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Explosive Pulsed Power: Ferroelectric Generators for Advanced Munitions


OBJECTIVE: The objective of this effort is to develop very compact explosive driven ferroelectric generators capable of producing more than 500 kV at the input terminals of a variety of loads. DESCRIPTION: As we develop new munitions with different types of payloads, there is an ever increasing requirement for smaller, lighter, and cheaper electrical power sources for use in a variety of munitions ranging in size from 25 mm (1 inch) diameter to 18 cm (7 inches) diameter. In the case of smaller munitions, the number of available useful power supplies is limited. One type of pulsed power source that can meet these limitations is explosive pulsed power. The field of Explosive Pulsed Power (EPP) [1 4] was established in the early 1950s. These power supplies either convert the chemical energy stored in explosives into electrical energy or use the shock waves generated by explosives to release the energy stored in materials such as ferroelectrics or ferromagnetic. Explosive pulsed power generators are currently under investigation by several Department of Defense Laboratories as power supplies for new classes of warheads and munitions. Of particular interest is the Ferroelectric Generator (FEG), since it is one of the few power supplies capable of generating very high voltages required to drive high power microwave tubes in the available payload volume on current small munitions. The potential Achilles heel for FEGs is that they are very low energy devices. For them to be useful, one needs to be able to use several FEGs to power a single circuit. This means that one must use a single switch for the oscillator, as opposed to dielectric breakdown switching. Thus, we need either two or three times the energy from a single FEG or a switch that requires exceedingly little energy to switch while still being able to control up to 500 kV. If either or both of these needs cannot be met, then the FEG will probably not end up being useful for our sort of applications. Thus, the objectives of this effort are to investigate those mechanical or electric processes that can be modified to increase the output of FEGs from the state-of-the-art value of 100 kV to 500 kV and to ascertain their capabilities to drive payloads such as High Power Microwave (HPM) sources. This would include investigating the influence of such fundamental processes as shock dynamics, the electrical, mechanical, and chemical properties of ferroelectric and potting materials used, methods for controlling electrical breakdown, power conditioning techniques (switches, transformers, etc.), load characteristics, and so on when driving one or more types of HPM loads. Since the load impacts the operation of the FEG, it is important that tests be done with the load. The desired goal is to deliver 500 kV pulses to various HPM loads including orbitrons, magnetrons [5], Virtual Cathode Oscillators (VIRCATORs), and/or Magnetically Insulated line Oscillators (MILOs) having volumes as feasibly small as technically possible. PHASE I: The goal of Phase I is to identify those mechanical, electrical, and/or chemical characteristics of the generator that could be modified in order to improves the performance of FEGs designed to drive HPM payloads. This will include doing proof-of-principle experiments to verify that the correct parameters to be modified to meet the objectives of this Topic have been identified. Since the type of explosives used impacts the operation of the FEG, explosive tests need to be done. This will necessitate the requirement that the proposing firm have access to approved explosive test facilities. PHASE II: The objective of Phase II is to finalize the design of the FEG and demonstrate that it can deliver 500 kV to various high power microwave sources. The proposing Firm must also address any power conditioning and integration issues. In addition, the proposing Firm should also address any manufacturing issues that would impact the production of these power supplies. PHASE III: These FEGs would be used in pulsed technologies that are applicable to multiple military and commercial applications requiring pulsed power. These include portable water purification units, portable nondestructive testing systems, portable lightning simulators, expendable X-ray sources, burst communications and telemetry, and oil and mineral exploration. Since several government labs and prime contractors are developing advanced munitions, the contractor will need to have developed a business plan for working with these agencies and companies.
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