Mainz 2022 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 9: Diagnostics, Control, Modeling, Modern IT Applications

AKBP 9.6: Talk

Wednesday, March 30, 2022, 15:15–15:30, AKBP-H13

Microbunching Studies for FLASH2020+ Using Efficient Semi-Lagrangian Vlasov-Simulation — •Philipp Amstutz and Mathias Vogt — DESY, Hamburg, Germany

In semi-Lagrangian approaches a solution to the Vlasov-Equation is obtained by back-tracking its characteristics and subsequently evaluating the initial condition. These methods yield a smooth numerical approximation to the phase-space density (PSD), which can put them at an advantage over particle-based methods. For instance, when studying small-scale effects where the inherent stochastic noise of particle-tracking methods becomes burdensome, semi-Lagrangian schemes are a promising alternative.

In free-electron lasers the electron bunches typically exhibit an “exotic” structure in the longitudinal phase-space resembling a fine, wiggling hair-like band. Such PSDs are not efficiently captured by a regular grid, as large parts of the minimum bounding rectangle of the PSD are void and do not contribute to the dynamics of the system. We present studies of the microbunching instability for FLASH2020+ using SelaV – a semi-Lagrangian Vlasov code we developed, which employs tree-based domain decomposition to efficiently handle exotic PSDs.