unless certain special techniques are employed. As the aim of the present study is to develop a compact system, the use of a pump for providing a fluid flow between the electrodes of the spark gap is ruled out, and a novel spark-gap switch was therefore developed based on the principle of corona-stabilization. For simplicity, an omnidirectional dipole-type structure was used as a transmitting antenna. Radiated electric field measurements were performed using a time-derivative sensor, with data being collected by a suitable fast digitizing oscilloscope. Post-numerical processing of the collected data was necessary to remove the ground reflected wave effect. Measurements of the radiated electric field at 10 m from the radiating element indicated a peak amplitude of 12.4 kV/m. Much of the work detailed in the thesis has already been presented in peer reviewed journals and at prestigious international conferences.
- Mechanical, Electrical and Manufacturing Engineering