A hierarchical approach for modeling X-ray beamlines: application to a coherent beamline

Abstract

Different approaches to simulate a modern X-ray beamline are considered. Several methodologies with increasing complexity are applied to discuss the relevant parameters that quantify the beamline performance. Parameters such as flux, dimensions and intensity distribution of the focused beam, and coherence properties are obtained from simple analytical calculations to sophisticated computer simulations using ray-tracing and wave optics techniques. A latest-generation X-ray nanofocusing beamline for coherent applications (ID16A at the ESRF) has been chosen to study in detail the issues related to highly demagnifying synchrotron sources and exploiting the beam coherence. The performance of the beamline is studied for two storage rings: the old ESRF-1 (emittance 4000 pm) and the new ESRF-EBS (emittance 150 pm). In addition to traditional results in terms of flux and beam sizes, an innovative study on the partial coherence properties based on the propagation of coherent modes is presented. The different algorithms and methodologies are implemented in the software suite OASYS. These are discussed with emphasis placed upon the their benefits and limitations of each.

A fast and lightweight tool for partially coherent beamline simulations in fourth-generation storage rings based on coherent mode decomposition

“…Diffraction patterns show higher visibility due to the increased coherent fraction in new sources, and its accurate modelling is fundamental for the design and optimization of beamlines. The physical models for the limiting cases of full incoherence (usually simulated by geometrical ray-tracing) or by propagating a single wavefront (valid for fully coherent radiation) are not sufficient for a complete understanding of the beam transport (Sanchez del Rio et al, 2019). The coherent fraction of the radiation emitted by new generation storage rings, although much improved with respect to previous generations, is still of the order of a few percent at hard X-rays, which means that it is mandatory to account for partial coherence.…”

Compensation of heat load deformations using adaptive optics for the ALS upgrade: a wave optics study

“…Simulations of the beamline optics can be performed in different degrees of approximation and effort, starting from analytical formulas, performing ray-tracing, and also wavefront propagation (Sanchez del Rio et al, 2019). Different packages for such simulations are available in the OASYS suite (Rebuffi & Sanchez del Rio, 2017a).…”

Perturbation perspective of partial coherence discussion on imperfect x-ray optical elements

“…Although wave optics simulations yield more accurate results than ray tracing for DLSR and X-ray FELs, they also require substantially more computational resources. Some improvements 11,12 have been done to make wave optics simulations less computationally demanding.…”

“…It can deal with various SR source models such as Gaussian-Schell model or more rigorous undulator models. In addition, the existing measures 11,12 to reduce the computation load can be integrated into this framework. It is shown in this paper that the coherent mode decomposition can be used to deal with the 4D convolution which comes from the proposed theory.…”