Würzburg 2018 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 8: Poster session

AKBP 8.19: Poster

Wednesday, March 21, 2018, 18:00–19:30, NW-Bau - HS2

3D space charge tracking using fast multipole methods^* — •Steffen Schmid, Erion Gjonaj, and Herbert De Gersem — Institut für Theorie Elektromagnetischer Felder, TU Darmstadt, GER

In high brilliance photoinjectors, such as the PITZ gun used at the EXFEL, the particle bunch properties are strongly influenced by space charge effects [1]. Computer simulations allow to investigate systematically how these effects influence the beam dynamics of the bunch. This knowledge is needed for the optimization of a photoinjector.

Currently, most of the simulation codes are based on particle-particle (PP) or particle-mesh (PM) algorithms. PP-codes are very flexible, but computationally expensive. PM-algorithms are more efficient, but less flexible and conceptually more complicated.

The fast multipole method [2] (FMM) combines some of the advantages of both of the aforementioned approaches. We present a code which uses "ExaFMM" [3] to provide the space charge interaction forces to an in-house developed particle tracker.

In this contribution, a numerical analysis of the approximation errors and the speedup gained by using the FMM-code is shown. Furthermore, FMM and PP beam dynamics simulations for the PITZ photoinjector are compared. The results suggest to use the FMM-code as a basis for the implementation of more advanced interaction models.

[1] Y. Chen et al., IPAC, Richmond, VA, USA, MOPWA029 (2015)

[2] L. Greengard et al., J COMPUT PHYS, 73, CP975706 (1997)

[3] R. Yokota et al., "ExaFMM", https://github.com/exafmm/exafmm

^* This work is supported by the DFG in the framework of GRK 2128