Research On The Fiber Coupling Of Ultraviolet Light Source In Charge Management

Space gravitational wave detection missions focus on low-frequency sources which means a new window for detecting the universe.Space high-precision inertial sensor is one of the core techniques and it is mainly composed of a Test Mass,the electrodes,the capacitance sensing and feedback control circuits.Since cosmic rays and high-energy charged particles in space will cause the test mass to be charged,and it will introduce chargerelated noise of the inertial sensor and ultimately affect the scientific objects of the missions.So the charge on the test mass must be controlled at an accepted level.At present,charge management based on ultraviolet discharge technique is developed.The source of the ultraviolet light could use a radio frequency mercury lamp which has large size,low efficiency.Then Ultra Violet Light Emitting Diode(UV LED)as the ultraviolet light generator is investigated,and use ultraviolet fiber for transmission to avoid the influence of thermal noise of UV LED on Test Mass.This thesis mainly studies theoretical and experimental analysis on the coupling efficiency between the UV LED and optical fiber transmission.Finally,a prototype is developed,and the long-term performance is tested.The main work of this thesis is as follows:The basic principles of charge management and the current status of UV discharge technology is introduced.Then it focuses on the analysis of the characteristics of UV LEDs and the transmission principles of optical fibers.A UV light source system scheme is designed.Based on the principle of light propagation,the UV LED-lens-fiber coupling model is established,and the relationship between the coupling efficiency and influencing factors are analyzed based on numerical calculation.According to the above calculations,under the condition of selecting suitable parameters,the coupling efficiency of UV LED and single fiber finally reaches 30%,meet the requirements of charge management.For the proposed scheme design and theoretical analysis,the simulation of the coupling system based on ZEMAX(optical design software)is carried out,and a set of UV LED-lens-fiber coupling experiments is built using a high-precision XYZ-R(four-axis motion)stage system.The simulation results and experimental results show that they match the theoretical calculations.Finally,a set of four-channel integrated UV light source system is further developed,and a performance test experiment of up to 1200 hours is carried out,which finally verifies the reliability of the light source system.This work provides a basis for the application of UV light sources in charge management technology.