Residual temperature measurements of light flash under hypervelocity impact

Experimental and theoretical results for light flash temperatures are presented for impacts on soda-lime glass by iron projectiles. The experiments were performed with a 2 MV Van de Graaff, where iron dust particles (0.14–0.63 μm in diameter) impacted soda-lime glass at a velocity range of 5–20 km s−1. Theoretical calculations were based on the assumption of the Mie–Gruneisen equation of state (EoS) with different values for the Gruneisen coefficient and hydrodynamic behaviour (no strength effects were considered). Within the scatter of experimental data, results suggest a constant value for the average light flash temperature of approximately 2600 K independent of iron dust impact velocity. Although theoretical calculations are limited by the use of the Mie–Gruneisen EoS up to the point of incipient vaporisation of the target material, relatively good agreement with experiments is observed. This agreement suggests that the observed constant temperature may be due to material phase change from incipient to complete vaporisation over the range of velocities considered.