• Y.Y. Ma, S. Kawata, K. Takahashi
  Center for Optical Research and Education, Utsunomiya University, Utsunomiya
• Y.Q. Gu, Y.Y. Ma
  Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang
• F.Q. Shao
  National University of Defense Technology, Graduate School, Changsha
• Z.M. Sheng
  Shanghai Jiao Tong University, Shanghai
• Y. Yin, T.P. Yu, D. F. Zhou
  National University of Defense Technology, Changsha, Hunan
• M.Y. Yu
  Ruhr-Universität Bochum, Bochum
• H.B. Zhuo
  National University of Defense Technology, Parallel and Distributed Processing, Changsha

Energetic protons of tens MeV or more produced by intense lasers have been observed in recent experiments and numerical simulations. Meanwhile, significant efforts have been made to improve the proton beam quality *,**,***. For most applications, it is important to improve the quality of the proton beam both during the production and during the propagation. Some schemes are proposed to improve the quality of the proton beam both during the production form the laser plasma interaction and during the propagation. The physics is investigated by 2D3V and 3D particle-in-cell codes PLASIM and PLASIM3D. In this paper, we propose to use an umbrella-like target to accelerate, and collimate protons. It is found that high intensity collimated MeV-proton beams can be produced ****. We also propose a scheme to generate quasi-monoenergetic proton beam from the interactions of an ultra-intense laser pulse and a thin tailored hole target. Particle simulation shows that a monoenergetic proton beam is generated from the hole. The propagation of a proton beam both in vacuum and in a plasma is also studied. Compared with the propagation in vacuum, the proton beam quality can be improved obviously.

* T. Toncian, et al. Science 312, 410(2006).
** B. M. Hegelich, et al. Nature 439, 441(2006).
*** H. Schwoerer, et al. Nature 439, 445(2006).
**** Y. Y. Ma et al., Phys Plasmas 16, 34502(2009).