The cavity-based X-ray free-electron laser(XFEL)has promise in producing fully coherent pulses with a bandwidth of a few meV and very stable intensity,whereas the currently existing self-amplified spontaneous emission...The cavity-based X-ray free-electron laser(XFEL)has promise in producing fully coherent pulses with a bandwidth of a few meV and very stable intensity,whereas the currently existing self-amplified spontaneous emission(SASE)XFEL is capable of generating ultra-short pulses with chaotic spectra.In general,a cavity-based XFEL can provide a spectral brightness three orders of magnitude higher than that of the SASE mode,thereby opening a new door for cutting-edge scientific research.With the development of superconducting MHz repetition-rate XFEL facilities such as FLASH,European-XFEL,LCLS-II,and SHINE,practical cavity-based XFEL operations are becoming increasingly achievable.In this study,megahertz cavity enhanced X-ray generation(MING)is proposed based on China’s first hard XFEL facility-SHINE,which we refer to as MING@SHINE.展开更多
The spectroscopic methods for the ultrafast electronic and structural dynamics of materials require fully coherent extreme ultraviolet and soft X-ray radiation with high-average brightness.Seeded free-electron lasers(...The spectroscopic methods for the ultrafast electronic and structural dynamics of materials require fully coherent extreme ultraviolet and soft X-ray radiation with high-average brightness.Seeded free-electron lasers(FELs)are ideal sources for delivering fully coherent soft X-ray pulses.However,due to state-of-theart laser system limitations,it is challenging to meet the ultraviolet seed laser’s requirements of sufficient energy modulation and high repetition rates simultaneously.The self-modulation scheme has been proposed and recently demonstrated in a seeded FEL to relax the seed laser requirements.Using numerical simulations,we show that the required seed laser intensity in the self-modulation is~3 orders of magnitude lower than that in the standard high-gain harmonic generation(HGHG).The harmonic self-modulation can launch a singlestage HGHG FEL lasing at the 30th harmonic of the seed laser.Moreover,the proof-of-principle experimental results confirm that the harmonic self-modulation can still amplify the laser-induced energy modulation.These achievements reveal that the self-modulation can not only remarkably reduce the requirements of the seed laser but also improve the harmonic upconversion efficiency,which paves the way for realizing high-repetitionrate and fully coherent soft X-ray FELs.展开更多
基金supported by the CAS Project for Young Scientists in Basic Research(No.YSBR-042)the National Natural Science Foundation of China(Nos.12125508,11935020)+1 种基金Program of Shanghai Academic/Technology Research Leader(No.21XD1404100)Shanghai Pilot Program for Basic Research–Chinese Academy of Science,Shanghai Branch(No.JCYJSHFY-2021-010).
文摘The cavity-based X-ray free-electron laser(XFEL)has promise in producing fully coherent pulses with a bandwidth of a few meV and very stable intensity,whereas the currently existing self-amplified spontaneous emission(SASE)XFEL is capable of generating ultra-short pulses with chaotic spectra.In general,a cavity-based XFEL can provide a spectral brightness three orders of magnitude higher than that of the SASE mode,thereby opening a new door for cutting-edge scientific research.With the development of superconducting MHz repetition-rate XFEL facilities such as FLASH,European-XFEL,LCLS-II,and SHINE,practical cavity-based XFEL operations are becoming increasingly achievable.In this study,megahertz cavity enhanced X-ray generation(MING)is proposed based on China’s first hard XFEL facility-SHINE,which we refer to as MING@SHINE.
基金supported by the CAS Project for Young Scientists in Basic Research(Grant No.YSBR042)the National Natural Science Foundation of China(Grant Nos.12125508 and 11935020)+1 种基金the Program of Shanghai Academic/Technology Research Leader(Grant No.21XD1404100)the Shanghai Pilot Program for Basic Research of the Chinese Academy of Sciences,Shanghai Branch(Grant No.JCYJ-SHFY-2021-010).
文摘The spectroscopic methods for the ultrafast electronic and structural dynamics of materials require fully coherent extreme ultraviolet and soft X-ray radiation with high-average brightness.Seeded free-electron lasers(FELs)are ideal sources for delivering fully coherent soft X-ray pulses.However,due to state-of-theart laser system limitations,it is challenging to meet the ultraviolet seed laser’s requirements of sufficient energy modulation and high repetition rates simultaneously.The self-modulation scheme has been proposed and recently demonstrated in a seeded FEL to relax the seed laser requirements.Using numerical simulations,we show that the required seed laser intensity in the self-modulation is~3 orders of magnitude lower than that in the standard high-gain harmonic generation(HGHG).The harmonic self-modulation can launch a singlestage HGHG FEL lasing at the 30th harmonic of the seed laser.Moreover,the proof-of-principle experimental results confirm that the harmonic self-modulation can still amplify the laser-induced energy modulation.These achievements reveal that the self-modulation can not only remarkably reduce the requirements of the seed laser but also improve the harmonic upconversion efficiency,which paves the way for realizing high-repetitionrate and fully coherent soft X-ray FELs.
