Multimode polymer chirped fiber Bragg grating for shock and detonation velocity.

Shock and detonation velocities are today measured continuously using long silica chirped fiber Bragg gratings (CFBGs). These thin probes can be directly inserted into high-explosive samples. The use of a polymer fiber increases the sensitivity at low pressure levels when studying, for instance, shock-to-detonation transitions in wedge tests. The 22-mm-long multimode polymer CFBGs have, therefore, been manufactured and characterized. A first detonation experiment was realized on a narrow Formex strip using such a sensor. The feasibility is demonstrated, and the associated uncertainties, mostly coming from the use of a multimode fiber, are discussed.