Proton Acceleration in Underdense Plasma by Ultraintense   Laguerre-Gaussian Laser Pulse
  Three-dimensional particle-in-cell simulation is used to investigate the witness proton acceleration in underdense plasma with a short intense Laguerre-Gaussian (LG) laser pulse. Driven by the LG10 laser pulse, a special bubble with an electron pillar on the axis is formed, in which protons can be well-confined by the generated transversal focusing field and accelerated by the longitudinal wakefield. The risk of scattering prior to acceleration with a Gaussian laser pulse in underdense plasma is avoided, and protons are accelerated stably to much higher energy. In simulation, a proton beam has been accelerated to 7 GeV from 1 GeV in underdense tritium plasma driven by a 2.14x1022 W/cm2 LG10 laser pulse. 
Xiaomei Zhang, Baifei Shen, Lingang Zhang, Jiancai Xu, Xiaofeng Wang,   Wenpeng Wang, Longqiong Yi, and Yin Shi
physics.plasm-ph physics.optics