Research On The Plasma Properties And Driving Performance Of Energetic Hydride Films

The slapper detonator has the characteristics of high safety,accurate time control and fast response.It can effectively improve the survivability and operational efficiency of weapon systems in complex battlefields,which is of great significance to the national defense.However,the low energy conversion efficiency and high initiation threshold of slapper detonator greatly restrict its application in many munitions.Facing the urgent need to improve the safety and operational efficiency of the current weapon systems,aiming at increasing the energy conversion efficiency of the slapper detonator,this dissertation proposes to use the energetic hydride films to significantly improve the energy conversion efficiency.Specifically,this dissertation systematically investigated the preparation and characterization of MgAlH_x film,the characteristics of the plasma flow field and driving effect of electrical explosion and photoexplosion of MgAlH_xfilms,the design and performance of laser slapper detonator incorporating MgAlH_xfilms,etc.The effects of sputtering power,Ar/H₂ gas flow rate ratio,working pressure,composition of MgAlmosaic target and temperature of the substrates on the deposition of MgAlH_x films were studied by reactive magnetron sputtering.MgAlH_x films with different hydrogen content were successfully prepared by adjusting the flow rate ratio of Ar/H₂ mixture gas.The results of neutron reflectivity test showed that the hydrogen content of MgAlH_x film could reach up to 11at.%.XRD results showed that when the hydrogen content was small,hydrogen mainly existed in the form of Mg H₂ in MgAlH_xfilms.With the increase of hydrogen content,metal hydrides such as Mg H₂ and Mg(Al H₄)₂ would coexist in MgAlH_x films.The electrical explosion process of Al,Mg Al,MgAlH_0.11 and MgAlH_0.25 exploding foils were measured by high-speed photography and atomic emission spectroscopy.The results showed that the ionization degree of exploding foils was enhanced by adding hydrogen into the exploding foils,while the electron temperature and electron density of the exploding foils increased with the increase of hydrogen content.The flyer velocities of the four kinds of exploding foils were measured by PDV under the charging voltage of 3KV,4KV and 5k V.The results showed that the terminal flyer velocities of MgAlH_0.25 exploding foil were the highest,which could reach 1967.0m/s,2444.8m/s and 2944.8m/s respectively.The photoexplosion process of Al,Mg Al,MgAlH_0.11 and MgAlH_0.25 films were measured by high-speed photography and atomic emission spectroscopy.Results showed that the ionization degree of the films was enhanced by the introduction of hydrogen.The electron temperature and electron density of laser induced plasma increased with the increase of hydrogen content.Time-resolved shadowgraph technique was used to measure the evolution process of laser induced plasma plume of Al,Mg Al,MgAlH_0.11 and MgAlH_0.25 films.Results showed that the shockwave energy conversion efficiency of MgAlH_0.11 and MgAlH_0.25 films was 18.5%and 76.6%higher than that of MgAlfilms,respectively.The results of PDV tests showed that the terminal velocities of MgAlH_0.11 and MgAlH_0.25 films were 6%and 15%higher than that of MgAlfilm,and 38%and 50%higher than that ofAlfilm,respectively.The homogenization of laser beam morphology and the influence of beam morphology on the characteristics of fiber coupling and flyer driving were studied.The beam shaping elements were designed and fabricated.A uniform energy distribution was obtained,which increased the coupling threshold of optical fiber by 29%and the maximum coupling energy reached up to 59 m J.The terminal velocities of the flyers driven by the modified laser beam and fiber emitted laser beam were up to 68%higher than those driven by the original laser beam.Meanwhile,the flyer driven by fiber emitted laser was more integral and flat.The laser slapper detonators based on Al,Mg Al,MgAlH_0.11 and MgAlH_0.25 films were designed,and the initiation results showed that the minimum initiation energy density of CL-20 explosive was about 14.2J/cm²,12.4J/cm²,10.6J/cm² and 8.8J/cm² respectively,which indicated that MgAlH_x energetic film can effectively improve the energy conversion efficiency and reduce the initiation threshold of the laser slapper detonator.Therefore,the prototype of a low energy threshold laser slapper detonator incorporating optical fiber was obtained,which verified the feasibility of MgAlH_x films in the application of slapper detonators.