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TY - UNPB AU - Su, Q. AU - Hua, J.F. AU - Lu, W. AU - Pai, C.H. ED - Schaa, Volker RW ED - Ji, Daheng ED - Li, Lu ED - Zhao, Ning TI - Temporal Diagnostics of the Ultrashort Electron Bunch Generated in Plasma-based Accelerators J2 - Proc. of SAP2017, Jishou, China, 28-30 August 2017 C1 - Jishou, China T2 - Symposium on Accelerator Physics T3 - 13 LA - english AB - Plasma-based accelerators have the potential to generate few-femtosecond ultrashort electron bunches, which enable the study of ultrafast dynamics and the realization of high peak current beams. The duration of the electron bunch is usually investigated based on coherent transition radiation in a laser wakefield accelerator. In order to diagnostic the longitudinal profile, however, the reconstruction from the spectrum measured from the mid-infrared spectrometer is required for random temporal distribution of ultrashort electron bunch. We discuss the ambiguities in phase retrieval problems and introduce the concept of compressed sensing and a sparsity based weighted greedy sparse retrieval(GESPAR) algorithm for bunch profile reconstruction. The GESPAR algorithm is demonstrated to have the better performance than the traditional phase retrieval algorithms such as Kramer Kronig reconstruction and Gerchberg-Saxton algorithm with truncated noisy spectrum. This new method has been developed to measure the downramp injected electron bunch in our laser wakefield experiment, which is applicable for the temporal characterization of ultrashort electron beam with complex structures. PB - JACoW CP - Geneva, Switzerland ER -