Improving Manganin Gauge Measurements Near Radiographic Fiducials

Manganin gauges are fielded in high explosive experiments to measure in situ stresses. Flash X-ray radiography is fielded to measure in situ dynamic flow, requiring radiographic fiducials, typically Ta foil, to be embedded within the experiment. For a more complete in situ measurement of the dynamic event (flow and stress together), manganin gauges are placed in the same layers as the foil fiducials. However, these foils naturally have a high mechanical impedance, and this gauge/foil configuration greatly perturbs the measured dynamic stress. We conducted experiments to test the performance of different arrangements of manganin gauges and Ta foils. Three different gauge/foil configurations were tested, as well as a solitary gauge as control. Gauge/foil layers were placed between high-density polyethylene (HDPE) discs and impacted by a projectile in a gas gun, a simplification of the high explosive experiment configuration. The stress measurements were minimally perturbed when a section of foil was removed near the active element of the gauge, as expected. An experiment is planned to test whether a modification of foil impacts the radiographic measurement of the dynamic flow.