title: Large-charge quasimonoenergetic electron beams produced by off-axis colliding laser pulses in underdense plasma.
abstract: Electrons can be efficiently injected into a plasma wave by colliding two counterpropagating laser pulses in a laser wakefield acceleration. However, the generation of a high-quality electron beam with a large charge is difficult in the traditional on-axis colliding scheme due to the growth of the electron beam duration coming from the increase of the beam charge. To solve this problem, we propose an off-axis colliding scheme, in which the collision point is away from the axis of the driver pulse. We show that the electrons injected from the off-axis region are highly concentered on the tail of the bubble even for a large trapped charge, thus feeling almost the same accelerating field. As a result, quasimonoenergetic electron beams with a large charge can be produced. The validity of this scheme is confirmed by both the particle-in-cell simulations and the Hamiltonian model. Furthermore, it is shown that a Laguerre-Gauss (LG) laser can be adopted as the injection pulse to realize the off-axis colliding injection in three dimensions symmetrically, which may be useful in simplifying the technical layout of the real experiment setup.
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: Z G
authors.initials: ZG
authors.lastname: Deng
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: Z M
authors.initials: ZM
authors.lastname: Zhang
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: B
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: S K
authors.initials: SK
authors.lastname: He
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: J
authors.initials: J
authors.lastname: Teng
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: W
authors.initials: W
authors.lastname: Hong
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: K G
authors.initials: KG
authors.lastname: Dong
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.|IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Y C
authors.initials: YC
authors.lastname: Wu
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.
authors.forename: B
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.|IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Gu