Research On Thermal Distribution Characteristic Of Satellite-to-ground Optical Communication Terminal

Part of the satellite-to-ground optical terminal is exposed to the space, whichinduces serious impact on the optical terminal, such as the space radiation,pollution and temperature nouniformity and so on. It’s known that temperaturedistortion leads to thermal deformation of the optical elements, thus beam pointingand wavefront will change when beam pass the optical elements, which will affectthe optical field distribution. In order to study the characteristics of the on-orbitterminal, the main work of this paper is:1. Thermal model of the terminal has been built, based on which the thermalcharacteristics of the optical terminal has been analyzed. Thermal analysisof the optical terminal involved with heat conduction and thermalradiation and coupled heat transfer has been discussed. The thermalcharacteristics of the terminal ha been analyzed. Typical structure surfacesfor the heat transfer terminal include sphere surfaces of the primary mirrorand secondary mirror, each part of which has been disposed as a quadricsurface. Terminals have been disposed into finite-element nodes. Based onwhich thermal calculation has been carried out by means of node networktechnique (i. e., lumped parameter method). The simplified model built byPro/E has been introduced Patran to get nodes. Proper size is of greatimportance for the fact that small size will increase the calculation timeand software Thermica is limited by the numbers of the radiation nodesand large size will decrease the accuracy of calculation. In general,gridding length is set to be0.05and cabinet is0.5which keep theuniformity of the node network and thus the corresponding calculation isfeasible;2. The six parameters needed in determining the satellite orbit has beenanylyzed. The six parameters are defined at some reference time or epoch,with which the velocity and location can be calculated;3. The illumination condition of the satellite has been analyzed. When theaircraft flies into the shadow of the earth, the earth blocks the sun’s raysfrom striking the aircraft. With regards to illumination condition of theterminal on-orbit, the design of thermal control of terminal on-orbit has been conducted;4. External thermal flux of the terminal on orbit has been simulated. In thissimulation, the thermal flux on the nodes of outside surface of theturntable have been considered and different thermal control schemeshave been compared with each other which provides a basis for the designof thermal control system;5. Finally, the relevant heat distraction methods of the plain elements havebeen analyzed and the main design parameters and schemes of the thermalcontrol have been given.