Research On PMT Implosion Shock Wave Characteristics And Protective Devices

The photomultiplier tube(PMT)is the core component of the neutrino detection test.It is a thin shell structure of internal vacuum made of glass material,arranged to work in deep water and withstand high hydrostatic pressure.If a PMT is accidentally crushed,high-pressure water flows to the center and collides with each other to cause implosion,then generates implosion shock waves,a chain of explosions around the PMT will be caused,it is called martyrdom.Aiming at the problem of martyrdom explosion of PMT working in deep water,combined with the needs of actual engineering,taken the PMT in Jiangmen Neutrino Test Station as the research object,characteristics of spheroid PMT implosion shock wave are explored,the protective devices to prevent the martyrdom of PMT are improved and manufactured,the strength of the PMT installation module is checked,the effectivenes of the blasting protection of the protective device is verified.A martyrdom protection method for PMT in neutrino test station is provided in this paper.Firstly,combined with the domestic and international research status of implosion and martyrdom,the status and problems of the martyrdom protection of PMT in Jiangmen neutrino test station are analyzed in detail.The simulation method of simulating underwater implosion by Euler-Lagrange coupling(CEL)algorithm in Abaqus software is introduced,and the method of using bare PMT implosion test to verify the accuracy of the implosion simulation is carried out.On this basis,the characteristics of ellipsoidal implosion were studied by numerical simulation,the process of ellipsoid implosion,the distribution and propagation law of implosion shock wave in all directions,and the change law of the intensity of ellipsoid implosion shock wave with the ratio of length to length are obtained.Secondly,the structure and connection method of the upper and lower protective covers of the PMT sacrificial explosion protection device are improved,the stability and strength of the protective device by the method of finite element simulation are checked,and the explosion protection test equipped with protective device PMT is carried out.The results show that,compared with bare PMT implosion,the peak value of PMT implosion shock wave with protective device is reduced by nearly 20 times,and the pulse width is reduced by nearly 2 times.The the intensity of the implosion shock wave of the PMT are reduced effectively by protective device,the death of the nearby PMT is avoided,and meets the requirements of the protection of the explosion.Finally,for the problem that the deformation of the module will cause the collision and explosion of the PMT,the strength of the installed module is studied.According to whether the protective device is broken,the load that the module bears is divided into two types: static pressure differential load and dynamic impact load.Verified the strength of the module under the two loads is simulated,and further analysis shows that the deformation of the module will not cause PMT The conclusion of a collision and explosion.Then,the strength check tests of the installation module with multiple PMTs are carried out,the verification of the strength and reliability of the PMT installation module are completed.The results of tests show that: the strength of the module meets the requirements,and the deformation of the module will not cause the collision and blasting of the PMT;at the same time,the PMT blasting threshold is concluded through two PMT blasting tests.