Scientists Envision X-ray Free Electron Lasers with Intermediate Energy Electron Beam

Accelerator scientists from Shanghai Institute of Applied Physics, Chinese Academy of Sciences, have recently envisioned an x-ray free electron laser (FEL) oscillator with intermediate energy electron beam. To do this, a crystal-based cavity resonant at a higher harmonic of the undulator radiation, together with phase shifting is utilized to enable harmonic lasing of the x-ray FEL oscillator. This work was published on Physical Review Letters, 108, 034802 (2012).

The development of x-ray FEL corresponds to the strongly growing demand for photon sources within material and biological sciences. Currently, the world’s first hard x-ray FEL, the Linac Coherent Light Source (LCLS) is in user operation and another four hard x-ray FEL facilities will come into use in a few years. These x-ray FELs work with 5.8~17GeV electron beam from large accelerators, which is time-consuming and cost ineffective. Thus, compact x-ray FEL configuration, just like intermediate synchrotron light source, is of great interest in advanced light source community.

Intermediate energy x-ray FEL oscillator predicts that fully coherent FEL radiation with MW peak power, in the spectral region of 10~25keV, could be generated with reduced energy (e.g., 3.5GeV) electron beam from energy recovery or high repetition superconductive linac. And it demonstrates peak brilliance comparable with that of a high-gain self amplified spontaneous emission (SASE), e.g., the LCLS, and average brilliance 3 orders of magnitude higher than SASE.

“With these characteristics, our new concept significantly cuts the costs and size of x-ray FEL facility. It will contribute to the development and popularizationof x-ray FELs, energy recovery and superconductive linac, and thus may open up new scientific opportunities in various research fields.” Dr. DENG Haixiao from FEL group at Shanghai Institute of Applied Physics said.

An x-ray FEL oscillator with intermediate energy electron beam.(Image by DENG Haixiao et al)

Temporal and spectral performance of the intermediate energy x-ray FEL oscillator.(Image by DENG Haixiao et al)

This work is partially supported by Natural Science Foundation of China, Shanghai Natural Science Foundation and Major State Basic Research Development Program of China. It is accomplished by DAI Jinhua, DENG Haixiao and DAI Zhimin et al from Shanghai Institute of Applied Physics, Chinese Academy of Sciences.