Study of an adjustable integration mold for X-ray optics

Alden Gjoni - Politecnico di Milano

X-ray astronomy has great importance in the study of high-energy celestial phenomena, which play a crucial role in the dynamics of the Universe. Most of the baryonic component of the Universe is locked up in hot gas at temperatures of millions of degrees, and processes close to the event horizon of black holes occur at extreme energies, which require space-based observations in the X-ray portion of the electromagnetic spectrum. Observations in the far, early Universe require large X-ray telescopes, with state-of-the-art optic modules organized in a nested system of hundreds of concentric mirrors shaped as portion of paraboloids and hyperboloids. The fabrication of a high number of mirrors, each with different optical properties, is demanding both in terms of production times and costs.

This thesis studies the realization of an adjustable mold that can be shaped into the different theoretical configurations needed for X-ray space telescope mirrors production. To define the best load configuration for the desired deformation, optimization methods have been implemented, exploiting the MSC NASTRAN numerical solver.

First, a gradient based algorithm has been exploited to determine the optimal load distribution. Then to better tune the optimizer search, a global optimization algorithm has been preferred which more efficiently explored the solution space to obtain the optimal configuration in terms of actuator forces distribution. A multi-objective version of the global optimization algorithm has been adopted to better tune the actuation distribution along the different regions of the mold. The study traded off the mold material and thickness as well as driver parameters and shaped the numerical analyses with parameters obtained through experimental characterization.