Study On Density Measurement Of Optical Signal Of Plasma

As the advent of laser,laser-driven flyer impact initiation technology is one of the safest technologies for igniter explosion.Plasma optical signal is produced by laser-driven materials,which make the plasma optical signal generated by the laser-driven plates become an important research topic.The optical signals commonly used in plasma electron density testing methods are complex and expensive,while optical interference technology has important advantages of simple experimental platform,no interference from the measured object,with low cost and high efficiency.On the basis of optical interference technology,the electron density of plasma optical signal is measured and systematically studied,which is helpful to improve the research technology of igniters.It can also provide technical index for materials developed,as well as scientific basis for the safety performance promoting of laser-driven flyer impact initiation technology.With the moire deflection test technology,the overall design of plasma density measurement optical signal was determined in this thesis.Based on the calculation of the optimized inverse Abel transform,the reconstruction effect of the simulated field to verify the correctness of the calculation was analyzed.The relationship between distortion and refractive index was deduced,and the relationship between the refractive index and the electron density was also clarified with the plasma physics equation.The initial structure design of beam expanding collimation optical system and object telecentric optical system were completed,and optimized according to the optical signal of plasma density measurement.The results of design and tolerance analysis show that the requirements of optical signal of plasma density test system can be satisfied in the beam expanding collimation optical system and the object telecentric optical system designed results.The effective information of the image can be collected with fringe skeleton extraction method and the flourier transform method.The refractive index field and the temperature field of plasma optical signals generated by the laser drive TC4(Ti-6Al-4V)plate and Al2O3 plate were reconstructed.The refractive index(n-1)of TC4(Ti-6Al-4V)plate is between 1.15×10-5 and 1.30×10-5,with the temperature between 6100 K and 7000 K.The refractive index(n-1)of Al2O3 plate is between-2.49×10-5 and-1.70×10-5,with the temperature between 13000 K and 13430 K.The electron densities of plasma optical signals generated by TC4(Ti-6Al-4V)plate and Al2O3 plate were measured.The electron density of TC4(Ti-6Al-4V)plate is between 0.64×1016 cm-3 and 1.40×1016 cm-3,and the electron density of Al2O3 plate is between 1.12×1017cm-3 and 1.36×1017 cm-3.