Explanation of anomalous shock temperatures in shock-loaded Mo samples measured using neutron resonance spectroscopy

Neutron resonance spectrometry (NRS) has been used to measure the temperature inside Mo samples during shock loading. The temperatures obtained were significantly higher than predicted assuming ideal hydrodynamic loading, a discrepancy which we now explain. The effects of plastic flow and nonideal projectile behavior were assessed. Plastic flow was calculated self-consistently with the shock jump conditions: this is necessary for a rigorous estimate of the locus of shock states accessible. Plastic flow was estimated to contribute a temperature rise of 53 K compared with hydrodynamic flow. Simulations were performed of the operation of the explosively driven projectile system used to induce the shock in the Mo sample. The simulations, and related experiments, indicated that the projectile was significantly curved on impact, and still accelerating. The resulting spatial variations in load, including radial components of velocity, should increase the apparent temperature that would be deduced from the width of the neutron resonance by 160 K. These corrections are sufficient to reconcile the apparent temperatures deduced using NRS with the accepted properties of Mo, in particular, its equation of state.