Research On Electromagnetic Radiation Shielding Based On Intense Laser Irradiation

As a controlled fusion method,inertial confinement fusion has attracted worldwide attention.The electromagnetic pulse generated during the interaction between a strong laser and a substance has a large intensity,a frequency bandwidth(tens of MHz-5GHz),and is accompanied by high-energy rays.The sensitive diagnostic equipment has been in such a complex environment for a long time,which is easy to cause equipment failure,data loss and even damage to the equipment.Therefore,the electromagnetic protection of the equipment is urgent.Therefore,obtaining the electromagnetic field in a complex laser environment protection is very important.In this thesis,the electromagnetic shielding research is carried out based on the complex environment generated when the strong laser interacts with the material.First,the electromagnetic interference coupling principle and the electromagnetic shielding principle are introduced.Based on the transmission line principle to achieve the electromagnetic protection and finish the design of the experimental and data analysis.Aiming at the neutron,gamma ray and super-strong electromagnetic pulse generated during the experiment of the Shenguang laser device,a multilayer shielding material that can realize neutron,gamma ray and electromagnetic pulse at the same time.Through the combination of experiment and simulation,it was found that the thicker the multi-layer shielding material,the better the shielding effect;the experiment found that0.5mm PTFE,0.4mm copper film and 2.4mm lead can achieve attenuation of interference signals more than 450 times,At the same time,the experiment shows that the interference coupling of the coaxial cable cannot be ignored,and it must be paid attention to in the actual shielding operation.The simulation shows that0.5mm PTFE,0.4mm copper film and 2.4mm lead can achieve more than 1200 times the interference signal attenuation.At the same time,it is found that for high-strength and high-frequency electromagnetic pulse shielding,under the same thickness,the better the conductivity,the better the electromagnetic shielding effect.The shielding effect of metal copper material> the shielding effect of metal aluminum material> the shielding effect of metal iron;For the same material,the thicker the material,the better the electromagnetic shielding effect;For the metal material of the same thickness,the denser the metal mesh,the better the electromagnetic shielding effect.When the shielding requirements are higher and the heat dissipation and ventilation requirements are lower,the larger the mesh number of the metal mesh,the better the electromagnetic shielding effect.The experiment shows that the 200 mesh metal mesh can reduce the interference signal to the noise level,and the simulation shows that the 200 mesh metal mesh can realize electromagnetic attenuation of the signal is more than 80 d B;and for the electronic equipment with high requirements for heat dissipation and ventilation and slightly lower requirements for shielding,the 100 mesh or 150 mesh metal mesh is more suitable.Next,a multi-layer shielding structure is designed which can simultaneously shield neutrons,gamma rays and electromagnetic pulses,simulates and measures the shielding effectiveness,and has important reference value for the electromagnetic interference of Shenguang series devices;On this basis,the electromagnetic protection of electronic equipment with heat dissipation and ventilation requirements is further studied,and the method of electromagnetic protection under special requirements is provided.Our research has practical significance for increasing the safe operation and data accuracy of sensitive diagnostic equipment in inertial confinement fusion experiments.