Precisely Controlled Reactive Multilayer Films with Excellent Energy Release Property for Laser-Induced Ignition

Three types of reactive multilayer films (RMFs) were integrated to the energetic flyer plates (EFPs) by depositing TiO₂, MnO₂, and CuO onto aluminum films with different modulation periods using magnetron sputtering technology in this study. The effects of the laser ignition property and laser reflectivity on the RMFs and the thermal behavior of the RMFs were analyzed and compared with those of a single-layer Al film. A high-speed video, photonic Doppler velocimetry (PDV), and a thermal analysis were utilized to characterize the flame morphology, EFP velocity, and chemical thermal behavior, respectively. The surface reflectivities of the TiO₂/Al, MnO₂/Al, and CuO/Al layers were measured using laser reflectivity spectrometers. The results showed that RMFs with smaller modulation periods exhibited excellent laser ignition performances, and EFP with MnO₂/Al had the best performance. These RMFs achieved flame durations of 120-220 μs, maximum flame areas of 7.523-11.476 mm², and reaction areas of 0.153-0.434 mm² (laser-induced with 32.20 J/cm²). Flyer velocities of 3972-5522 m/s were obtained in the EFPs by changing the material and modulation period of the RMFs. Furthermore, the rate of the chemical reaction and laser energy utilization were also enhanced by reducing the modulation period and using different material. This behavior was consistent with a one-dimensional nanosecond-laser-induced plasma model. The RMFs of MnO₂/Al exhibited the highest level of energy release and promoted laser energy utilization, which could better improve the performance of laser ignition for practical application.