Influence of SXFEL resistive wall wakefield on beam phase space distortion

X-ray free-electron laser (XFEL), due to its ultra-high brightness, ultra-short pulse and other characteristics, has been built worldwide. Based on the theory of wakefield, we calculate the resistive wall wakefield from the linear accelerator (linac) exit to the end of the undulator in Shanghai X-ray free electron laser (SXFEL) with bunch traveling through the 245 m stainless steel transfer line and copper beamline in undulator. Then we analyze the resistive wall wakefields which eventually lead to the distortion of the longitudinal phase space within the bunch. Finally, the theoretical predictions of influence of resistive wall wakefield are compared with experiment results on SXFEL, which shows great agreement. The detailed research provides a direction for subsequent FEL optimization.