Characterization of high energy density capacitors under projected US Navy ETC gun operating conditions

The US Navy has been developing electrothermal-chemical (ETC) gun system technologies since 1990 for use in ship self-defense and surface fire support missions. Emphasis has been placed on the capacitor-based pulse forming network (PFN) as the primary means of energy storage and pulse shaping. Defining and understanding the electrical and mechanical performance characteristics of high energy density capacitors is critical for both the PFN designer and overall weapons system engineering. Aerovox Type LM power capacitors (2.4 MJ/m/sup 3/) were evaluated under the projected Navy operating scenarios, including rep-rate and burst modes. The Aerovox Type LM capacitors, first used in the US Army 8.5 MJ Pulsed Power Module in 1991, are known to be nonlinear with respect to capacitance and voltage. Additionally, the charge/discharge efficiency is known to be lower for this capacitor than for other, lower energy density capacitors. The life characteristics of the capacitor have been established under normal operating conditions. This paper discusses the performance of the Aerovox Type LM capacitors in both normal and fault mode conditions. The parameters discussed include temperature variations, voltage reversal and peak current performance. Thermal stability and fault mode performance for the power capacitor is also defined.