Simulation of generating ultrafast pulses using an LPA at SXFEL

Abstract

Plasma accelerators can generate electron beams with a smaller physical footprint and properties un-achievable with conventional modulation methods. The Laser Plasma Accelerator (LPA) platform at the SASE (self-amplified spontaneous emission) line of Shanghai Soft X-ray Free-Electron Laser Facility (SXFEL) has been being constructed since 2020. The synchronization of the LPA platform and the electron beam from SXFEL has been achieved in 2022. The acceleration, and the energy modulation of the electron beam of the LPA platform is observed by an energy spectrometer. The designing and the commissioning of the LPA platform is ongoing. Simulation of the LPA system can be performed by the code Quick PIC, and the accelerated or modulated electron beam can be used to generate XFEL with different properties, such as ultrafast XFEL, large bandwidth XFEL and so on. In this paper, we will present the possibility of generating ultrafast XFEL by the electron beam modulated by the LPA platform. Preliminary start-to-end simulation result shows that we can achieve ultrashort XFEL pulses with the pulse duration of 4.8 fs by simple method, and the pulse duration can be further reduced by changing the setup of the LPA.