Temperature Measurements of Shock Compressed Pentaerythritol Tetranitrate (PETN) Inferred from Emission Spectra and Pyrometry

Experiments were performed to measure the temperature of the gas phase detonation products in neat PETN.  This provides data for the reaction equation of state (EOS) as well as modelling and simulation comparisons.  The data will be particularly useful for understanding reaction rates and initiation mechanisms, including statistical hot spot models, which are heavily temperature dependent.  In the present work, a copper flyer plate was used to drive a sustained shock wave through a 5-mm thick explosive sample near the Chapman-Jouguet (CJ) pressure.  The resulting optical emission was captured by optical fibers looking through a LiF window and coupled into three different detection systems: (1) pyrometry with discrete wavelength multi-channels, (2) calibrated spectrometers where visible light (400-700 nm) was dispersed onto streak-cameras and (3) a broadband Thorlabs spectrometer with a linear CCD array detector.  In addition, photon doppler velocimetry (PDV) was utilized to measure the shock velocity at the LiF window interface.  A discussion of this work will include the differences between the different systems, the experimental parameters, data analysis, contributions to uncertainty, and implicit assumptions used to infer temperature from the optical spectra, as well as suggestions for future experiments.  This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.