Tomasz Galek

Extraction of effective permittivity and permeability of metallic powders in the microwave range

In this work, effective electric permittivity and magnetic permeability of metallic‐dielectric mixtures are extracted from electromagnetic full 3D simulation data in the microwave range. The numerical method used here is the finite integration technique with periodic boundary conditions. Simulated mixtureshaveperiodicextendindirectionsperpendiculartothedirectionofthe planewave. Thus, itissufficienttoanalyzeaunitelementinordertoextractthe effective electric and magnetic properties. Using this procedure, the behavior of fine copper powders irradiated by microwaves at a frequency of 2.45GHz is simulated. Then, the relation between particle size and the mixture’s effective properties is studied. By introducing a thin copper oxide or conductive layer it is possible to emulate the effective properties of metallic powder compacts in the early stage of sintering. Thus, this work contributes to improving the insight into the mechanisms of microwave absorption in powders of conductive materials in contrast to non-absorption in bulk metals.

Erratum: Eigenmode Compendium of the Third Harmonic Module of the European X-ray Free Electron Laser [Phys. Rev. Accel. Beams 20 , 042002 (2017)]

We regret the oversight of not acknowledging the significant amount of work by several colleagues in the field (see [1–4] and references therein). In particular, we would like to highlight the work performed at the Istituto Nazionale di Fisica Nucleare (INFN) for the realization of the third harmonic system of the European XFEL. We are also grateful to W.-D. Möller and E. Vogel from DESY and H. Edwards and T. Khabiboulline from FNAL for facilitating rapid access to the technical drawings of the FLASH third harmonic module ACC39. Based on drawings of the FLASHmodule and articles on the module for the European XFEL such as [5], the CADmodel of the third harmonic cavity string, which is available via [6], was assembled. Furthermore, wewould like to thank the colleagues from INFN and DESY, in particular P. Pierini, E. Vogel and the XFEL operation team for supporting and facilitating our measurements at the third harmonic module during the busy injector commissioning period. We also would like to express our appreciation to J. Chen from INFN for sharing his experience in measured and simulated rf properties of the third harmonic cavities, especially for the modes with field energy strongly localized at the region of the first cell, the main coupler and the nearby beam pipe (see modes with the indices 105 to 112 in the compendium [7]).

Analysis of higher order modes in large superconducting radio frequency accelerating structures

Superconducting radio frequency cavities used for accelerating charged particle beams are commonly used in accelerator facilities around the world. The design and optimization of modern superconducting RF cavities requires intensive numerical simulations. Vast number of operational parameters must be calculated to ensure appropriate functioning of the accelerating structures. In this study, we primarily focus on estimation and behavior of higher order modes in superconducting RF cavities connected in chains. To calculate large RF models the state-space concatenation scheme, an efficient hybrid method, is employed.