Experimental investigation of spectral evolution in flash radiation by hypervelocity impact on aluminum plates

In this study, a series of hypervelocity impact tests were carried out based on a two-stage light gas gun, and the sequence spectrum and radiation evolution data of the impact products under different impact conditions were obtained. The diameter of the projectile is 3–5 mm, the impact velocity is 3.13–6.58 km/s, and the chamber pressure is 0.56–990 Pa. The spectrum of ejected debris cloud in the 250–310 nm band were obtained using a transient spectral measurement system and a multi-channel radiometer measurement system. The test results reveal that the flash radiation intensity increases as a power function with the kinetic energy of the impact. Furthermore, the peak value of the line spectrum decreases as the chamber vacuum degree increases, while the radiation width gradually expands. The line spectrum in the spectral characterization curve corresponds to the ejected debris clouds splitting phase, which does not produce significant line spectrum during material fragmentation and is dominated by the continuum spectrum produced by blackbody radiation. There will appear one or three characteristic peaks in the flash radiation time curve, the first and second peaks correspond to the penetration phase and the third peak corresponds to the expansion phase of the ejected debris clouds on the time scale, the first and second peaks are more sensitive to the chamber vacuum degree, and when the pressure is higher than 99 Pa, the first and second characteristic peaks will disappear. The radiant heat attenuation of the flash under different impact conditions is significantly different, the attenuation exponent has a power function relationship with the impact velocity and the chamber vacuum degree, while the attenuation exponent has a linear relationship with the diameter of the projectile, the specific expression of the attenuation exponent is obtained by fitting. The findings from this research can serve as a valuable reference for remote diagnostic technologies based on flash radiation characteristics.