# A hierarchical approach for modelling X-ray beamlines. Application to a coherent beamline

## TL;DR

This paper presents a hierarchical modeling approach for X-ray beamlines, combining analytical, ray-tracing, and wave optics methods to evaluate performance, with a focus on a modern nanofocusing beamline and coherence properties.

## Contribution

It introduces a multi-level modeling framework for X-ray beamlines, integrating various simulation techniques and analyzing coherence for different storage rings.

## Key findings

- Performance differences between ESRF-1 and ESRF-EBS beamlines.
- Validation of modeling approaches against experimental parameters.
- Insights into partial coherence and beam focusing capabilities.

## Abstract

We consider different approaches to simulate a modern X-ray beamline. 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. Those are discussed with emphasis placed upon the their benefits and limitations of each.