Numerical Calculations of Wake Fields and Impedances of LHC Collimators' Real Structures

TL;DR

This paper presents detailed numerical simulations of the wake fields and impedances of LHC collimators, which are crucial for understanding beam stability and machine performance.

Contribution

It provides comprehensive numerical analysis and benchmarking of LHC collimator impedance calculations, including validation against analytical and semi-analytical methods.

Findings

Accurate impedance calculations for complex collimator structures.

Validation of simulation results with experimental and analytical data.

Insights into the impact of collimator materials on impedance.

Abstract

The LHC collimators have very complicated mechanical designs including movable jaws made of higly resistive materials, ferrite materials, tiny RF contacts. Since the jaws are moved very close to the circulating beams their contribution in the overall LHC coupling impedance is dominant, with respect to other machine components. For these reasons accurate simulation of collimators' impedance becomes very important and challenging. Besides, several dedicated tests have been performed to verify correct simulations of lossy dispersive material properties, such as resistive wall and ferrites, benchmarking code results with analytical, semi-analytical and other numerical codes outcomes. Here we describe all the performed numerical tests and discuss the results of LHC collimators' impedances and wake fields calculations.