Ultralow-emittance measurement of high-quality electron beams from a laser wakefield accelerator

Qin, Zhiyong and Yu, Changhai and Wang, Wentao and Liu, Jiansheng and Li, Wentao and Qi, Rong and Zhang, Zhijun and Liu, Jiaqi and Fang, Ming and Feng, Ke and Wu, Ying and Ke, Lintong and Chen, Yu and Xu, Yi and Leng, Yuxin and Wang, Cheng and Li, Ruxin and Xu, Zhizhan (2018) Ultralow-emittance measurement of high-quality electron beams from a laser wakefield accelerator. Physics of Plasmas, 25 (2). 023106. ISSN 1070-664X

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    Abstract

    By designing a cascaded laser wakefield accelerator, high-quality monoenergetic electron beams (e beams) with peak energies of 340–360MeV and rms divergence of <0.3 mrad were produced. Based on this accelerator, the e-beam betatron radiation spectra were measured exactly via the single-photon counting technique to diagnose the e-beam transverse emittance in a single shot. The e-beam transverse size in the wakefield was estimated to be ~0.35 lm by comparing the measured X-ray spectra with the analytical model of synchrotron-like radiation. By combining the measured e-beam energy and divergence, the normalized transverse emittance was estimated to be as low as 56 um mrad and consistent with particle-in-cell simulations. These high-energy ultralow-emittance e beams hold great potential applications in developing free electron lasers and high-energy X-ray and gamma ray sources.