Preparation Of Homogeneous Stress Film On Fused Silica Surface By Ion Injection Numerical Simulation Study

Fused silica is widely used in high-power laser devices due to its excellent mechanical,optical and stable chemical properties,and the maximum laser carrying capacity of fused silica optical elements largely determines the operating flux of highpower laser devices.However,micro cracks in the subsurface defects of fused silica optical elements are prone to damage growth under UV laser irradiation,leading to brittle fracture of the element,which has a significant impact on the laser damage resistance of fused silica elements and severely limits the service life of the element and the stable operation of the laser device with high throughput.Appropriate compressive stresses applied to the surface of fused silica components can inhibit the generation and expansion of micro cracks and offset part of the thermal stresses generated by laser irradiation,which is an effective way to enhance the resistance of components to laser damage.Thesis,the formation of a homogeneous stress film on the surface of fused silica by ion injection is studied theoretically.Firstly,the process of oxygen and argon ion injection into fused silica is calculated by Monte Carlo method(MC),and the ion range and concentration distribution,energy loss and irradiation damage of the fused silica target at different injection energies are analyzed.Next,the Finite Element Method(FEM)was used to simulate the crack expansion behavior of fused silica components under the action of shock waves,and the suppression effect of surface compressive stress on the crack expansion was analyzed.The main contents and results are as follows:(1)The ion range and concentration distribution,energy loss and irradiation damage of fused silica were investigated for oxygen and argon ions injected into fused silica elements with different energies.The results of SRIM calculations showed that the concentration distribution of injected ions in fused silica was approximately Gaussian distribution,and the maximum concentration was located at its average projected range.The higher the injection energy,the deeper the ion is injected,the wider the distribution,and the maximum ion concentration decreases.Most of the energy of the injected ions is transferred to electrons and a small portion to phonons.As the injection depth increases,the energy transferred to electrons decreases,while the energy transferred to phonons first increases and then decreases.Most of the energy of the recoil atom is transferred to the phonon and a small portion to the electron,and the energy transferred to both the electron and phonon increases and then decreases as the injection depth increases.Ion injection produces irradiation damage on the fused silica surface,and the depth of distribution of the damage corresponds to the depth of distribution of the ions in the fused silica.The higher the ion injection energy,the more severe the damage to the fused silica.The heavier the mass of the ions and the shallower the depth of injection for the same injection energy,the more severe the damage to the fused silica.(2)The crack expansion behavior of fused silica components under the action of shock waves was studied,and the effects of different strengths and different directions of compressive stress on the crack expansion were analyzed.ANSYS simulation results showed that with the continuous loading of shock waves,the cracks expanded in the direction of the shock waves,and the total length and width of the cracks were increasing,the stronger the shock wave strength,the greater the equivalent force at the crack tip,and the more rapidly the cracks expanded.When a certain compressive stress is applied on the surface of the component,the crack expansion is inhibited,and the larger the compressive stress is,the smaller the equivalent force at the crack tip and the slower the crack expansion;the compressive stress perpendicular to the crack expansion direction can inhibit the crack expansion more effectively.