First Tests with the Self-triggered Mode of the New MicroTCA-based Low-charge Electronics for Button and Stripline BPMs at FLASH

The FLASH facility at DESY is currently enhanced by a second beamline (FLASH2) to extend the capacity for user experiments. In addition, certain support systems like the timing system and the BPM system at the existing FLASH accelerator have been partly renewed and are now under commissioning. New button BPM electronics based on the MTCA.4 for physics standard is provided for the FLASH2 beamline and is foreseen as a replacement of the old BPM electronics at FLASH. Compared to the predecessor of the FLASH button BPM electronics, the new system has been specifically designed for low charge operation exceeding a wide dynamical charge range between 100pC and 3nC. Special provisions have been made to enable single bunch measurements in a self-triggered mode, enabling timing-system-independent measurements during commissioning and at fallback during normal operation