Development Of A Pumped Lc Tank Circuit For Use In An Adiabatic Pulsed Inductive Heating Application

In any high-energy pulsed power experiment, the metallic conductors are expected to heat up significantly due to resistive losses. In the pulsed case, the effects of local heat transfer are decreased due to the limited thermal diffusion time, so the process is considered to be adiabatic rather than isothermal. Previous results indicate that the high-temperature mechanical properties of metallic conductors significantly depend on the rapidity and duration of heat deposition [1-5]. With this in mind, it is important to understand the mechanical properties of metals heated rapidly so that the correct mechanical properties are considered when designing high energy experiments. An expanding ring experiment has been performed at the Institute for Advanced Technology (IAT) to test such mechanical properties. The experiment uses a primary coil powered by a near-critically damped RC circuit to induce a current pulse in a thin specimen ring that expands and fragments due to electromagnetic forces. So that the heating time is minimized, an inductive heating source has been developed to rapidly heat the specimen ring. Temperatures as high as the material's melting temperature can be reached within a few milliseconds, prior to the application of electromagnetic expansion forces. The source employs a pumped LC tank circuit with a resonant frequency of roughly 25 kHz to induce a current in the ring. The current in the primary and secondary coils are measured using Pearson and Rogowski coils. A high-speed infrared camera is used to measure the temperature of the ring specimen during heating. The data generated will quantify the rate of heating sensitivity of material properties in commonly used materials for development and validation of appropriate constitutive equations.