Showing papers by "FengChao Wang published in 2010"

Ultrahigh energy proton generation in sequential radiation pressure and bubble regime

Abstract: Protons in a microtarget embedded in an underdense high-mass plasma can be accelerated sequentially by the radiation pressure of a short circularly polarized laser pulse and the induced wake bubble field in the background plasma, which has been shown in detail by two-dimensional particle in cell simulations. It has been found that instead of using transverse Gaussian pulses proton energy can be increased dramatically by using a transverse super-Gaussian laser pulse. With a 2.14x10{sup 23} W/cm{sup 2} laser pulse in a tritium plasma of density 1.5x10{sup 20}/cm{sup 3}, 76 GeV high-quality quasimonoenergetic protons have been obtained. The scaling relations between the obtainable proton energy and the laser amplitude as well as the background plasma density have been shown.

Controlled electron acceleration in the bubble regime by optimizing plasma density

Abstract: Improvement of the quality of the monoenergetic electron bunch generated in the laser wakefield is investigated. The electrostatic field is more intense near the back of the bubble than at other locations in the bubble. By optimizing the density gradient of background plasma, the local dephasing problem can theoretically be overcome and the electron bunch can be stably accelerated at the back of the bubble so that the accelerated electrons experience nearly the same electric field. Three-dimensional simulations were performed. Compared with the standard wakefield acceleration schemes, a better-quality electron bunch, with narrower energy spread and higher energy, is obtained with a shorter acceleration distance.

Effects of pulse duration and areal density on ultrathin foil acceleration

Abstract: The influence of laser pulse duration and areal density of target in the interaction of a circularly polarized pulse with an ultrathin overdense foil is investigated. One-dimensional particle-in-cell simulation shows that with an appropriate laser-pulse rising front, the light pressure acceleration regime is effective even though the thin foil is transparent. As the laser intensity evolves, three stages in the acceleration process can be identified: at first the total reflection of the laser pulse, followed by partial reflection, and then near total reflection again due to the Doppler effect. The influences of the rising front of laser pulse and areal density of the ultrathin foil are investigated. It is found that an optimal laser pulse rising front exists for obtaining high (saturation) ion energy with the same laser energy within a short time. An optimal areal density also exists for obtaining the highest energy. For the same laser pulse, a higher areal density or a higher density with same areal density is more appropriate for obtaining a stationary state for making light pressure acceleration mechanism more effective.