Computationally Modeling the Effects of Surface Roughness on Soft X-Ray Multilayer Reflectors

• Main Author: Johnson, Jedediah Edward Jensen
• Format: Others
• Published: BYU ScholarsArchive 2006
• Subjects: electromagnetic scattering; roughness; Nystrom; integral equation; multilayer; Astrophysics and Astronomy; Physics
• Online Access: https://scholarsarchive.byu.edu/etd/1075; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=2074&context=etd

Electromagnetic scattering from a rough two dimensional homogeneous scatterer has been computationally modeled. The scatterer is intended to simulate reflection from a two interface multilayer. The rough scatterer was created from Gaussian random points centered about an ideal interface. The points were connected with a third order spline interpolant which accounts for correlation between neighboring surface atoms. The scalar electric field integral equation (EFIE) and magnetic field integral equation (MFIE) were solved using the Nystrom method to obtain the reflected intensity as a function of observation angle. Verification of the accuracy of the code was obtained by means of comparison with well-known analytic solutions and approximations. The predicted Nevot-Croce factor drop in reflectance was found to be in general agreement with the computed decrease in reflectance due to surface roughness. However, an angle dependent difference was also noticed, indicating the Nevot-Croce factor might need revision. The code is being modified to run on a supercomputing cluster where longer, more realistic surfaces can be analyzed to determine whether an improved roughness correction factor is needed.