Cao Y, Hu LX, Hu YT, Zhao J, Zou DB, Yang XH, Zhang FP, Shao FQ, Yu TP. Direct acceleration of collimated monoenergetic sub-femtosecond electron bunches driven by a radially polarized laser pulse.
OPTICS EXPRESS 2021;
29:30223-30236. [PMID:
34614749 DOI:
10.1364/oe.437827]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
High-quality ultrashort electron beams have diverse applications in a variety of areas, such as 4D electron diffraction and microscopy, relativistic electron mirrors and ultrashort radiation sources. Direct laser acceleration (DLA) mechanism can produce electron beams with a large amount of charge (several to hundreds of nC), but the generated electron beams usually have large divergence and wide energy spread. Here, we propose a novel DLA scheme to generate high-quality ultrashort electron beams by irradiating a radially polarized laser pulse on a nanofiber. Since electrons are continuously squeezed transversely by the inward radial electric field force, the divergence angle gradually decreases as electrons transport stably with the laser pulse. The well-collimated electron bunches are effectively accelerated by the circularly-symmetric longitudinal electric field and the relative energy spread also gradually decreases. It is demonstrated by three-dimensional (3D) simulations that collimated monoenergetic electron bunches with 0.75° center divergence angle and 14% energy spread can be generated. An analytical model of electron acceleration is presented which interprets well by the 3D simulation results.
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