Major progress of the Shanghai Soft X-ray Free-Electron Laser
The Shanghai Soft X-ray Free-Electron Laser Facility.
The Linac tunnel.
The Shanghai Soft X-ray Free-Electron Laser (SXFEL) is expected to open to users by the end of this year, greatly facilitating research into the nanoscale world.
The SXFEL, the first X-ray free-electron laser user facility in China, is known as the fourth-generation light source. It can photograph and film molecules, providing a revolutionary research tool for physics, biology, chemistry and other research areas.
Recently it has made a breakthrough in the development of the X-ray free-electron laser in China.
The FEL lasered at wavelengths of 5.6 nm, 3.5 nm, 2.4 nm and 2.0 nm successively, achieving a full coverage of the "water window". The saturated FEL was obtained at 3.5 nm with a peak power of 500 MW, and the X-ray beam was successfully transported through the beamline to the experimental station.
The so-called “water window” is occupied by the soft X-ray radiation with the wavelength range from 2.2 nm to 4.4 nm.
This spectral window owes its name and significance to the fact that at those frequencies, photons are not absorbed by oxygen (and hence by water), but they are by carbon.
This is ideal for studying organic molecules and biological specimens in their natural aqueous environment, thus of great importance to many scientific applications.
In the “water window”, the free-electron laser has the peak brightness more than one billion times higher than that of synchrotron radiation, and has high degrees of coherence.
The SXFEL, together with Shanghai Synchrotron Radiation Facility (SSRF), Shanghai High Repetition Rate X-ray FEL and Extreme Light Facility (SHINE), Shanghai Superintense Ultrafast Laser Facility (SULF), will form a cluster of photon science facilities, supporting a photon science research center with global influence in Zhangjiang, Shanghai.
The development of the SXFEL is divided into two phases, the test facility and the user facility. The final goal is to build a high brightness soft X-ray free-electron laser source with wavelengths covering the “water window” and supply the light to the first five experimental stations.
The test facility was approved by in November 2020. Then it was upgraded to the user facility, and its construction completed in January this year.
Currently the SXFEL consists of a photo-injector based high-gradient C-band linac, two bunch compressors, two undulator lines, two beamlines and five experimental stations.
Now, workers are further optimizing the facility performance, and its design goals will be achieved by the end of this year. At that time, the SXFEL will become an important research platform for the photon science in China.
The Undulator tunnel.
