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@inproceedings{schmid:ipac2021-thpab229,
author = {S.A. Schmid and H. De Gersem and E. Gjonaj},
title = {{Energy-Binning Fast Multipole Method for Electron Injector Simulations}},
booktitle = {Proc. IPAC'21},
pages = {4244--4246},
eid = {THPAB229},
language = {english},
keywords = {space-charge, simulation, electron, multipole, cathode},
venue = {Campinas, SP, Brazil},
series = {International Particle Accelerator Conference},
number = {12},
publisher = {JACoW Publishing, Geneva, Switzerland},
month = {08},
year = {2021},
issn = {2673-5490},
isbn = {978-3-95450-214-1},
doi = {10.18429/JACoW-IPAC2021-THPAB229},
url = {https://jacow.org/ipac2021/papers/thpab229.pdf},
note = {https://doi.org/10.18429/JACoW-IPAC2021-THPAB229},
abstract = {{In a high brilliance electron injector, small beam energy and large charge density give rise to strong space charge effects. Furthermore, a large relative energy spread during the beam generation modifies the space charge interaction between different regions of the particle bunch. Therefore, modeling the phase space evolution in an electron injector requires a numerically efficient particle tracking code that can handle space charge interactions of spatially and energetically strongly inhomogeneous particle distributions. We implemented an energy-binning scheme for a meshless fast multipole method (FMM). The energy-binning approximates the momentum distribution of the beam by assigning particles to adaptive tree structures defined at different Lorentz frames. Based on the tree structures, the FMM computes a hierarchical approximation for the space charge interaction of the particle bunch. We use the energy-binning FMM to simulate the beam generation in the photoinjector of the European XFEL developed at DESY-PITZ. Furthermore, we present numerical convergence and performance studies and compare the simulation results to direct particle-particle methods.}},
}