IPAC2011 - List of Authors (Sheng, Z.M.)

Paper	Title	Page
THPS014	Laser Thin Gas Target Acceleration for Quasi-monoenergetic Proton Generation	3451
	M.Q. He, G. Dudnikova, C.-S. Liu, T.-C. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su UMD, College Park, Maryland, USA Z.M. Sheng Shanghai Jiao Tong University, Shanghai, People's Republic of China
	We propose a scheme of laser thin gas target acceleration for quasi-monoenergetic proton generation. The scheme uses gas target of thickness about several laser wavelengths with gas density spatial distribution of Guassian or square of sine shape. We performed Particle-In-Cell simulation using circularly polarized laser of normalized maximum amplitude ~5 and hydrogen gas target of thickness ~5 laser wavelength with peak density three times of the critical density. The simulation demonstrates several key physical processes involved in the laser thin gas target acceleration and the observation of quasi-monoenergetic protons. During the early phase of the laser plasma interaction, electron and ion cavities are observed. A compressed plasma layer is formed. The reflected protons in front of the compressed layer are accelerated and thus a bunch of quasi-monoenergetic protons are obtained. The compressed layer is finally destroyed due to Rayleigh-Taylor instability. The acceleration of the quasi-monoenergetic proton then stops with maximum energy about 8 MeV. It is also found that gas target thickness plays an important role for efficient quasi-monoenergetic proton generation.

Paper

Title

Page

Laser Thin Gas Target Acceleration for Quasi-monoenergetic Proton Generation

3451

M.Q. He, G. Dudnikova, C.-S. Liu, T.-C. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
UMD, College Park, Maryland, USA
Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People's Republic of China

We propose a scheme of laser thin gas target acceleration for quasi-monoenergetic proton generation. The scheme uses gas target of thickness about several laser wavelengths with gas density spatial distribution of Guassian or square of sine shape. We performed Particle-In-Cell simulation using circularly polarized laser of normalized maximum amplitude ~5 and hydrogen gas target of thickness ~5 laser wavelength with peak density three times of the critical density. The simulation demonstrates several key physical processes involved in the laser thin gas target acceleration and the observation of quasi-monoenergetic protons. During the early phase of the laser plasma interaction, electron and ion cavities are observed. A compressed plasma layer is formed. The reflected protons in front of the compressed layer are accelerated and thus a bunch of quasi-monoenergetic protons are obtained. The compressed layer is finally destroyed due to Rayleigh-Taylor instability. The acceleration of the quasi-monoenergetic proton then stops with maximum energy about 8 MeV. It is also found that gas target thickness plays an important role for efficient quasi-monoenergetic proton generation.