Mechanism And Ignition Performances Of Energetic Igniters Based On Al/CuO Composite Thin Films

Compare with bridgewire electro-exploding devices（EEDs）,semiconductor bridge（SCB）EEDs have the advantages of better ignition performances and safety.After decade’s development.SCB gradually reflects its large-scale application prospects in civilian and military fields.However,limited by bridge mass and stimulus energy,it probably appears unreliable ignition when SCB ignites insensitive explosive or any exsiatance of air gap between explosive and the bridge.Therefor,in this dissertation,based on the mature SCB ignition technology,a new kind of energetic igniter has been designed and fabricated by using the ion beam sputtering technique.The energetic igniter is a combination of polysilicon film and Al/CuO nano energetic multilayer films（nEMFs）.A research has been made on the function process,energy transfer mechanism and ignition performances of the energetic igniters.The main research contents and conclusions are as follows:（1）The function process and the energy transfer mechanism have been diagnosised and analyzed by employing the technology of infrared thermal imaging and the ultra-high speed photography,sperately.The results show that:under the stimulus of low-amptitude long pulse,the energy transfer meachanism between the Al/CuO nEMFs and polisilicon film is a combination of heat conduction and thermal feedback.The heat released by chemical reaction of Al/CuO feeds back to the polysilicon film,and accelerates or promotes its futher function.While under the stimulus of high-amptitude short pulse,the mechanism is a combination of heat conduction,heat convection and radiation heat trasfer.The Al/CuO nEMFs were forces to form fragments by the shcok wave generated with plasma growth.Heat convection and mass transfer occurs between the freagments and plasma.During the entire function process,stimulus current only flows through polysilicon film and contact pads.The endothermic effect of Al/CuO nEMFs leads to a delay on reaching the characteristic phenomenons.And the calculated plasma expansion maximum speed is 0.958km/s and maximum flying speed of Al/CuO fragements is 2.05km/s.（2）The characteristic parameters,electro-explosive growth process and emission spectrum have been tested,and influence of stimulus energy,bridge type and size have been analyzed.The results show that:bridge structure leads to different variations of characteristic parameters.The spatial size and durations of the elctro-explosive products increase with the increase of stimulus energy.Under the same input energy,plasma spatial size increase with the decrease of the bridge size,while amount of Al/CuO fragements increase with the increase of bridge size.The spatial size and durations of energetic igniters were larger and longer than that of polysilicon igniters.The variations trend of electron temperature and density coincides the process,the temperature range is 4700K～7000K and lasts for 12μs,the elctron density range is（1.6～2.9）×10¹⁶·cm^-3.（3）The physical-field parameters distribution of each film during the function process has been simulated by using finite element simulation software.The parameters include surface temperature,current density and thermal gradient.The result show that:current flows through polysilicon film,generates Joule heat,and then transfers heat to substrate,conduct pads and Al/CuO nEMFs.Temperature of each single layer of the nEMFs was far lower than polysilicon layer because of the heat insulation effect of the insulating layer.Temperature difference among the nEMFs is small.Due to the special structure,current density around the V type angles is higher than the rest bridge area.The current distribution of rectangular bridge is much more uniform,and current density near the bridge edge is slightly higher.Generally,current density decrease with the incease of bridge volume,which means the heat production rate is inversely proportional to the volume of the bridge.（4）According to status of products,function mechanism and related hypothesis,a one-dimension gas-solid two-phase flow model has been stabulished to simulate the micro convective mass and heat transfer process between plasma,Al/CuO reaction products and explosive particles.Results show that:compare with polysilicon igniters,because of futher internal heat source,the heating rate,maximum value and duration of surface temperatue of the explosive particles is higher and longer during the ignite process of energetic igniters.Futhermore,temperature,pressure and density of the gas phase are all improved,which indicates a better ignition capability of energetic igniters.As parameters value increase,it is propitious to explosive ignition;the parameters include plasma radius,plasma temperature,condensed gas content,reaction rate of Al/CuO,explosive loading density,particle radius and thermal conductivity.（5）The ignition performances with LTNR of the igniters have been discussed,results show that:under low stimulus energy,Al/CuO nEMFs absorb heat form polysilicon film,reaches to reaction temperature,and then accalaretes ignition process by relasing heat from chemical reaction.But this boosting effect gets weaker with the increase of stimulus energy,because plasma temperature is higher than chemical reaction heat under high input energy.The design of V type angles helps to reduce function required energy and reduce igniton delay time.（6）A non-contact charging structure with air gap between the igniter chip and explosive particles has been desiged and implemented.The ignition performances with different standoff have been experimentally discussed.The explosive is a mixture ignition powder of lead thiocyanate and potassium chlorate.Results show that:the all-fire voltage of energetic igniters with the standoff of 1.5mm,2.5mm and 3.5mm respectively is 30.22V,40.34V and 61.21V.Furthermore,two of three tested samples fired at 60V stimulus voltage at the sandoff of 4.5mm,while one fired at 5.5mm.However,none of the polysilicon igniters fire under the same condition.The experiment results demonstrate higher output energy of energetic igniers than polysilicon igniters,and it may realize non-contact igniton.