Zhuo Hong-Bin

Simulation of the Quasi-Monoenergetic Protons Generation by Parallel Laser Pulses Interaction with Foils

A new scheme of radiation pressure acceleration for generating high-quality protons by using two overlapping-parallel laser pulses is proposed. Particle-in-cell simulation shows that the overlapping of two pulses with identical Gaussian profiles in space and trapezoidal profiles in the time domain can result in a composite light pulse with a spatial profile suitable for stable acceleration of protons to high energies. At ~2.46 × 1021 W/cm2 intensity of the combination light pulse, a quasi-monoenergetic proton beam with peak energy ~200 MeV/nucleon, energy spread <15%, and divergency angle <4° is obtained, which is appropriate for tumor therapy. The proton beam quality can be controlled by adjusting the incidence points of two laser pulses.

Preliminary experimental study and simulation of an energy-tunable quasi-monochromatic laser-Compton X/gamma-ray source

We propose a slanting collision scheme for Compton scattering of a laser light against a relativistic electron beam. This scheme is suitable to generate an energy-tunable X/gamma-ray source. In this paper, we present theoretical study and simulation of the spectral, spatial and temporal characteristics of such a source. We also describe two terms laser-Compton scattering (LCS) experiments at the 100 MeV Linac of Shanghai Institute of Applied Physics, where quasi-monochromatic LCS X-ray energy spectra with peak energies of similar to 30 keV are observed successfully. These preliminary investigations are carried out to understand the feasibility of developing an energy-tunable quasi-monochromatic X/-gamma-ray source, the future Shanghai Laser Electron Gamma Source.

Stimulated Raman Backscattering Amplification Using Multiple Pump Pulses

A multiple-pump-pulses-stimulated Raman backscattering amplification (m-SRA) scheme is proposed and examined using 1D PIC simulations. Compared with the SRA using a single long pump pulse, higher energy conversion efficiency can be obtained with the same output laser intensity by employing the m-SRA scheme. Unwanted Raman forward scattering can be suppressed in the m-SRA case. Favorable pulse envelope and frequency characteristics of the seed pulse after amplification are obtained by using the m-SRA scheme.

Parallel Solution Algorithm for the Multi-Group Particle Transport Equations on the Unstructured Meshes:

The numerical simulations for solving the transport equations lead to the large computation and need to implement parallel calculation. On the unstructured grids, the communicating delays, sorting algorithms and inserting algorithms limit the performance of current algorithms, which decrease the scalable parallel performance. This paper presents an effective way to implement the scalable parallel numerical simulation on the clusters by combining the energy groups and the space domain decomposition. Based on the list schedule, we first design a multi-group parallel method to solve the load unbalance problem which is brought about by the energy group parallel decomposition. After we describe the priority algorithm to arrange the orders for all meshes, we present a parallel algorithm based on geometry domain decomposition. A parallel code combining those two algorithms was designed. Using the code, we solved a two dimension particle transport equations on a cluster, performance results show the algorithms have well scalability.

Particle simulation of plasma electron trapping and acceleration in proton driven plasma wakefield using density transition

Numerical simulations are conducted on the scheme of energetic proton-bunch driven plasma wakefield acceleration and the possibility of the selfinjection scenario in proton-bunch driven plasma wakefield acceleration by using a density transition of plasma with the help of 2D3V PIC code. The simulations show that enhanced selfinjection of electrons in the scenario is realized successfully. It is found that the number of trapped particles increases as the amplitude of density transition increases．