空间三轴激光陀螺放电区微晶玻璃Li^(+)迁移规律研究

Study on Li ion migration of glass-ceramic in discharge area of space triaxial laser gyroscope

空间三轴激光陀螺是一种将三个敏感环路正交集成于一块微晶玻璃基体上的空间激光陀螺,在航空、航天、军事等领域得到了广泛应用。随着军用装备对高性能激光陀螺长期通电性能稳定性的要求不断提高,提高激光陀螺长期通电性能稳定性、延长激光陀螺工作寿命已成为国内外激光陀螺专业领域研究人员共同关注的重要课题。国外多项专利提到了微晶玻璃中的Li^(+)在电场的作用下发生迁移并影响激光陀螺工作寿命,但未见具体研究。文中对空间三轴激光陀螺开展了通电寿命试验,并结合飞行时间二次离子质谱分析技术,研究了放电区微晶玻璃LAS(Li_(2)O-Al_(2)O_(3)-SiO_(2))表面的Li^(+)迁移现象,结果表明:微晶玻璃中Li^(+)在激光陀螺电场及谐振腔内等离子体的作用下向谐振腔方向迁移,并脱离微晶玻璃进入谐振腔,然后随等离子体流动,最终沉积在阴极表面。该结果对提高激光陀螺长期通电性能稳定性、延长工作寿命等相关研究具有重要推进作用。

Objective Space triaxial laser gyro is a kind of space laser gyro which integrates three sensitive loops orthogonally on a glass-ceramic substrate.It has been widely used in aviation,aerospace,military and other fields.With the increasing requirement of military equipment for the long-term power-on stability of performance of high-precision laser gyro,improving the long-term power-on stability of performance of laser gyro and extending its working life have become an important topic for researchers in the field of laser gyro both at home and abroad.Foreign companies such as Litton,Honeywell,Thales,etc.had mentioned that Li^(+)on the glass-ceramic substrate migrated under the action of electric field,and in turn,it reduced the working life of laser gyro,but no specific research has been made.In order to improve the long-term power-on stability of performance of laser gyro and prolong its working life,Li^(+)migration on the surface of LAS(Li2O-Al2O3-SiO2)glass-ceramic in the discharge area was researched.Methods The accelerated power-on life test of space triaxial laser gyro was carried out,the intensity curves with the sputtering depth of Li^(+)in the glass-ceramic in the discharge and non-discharge area,mirrors,and the inner and outer surfaces of cathode of this laser gyro was tested with the time-of-flight secondary ion mass spectrometry(TOF-SIMS)analysis,the law of Li^(+)migration in the glass-ceramic and the resonator of space triaxial laser gyro was clarified.Meanwhile,the electric field of the laser gyro in the working state was modeled and simulated by COMSOL Multiphysics.Furthermore,the migration mechanism of Li^(+)in the glass-ceramic and the resonator was discussed.Results and Discussions The color of the glass-ceramic surface in the discharge area of the test gyro was changed significantly(Fig.4).The intensity curves of major elements with the sputtering depth in the glassceramic in the discharge and non-discharge area,mirrors,and the inner and outer surfaces of the cathode was tested by means of TOF-SIMS.It was found that Li^(+)on the surface of the glass-ceramic in the discharge area had migrated into the resonator(Fig.6-7),and deposited on the inner surface of the cathode uniformly(Fig.8).Meanwhile,no significant Li^(+)deposition on the mirror which located in the discharge area,or even entered into the film(Fig.9).COMSOL Multiphysics was used to simulate the electric field distribution of the laser gyro under the working condition.The Li^(+)migration mechanism in the glass-ceramic was discussed combined with the simulation results.It showed that Li^(+)migrated to the surface of glass-ceramic and entered into the resonator under the action of electric field,which decreased the Li^(+)concentration and changed the refractive index of glassceramic.So it showed different light reflection characteristics from the surrounding area.Furthermore,since the electric field intensity in the mirror in the discharge area is relatively small,the flow path of the plasma in the resonator follows the principle of the shortest path,most of the plasma will not directly touch the mirror,Li^(+)mainly moves to the cathode with the plasma and deposits on the inner surface of the cathode,therefore no obvious Li^(+)was detected on the mirror.Conclusions Li^(+)migrated into resonator under the action of the electric field and plasma of glass-ceramic in the discharge area of space triaxial laser gyroscope,and then flowed with the plasma,finally deposited on the inner surface of the cathode.This phenomenon may reduce the temperature-varying dimensional stability of glassceramic and the working life of cathode,and then decreased the long-term power-on performance stability of the laser gyro.Some measures and suggestions are proposed to suppress Li^(+)migration based on its migration law,the specific suppression methods of Li^(+)migration will be further studied.