Research On Shock Initiation Of HNS-? Using Laser-Driven Multilayer Flyers

High safty,high reliability,miniaturization and intelligence are the developing directions of the advanced weapons and ammunition.Initiating explosive device as the initial engergy resource of the weapon system has the direct bearing on the whole system performance.Laser detonation and ignition technology has strong resistance ability to electrostastic,radio frequency,stray current and electomagnetic environment,so the advanced laser initiating explosive decvice has wide application prospects in the weapon and ammunition systems.The shock initiation of explosive using laser driven flyer is currently one of the most advanced safty initiation technology,its main principle is laser induced plasma driving flyer to impact explosive and shock initiate the explosive.Compared with laser initiating primary explosive and laser igniting explosive to transfer combustion to detonation,laser driven flyer shock initiation technology has characteristics of prompt initiation,high safty and high reliability,but to improve the efficiency of laser driven flyer and reduce the initiation laser energy is the difficulty of this technology.In this paper,the design and preparation of multilayer flyer,the mechanisms of laser driven flyer and shock initiation of HNS explosive by laser driven flyer have been studied.The main research results are as follows:(1)Using RF magnetron sputtering technology directly sputtering Al2O3 target to deposite the Al2O3 insulation layer whose surface was uniform,compact,without defects such as holes,and could satisfy the quality requirements of the multilayer flyer.Three kinds of multilayer flyers(Al/Al2O3/Al,C/Al/Al2O3/Al and Mg/Al/Al2O3/Al)have been designed and prepared.(2)The performances of laser driven multilayer flyers have been studied.The flyer velocities under different laser energies have been measured by Photon Doppler Velocimetry.The results showed that Mg as the alblation layer of the flyer could obviously improve the velocity of the flyer.The C absorption layer increased the flyer velocity at lower laser energies while decreased the velocity of flyer under higher laser energies.Using the polyvinylidene fluoride(PVDF)piezoelectric sensor compared the impact stresses of laser driven Al single-layer flyer and Al/Al2O3/Al multilayer flyer.The addition of Al2O3 insulation layer greatly improved the impact stress of flyer.The planarity and integrity results of laser driven flyers were indirectly obtained by analysing the impact craters on the glass slide using laser confocal microscope.The planarities and intergrities of Al,Al/Al2O3/Al and Mg/Al/Al2O3/Al flyers were better under the lower laser energies than that under the higher laser energies.The addition of C layer decreased the planarity and intergrities of C/Al/Al2O3/Al flyer.(3)According to the Gurney theory and based on the Lawrence model,a numerical model for laser driven multilayer flyer was established and calculated the multilayer flyer velocities under different laser energy densities.Through the comparison of simulation results with experimental results could be found that the simulation results were in good agreement with the experimental results at lower laser energy densities.While at higher laser energy density,as a result of the uneven distribution of laser energy density,the measured flyer velocity was higher than the calculated one.In general,the established model could relatively accurately simulate the velocity of laser driven multilayer flyer.(4)The shock initiation performance and mechanism of HNS-? using laser driven multilayer flyers have been studied.Using laser driven Al single-layer flyer,Al/Al2O3/Al,C/Al/Al2O3/Al and Mg/Al/Al2O3/Al multilayer flyer to impact the HNS-? explosive whose charge densities were 1.6g/Cm3 and 1.5g/cm3,and using the critical criterion of Walker-Wasley for shock initiation of heterogeneous explosives to evaluate the thresholds of laser driven flyers to initiate the two charge densities HNS-?.The results showed that the initiation ability of the three kinds of multilayer flyers to the HNS-? was better than that of the Al single-layer flyer,the HNS-? with 1.6 g/cm3 charge density was more easily initiated by laser driven flyers than the HNS-? with 1.5 g/cm3 charge density.(5)The shock initiation processes of HNS-? with 1.6g/cm3 charge density by laser driven Al single layer flyers and Al/Al2O3/Al multilayer flyers were numerical simulated using ANSYS/LS-DYNA explicit dynamic software,and the mechanism of laser driven flyers to shock initiate HNS-? was studied.Through the analysis shown that guarantee the flyer velocity was high enough to form a strong shock wave when impacted to the HNS-? could induce chemical reaction in the HNS-? and the released energy could enhance the intensity of the shock wave to make it growing into a detonation wave.This condition is important to successfully initiate the HNS-? using laser driven flyers.