Design And Fabrication Technology On Soft X-ray Grazing Incidence Concentrators

Spacecraft traveling into deep space, here defined as those distances from Earth beyond geostationary orbit, can’t be navigated by the Global Positioning System(GPS). The current predominant sources of navigation information for deep space probes are X-ray pulsars. By observing the arrival time of pulsars at a spacecraft from several pulsars in different directions, a spacecraft could determine its location and get navigation information. In order to improve the detectability, an optical system is in need to collect large amounts of radiations from X-ray pulsars and focus them. It is one of the key technologies of X-ray pulsar navigation. Due to the optical property of X-ray, grazing incidence optical system based on the theory of total reflection is adopted.This paper focuses on X-ray optical concentrating systems with high sensitivity, including: optical system design, fabrication of the reflectors, and surface profile measurement etc.1. According to the structure of Wolter-I type grazing incidence system and the requirements of X-ray concentration, nested paraboloid system with single reflection was designed and optimized. The structural parameters were optimized by calculating the effects of the parameters on performance of the concentrating system. Engineering analyses on the optical system were performed, including the effects of spoke structures and surface profile error of the reflectors on the performance of the system.2. Performance of nested conical structure and Micro-channel plates were calculated, including effective area, reflectivity, and relative intensity gain. Performance of the two systems was compared with the performance of nested paraboloid system respectively. According to the comparison, nested paraboloid system with single reflection is more suitable to operate as X-ray concentrator.3. Simulation of thin glass sheet thermal slumping process on a concave mold was performed through finite element method(FEM). The effects of different process parameters, i.e. heating and cooling rate, and soaking temperature on the final shape of formed glass were studied. According to the prediction, thermal slumping process parameters were optimized. The relationship of the surface profile between the desired reflector and mold was derived. The compensation of the mold surface equation was calculated according to the relationship. After the mold was designed and fabricated, quadrant parabolic reflector was fabricated by thermal slumping process.4. The micro-roughness and surface profile of the fabricated reflector were measured. The RMS micro-roughness of the reflector was 0.38 nm. By comparing with the surface profile of the mold, the fabrication error was derived. The PV and RMS fabrication error was 4.7μm and 2.3μm, respectively. According to the surface error analysis, deviation between the formed reflector and the ideal equation was mainly caused by the mold.5. Imaging performance of the quadrant parabolic reflector was tested. The resolution was about 1.48 arcmin. It is indicated that glass thermal slumping process for the fabrication of thin foil reflectors is feasible. The surface profile error source analysis and imaging performance test of the reflector are beneficial for the improvement of surface profile and manufacture of the concentrator in the future.