Recently, Prof. Xu Zhizhan, State Key Laboratory of Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences led a research team led by Prof. Li Ruxin to make breakthroughs in the study of accelerating the generation of high-brightness and high-quality electron beams by the super short laser-driven tail wave field. The research team proposed a new scheme of cascaded wakefield acceleration, which broke through the major technical bottleneck of laser energy dispersion such as energy dispersion difficult to be compressed and so on. The experimental results obtained high brightness and high quality (200-600 MeV, 0.4-1.2% , Flow intensity of 1-8 kA, divergence angle ~ 0.2 rms mrad), the electron beam six-dimensional phase space brightness of 1015-16A / m2 / 0.1%, much higher than the current international reports of similar studies, in the For the first time in the world, the brightness of electron beams that can be obtained on a state-of-the-art linear accelerator is approached. Relevant research findings were published on Physics Review Letters 117, 124801 (2016), September 16, and the papers were selected by Editors' Suggestion in the international physics field as Highlighted Articles ) Posted.
Developing miniaturized, low-cost laser particle accelerators has long been the goal scientists have dreamed of. Super short laser-driven tail wave field electron accelerator with more than three orders of magnitude higher than the traditional RF accelerator ultra-high acceleration gradient for the realization of miniaturized high-energy particle accelerator provides a new technical approach to the future of the synchronization Radiation devices, free electron lasers and high-energy physics research will also have a profound impact. In recent ten years, many important progresses have been made in the research on the electron acceleration of the laser tail wave field. However, many challenges and challenges in generating high quality electron beams, such as divergence compression and stability improvement, have led to its application research restricted.
In recent years, the team of Shanghai Institute of Optics and Fine Mechanics conducted a unique research on the direction of electron acceleration in the laser tail wave field. For the first time in the world, a quasi-single-energy high-energy electron acceleration scheme of cascade two-wavy wave field was successfully achieved. Physic Rev. Lett. 107, 035001 (2011); Appl. Phys. Lett. 103, 243501 (2013)]. In this study, a new cascade wavefield acceleration scheme was innovatively designed. By introducing a high-density plasma between the two cascaded plasmas, the steady-state acceleration and energy chirp reversal Which can overcome the single-stage tail wave field acceleration program can not independently control the technical bottleneck, the experiment obtained high quality (200-600 MeV, can be dispersed 0.4-1.2%, the flow of 1-8 kA , Divergence angle ~ 0.2 rms mrad). The all-round improvement of all the important performance indexes of electron beam makes the highest six-dimensional phase space brightness of electron beam reach 6.5 × 1015A / m2 / 0.1%, which is much higher than the results of similar studies reported in the world at present. For the first time approaching the brightness of electron beams available with state-of-the-art linear accelerators. The 3D particle simulation also reveals that the new cascade acceleration scheme can effectively suppress the secondary injection of electrons and achieve the steady-state acceleration of the electron beam, and obtain low energy dispersion by controlling the energy chirp and the compression energy dispersion of the electron beam Divergence angle and high intensity high-intensity high-quality electron beam.
The reviewers spoke highly of the results of the study: "The brightness is by far the highest achieved by the laser tail wave field accelerator." "Compared with the previous solution, the program properly controls the self-injection electron beam Of the injection phase ... And the energy beam of the electron beam can be compensated during acceleration ... is a new solution that produces hundreds of MeVs with a thousandth order of relative energy dissipation and high charge amount of high quality , A major advance has been made in the field of high-brightness electron beams ... ";" A new method of 200-600 MeV electron beam with low energy divergence, low divergence angle has been developed with an optimized structure of density distribution Record of the electron beam quality. "
A breakthrough has also been made in the application of the high-brightness and high-energy electron beam obtained by this scheme to the production of inverse compton scattering gamma ray source. The ultra-high brightness quasi-monochromatic MeV-level gamma ray source was generated by the electron beam and the super-short laser collisions. Its highest peak brightness reached 3 × 1022 photons s-1 mm-2 mrad-2 0.1% BW, Compared with the brightness of the same type of gamma ray source reported in the world, it is more than one order of magnitude higher than the peak intensity of the same energy region of a conventional gamma ray source by 100,000 times. Relevant findings have recently been published in Scientific Reports 6, 29518 (2016). At present, the research team is working on a miniaturized all-optical free-electron laser device. Utilizing this cascaded wakefield acceleration scheme to successfully generate high brightness and high energy electron beams will significantly facilitate the research progress in such important fields as miniaturized free-electron lasers.
The research has been supported by the National Natural Science Foundation of China, Ministry of Science and Technology, Chinese Academy of Sciences and other related projects. (Shanghai Institute of Light Machinery Laser Physics State Key Laboratory Feed)
(A) experimental high-quality electron beam energy and divergence angle distribution (530-580 MeV); (b) high quality electron beam spectra corresponding to (a); (c) Brightness B6D, n, comparable to the world's most advanced linear accelerator.
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