Chemical Imaging of Explosions – Mapping BO₂ Light Emission

This work describes chemical imaging of BO 2 formed during ballistic initiation of 1 : 1 by weight powder‐mixtures of boron (B) and potassium nitrate (KNO 3 ) contained within a polyethylene spherical projectile (25 mm diameter). Initiation was achieved by impact of the gas‐gun‐launched B/KNO 3 ‐filled projectile with an anvil in a windowed, air‐filled chamber. To monitor the subsequent chemical reaction, a two‐camera, optically‐filtered method to map discrete chemical emission from the BO 2 molecule was used. This technique distinguishes incandescence of hot particles produced during the event from discrete chemical emission by BO 2 near a wavelength of 546 nanometers (nm). The dependence of delay in BO 2 chemical emission (that exceeded particle incandescence) with impact velocity was investigated and chemical emission movies which ratio the intensity of discrete to thermal emission are discussed. Emission spectra (300–1000 nm wavelength) were recorded during the impact event, and used to determine a grey‐body temperature of the hot particles during the time when BO 2 emission was most intense.