title: Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV.
abstract: Laser-plasma accelerators of only a centimetre's length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.
authors.affiliation: University of Texas at Austin, Department of Physics, 1 University Station C1600, Austin, Texas 78712-1081, USA.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wang
authors.forename: Rafal
authors.initials: R
authors.lastname: Zgadzaj
authors.forename: Neil
authors.initials: N
authors.lastname: Fazel
authors.forename: Zhengyan
authors.initials: Z
authors.lastname: Li
authors.forename: S A
authors.initials: SA
authors.lastname: Yi
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Watson
authors.initials: W
authors.lastname: Henderson
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Chang
authors.forename: R
authors.initials: R
authors.lastname: Korzekwa
authors.forename: H-E
authors.initials: HE
authors.lastname: Tsai
authors.forename: C-H
authors.initials: CH
authors.lastname: Pai
authors.forename: H
authors.initials: H
authors.lastname: Quevedo
authors.forename: G
authors.initials: G
authors.lastname: Dyer
authors.forename: E
authors.initials: E
authors.lastname: Gaul
authors.forename: M
authors.initials: M
authors.lastname: Martinez
authors.forename: A C
authors.initials: AC
authors.lastname: Bernstein
authors.forename: T
authors.initials: T
authors.lastname: Borger
authors.forename: M
authors.initials: M
authors.lastname: Spinks
authors.forename: M
authors.initials: M
authors.lastname: Donovan
authors.forename: V
authors.initials: V
authors.lastname: Khudik
authors.forename: G
authors.initials: G
authors.lastname: Shvets
authors.forename: T
authors.initials: T
authors.lastname: Ditmire
authors.forename: M C
authors.initials: MC
authors.lastname: Downer