A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of...A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of the paraboloidal primary mirror,the mirror is discretized into equal thickness shell elements by considering shell curvature.And the material nonlinear constitutive relation of flexible mirror is acquired using Absolute Nodal Coordinate Formulation(ANCF).Furthermore,the primary mirror of F-DST can be regarded as a clustered multi-body system,and its dynamic equations of elastic deformation and deployment motion are established by virtual work principle.Finally,the deployment motion of primary mirror by different driving conditions are simulated,the results show that the vibrations of mirrors that driven by elastic hinge device are more than that driven by servo motor.In addition,single sub-mirror deployment process will perturb the pointing accuracy of primary mirror,and the multiple sub-mirrors simultaneously deploying will seriously affect all the sub-mirrors surface accuracy because of the coupling effect.Thus,there are theoretical value and practical significance for the controlling surface accuracy and attitude accuracy of space telescope.展开更多
The surface contamination layer on mirrors can cause significant degradation of the optical performance, which is widely observed in applications, particularly in the fabrication of X-ray focusing telescopes. In this ...The surface contamination layer on mirrors can cause significant degradation of the optical performance, which is widely observed in applications, particularly in the fabrication of X-ray focusing telescopes. In this paper, we study the natural contamination layer arising from adsorption precipitation of hydrocarbons or other organic and water molecules in the absence of any external factor. Temporal evolution of the layer formed on super-smooth fused silica, borosilicate glass, and silicon substrates is studied by X-ray reflectometry, atomic force microscopy, and transmission electron microscopy for a one-year period after surface cleaning. The general characteristics of adhesion layer growth are established and discussed. The reconstructed dielectric constant profiles demonstrate that an increase in the adhesion layer thickness, deposited mass and density over time obeys power laws with extremely small exponents. Therefore, the adhesion layer growth is rapid immediately after surface cleaning, with a - 1 nm thick layer formed within the first day on all three substrates studied, while the layer density is low （- 1 g/cm^3）. The layer growth on the fused silica and silicon substrates became very slow in the succeeding days, with only a 1.4-1.5 nm thick layer and 1.2-1.3 g/cm^3 density after one year of storage in air. At the same time, the adhesion layer growth on the glass substrate showed unexpected acceleration about two months after cleaning, so that the layer thickness reached - 2.2 nm after one year of storage. The reason for this effect, which is connected with leaching of the glass, is discussed briefly.展开更多
基金based on Project 51575126 the National Natural Science Foundation of ChinaProjects 2013M541358 and 2015T80358 the China Postdoctoral Science Foundation。
文摘A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of the paraboloidal primary mirror,the mirror is discretized into equal thickness shell elements by considering shell curvature.And the material nonlinear constitutive relation of flexible mirror is acquired using Absolute Nodal Coordinate Formulation(ANCF).Furthermore,the primary mirror of F-DST can be regarded as a clustered multi-body system,and its dynamic equations of elastic deformation and deployment motion are established by virtual work principle.Finally,the deployment motion of primary mirror by different driving conditions are simulated,the results show that the vibrations of mirrors that driven by elastic hinge device are more than that driven by servo motor.In addition,single sub-mirror deployment process will perturb the pointing accuracy of primary mirror,and the multiple sub-mirrors simultaneously deploying will seriously affect all the sub-mirrors surface accuracy because of the coupling effect.Thus,there are theoretical value and practical significance for the controlling surface accuracy and attitude accuracy of space telescope.
基金Supported by the National Key R&D Program of China(2016YFA0401304)the National Natural Science Foundation of China(NSFC)(61621001,U1731242,U1732268)the Ministry of Science and Higher Education of Russian Federation within the State assignment FSRC “Crystallography and Photonics” RAS
文摘The surface contamination layer on mirrors can cause significant degradation of the optical performance, which is widely observed in applications, particularly in the fabrication of X-ray focusing telescopes. In this paper, we study the natural contamination layer arising from adsorption precipitation of hydrocarbons or other organic and water molecules in the absence of any external factor. Temporal evolution of the layer formed on super-smooth fused silica, borosilicate glass, and silicon substrates is studied by X-ray reflectometry, atomic force microscopy, and transmission electron microscopy for a one-year period after surface cleaning. The general characteristics of adhesion layer growth are established and discussed. The reconstructed dielectric constant profiles demonstrate that an increase in the adhesion layer thickness, deposited mass and density over time obeys power laws with extremely small exponents. Therefore, the adhesion layer growth is rapid immediately after surface cleaning, with a - 1 nm thick layer formed within the first day on all three substrates studied, while the layer density is low （- 1 g/cm^3）. The layer growth on the fused silica and silicon substrates became very slow in the succeeding days, with only a 1.4-1.5 nm thick layer and 1.2-1.3 g/cm^3 density after one year of storage in air. At the same time, the adhesion layer growth on the glass substrate showed unexpected acceleration about two months after cleaning, so that the layer thickness reached - 2.2 nm after one year of storage. The reason for this effect, which is connected with leaching of the glass, is discussed briefly.
