Laser acceleration of protons using multi-ion plasma gaseous targets
Tung-Chang Liu, Xi Shao, Chuan-Sheng Liu, Bengt Eliasson, WT Hill III, Jyhpyng Wang, and Shih-Hung Chen
New Journal of Physics 17, 023018 (2015)
Wepresent a theoretical and numerical study of a novel acceleration scheme by applying a combination of laser radiation pressure and shielded Coulomb repulsion in laser acceleration of protons in multi-species gaseous targets. By using a circularly polarized CO2 laser pulse with a wavelength of 10 μm—much greater than that of a Ti:Sapphire laser—the critical density is significantly reduced, and a high-pressure gaseous target can be used to achieve an overdense plasma. This gives us a larger degree of freedom in selecting the target compounds or mixtures, as well as their density and thickness profiles. By impinging such a laser beam on a carbon–hydrogen target, the gaseous target is first compressed and accelerated by radiation pressure until the electron layer disrupts, after which the protons are further accelerated by the electron-shielded carbon ion layer. An 80 MeV quasi-monoenergetic proton beam can be generated using a half-sine shaped laser beam with a peak power of 70 TW and a pulse duration of 150 wave periods.
Institute of Atomic and Molecular Sciences Academia Sinica
